Cool Roof Philippines – metal roofs and cool buildings in the tropics

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How to build a hollow block house in the Philippines, or any place in the tropics and keep it cool. Concrete/hollow block houses with metal roofs are the norm in the Philippines and elsewhere in tropical Asia. Filipinos don’t build such houses out of ignorance. They have critical advantages. They resist typhoon damage. If they’re flooded, they can be cleaned out and used again. For the most part they are termite proof. Locked up at night, they provide pretty good security to residents. They are mostly built with low-tech local materials by local workers well versed in building with concrete and hollow blocks. Such houses can be quite inexpensive. So, in most respects they are very well suited to the Philippine tropical context, but there is one huge and notorious disadvantage — they are so hot. The mass of block and concrete bake in the tropical sun and this retained heat is re-radiated into the house day and night.

Compounding the problem is the metal roof which can turn the attic into an oven. The overall effect is a house which can be markedly hotter than than the outdoor temperature and very uncomfortable. Our own apartment is routinely over 90 degrees inside even when it’s in the 70s at night. The coolness of the tropical nights don’t penetrate our bedrooms which remain hot all night. It’s painful to switch on the air conditioning when just outside the walls is a lovely, comfortable tropical night.

Here’s how we are trying to avoid this fate in our new house. Firstly, we tried to design the house to resist the sun. Our eave overhang is almost 1.5 meters, almost 5′. The overhang, combined with the relatively low eve height outside (about three meters) and big windows placed high on the walls, keeps most the sun from the windows and minimizes sun on the concrete building itself. The house is mostly shaded from the midday sun — say from 9am to 3pm. We’ll plant plants, shrubs and trees to further keep the sun out of and off of the house. It’s amazing how many Philippine houses are designed with little or no regard for the tropical environment in which they will be situated. The main focus seems to be on grandiosity.

Overhang will shade the house

Overhang will shade the house. Big windows will let in the breezes.

Our "cool" roof

Our "cool" roof

We also really focused on keeping the roof and attic cool. We used a very light colored reflective roof material. Such reflective roofs reflect much more of the solar radiation than the more popular dark colors. Dark colors such as dark red, dark green, brown and terra cotta are popular because they mimic the look of clay title but this is a triumph of appearance over comfort. Houses with absorptive roofs need bigger air conditioning units which have to work harder to disperse the absorbed heat. With no aircon the house is just hot.

Our next step was to install reflective metal foil underneath the metal roofing. This reflects back a significant amount of the radiant heat that makes it through the roof. Next is a 25mm layer of fiberglass bat insulation. The foil and fiberglass insulation were add-ons to our roofing contract. The fiberglass insulation is referred to as “ACI” insulation. ACI is a now defunct manufacturer of fiberglass bats but fiberglass is now all called “ACI” just as all toothpaste is called Colgate.

Fiberglass insulation.

The metal roof is screwed to steel roof supports called purlins. The roof installers wanted to put the fiberglass insulation over the top of the purlins and then screw-down the sheet metal roofing. This of course would have totally compressed the fiberglass at the purlins, reducing its insulative value. Just imagine installing fiberglass batts over studs rather than between them and then nailing on plywood sheathing!

Of course the notion of insulation is much more foreign to the Filipino than to those of us from the north where insulation is a fact of life and survival. While they did not really understand my objection to compressing the batts, they agreed to install it the way I wanted it installed. They drilled holes through the 3″ high metal purlins and threaded a network of 16 gauge wire to support the bottom of the insulation. The wires were spaced every 20cm.

The reflective foil did not come attached to the fiberglass batts so the workers manually glued the foil to the batts using contact cement. This sounds awkward but went well. First they sawed the 120cm wide rolls of fiberglass in half to create batts to fit between the purlins which are spaced 60cm on center. The batts, with the foil up, where laid over the network of wires and then the roof panels were screwed down. The wires were 1.5″ down from the top of the purlins so that there was a 1/2″ airspace between the underside of the roof panels and the reflective foil. This is ideal.

Roof going on over foil and fiberglass

Roof going on over foil and fiberglass

The end result is a reflective light colored roof, a 1/2″ airspace, reflective foil and then 25mm of fiberglass insulation. This combination should make the house several degrees cooler. In fact it seems to be working. Since the roof was installed, we’ve had very hot weather but the house seems cool. There was no added cost for the light colored roof. Our roofing came from DN Steel. They call the color “beige”. The foil and the fiberglass added about P50,000, installed. The roof also has two large ventilators at the peaks and will have soffit vents to further control heat in the attic area.

The roofing and insulation was purchased through Far Eastern Hardware on Quezon Street in Iloilo City.  Victoria Ang is the person to contact: cellphone 63-918-888-2228.  Her crew installed the roof .  Victoria has an engineer she sent to help us when our crew had problems following the roof plans.  This was a huge help.  We purchased much of our building materials and power tools from Far Eastern and can recommend them.  They never tried to short or cheat us or to supply undersized materials.  It’s also a great place for the builder.  They stock just about everything including AEG, Makita and Bosch power tools and all the accessories such as cobalt and carbide drill bits, cut off saw blades, grinding wheels and so forth.  We standardized on Bosch supplies and AEG power tools.  Whenever we post this kind of recommendation, there is a certain percentage of readers who assume that we must get something in return.  We don’t.  We have no relationship with Far Eastern except that of a satisfied customer.  It is we who like to reward those who have treated us honestly with our recommendation to others and to help our readers with our experiences.

There are other things we’ve done and will do to make the house cool. Our property is located in an open and very breezy agricultural area. We put in exceptionally large (240 x 160 cm) windows casement windows. We like casement windows because 100% of the window opening can be open, whereas sliding windows leave 50% closed, even when the windows are fully open. We also put two windows in each bedroom for cross ventilation, except for one room. Since the windows are exceptionally large, thermal mass is reduced and air circulation increased. Our ceilings are over ten feet high. Each will have a Hunter ceiling fan.

Workers install Mahogany ventilator in roof peak

Workers install Mahogany ventilator in roof peak

Completed ventilator

Completed ventilator. Screening is behind

Theory confronts reality update 2-5-11. The triangular roof vents shown above have been closed off with sheets of plywood on the inside.  Our site is so exposed and windy that storms blow rain in through the ventilators.  This threatens to damage our Hardiflex ceilings.  It does not help that the ventilators almost precisely line up with the prevailing winds, the “Amihan” NE monsoon and the “Habagat” SW monsoon.   Such ventilators might work fine in a more sheltered location, but ours is anything but.  Fortunately, we have a large soffit ventilator in each corner plus other roof vents in the porch ceiling.  Some easy means of opening and closing the vents is a project for the future.

It’s our hope that all these things will combine to reduce the interior temperature of the house by several degrees compared to what it would be without the steps we took.  Our house is still a concrete house exposed to the hot sun.  The things we have done have kept the house cooler.  Much of the year no air conditioning is needed.  The advantages of our big windows are especially obvious.  Our rooms are wonderfully bright and if there is any breeze at all, the rooms are quite comfortable unless it is very hot and still.

We rented an apartment in a concrete house that had poor ventilation.  It was like an oven.  Air conditioning was needed almost year round.  Our house is infinitely better, mostly because of our breezy location and big windows.

Here’s the big difference.  A concrete house with small windows and poor cross ventilation will be hot inside no matter what the weather is outside.  A house with big windows and good cross ventilation will be hot when it’s hot outside, but cool air will flood the house in the mornings and evenings.  The house will be more pleasurable because of the fresh air and will not require air conditioning when it’s cool outside.  It very hot at the time of year we write this, around 37C or close to 100F midday. Because we don’t have window screens yet (see our post about that) we keep windows closed at night to keep the bugs out.  As soon as Bob gets up at 5:00 or 5:30am, he opens all the windows.  The house cools off almost instantly as the 75F air pours in and stays quite comfortable for the next five or six hours.

We’ll use our two air conditioners during the hottest weather, but far less than than we did in our oven-like apartment.   We’ve planted dozens of trees.  When they are all big enough to shade the house, it will be cooler still.  Building a “cool house” does not transform a house in the tropics but it can, at very little cost, make it more comfortable more of the year and save far more in air conditioning costs that the “cool house” features themselves cost.

Electricity is expensive here.  At present it’s almost 25 cents (US) per kwh.  Much of it is produced by coal burning power plants. Incorporating “cool house” features will  money and reduce your use of  coal-fired electricity.

Listen to “The Chilling Facts about Air Conditioning” podcast on Tom Ashbrook’s “On Point” at http://www.onpointradio.org/2010/05/chilling-facts

Lots more reading on cool roofs at the Lawrence Berkeley National Laboratory http://coolcolors.lbl.gov/

NYT: White Roofs Catch On as Energy Cost Cutters http://www.nytimes.com/2009/07/30/science/earth/30degrees.html?_r=1

http://www.fsec.ucf.edu/en/publications/html/FSEC-CR-1220-00-es/index.htm

(Apologies to those who find this post duplicative.  It’s just a new summary of previous posts.)

Comments (66) Write a comment

  1. Jason, you are very right to be apprehensive about vents. I am told that there are vent designs used on ships which are impenetrable. The location of our house is very exposed. We had problems with our vents at the peak almost immediately. We covered them up with sheets of plywood, on the inside of the attic and have never used them. We were trying to duplicate the look of a bahay kubo, but frankly I wish we had built a simple hip roof with no roof vents. It would have saved quite a bit of money and complexity with the roof framing, the roofing and ongoing maintenance (the louvered vents are wood). We also installed fairly large vents at each corner and wood soffit vents. Our roof volume is quite big because our roof pitch is steeper than most bungalows. The corner and soffit vents are completely adequate. My advice is a light colored roofing material and insulation, preferably fiberglass. The reflective foil and fiberglass insulation directly under the roofing does seem to help. We also added fiberglass insulation in the attic on top of the ceilings. Using preformed perforated metal soffit material might be good but we used 1/2″ marine plywood and it is holding up quite well. It was painted on both sides before being installed and then painted on the outside after insulation. Dirt and mold built up and the painted plywood soffits have to be washed every year. Once this is done, they look like new after six years. Hope this helps. Bob and Carol

    Reply

  2. In the Philippines, the most effective way to minimize the heat load on a house is to shade it and thus never allow the house to absorb radiant heat energy.
    Consequently, one may want to use a “fly roof” to shade their house’s weather-tight roof.
    In the attached link, a gentleman has used a “double-roof” configuration and even applied the concept to his exterior walls.
    http://www.kotaronishiki.com/

    Reply

  3. Hello Bob and Carol,

    Thanks a lot for your post, which taught me a lot. Since I am currently in the process of designing a house in the Philippines (Batangas province), and I would like it to be cool I was very interested in what you had to say.

    A key issue for me is the choice of roofing material. I am not a professional but my research tells me a cool roof should have solar reflectivity (SR) AND high infrared emittence (IE). To get the first I need to use white, or in any case, light colored materials. That is what you do with your white roof. But to get the second, I need a material that can store heat and reemit it at night. This seems to suggest ceramic or concrete tiles, or coated metal tiles. But you chose metal. This has made me wonder if tiles are really the best choice. Incidentally tiles are expensive and heavy (structural implications) and I am having huge difficulties finding light colored materials from Philippines suppliers. I would be really grateful to hear your views…(and suggestions for suppliers).

    I also have a second question: I have been doing my calculations using the DoE cool roof calculator (http://web.ornl.gov/sci/roofs+walls/facts/CoolCalcEnergy.htm). The calculations seem to show that in a tropical climate insulation has very little effect on cooling. What do you think?

    Looking forward to hearing from you

    Richard

    Reply

    • Richard,

      Tiles are really beautiful. In NY our roof was of slate tiles. Having so much weight up high is a danger in earthquakes, the roof can act like a pendulum putting strong stress on the house below. Of course anything can be engineered around. That adds to the expense. Also the roof structure must be strong to support the weight and the tiles themselves are not cheap. Why do you want to store heat for the night? Is your location up in the mountains? I will take a look at the calculator and get back to you. I had an engineer tell me that every 1″ of fiberglass insulation in the ceiling alone would reduce my cooling load by 5 to 10%. Bob

      Reply

      • Hi and thanks for the prompt reply.

        As I understand it, the point of using materials with high thermal emittence is to ensure that the roof can radiate away the heat that accumulates during the day. I read about it here (https://heatisland.lbl.gov/sites/all/files/coolroofguide_0.pdf). Have a play with the DoE calculator – it really gives a good idea of the effects. You can also test the effects of insulation…

        Perhaps more importantly, I’d love to hear about your experience of living under your white metal roof. How does it feel? How does your house compare to other houses you visit?

        Reply

        • Richard, regarding our white metal roof, we wish we could give you some guidance, but we have nothing to compare it too. Our only roof is white! I just have to rely of the many proponents of lights colored roofs and their statistics. Bob and Carol. P.S. white and dark color roofing panels are the same price. The logic is with white.

          Reply

          • Hi Bob and Carol,

            I agree with you – white is a no-brainer – obviously the best choice. But I would also like to build a roof with higher thermal emissivity than is possible with metal alone and here I am having huge difficulties in finding building materials that are actually white. White clay tiles exist but are terrifyingly expensive. Our suppliers have given up on concrete because it leaks. Now we are looking at stone-coated metal (Decra) but finding light colors seems very hard…Any advice would be very welcome.

            Reply

            • Richard, the normal metal roofing here is similar to what we would use on a barn in the U.S. In the U.S. some standing seam roofs are installed. A machine is used to fold-over the seams in the panels. The panels are held to the roof by hidden cleats. When I read your post, I had this crazy thought of the stainless steel standing seam roofs I am aware of. Gutters also can be of stainless steel. This kind of roof is not restricted to the preformed panels we see in the Philippines. Any sheet metal works. Copper is also popular. Perhaps copper with a lacquer finish to delay discoloration (aka “Patina”) would be quite reflective. I would be surprised if such roofs are not used in the Alpine parts of your country. They work very well in high snowfall regions. Anyway, you can make your roof out of any metal, not just that on offer from the roofing suppliers. Just a thought.

              Reply

  4. Hello Bob/Carol,

    Thanks for this informative post. I live since 1990 in Iloilo-city. I think we have even met each other on one or two occasions!

    As of now we are considering to build a new house, focusing on efficiency and low-maintenance. The reason we want to build new is that (aside our house becoming too big with the children away) the quality of building materials improved a lot over the years; the is labor more skilled in handling modern techniques and we would like to focus on low maintenance and low energy consumption.

    For those people who are interested in high efficiency housing I would recommend to “google” on “integrative passive design for climate change: a new approach for tropical house design in the 21st century”.

    This will lead you to an informative PDF file. Although the house they suggest in this PDF will be very far off from the house I have in mind I hope it will have a lot of the ideas in it.
    Aside from that I also like to see how I can control humidity levels because humidity has a big impact on “comfort-level”. Another challenge!

    Again, your blog is very interesting, and I just wanted to share this information with you which I found on the internet.

    Barend

    Reply

    • Thanks for the link. I have downloaded the PDF. It looks like a good read. I am working on an an expanded article on building concepts for tropical climates. Thanks again.

      Bob

      Reply

  5. Pingback: Looking for fibreglass insulation

  6. Hi
    I unfortunately have already purchased my house. having lived in several with no real heat issues I was really surprised when my new house turned out to be exactly like you described, sitting under an oven! Im looking at attic extractors and also ceiling extractors, do you have any opinion on these? I have researched companies in cebu but cant find any that can offer simple solutions that at least reduce the problem. Most are reallly complex, covering the ceiling and walls in a spray type material that turns out to be very very expensive. the cost of which would probably not be met in my lifetime!
    HELP!!!
    Thanks

    Reply

    • planning a house in tropical is a bit tricky since you have to orchestrate every element and solution to expel heat as much as possible, so you have to be very kin in orienting every living spaces to avoid suns direct heat and selecting what type of material and color as well, in the Philippines, metal roof, concrete hollow blocks and cement are common building material since it is economical at least for a descent house design with durability and security. so first you need to study the orientation of the sun and the wind, eaves depth must be substantial to block most of the sunlight and also window height should be optimal and should be placed where most wind comes from, install transfer fans if possible to bring in cool air from outside, ceiling fan however is not advisable to use in my opinion since warm air rises up to the ceiling and what happen is warm air will be pushed back down, plant medium height leafy trees such as Indian tree close to the edge of the roof at the east and west side of the house to block the sunlight during when most time the wall is exposed, paint the exterior wall with wall white or off white color, choose white color roof to reflect most sunlight underplayed with fiber wool or p.e type of roof insulator, , grass is a very good ground cover to surround the house since it does not absorb heat.

      Reply

    • Terry, we are in the process of bringing Energy Shield Paint Additive to the Philippines. In applications in India & the Middle East we have realized a difference of 18 degrees Celsius between the roofing covered with our product & roofing not covered. Inside the building there was a difference of 5 degrees Celsius.
      Geoscience Labs in the USA in their testing found a savings of 42% in energy using our product.
      If you would like more information, please contact me at kevinmcnamara@converdegroup.com

      Reply

  7. Wonderful detailed information on this site.
    We have purchased a Lot in Panglao and will commence a bungalow build in January next year. I have been considering the ventilation of the roof space by using two ‘sky light’ windows installed in the roof; these to be special heat reflecting coated.. The roof design I have gone for is quite steep 45 degrees, this creates a large roof space which I have thought would be ideal storage and additional room space. I obviously appreciate the in the roof space but by providing an open ‘attic hatch and by opening the sky lights you end up with a flow of air from the cooler lower floor to the attic rooms and out. Any comments on the use of sky lights As an addition to reflective coverings etc.?

    Reply

    • Hi Terry, Panglao is coral and also generates heat from the ground. You would want to ventilate your home as much as possible.

      I suggest you use a combination of slide and jealousie windows. Slide with screen to have a big opening for view and air. About 4 jealousie blades above that for when it is drizzling or light rain outside.

      For the roof, I would suggest a gabled design or a modified curved roof gable if the house is of modern design. If possible to incorporate Dormers on the roof since you plan to use the attic space that would be best. Place jealousie windows on these dormers.

      You may want to consider “active” roof ventilation using solar powered ventilators. They are less than $200 on amazon.

      ROOF MATERIAL, ideally for Panglao “Onduline” asphalt sheets anti-rust, quieter than steel during rain. cheaper alternative for rust free “Metplas” PVC roofing. Both are also good insulator roofs. Paint the roof white.

      If on a budget, 0.6mm galvalume ordinary corrugated sheets. Install “tarpfoil” (P7000/ 6ft x 30m roll) insulator/deflector sheets UNDERPURLIN leaving air space between the steel roof and the insulator. The fastest way to do this is first to screw 3″ wide strips of 9mm plywood to the bottom of your roof purlins. Then staple the 6 foot wide tarpfoil material to the plywood strips. In your case, since you will be using the attic, screw on 9mm gypsum panels to the bottom of your purlins in effect sandwiching the foil between the roof and ceiling. If your purlins are spaced more than 50cm use 12mm gypsum.

      On another note, Panglao is termite nation, spend the money on steel wall studs and make sure to do termite trenching every 3 years.

      Reply

  8. Hi Bob and Carol. Nice looking house. Well done!

    We just built a house just outside Manila with several louvered vents that look almost exactly like yours. Our architect used louvered cement blocks inside (the type that warehouses use), then screening, then the external louver. I don’t know if this will stop wind driven horizontal rain, but the double louvers should be better than one.

    We also have oversized windows, and all bedrooms have windows on three sides. This cross ventilation seems to be crucial. Ceiling fans are all we need even on the hottest days. At night, we sleep with light blankets. This, even with a brown G.I. roof and ordinary bubble and foil insulation.

    George

    Reply

  9. Our house used red oxide painted steel work in the roof and I now find after 5 years that if I touch the surface I pick up red rust. I put this down to the humid atmosphere.
    Insulating the roof is done by spreading the 5 inch fibre over the room ceilings. Attaching the insulation to the roof underside will cause the steel to become tremendously hot and make it expand more than ordinarily. The movement could cause minute cracks that enable rain ingress for rusting.
    I plan for a normal gable steel roof with large gable openings. In each outside room wall at the soil level we will have 2 ventilation slots CHB size. Across the other side of the rooms will be ventilator openings in the ceiling where hopefully the hot air will be drawn from the room and out through the gable ends.
    Shade trees can be strategically grown close to south facing windows and provide some where to sit under during the hot afternoons.

    Reply

  10. i appreciate your effort and some things need to be done to optimize cooling.at present,my house is always 2 to 3 degrees C lower than outside ambient temperature.i have a design for an opening that vents out hot air and does not let in water even during heavy downpour.contact me if your interested.thanks

    Reply

    • Cliff,

      Sorry for the late reply. I would be very interested in a roof vent solution. Our situation is not resisting a downpour but keeping out near horizontal typhoon-driven rain.

      Bob

      Reply

    • Hi Cliff
      im interested in your ideas. I have lived here for several years with no real heat issues…until now, I bought my own place and its like an oven. Three bedroom bungalow with metal roof! What a fool i was! It’s too late to move elsewhere as the amount of building going on in cebu means there is no shortage of new houses so im stuck with looking at economical solutions for my current place. I was looking at house ceiling extractor fans and attic (roofspace) extractors, any opinions on this?
      Appreciate your advice!

      Reply

    • Hi Cliffe,looking for ways to keep the house cooler when i build it,would be intrested to know your solution,or adapted design. James

      Reply

  11. Hi Bob and Carol.
    Congratulations, your house is awesome and your website a “gold-mine” of precious and detailed information!
    I am in the process of building our own house in Moalboal-Cebu and it’s pleasant to see that we independently came to the same conclusions about roof-ceilings and the way to keep the house cool.
    When i talked about a WHITE roof people there were looking at me with a surprised smile as if i were asking for chicken’s milk!
    May I ask you a question? What material is the reflective foil you put on the fiber-glass insulation? They suggested me Poliethylene foam alluminized but i would prefer double bubble double aluminium foil. What do you think? Thanks! Lorenzo – Italy

    Reply

    • Lorenzo,

      Thanks for the kind words. The foil we used is just ordinary reflective foil reinforced with some kind of strands. It very much like we’d see in the USA attached to fiberglass batts. I was suspicious of the aluminized foam for two reasons. I doubted that the foam would hold up over time in the heat of an attic and having all that foam up there would accelerate any fire and create lots of toxic fumes. Besides, I was not confident that it would really do that much insulating. I have some left-over foil — wish I could give you a sample. I’m sure it must be available in Cebu City. The aluminized foam seems to be the easily available default option.

      Bon chance,

      Bob

      Reply

    • Lorenzo,
      Moal-Boal is a beautiful coastal area. My advise since you get breeze with a high salt content is to make sure your steel roof and trusses are well protected from the elements to avoid rust.

      Len

      Reply

  12. Hi! a late comment I have been thinking of building in balacan and wondered if you had seen the use of formed styro hollow blocks that are filled with concrete they seem to offer very good insulation not sure of cost though

    Reply

    • I am familiar with the product you are talking about, and am also interested in using it in the Philippines when I build there(not for a long time yet). I know they have started to use it in the Philippines, and was hopign someone else could shed some light on their efforts of using it. It is a VERY strong and insulated product. It is by far better than building with block. Especially when you read about Bobs experience with them. If the price isn’t much more, I would say build with it. I know I will if it is available and not too much more than block. One of the nicest features, besides it’s greater strength, is the insulation value. Great for keeping your home cool on those HOT Philippine days.

      Reply

  13. i like your webside well done!!!!!
    i am from europe and i have been in 2010 in the philipinnes in Palawan
    i will return in 2012 and live there
    my question is is there possible too visiting new home in IIoilo city
    I want too look at the house for the roof so nice done -and adjust it meaby in other place in palawan puerto princesa city for my self and my woman
    willy

    Reply

  14. Why wouldn’t you put in an attic fan or large wall fan to blow out the hot air at night till dawn and suck in the cold night air. Works great!

    Reply

    • Vince,

      I’m certain you are right. Except for one bedroom, we don’t have window screens yet. Partly that’s because we have not yet figured out the best type of window screens, partly because the screens will cost about P8,000 per window but also because closed windows keep out noise and are a bit more secure — you have to break a window as the first step in a break-in. But, once we get screens we’ll look for a a big 220v attic fan and give it a try. Thanks for your suggestion.

      Bob

      Reply

    • Hi Vince
      you are just the person I have been looking for! This is exactly what I have been considering. I have a metal roof, its like sitting under an oven. I was investigating your idea the other day in Ace hardware. The guy seemed to think I was crazy My idea was to vent from the house to the roofspace in the morning and evenings. Also I was planning to put an attic extractor to the outside but im worried about overheating. The fans I was looking at didnt seem to have any thermostatic control to avoid overheating as I suspect they would need to work very hard! Any advice you can give would be much appreciated. I was also wondering about insulating the roof. In the UK we insulate the ceiling floor in the attic, it seems here they put insulating foam inside on the actual roof, is that economical? Seems more sensible to put it on the floor of the roofspace??? please help! Thanks
      Terry

      Reply

      • Terry,

        In building a house in the tropics, it seems to me that one of the main decisions one has to make is whether you mainly plan on using air conditioning, more or less 24/7, or whether you will build to mostly use more “natural” means to keep cool. The former implies smaller windows and insulation. If you live in a city, designing for aircon makes sense. It’s noisy in the city and the air quality is probably bad. I would not go overboard with insulation. In a naturally cooled house, the thin foil/foam insulation will do almost as much as thicker insulation, will cost less and be less susceptible to pest infestation. I have heard of using big whole house fans in the attic to suck in cool air after dark. They are probably a good idea. If buiding a hollow block house, do everything you can to keep the sun off the house — trees, louvered sun screens etc. A block house baking in the sun all day is going to be miserable, cool roof or no. If you try to solve the problem with air conditioning, you’ll spend a great deal on electricity.

        Bob

        Reply

      • I am sure that adding attic insulation and ventilation would help. There are commercial-duty exhaust fans that I have seen restaurants using here. Look at the top fan at http://www.niagarafans.com/prod_gen.htm It says it’s available in sizes as small as 18″. As soon as the sun goes down, or a bit before, it cools off. Sucking that cooler air in through the windows and out through the attic could make the house more comfortable sooner and also cool the thermal mass of block so that the next day you’d have a head start.

        Here’s a site which has LOTS of ideas and links on keeping cool http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm without air conditioning.

        Work to keep the sun off the house and it’s going to help more than all the attic insulation in the world. You can fast growing shade trees. The common Philippine “umbrella tree” ( Talisay) grows very fast. Simple awnings over windows also help. You could also use climbing vines on simple wall trellises to shade the house.

        Good luck!

        Bob

        Reply

        • Hi Bob,

          I wonder if your familiar with the “Paulownia” tree. It is native to China but grows very well in my home state of Florida. I planted my from a seed 4 years ago and it is 35 feet tall now. I know this tree grows in the Philippines because I saw one of them a little ways outside of Manila. They make a superb shade tree and strong enough to handle most Hurricanes we get here in Florida.

          I found this on Wikipedia, http://en.wikipedia.org/wiki/Paulonia.

          FYI, it has very nice looking purple and white flowers.

          Reply

          • We were not familiar with it, so thanks for bringing it to our attention. We did read the Wikipedia article which says that it does not tolerate high water tables so it would not like it at our house where the water table is very near (or above!) the water table during the rainy season. We have a variety of trees and shrubs. Some love the water and do best during the rainy season. The Acacia is one example. It’s dry now and all the Acacias look poorly. On the other hand, the Bougainvilleas hate water. Standing water can kill them. They just barely survive the rain and love it when it dries out. That’s when they bloom like crazy.

            Reply

            • Hi Bob,

              I had reservation myself regarding the moisture level of my soil as I am 7 miles from the ocean. My brother (whom I got my seed from) has four of these in his yard that are at or near 50 ft. tall and he is 1 mile away from the ocean and is much closer to sea level. Generally speaking, we don’t get the amount of rain as you do annually but at times the rain really comes down. Last summer we got 6″ in 20 minutes and the Paulownia tree seemed to weather it just fine. It seems the Paulownia tree will tolerate heavy rains as long as the soil drains well. FYI, once established, they are VERY drought tolerant.

              I’m not trying to persuade you into planting a Paulownia tree, I just thought for I would mention my own experience for the sake of your fellow expats that might be looking for a FAST (1″-3″+ a day) growing tree that grows well in black earth or as in my brothers case, sandy salty earth.

              Reply

  15. Too bad on the roof ventilation, we went with putting the vents on the overhang where the roof sits on the blockwork. Still got the issue of heat rising which is where those spinning roof vents come in as the hot air will force them to turn but with a cap on the top unlikely to see any water come in.

    Reply

  16. Hi

    Great site, very, very interesting reading. Sorry to hear about your ‘hack’. I’m planning to have a go myself at house building in a couple of years. The costs you quote are very useful for my budgeting !!

    I lived in Saudi Arabia for 6 years and of course heat there is considerably higher than we experience here in the Philippines. It is illegal to own or sell a thermometer which shows a temperature above 50C in saudi. The reason ? workers are allowed to stop working outside if the temp goes above 50C. Anybody who claims it is hotter are shown the temp at 50C, if they can prove it is hotter, they are arrested for owning a banned piece of equipment. I know you will not believe that but it is true. We used a cooker thermometer and the temp out in the sun at around 2 pm would be in the order of 67C in the shade around 52C. Modern western style houses use a concrete slab for the roof as well but the locally built houses all have a turret in the roof which draws hot air up like a chimney. Almost all traditional houses in hot climates have this peak and the purpose is simple; hot air chimney. Look at traditional Thai and Burmese house. It will feature in my design as I intend to have an open roof I will box my metal frames with wood for aesthetic reasons.

    I intend to use a type of fibre board for the roof. It’s similar to fibre glass but is designed to be non-heat absorbent. Surface of course will get very hot but underneath it is much much cooler. The big advantage is that it does not radiate that heat. The biggest cooling mechanism will be the tower. Your point about the driving rain is something I will make sure I account for and test thoroughly. The fibre board cuts easily and is totally water and pest proof. It costs more but I will be installing myself so I will save money overall and I will not need to use any insulation. The internal wood price will be a lot more expensive but again I will not have any ceiling costs.

    Your site has inspired me to ensure that I will document everything I do, all the decisions; good and bad. l am still reading so will probably add comments again later.

    Congratulations and thanks again for all this effort.

    Cemlyn

    Reply

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  19. carol and bob, is it true that the welders make 5$ per day? the house will cost about 35$ per sq ft? i think a custom/concrete house like this in the usa would cost almost 10X as much!! love the learning process (ie, rain blows through the louvered vents, etc…) what a great project, who needs to retire when you can build your own house in a foreign country!!?? still working on my house! did you see pics on FB? am working on ladders now down the cliff to access the water, (since i pay high waterfront taxes, i might as well use it!! not for the faint of heart though!)

    Reply

    • Hi Tom,

      The cost per square foot for the house (not including the perimeter fence, lot or garage) was about $38. It would be a little more today because the dollar continues to weaken.

      Our foremen earned P350 ($7.77) per day, skilled workers (masons, welders) P280 ($6.25) and laborers P200 ($4.45). We provided a place to stay (the bamboo guest house), rice, bottled water (nobody drinks tap water!) and an ulam allowance. Ulam is something eat with rice, generally fish or chicken. Workers who stayed with the job until the end received a bonus — up to $225.

      The work day was 7am to 5pm with an hour off for lunch. One crew member did the cooking for all the crew.

      I wish I had you here during construction as my foreman!

      Reply

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  22. Hi Bob,
    Galvanised purlings are available that would I think would outlive the painted steel ones. Interested to know why you chose to go the paint way?
    Peter

    Reply

    • Hi Peter,

      Galvanized are definitely available and, of course, more expensive. My foreman favored epoxy painted regular steel purlins so that’s what we did. I just don’t know how much of a risk purlin corrosion is. After all, they are enclosed in a dry attic. I’ll keep an eye out for rust and let you know.

      Bob

      Reply

  23. For our bungalow we will adopt the roof framework that allows space and choose the simple roof with large gable ends. With the space and access we can install a water tank with overflow for faulty cisterns and drop down feeds to each required point.
    The roof space can also be the centre point for all the electric cable feeds.
    I’ve seen many rooftops in the Philippines and seen them fade and become grubby with this tropical atmosphere, the lovely Mediterranean style tiles that remind me of Cadiz in Spain. Unfortunately the air here is not Spain and the colour soon changes. To keep the roof lightweight (earthquakes) I’ll choose a dark grey colour steel and open up the gable ends to allow the movement of air. From each of the rooms we can have large ceiling vents that will allow passage or hot air, the unwanted heat from the roof will help in drawing cooler air from the lower regions.
    A spare room in the bungalow will contain a stairway up into the loft and only be accessible from outside. This can be my workshop and the stairwell will become a room divider inside the bungalow with the space underneath used for storage in the Kitchen.
    Windows have been a topic for thought and the idea of doing away with glass just might work. Cover the windows outside with an attractive steel grill and have an insect screen fitted into the window space to repel boarders. With the 5ft overhang of the roof we might just be successful doing it this way, if not we can always retrofit.

    Reply

    • Peter,

      Sounds like some good plans. I’d only express skepticism about the idea of not having window glass. Of course this partially depends on how sheltered you location is. Where we are building our house it’s quite exposed. I worry about water getting in even when the windows are closed. We don’t have glass in our windows yet. With small storms we have had since the roof is on, water has been blown in all over the inside. You’ll certainly have to have tight windows to stay dry during the typhoons.

      Most typhoons come from the SW. Even during windy, rainy weather we we able to keep our E and N windows open in our Iloilo City apartment. One of the great things about living here is almost always having windows open but when the typhoons come you’ll have to be able to close them.

      Just my 2 pesos worth. Best wishes.

      Bob

      Reply

  24. Bob I have been following your blog with interest for some time now. When you started on your house you I think said you would publish a floor plan of your house, I am keen to see if it has a dirty kitchen and an outside laundry

    Regards Ian

    Reply

    • Ian,

      We’ll have a dirty kitchen at the bahay kubo bamboo house once the workers have departed. The laundry will be part of the car port with a secure area for the washing machine, a sink and laundry drying area under the car port roof. I’ll try to get around to publishing the floor plan but it does not include either the car port or bahay kubo.

      Bob

      Reply

  25. JJohn,

    Our overhang was 1.2M in the plans. The gutter adds about 25CM. If I had it to do over again I would go just about 1.4M + gutter. I don’t think more would help as very little sun hits the house. It’s 1:30 now and the west side has about 60CM of sun at the bottom of the wall. Filling and planting will take care of that. There is a tiny bit of sun on the east in the morning, more or less none on the south at any time as the sun is too high in the sky to clear the overhang. We already have quite a few trees growing.

    The big windows (240×160) also seem to help. I’ll be sad to put in the screens which really reduce the air flow — maybe by 50%?

    I was tempted to suggest moving the windows even higher on the walls but so little sun comes in the windows that I am not sure how much it would help. Cross ventilation is essential.

    We are blessed to have a site really swept by the prevailing winds. That’s what makes the windows and cross ventilation really work. It’s so windy some have suggested we look into a windmill!

    I suspect double glazing is available. Since our plan was to have windows open all the time, we never considered double glazing. Fortunately, so far we have no close neighbors and noise is not a problem. That could change. If noise was a big problem it could suggest a totally different type of design — air con, insulation, double glazing.

    Bob

    Reply

  26. John,

    Our overhang was 1.2M in the plans. The gutter adds about 25CM. If I had it to do over again I would go just about 1.4M + gutter. I don’t think more would help as very
    little sun hits the house. It’s 1:30 now and the west side has about 60CM of sun at the bottom of the wall. Filling and planting will take care of that. There is a tiny bit of
    sun on the east in the morning, more or less none on the south at any time as the sun is too high in the sky to clear the overhang. We already have quite a few trees growing.

    The big windows (240×160) also seem to help. I’ll be sad to put in the screens which really reduce the air flow — maybe by 50%?

    I was tempted to suggest moving the windows even higher on the walls but so little sun comes in the windows that I am not sure how much it would help. Cross ventilation
    is essential.

    We are blessed to have a site really swept by the prevailing winds. That’s what makes the windows and cross ventilation really work. It’s so windy some have suggested
    we look into a windmill!

    I suspect double glazing is available. Since our plan was to have windows open all the time, we never considered double glazing. Fortunately, so far we have no close
    neighbors and noise is not a problem. That could change. If noise was a big problem it could suggest a totally different type of design — air con, insulation, double glazing.

    Reply

  27. Hi bob well your house is really coming on now , very nice looking property ,here in australia we use the same system now with most new homes haveing colourbond roofing (powder coated corrogated galv iron) there was atime when tiled roofs where all the rage my house is one and i tell you in the middle of summer you dont want to go into the roof space ,to combat this we have nere what is called a whirlibird (tradename) and what it does is sucks the hot air out of your roof space when it is really hot here the one on my roof is really moving like a ventilater but in reverse ,it has long been known here that homes should have wide veranders for just the reason you said to keep the sun of the walls of the house however the desighners have moved away from this and have started building homes with no veranders at all i suppose in this day and age we all hve an aircon we go from an aircon office to the car and to the home but if you look back to earlier homestaeds they have a verander of about 6 feet all the way round ,just one question is your construction cost in american dollars ? also are the water pipes chased into the walls anyway nice looking home
    regards chris & ana

    Reply

    • Hi Chris,

      I just listened to a great podcast called “The Chilling Facts about Air Conditioning”. There’s a link on . One of the main points is that cheap energy, cheap oil and coal has caused the construction of decades of buildings which abandon traditional building designs for tropical environments and which are almost totally unusable without air conditioning. The fear is that rising energy prices and global warming regulations are going to force changes in building design and bring into question the economic and environmental viability of millions of buildings. It was interesting to hear to callers from the American South more or less saying that life would not be possible or worth living without air conditioning. I was listening to the podcast in my bamboo construction office when it was very, very hot and thinking how spoiled these people are!

      I don’t know the total cost because the project is ongoing but my estimate is about $365.00 (US) per square meter.

      The main 1″ waterline circles the exterior wall underground with risers for the kitchen and bathrooms embedded in the exterior walls. That way, if repairs are needed, the tiling should not have to be disturbed. We terminated the risers with brass or stainless steel nipples and elbows in the kitchen and bathrooms so that if faucets or valves need repair or replacement in the future, that we don’t gamble on plastic threaded parts.

      Tigbauan, Iloilo
      Philippines
      http://

      Reply

  28. Bob what about roof fans? I wonder if that would help keep some of he heat out of the area under the roof. House is looking great. Ron

    Reply

    • Thanks Ron,

      I’ve been mulling over roof fans but I think I’m going to wait, maybe monitor temperatures in the “attic” and if they’re high decide what to do. What about insulation above

      the ceiling as well as under the roof?

      Bob

      http://

      Reply

  29. Thanks for the very descriptive journal. I remember my brother-in-law installing an attic fan, do they have it in the Philippines?

    Reply

  30. Hello again,
    Your House is looking awesome. I have also been thinking of ways to keep a house cool before my wife and I start to build our house over there in Argao, Cebu. I have been wondering if there is some way to attach 1.5 to 2 inch Styrofoam insulation board over the exterior of a house built with blocks. Then put some reinforcing wire mesh over that and apply the final cement plaster finish over this. Kind of like they do with Stucco over here in the states. This would add some insulation value to the walls. Do you think something like this is possible at a reasonable cost over there?

    Reply

    • I wish I could advise you but I have not researched this. Maybe someone else can pipe in. Maybe the insulation would be better protected inside? I recall there are some composite concrete/foam panels available or you could abandon hollow block and use hardiflex and steel studs with insulation in between? Good luck!

      Reply

  31. Great job Bob, I think you’ve resolved the issue of having an uncomfortable home in the tropics! I love the casement
    windows much more than the sliders or single hangs, more
    of the summer breeze coming in for sure. The house is looking great! God Bless…lady

    Reply

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