Roof going on over foil and fiberglass
How did you stick the fiberglass insulation so it seems like its one seamless part? are they over lapping? or did you tape them together? Also how are the ends tied down?
The fiberglass was in quite long rolls, I suppose because it is thinner than the 4″ or 6″ rolls so more length per roll. So, there were few joints. The insulation is only supported by the wires between the purlins, no tape or other support. Perhaps the foil being glued to the raw insulation made a stiffer product?
Thanks for your reply Bob, I appreciate it, I am learning more everyday. Regarding the foil question – I found out on some websites it doesnt matter which side it faces as long as the Shiny side faces an air gap. It doesn’t matter which direction because high reflectivity = low emissivity. Even if it faces down, the heated foil can’t radiate downward. The main thing is that the shiny side doesn’t touch any surfaces otherwise the heat will conduct into the material.
I still strongly feel that the shiny side should face up – however I also came across information that if dirt, dust and debris go ontop of the foil, it will lose some of its reflectivity. This is something I am still not too sure of since this is thermal heat radiation & not light. thermal should still reflect off foil even if it is covered by dust right? Sorry for the long post.
These are really engineering questions that I can’t answer. I just followed the advice I found online on credible sites. The gap between our foil and the underside of the roofing is quite small so perhaps not too much dust will accumulate.
It’s hard for us to judge how well our system is working, but I think pretty well. I have been in other Philippine “attics” and they were much hotter than ours. We are in the process of adding fiberglass insulation on top of the ceiling Hardiflex in the rooms we air condition.
It’s hard to decide if you should design your house to be air conditioned (insulation, smaller double pane windows) or not (big windows, high ceilings). I find I really don’t like sealed-up buildings!
how to install foil and fiberglass what is kind of material to hold in between these purlins that my question please your answer, sir
The fiberglass insulation is held up by 16 gauge galvanized tie wire running between the purlins. You can see it here: http://myphilippinelife.com/our-philippine-house-project-roof-and-roofing/roof_inside_5_17/
Small holes are drilled in the purlins to accept the tie wire. It seems to work well. There is foil above the insulation and an air space before the bottom of the roofing.
Hope this helps.
Required fields are marked *.
Notify me of new posts by email.