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magic_scott

Need help for metal roof insulation

magic
7 years ago

Hi All:


I'm in Hawaii and if you're not familiar with our weather, the temperature is mostly in the 70 - 80's majority of the year with winter going into 60's on the low side. Humidity is pretty high about 60 - 70's for most of the year with winters going down to 40-50's.


Ok so here's my situation. We had our home renovated about 18 months ago and the general contractor (GC) we had wasn't that good so if some of the designs/decisions doesn't sound very good, you know why. At the time of the renovation, the GC got a roofer to inspect our asphalt 3-tab roof, and they deemed the roof to be ok, so I listened to them and we didn't replace the roof, instead they coated the roof with Gaco silicone roof coating. The roof is 19 years old. We've had a bunch of small leaks throughout the year and the GC has been coming back to add more coating to try to seal them. I haven't been able to totally put him at fault since we had termite tenting and photo voltaic panels installed as well. Anyway, so I've decided that I want to get the roof re-done and I'm really leaning towards a standing seam roof. The questions I have is what I should do as far as having the roofers install a radiant barrier or not.


As mentioned, the current roof is asphalt shingles on 1x8 wood planks as a base, 4:12 slope. About half of the roof is over a cathedral ceiling, exposed ridge beam for the living room and the remainder of the house has an attic. The roof for both sections actually have independent ridge lines so there's a transition between roofs. In the attic space, our contractor installed the foil with bubble radiant barrier attached to the rafters in the attic. We also have a ridge vent across the entire ridge of both sections of the roof that was previously done in the past. We also have two solar fans in the attic section of the house/roof.


The living room gets considerably hotter than the rest of the house thats under the attic. So given my setup, would a radiant barrier on top be really beneficial? The ridge vent on the cathedral ceiling definitely will get capped but what about the attic section?


One metal roof contractor offered a white rigid foam with foil on one side as an insulating layer and he was going to install purlins only on the cathedral ceiling section fearing that he will miss the rafter and the nails/screws will exposed inside. But on the attic section, he'll lay the foam layer on the underlayment then metal roof on top. Is purlins necessary for air gap purposes if using the rigid foam insulation?


Any other suggestions?


Please help.



Thanks!


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