Unvented roof creaks as sun heats it up in morning
I’m wondering if there is any way to fix this without pulling the shingles or sheeting.
I built a post and beam house wrapped in 4in EPS foam. The roof is a hot roof sandwich panel of 7/16 OSB with 4 inch of EPS in the middle. There is no adhesive and I think this is my mistake. We used 6in glavanized screws and hit the rafters underneath. There is spray foam inbetween every sheet of foam and they are pushed tight together. The walls are EIFS stucco and do not make any noises as they heat up.
The stackup from top to bottom:
-architectural asphalt shingles
-7/16 OSB (spaced 1/8 inch apart from eachother, screwed through to rafters with 6in galv screws)
-4 in EPS foam (held inplace with just a screw or two as the osb was immediately laid ontop next)
-synthetic underlayment (the framing was completed in december and had a few major snows that held off finishing the roof for two months. This was temporary but left inside the assembly)
-7/16 OSB (nailed with 8d nails to the rafters)
The noise is fairly loud and makes a sequence of creaks every few minutes for about two hours in the morning. It also makes a few less lengthy creaks as the sun sets. I believe the noise comes from inbetween the top sheet of OSB and the foam?
I know I only have 4in of foam all around the house and that does not meet code for the ceiling. I have thought about filling the rafter bays with cellulose too. But also, January’s heating bill was only $90. The only heat source is electric radiant wires that heat the slab. The house has big south facing windows and very limited surface area for the square footage (1500sqft). Adding cellulose insulation in the rafter bays may dampen the noise? But also, reading the article on cathedral ceilings, I know that I cannot have 8in of cellulose under 4in of EPS foam. That will put the condensation point inside the cellulose.
The shingle assembly was abruptly planned. I had been intending to put a metal roof on top of diagonal purlins above the foam but the HOA denied that after the roof was halfway built and I rushed to order shingles instead. I wish I did more research. I’m hoping I can reduce the noise somehow. The roof is only a year old now. I’d rather do a major fix to it when the shingles start to go and I can then put a metal roof on when there is new hoa leadership.
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