Reducing particulates in unvented and conditioned attic
We are building an unvented and conditioned attic. We do not want to use sprayfoam on the roofdeck for a variety of reasons, so we installed a vapor diffusion port on the ridgeline so we could use air permeable insulation on the under deck of the roof. We are in climate zone 3C. All makes sense here.
Since we have a supply and return in the attic space to help regulate humidity, I am wondering if we need to do anything special with the fiberglass batts/mineral wool to reduce particulate matter in the attic so it doesnt get spread throughout the house. Such as encapsulated fiberglass? I am leaning towards mineral wool over fiberglass as my gutt says it would create less particulate matter, though I have nothing to back that up.
Maybe I am overthinking this and just tossing a hepa filter on the return duct in the attic is enough. Our insulation guy is punting my question to our hvac folk and our hvac folk are punting to our insulation guy.
Since batts on the roofdeck in an unvented condition attic are clearly common enough to produce an IBC code, have folks seen this to be an issue? What measures can be taken?
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I'm very sensitive to fiberglass, if I have to work with it and don't have an N95 mask or equivalent I'll be outside on the sidewalk retching after a few minutes. It's murder on my skin and eyes.
I don't find rockwool appreciably better.
I would encapsulate it all with drywall.
Unfortunately encapsulating it with drywall isn't an option. It would be prohibitively expensive and would require us to put fire sprinklers in our attic space per local code.
rfb,
Cover it with taped house-wrap. That will both reduce particulates and provide an interior air-barrier, which will improve both the performance of the insulation, and reduce possible moisture accumulation on the underside of the sheathing.
I was hoping (though not expecting) there was a standard insulation practice material to achieve something similar. Like plastic sheathing it after the fact.
The house wrap is a very interesting idea though. How would it reduce moisture accumulation on the underside of the sheathing if the house wrap is vapor permeable? Wouldnt it still be able to accumulate on the sheathing?
rfb,
The main source of moisture accumulation is air not vapour movement. The housewrap acts as an interior air-barrier.
@malcom - i lost the ability to reply in thread. but in response to your last comment about vapor. in that theory, one could use faced fiberglass batts with the face facing the attic (not the roof deck) instead of housewrap + unfaced batts then, correct?
rfb,
I don't see why that wouldn't work, but I should add a caveat.
Because I'm not in a climate where vapour-diffusion ports are allowed, I haven't spent much time learning how best to build those roof assemblies. Hopefully others with more knowledge will chime in.