Moisture in Attic

[RoyalWapiti]

I’ve read the building science website and am still confused.

I have moisture in attic and have read all the many things that can or is causing it.

I’m still confused if the “Cold” zone area calls for a vapor barrier between ceiling drywall and insulation in attic. My house is traditional ranch with tyvek on walls, vinyl siding, R19 in walls. R38 in attic blown-in, no vapor barrier in ceiling.

I have a ridge vent and plenty of soffitt vents. Problem came from running humidifer unchecked… poor bathroom vents and I suspect no vapor barrier.

Does it need a vapor barrier? If yes, Can spray foam (icynene – professionally applied) be put down to form a barrier on to topside of drywall?

You never get the fruit if you don’t go out on the limb!

[Unregistered-sauerkraut57]

Yes you can have foam insulation sprayed directly to the backside of the drywall.

Before doing that though, I would look for other causes. Are the bathroom vents or kitchen hood venting into the attic? This is a BIG no-no. This causes all the moisture to go straight into the attic. If this is the case, odds are if they are properly vented (directly to the outside) the moisture problem will go away.

One other thing to look at: Are the soffet vents plugged up with insulation? Sometimes when they blow in insulation, they are not careful about making sure they are left open.

[Sauerkraut57]

Yes you can have foam insulation sprayed directly to the backside of the drywall.

Before doing that though, I would look for other causes. Are the bathroom vents or kitchen hood venting into the attic? This is a BIG no-no. This causes all the moisture to go straight into the attic. If this is the case, odds are if they are properly vented (directly to the outside) the moisture problem will go away.

One other thing to look at: Are the soffet vents plugged up with insulation? Sometimes when they blow in insulation, they are not careful about making sure they are left open.

[Billhart]

For a ceiling and vented attic does it say vapor barrier or retarder.

A resonably well constucted ceiling with a properly vented attic should not have a problem with moisture coming through.

The drywall should be enough of a retarder.

However, it is not unusally to have large (and small) holes in the ceiling allowing too much moisture into the attic.

Those need to be sealled off first.

The biggest ones are often soffits in bathrooms and kitchens. Also plumbing chases.

Smaller ones are around electrical boxes, where cables goes through the top plate, and can lights.

[Author]

Posts