Got the cellulose insulation, now what!
Okay, I guess I should know this, but I don’t.
Yesterday we had dense pack cellulose installed in our cathedral ceiling and wet spray cellulose blown into the few frame exterior walls we have in the loft (this is a log house). Do we put a vapor barrier over the wet blown stuff in the walls? Do we need to let it dry out first? (it doesn’t feel wet, but it probably still is a little bit) What would you use? None of these walls are in a bathroom, just 2 bedrooms and the main loft area (family room I guess you’d call it). Climate is cold if that makes a difference (9000 ft elevation in Colorado mountains).
So, just to clarify, I am only talking about the walls. On the ceilings they stapled something called “insul web” on the TJIs to keep in the cellulose.
Neither one of us had any experience with cellulose insulation, but after reading this forum for several years, went with cellulose. This stuff is very cool. It was the right choice for sure.
Replies
Let it dry first. Coupla weeks anyways.
Excellence is its own reward!
I personally agree with let it dry first.
But the company that installed for us said it would be fine to hang rock the next day. It ended up being a week or so before the hangers started and it seemed to be okay.
It was pretty moist if you felt into it's innards.View Image
Letting it dry could definitely not hurt, though if your wall cavity is able to breathe to the outside, as it should be able to through the gaps in the plywood (we usually drill some holes above the soffit line and under window sill plates as well) then even if it was damp at the time it was covered over, it should still dry out with no problems.
Let it dry, though there is not actually that much water involved. Less than one would think, anyways.
Skip the vapor barrier with cellulose. Consider the airtight drywall approach instead.
Google for "airtight drywall". Lots of information these days. Method is slowly gaining some ground... Vapor barriers can cause as many problems as they solve.
Edited 10/11/2003 7:38:54 PM ET by csnow
Actually, I should have mentioned, it will be 1x6 T&G over the top. So to vapor barrier or not to vapor barier, hmmmm. I don't think there is any such thing as airtight pine tongue and groove! LOL!
To all, thanks for the help. I always appreciate it.
If it were my house, I would want it airtight before the T&G went on.
I would suggest rough drywall behind or a layer of airtight plywood. Plywood would backup the T&G nicely. I'm not saying it is impossible to use a plastic vapor barrier behind T&G, but the detailing around breaches like outlets and windows would be tricky, and nailing the T&G will make a gazillion perfs in it.
If you were to find air leaks later, they would be very difficult to locate and repair behind the T&G.
I am actually doing a similar project right now using salvaged T&G with airtight plywood behind.
JMHO. Best of luck.
My experience: In Colorado everything dries no matter what you do!
Our cloth shower mat dries while laying on the vinyl floor.
Any jackass can kick down a barn, but it takes a carpenter to build one.
My opinion from Germany.
No vaporbarrier, but airtight special-paper before the drywall is installed. All Staples ansd seams taped.
Sealed electric boxes and water installations...sealed against airflow, which transports humidity.
Sealing is a meticulous job, especially in add-on and renovation projects (where the old meets the new).
Outside a vapor-open but water-tight house wrap. Almost every new house over here is tested with the "blower-door"- test for airtightness. You DO want airflow around the outside of the house (walls, roof) though.
If the cellulose is blown in, the installer needs some experience to not leave any cavities. These show on an infrared image of the house - the final proof.
Btw: With this wall/roof you don´t have to let the "wet" cellulose dry, Any humidity will be transported to the outside where it is vented throgh the airflow under the facade/roof tiles.
Kind regards, Mathias
Edited 10/12/2003 7:32:35 AM ET by Matt