[Deck]

I'm going to be installing some drywall in cold weather. Does anyone have any advice for me? I'm working disaster relief and most of the places I'm in have no heat. I know materials contract and expand depending on the weather so I did some reading to find out about drywall in those conditions. Here is some of what I read:
Gypsum Board in Cold Weather
finishing in freezing weather - Drywall Finishing - Contractor Talk

What's the worst that can happen if drywall is installed at 40 degrees or below?

Also because the area was flooded there are a lot of houses where the drywall and insulation was removed like a foot or so above the water line. When the new insulation is installed does its vapor barrier have to somehow connect to the hidden vapor barrier behind the already existing top half of drywall? What kind of damage can happen if the two vapor barriers aren't connected? And does anyone have any other advice for joining the drywall in this situation? I'm going to try to make sure they're the same thicknesses obviously.

Here's a picture typical of what I'm seeing

Also if someone can explain the why for this bullet point from the first link:

If a polyethylene vapor retarder film is installed on ceilings behind the gypsum board, it is important to install the blanket ceiling insulation BEFORE the gypsum board. If loose fill insulation is used, install the insulation IMMEDIATELY after the gypsum board.

One more thing, if anyone can give me advice on how to create a clean crisp horizontal cut line like in that pic. I anticipate I'll probably have to clean up some ragged lines. Is there some special tool with a guide or something that I can place horizontally and then drag a razor back and forth until the piece falls off? I'd rather not use a dremel, my concern is possible asbestos in joint compound going into the air.

Thanks

 

[joecaption]

There's not going to be any asbestos in joint compound.
The fastest way would be to check to see if the wall board was installed horizontal, if it is I'be be cutting it along the joint, pulling off the old tape.
That way your finishing at waist level, and along a tapered joint not a butt joint for ease of finishing and no hump.

 

[oh'mike]

One of the insulation pros--or a member that has been in this situation will be your best source of info---

I think you will be renting heaters----even if the product is not harmed by the cold---it will be days,even weeks between coats if you don't have heat----

 

[ToolSeeker]

Lots of questions First let me say Mike is right you will need heat without it your mud will never dry.
cold really does not effect hanging drywall but as long as you will have to have heaters anyway why not use them when you hang. It doesn't need to be hot, but it does need to be warm.

Also a fan to move the air will be a big help in drying. The vapor barrier should only need to go to the top of your repair. But let me ask you this what kind if insulation was in the wall before if it was batt and they pulled it all out how are you going to insulate the top of the cavity?

Now for the seam as stated if the rock was installed horizontally there should be a seam 4' down from the ceiling if this is true that is where you should seam also. But to eliminate the hump use a 5 or 6" knife to fill and bury your tape. 2nd coat use an 8" knife to put the mud on, remove with a 10" knife 3rd coat put on with a 10" take off with a 12".

Then according to what you have you may need to use your 12" and go 12" on both sides of the seam. The farther you feather it out the less noticable it will be. You don't say if you have done drywall before so let me remind you to leave about 1/2" up from the floor. Plus on that off angle corner I would remove the tape all the way up and re-mud it. Hope this helps your not looking at an easy job.

 

[jklingel]

the gap in the vapor barrier will severely compromise what it is intended to do. as much as a 3/4" square hole will let as much vapor into a wall as diffuses through a sheet of sheetrock (assuming the wall is not air barriered on the outside, as with plywood, and the wall thus leaks). what to do about it? dunno, but if you need a vapor barrier, slicing it down the middle really impacts its effectiveness.

 

[Dean CRCNA]

you're correct. There can be asbestos in the joint compound.

 

[Deck]

Thanks for all the advice guys. Can anyone explain those insulation comments I noted in my original post?

 

[mbryan]

There's not going to be any asbestos in joint compound..

Not true. We commonly see at least trace in compound. Texture quite often contains it and acoustic is very common.

The vapor barrier if cut will not be complete and therefore have the potential to leak. How do you fix it easily? Good question... We usually install the new insulation and then tape the centers of the bays but as you come to the stud it gets impossible.

Loose fill is the same as blown in insulation. The wall board must be in place or when you blow it you have the potential for it to fall out. You can use the product damp but I don't care for that method.

Sand the existing walls down as far as you can to aid finishing. Don't try to patch a seam in over existing texture as it will have a huge hump in it and not look good at all.