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What should I use to fill gap around doorframe for best isolation?
Old 8th February 2015
  #1
What should I use to fill gap around doorframe for best isolation?

Hi all -

I'm in final stages of a room build. I did three layers of 5/8" drywall and everything is extremely tight. Except things got sloppy around the door frame. The drywall wasn't run right up to it, and there is a decent-size gap (see image). The contractor I'm working with wants to fill it with regular expanding foam.

Before he does this, I wanted to check to see if there is anything better that I can put in there. After taking so much care to make sure everything else is so tight, I don't want to botch this part any worse than it already is. You can't tell from the picture, but the gap gets smaller toward the top of the frame. So any approach I take will need to be able to adapt to the areas where the gap decreases.

Appreciate all suggestions!

Thanks!


Last edited by yelmua; 8th February 2015 at 06:39 PM..
Old 8th February 2015
  #2
Here for the gear
 

How big is the gap and is it consistent from top to bottom? If so then Perhaps you could cut a strip of plywood to the height and width of the door, leaving a bit of room for sealant around the edge?
Old 8th February 2015
  #3
Here for the gear
 

Sorry, just read your post again and realise you've already said that the gap is uneven. Can you say by how much it decreases from top to bottom?
Old 8th February 2015
  #4
It's really all over the place. Along the top, it is half an inch and consistent. On the sides, it's as wide as 3/4" and as small as 1/4". This is where the sheetrock meets the jamb. If you look from the other side, it is actually much tighter.

Aside from the top, getting a piece of plywood in there just won't work, I don't think. Too much irregularity and the gap narrows as you get into the crack.
Old 8th February 2015
  #5
Here for the gear
 

Sounds tricky.

I am just nearing the end of my own build and had a very similar problem with a gap between the building shell and the base of my door frame. The gap sloped from 1/4" to 1/2" from one end to the other. I filled it with a 1/2" plywood strip of 40" x 5" , planed down at one end where the gap narrowed and stuffed the gap with wooden packers where I could fit them. I then just squirted in as much polyurethane glue as possible around the whole thing and it has worked perfectly.
Old 9th February 2015
  #6
I had similar gaps. I fit wood in on a few spots to take up the bulk of space and then filled in everything with heavy construction adhesive (used it to adhere the wood shims inside those slots). It's pretty dense. Liquid Nails. I wouldn't use the expanding foam stuff. It seems way too light.

Plus you'll have the wood trim and caulking over that.

I'd wait and see if Rod or Ethan or the like chime in. They'll give you probably much better advice.
Old 9th February 2015
  #7
Gear Maniac
 

Hi - Ram in fluffy rock wool insulation in - basically fill the void and keep ramming it in till you can't get any more in (use a wooden stick press it in) . Then cover with trim.

This should be flexible and fill the irregular shaped void.

DO NOT USE EXPANDING FOAM - it will be a weak spot for isolation and may even push your door frame out.

Why you have such a gap is beyond me - but it's obviously done now!

J
Old 9th February 2015
  #8
Thanks all for the suggestions. So far, we have: 1) cut wood pieces and fill with construction adhesive; 2) Pack with fluffy rock wool insulation, as tight as possible; and 3) Definitely DON'T use expanding foam. I need to pick an approach today. Any other thoughts out there? Or anyone to chime in confirming that they've used one of these approaches with success?

This is the very end of the build and a major weak spot right now. I want to make sure I do it right. Appreciate any other thoughts.

Brian
Old 9th February 2015 | Show parent
  #9
Gear Maniac
 

Quote:
Originally Posted by yelmua View Post

This is the very end of the build and a major weak spot right now. I want to make sure I do it right.

Brian
Unfortunately you have not done it right - as you have a gap! Can you take off the plasterboard and re-do (just around the door frame) - might be easier in the long run...

alternatively - ram with rock wool...

J
Old 9th February 2015
  #10
Yeah, i'm talking to them about redoing it. Just coming out a couple inches. Leaving the first layer, but filling it with something. And then putting layers two and three up against that, caulking excessively, etc.

My contractor asked about filling it with plaster, but I feel like if that was a good idea, someone would've raised it, haha.
Old 9th February 2015
  #11
Lives for gear
 
Rod Gervais's Avatar
 

Fill the void with insulation - I would not over pack it....... just make it snug.....

If it's snug (but not hard packed) it will not create a 3 point joint.......

Make sure the insulation sits back 3/8 to 1/2" from the surface of the drywall - and then caulk it with Big Stretch caulk........

Big Stretch has excellent adhesion and (as the name would suggest) amazing expansion coefficients....... I've used this caulk on joints over 1" in width without ever having an issue - this even for outside applications.

That will provide an air tight seal that will last.

Rod
Old 9th February 2015
  #12
Many, many thanks, Rod. I was close to having these guys start cutting the existing drywall to add new pieces. If what your suggestion will solve my problem and still give me good isolation, it seems like a fairly easy route to take.

And thanks everyone else for your thoughts as well.
Old 9th February 2015 | Show parent
  #13
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Rod Gervais's Avatar
 

Quote:
Originally Posted by yelmua View Post
Many, many thanks, Rod. I was close to having these guys start cutting the existing drywall to add new pieces. If what your suggestion will solve my problem and still give me good isolation, it seems like a fairly easy route to take.

And thanks everyone else for your thoughts as well.
Door and window openings are always weak points in our isolation assemblies... but seeing as we don't have Scotty hanging around waiting to beam us in - we do the best we can....

In a perfect world the clearance from the inside edge of frame to the edge of drywall would be 3/8" - but that is all about providing a cavity for backer rod (which is always my preferred approach because of the fact that it creates a very consistent caulk joint - both in back of joint profile and depth) - but 3/4" should not destroy your isolation levels as long as you seal up both sides really well.......

Rod
Old 9th February 2015
  #14
That sounds good. We'll do the seals on both sides. We have green glue acoustic caulk on hand. I assume that's OK to use vs big stretch so long as we have the insulation in there giving us something to caulk against. Then trim goes over that.
Old 9th February 2015 | Show parent
  #15
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Rod Gervais's Avatar
 

Quote:
Originally Posted by yelmua View Post
That sounds good. We'll do the seals on both sides. We have green glue acoustic caulk on hand. I assume that's OK to use vs big stretch so long as we have the insulation in there giving us something to caulk against. Then trim goes over that.
I cannot honestly answer that question............. Big Stretch was designed specifically to deal with large gaps (which of course means it works equally well with all gaps smaller than it's maximum opening width) - I cannot say the same for any typical acoustic caulk.........

So perhaps yes - perhaps no.........

And yes - the trim goes over that........

FWIW - I never (ever) specify acoustic caulks for my designs....... they are typically more expensive options with no real added benefit.

Rod
Old 9th February 2015
  #16
Big Stretch it is, then! One last question re: caulk and backer rod. Can i use that as a final seal between my two independent door frames or will that result in "coupling?" Aesthetically, I'd like to seal that up so you don't see through the walls when walking in the room, but not if it will create an issue.
Old 9th February 2015 | Show parent
  #17
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Rod Gervais's Avatar
 

Quote:
Originally Posted by yelmua View Post
Big Stretch it is, then! One last question re: caulk and backer rod. Can i use that as a final seal between my two independent door frames or will that result in "coupling?" Aesthetically, I'd like to seal that up so you don't see through the walls when walking in the room, but not if it will create an issue.
Backer rod and caulk don't physically couple construction elements - which is the one of the reasons we use this approach to seal the spaces between inner outer door frames when building acoustically isolated systems.

Rod
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