Existing basement framing - what to do?

Paul-Doug · Post by **Paul-Doug** » Sun Sep 07, 2003 12:59 am

Hi all,

Well I'm trying to get going on the basement studio and I'm not sure what I should do with the existing framing, insulation and vapour barrier. As you can see from the dimensions of the control room I can't really afford the 5-6 inches per wall that it takes if I were to leave it and build inside it.

In the pic you can see one corner of the basement.

It probably wouldn't be so bad if it were de-coupled from the floor and the ceiling joists...

So do I take them down, de-couple the top and bottom and put them back up with a douple layer of gypsum... then proceed to the angled walls?

Or can I get away with finishing off the insulation at the bottom applying the double layer of gypsum and relying on the inner angled walls, floated floor and ceiling to do the rest (isolation-wise)?

Your thoughts are greatly appreciated.

Paul

knightfly · Post by **knightfly** » Sun Sep 07, 2003 1:20 am

Paul, it would help to know things like how dry your basement is year round - there are some pretty hairy things that can happen to basement rooms, here's a very eye-opening article that I still need to read over a few more times for clarity -

http://www.buildingscience.com/resource ... ystems.pdf

Other than that, if you intend to float floors and suspend ceilings/walls, you should remove the other stuff you mentioned and use the extra space in the odd-shaped wall cavities for bass hangers - you'll need them to tame the extra bass from concrete walls' lack of bass trapping ability, and the extra air space between inner and outer walls will improve STC also... Steve

Paul-Doug · Post by **Paul-Doug** » Mon Sep 08, 2003 4:00 am

Thanks, Steve....

Ignorance is bliss and I'm decidedly less blissful having read the "basement insulation systems" document. Oh, dear!

The basement is dry year-round but I want to do this right.

So I need to remove the existing insulation, frame wall and vapour barrier. Then I need a recommended basement wall insulation system like the one on page 13 of the document: 2" EPS, frame wall on gasket with unfaced insulation and a layer of gypsum.

It seems to me that this system could make a reasonable outer wall for the control room - maybe with a double layer of gypsum. At least where the outer control room wall is adjacent to the concrete wall (top and right in the pic). It would save me some space. What do you think?

BTW, in the pic,
green - high-end absorbers on slanted wall
red - slot resonator
blue - bass traps

Thanks,

Paul

knightfly · Post by **knightfly** » Thu Sep 11, 2003 3:43 am

Yeah, Paul, that seems like it would work . I read through that basement article a bit more, and came to the conclusion that although too much information can be a pain in the ass, too little can leave you with no ass at all. Before I would commit to specific construction in ANY basement, I'd be digging around inside and out to find out what was already there... Steve

Ptownkid · Post by **Ptownkid** » Wed Jul 21, 2004 8:48 am

Let me see if I've got this right, vapour barrier (plastic) between studs and drywall is bad right? If that's the case, what should I do? Can I just skip it all together? Unfortunately, the walls are already up, because standard building practice WAS to put the vapour barrier on the face of the studs, not behind it. The only other solution that i can see, save pulling the walls down and putting plastic behind it, is to use rigid foam insulation between the studs. Problem is, that still leaves the back of the studs exposed and takes away from the space left to use roxul safe and sound.

Arrrrrrrrrrrgggggg...

serge instrumental · Post by **serge instrumental** » Wed Jul 21, 2004 12:51 pm

There is a BIG mistake here!

Vapour barrier on the studs is really out of the convention! It should be stappled on the structure to cover the thermal insulation. If it is not done this way, the huminity that comes from the inside of the room would go on the structure(wood frame) that would afterwards go to mushrooms!

So plastic on the house's structure(over the thermal insulation), then the inside walls(pine 2x3) could be filled with roxul(add resilient bars, etc.) then the finished wall(gyprock).

Ptownkid · Post by **Ptownkid** » Wed Jul 21, 2004 1:21 pm

You completely lost me here. From the above article, i get the impression that using a vapour barrier on the INSIDE of the studs isn't good. Is this correct? Isn't the moisture coming from outside the concern of vapour barriers?

What you're suggesting is a second wall, I'm talking about a basement, with only one 2X4 framed wall against concrete. Should I not bother to put a vapour barrier on the inside?

Post by **Aaronw** » Thu Jul 22, 2004 12:17 am

I just glanced at your first post, but the picture almost looks like the insulation is getting dark from mold in a couple spots. Have you checked the condition of the insulation against the wall?

Ptownkid · Post by **Ptownkid** » Thu Jul 22, 2004 1:45 am

If you're talking to me, the first post isn't mine. If you're talking to Paul, he's already decided to tear all of that down.

Still wondering if i should just skip the vapour barrier, the basement is pretty dry year round, and i have a dehumidifier.

Thanks

serge instrumental · Post by **serge instrumental** » Thu Jul 22, 2004 2:22 am

Shure it depends of the kind of weather he has. If there is cold winter, he needs a vapor barrier(if he needs to heat during cold weather)

And the gyproc has to be put on a 1x3 to have an air space so that the gyproc doesn't touch the vapor barrier.

So (from the outside) thermal insulation between the house's structure, vapor barrier stappled on the structure, forentz(1x3), then the gyproc.

My 2 cents

Beat Studio · Post by **Beat Studio** » Thu Jul 22, 2004 4:32 am

Ptownkid,

I am in the same situation as you. Budget and time means using the existing studs. Just cut ridged foam insulation between the studs and calk. Forget the vapor barrier. To make up lost space you can screw strips of drywall or wood to build the studs out.

knightfly · Post by **knightfly** » Thu Jul 22, 2004 12:10 pm

Rigid FOAM? Most foam board insulation is closed cell, which is worse than worthless in a wall for sound - the open cell foam is really expensive, and won't act as a vapor barrier (maybe good or bad, depending on where it is and what your climate is like) - rigid fiberglass or mineral wool can breathe, so is good for sound walls and will eventuall dry out, but only if air can circulate around it.

Generally, in climates where the space will be heated mainly, you want the vapor barrier to be on studs next to the heated side - where the opposite is true (deep south, for example) you want the vapor barrier on the outside. In other words, the barrier goes on the warm side of the wall.

As the "infamous basement article" stated though, a lot of how you attack your specific problem depends on what is already there, proper site drainage, and a few dozen other variables.

The only DEFINITE advice in ALL cases would be NOT to rush into anything unless you plan to demolish the whole thing in a couple of years, in which case you might not care how bad you screwed up.

Rod Gervais has had probably more experience in this area than anyone I know - maybe we can get him to suss out this particular situation(s)... Steve

Beat Studio · Post by **Beat Studio** » Thu Jul 22, 2004 2:40 pm

Figure 14 in the basement article was sort of what I had in mind. In my case with a very dry basement I think it will work fine with the insulation board between the studs. Saying that I would like to know for sure especially after watching a friend tear down half his basement family room due to mold.

knightfly · Post by **knightfly** » Thu Jul 22, 2004 3:02 pm

Figure 14 shows EPS insulation completely encapsulating the space, with a layer under the slab floor sealed to a layer up the inside of the concrete wall - inside that is fiberglass insulation - if your basement already has that construction, you'd be good - then all you'd need for a mass-air-mass wall would be the inner mass leaf.

However, if your basement wasn't already built that way, you could run into trouble.

They're also showing gypsum on the studs, with a semi-permeable paint applied - also, a well-drained outside stem-wall - all of which need to work in tandem to get the job done.

In Fig. 13, they show the same thing without the extra insulation, and comment that the inner wall can dry to the interior - it seems to me that using several layers of drywall and hermetically sealing the inner wall would defeat that property, and cause mold problems -

Man, I hate learning some things; they just get in the way of getting anything done

-

If you can describe exactly what you know to be your construction so far, let's see if we can reach a plan... Steve

Ptownkid · Post by **Ptownkid** » Thu Jul 22, 2004 11:06 pm

So I'm ok to use a vapour barrier? The wall is like this, I live just outside of Toronto if that helps any...

outside concrete wall, studs with safe and sound between them, vapour barrier (plastic), drywall. Inside the room is being treated with John's DIY absorbers so I'm not all that concerened about the acoustical properties of the walls.

Thanks