XPS Foam on uneven basement wall - Pt.2 (no spray foam)

jefferyscott

I realize that doing spray foam on an uneven basement cinderblock wall is the best way to handle the insulation. However, it is not in the budget. Period.

I have 30" of wall exposed to exterior and 52" below grade. 82" to the sill, I believe. *Wall has Drylok on much of it, but I am removing all the loose sections.

My plan is to run sheets longways with a gap 4" down from the sill. Attach with anchors/screws and PL300. Then use low-expansion Great Stuff to seal the edges all the way around. Airtight.

The most uneven part of the wall are below the 4' line from the sill, although it is certainly not level all the way across. I'll address the rest of the lower portion of the wall in a similar manner, working around the worst bulges.

Is it acceptable to have the foam not 100% in contact with the wall as long as it is sealed and airtight? 2x4 wall in front of the foam, FYI.

Thanks

TarheelTerp

You can say that "Period" stuff... but you know it won't be enough. Right?

I think that so long as you don't have air flowing through you won't have any issues.

hth

jefferyscott

Ya know, as soon as I typed "period" I thought it was a bad idea. Too dramatic...to final...too much overcompensation of the fact that Mrs. Jefferyscott has input on the budget..

I've uncovered some issues along the way of converting the basement to the mancave of music. Going to be a few thousand in other stuff to just get to safe, happy, and not blowing $ out the sill/rim/foundation.

When you say it won't be enough, what do you mean exactly? 2" XPS airtight won't be enough? I don't like 'better than nothing' and agree that half-way is no-way to go. Waste of money. But something is better than nothing in this case, right?
I figued air tight on the wall or airtight 70% on the wall would be similar. Or close.

This sucks. And I can't even cement out the low spots b/c it would be days / weeks of removing drylok. Maybe chisel off the high spots and go from there.

drtbk4ever

Where are you located Jeffery?

Do you plan to frame and finish a wall at some point?

__________________
Bill

A DIY Noob that knows just enough to be dangerous.

jefferyscott

So sorry. Missed the boat on that one.

NE Ohio. Zone 5b, I think.
1940 construction. Cinderblocks. Home is now waterproofed and stabilized, but previous movement was clearly an issue. Maybe an inch of movement in a few spots, and a couple of large (12" round) patches of some sort that stick out.

Will be finishing the basement into a music area with stud walls - rather non traditional construction to accomodate sound needs. The space is not ever going to be legal "living space" b/c of the ceiling height. But I'm going as close to code as possible.

Floor to ground level is 52". The floor is a full breakout, haulout and repour. Still some issues of staining in some places, and some at the floor/wall break, but I think I have some more landscaping issues to address this simmer.



The side walls are level and will be no issue.

Photoshop enhaced photo so you can see where the DryLok is pulled away a bit. I'm removing all of this at the moment. RE-PAINT the wall or leave exposted? It does NOT seem wet behind the pulled away (LIGHTER) paint. Have a test areas set up with plastic/tape and no condensation yet x4 days.

TarheelTerp

The comments and questioning.

I dunno... I was/am saying that if the air behind the board is trapped
there (air tight) somehow ... that you don't have air exchanges to the outside or to the tempered space... then that's probably OK enough.

brockmiera

What about using some low expanding foam in a criss cross grid behind the xps. It will help adhere the board to the wall and it will help isolate air movement in a small space. maybe a 1' x 1' grid? Cheaper than foaming the entire wall for sure.

jefferyscott

Was thinking this, too. Glad to see someone else thinking it. Get some elbow-high calf-birthin' rubber gloves on and just go at it. Will make a mess, for sure. The smaller the sealed chambers in the non-flush areas, the better. And totally seal off the the worst offending areas from the flush ones.

There will be a bead around the whole perimeter to seal the edges from exterior air, and adding inside would, I think, really help.

I almost threw in the towel this weekend and just put up the studwalls, but I really do need some insulation down there. Doing the Sill/Rim in the next few days. Then walls.

brockmiera

I am doing the same thing in my basement now. Poured concrete walls that have ridges everywhere there was a joint / form line. Anyway my issues was only about 1/4" so the PL300 compensated for it nicely. I'm no expert but I think you've got a great plan with the foam and that stuff is CRAZY sticky!

strategery

This kind of issue was covered on an episode of this old house. I believe it was the Cambridge house.

I think they scored a line a couple inches out from the wall and cut their boards to size to line up. I think they spray foamed a vertical bead on the back of the board.

There was also a temporary wall built in front of the boards to make sure it stayed straight in place and the expanding foam took care of filling the unevenness between the wall and the back of the board. Then more foam was used on the bottom to fill the openings and to ensure air didn't get behind the wall.

jefferyscott

YES. Episode 3. They do the basement at 16:25 minutes into episode. They're using a EPS (I assume by looks) with air channels in the back, but the similar concept. I like the idea of setting up the studs from the joists (hinged) and then having a preplanned plumb line. Plumb really doesnt matter 100% in my project b/c a wall will exist in front of it, but still a great idea.

Link is here:
http://www.thisoldhouse.com/toh/tv/v...636057,00.html

Gary in WA

I haven't seen an episode of that show yet, without giving me a laugh... "small dadoes are for air", lol. You don't want any air; either outside or interior to condense moisture on the colder concrete; http://www.buildingscience.com/docum...ts?full_view=1

http://joneakes.com/jons-fixit-database/743

Gary
PS That MA location requires R-10 below grade walls per IRC, may be same with their own state code;http://publicecodes.cyberregs.com/ic..._11_sec002.htm

yet ESP (1-1/2") is only R-5.4...... I'm sure they added another layer to the wall, lol.

__________________

jefferyscott

Well, the project is moving in a positive direction.
The XPS is scored (although I would just cut it otherwise) into sections that will allow me a much more controlled application to the wall. This will put much less pressure on the foam from any flexing that may have to occur and will allow me much better control of filling the gaps with the (window / door / low rise) Great Stuff as I go along.

I'm still clearing away some of the Drylok that is pulled away from the wall, and I have found several significant gaps and mortar line cracks with cold air spewing through them. Its like one more thing to fix / patch / fill after another, but in the end I'll have a very solid and wrapped up wall.

(...and I thought I could just go downstairs, throw up a few walls, and call it a mancave)