[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]

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.

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

Is it acceptable to have the foam not 100% in contact with the wall as long as it is sealed and airtight?

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.. :laughing:

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?

 

[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]

Ya know, as soon as I typed "period" I thought it was a bad idea.
When you say it won't be enough, what do you mean exactly?

The comments and questioning.

2" XPS airtight won't be enough?

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]

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.

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]

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

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/video/0,,20636057,00.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/documents/digests/bsd-103-understanding-basements?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/icod/irc/2009/icod_irc_2009_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)

 

[johnhend]

I've read that "good stuff" (can of expanding foam) burns the back of the board and not to use it except between joints

On the other hand i've also read "use goodstuff pro flexible window/door".

My experience with Good Stuff (any kind) is IT SEPARATES FROM ALL SURFACES: it always looses contact with the gap it is filling after a few years, it separates from most surfaces especially from any metals, *except* in some niche case cavity fill (where to separate it would have to push wood which it can't do because the cavity is too full to do so).

You would go back a few years later and find the Good Stuff is no longer in contact with either the foam board or the wall in places or everywhere, just loosely held, with a very light coat of mold over it.

Let me make this clear. If you cheat you may as well not use insulation and keep your money in your pocket OR use fiberglass and kneel to the fact you'll have to redo the wall (ie, for mold) at some point. The manufacturer calls for foam board adhesive which is latex based and comes in a caulk can - and appears to be caulk-like. (ugh - and deal with cutting and form fitting fiberglass - there must be another way!) I suspect many installations are cheated. Which is why I'm here online thinking rather than doing at the moment.

Of course if your foam is just floating and not bonded around the peripheral, air and head will just go AROUND IT and it will be absolutely useless. Of course.

The problem with caulk is it won't fill large gaps - or be very messy and take more applications - and completely f-up the concerete wall at the same time.

The "right way" is to have a professional screed the wall so that it is even for doing any work including installing foam board.

I have two plans on how to get around screeding the whole wall but because they are un-tested i'm going to just not say them.

I have another problem: my store has really old stock (tanned sides) and the foam board is not flat - it's slightly bowed itself (total rip off!). I know i could use fasteners - which require drilling the concerete everywhere (sucks).

One of my plans is to use a good quality tile mortar ("modifited with wide bonding ability") to fill in the gaps around the peripheral of the foam board. Another maybe (do not try!) is I have a huge can of drywall compound - which i hear by internet rumor can be used to fill pinholes in concrete walls. drywall compound might take up a 1/2" gap better than caulk (caulk will not)

That gets back to the real problem: if a floor or wall is not level then all work after it will be bastard-ized. Keep a level in your hands at all time and accept no comprimises to being level.

 

[johnhend]

I forgot to say in my case I have at least 1/2" to bend (if i installed that it would eventually pull out or off whatever i used as glue, fasteners too - foam is not rated for fasteners).

I am considering CUTTING or TILING the foam. I could slice the board where there are highs - my particular issue is there are many and they are hard to follow. Or I can TILE. Each smaller tile will have easily less than < 1/4 inch deflection which is fine for caulk. (i'm unsure i want caulk all over my concrete wall, honesty, what if i have to get it off??)

TILING (using 2' square sections) is ok but it will take LONGER and use more CAULK on my wall.

I have a huge bucket of USGS drywall compound (general purpose). I'm thinking of doing a test area with it. It's pretty good stuff. If it does dry and does set the foam tiles, I'm guessing it will last many many years with very minimal leakage. And if the wall ever does get screeded: it will be easy/non-damaging to remove it before screeding. But that's a rumor at this point.

 

[johnhend]

My bet is: PROPERLY SEALED AND BONDED 2' square sections (despite having say 1/8" lines not insulated in-between) is A HUNDRED TIMES BETTER than a duck tape job with good stuff that after a few years is separated and has air just going around the foam.

In my case I'd already have returned the foam and bought ceiling insulation except: I'm using metal stud with 600 mil stud spacing and modified concrete-to-drywall depth. I'd have to cut and fill with fiberglass in 3 dimensions it would be a total pain. And I'd then be assured that some years later: it'd have mold and have to be replaced purely because of the fiberglass.

And that's why i'm thinking fill gaps with good mud (mortar or USGS drywall mud). Because mold stays away from both of those - but caulk ruins concerete (if you have to re-bond to it someday) and really old caulk does separate (after 30 years) and does get covered with mold a little and does get deep tan (mold eats latex, paint and latex is a food source, and dark behind a wall with moisture and no airflow: perfect for mold).

 

[carpdad]

First lay out the wall lines, put the fire block against the ceiling joists (3/4" ply), then pressure fit the board against the floor and ceiling and use the can foam to seal all 4 sides. The insulation boards do not have to be part of the load bearing parts. As long as it will stay in place over time, it can be installed floating away from the wall. If you happen to break the seal or the board, just patch with more can foam.
Most cost effective insulation is stopping the air movement as much as you can.
Between panels, I leave about a width of the foam straw and inject a bead into the space. I have boarded the hvac duct and did not notice any separation although the air pockets were visible after I trim the spill over. In younger days I made a mistake of foaming the bottom end of the vertical t&g siding where the floor plates were letting in a lot of draft. This is outside and about 6" away from ground. Many many years later I went back to see what is happening there, I had to trim the accesses with razor and although the surface had deteriorated, the foam was stuck. I did have problem with good quality foil tape not sticking to xps blue boards, although gorilla tape would.

 

[Gary in WA]

And drywall mud does mold, open any bucket years later and throw it away. And XPS foam board does shrink to break the joints and allow air behind it to condense so what ever you use, research it first. And Drylok does mold. So even using GS/W&D canned foam at joints, it says on the product- about 3% in first 2 weeks. Links if you need them. Seal it with furnace cement and fiberglass furnace tape. Is the top course of CMU- filled with cement?

Gary