Working on finishing my basement. Trying to decide the best way to handle the insulate/framing.
-Put a dimple mat product up to grade
-then 2” rigid foam up against followed by wood frame and drywall.
or skip the dimple mat step and go 2” rigid foam directly on the wall?
id tuck the dimple mat into the current French drain system, and there is nothing currently on the cinder block walls.
thoughts?
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Replies
If no existing waterproofing is in place or existing is not working well, I often install this way. I run the mat from floor to ceiling and seal the edges very well, so no moisture makes it’s way out. I would place the mat up an additional 12” min from grade as water will wick up the block some. My preference is to use metal studs vs wood in basements.
I know exterior is better, but as for waterproofing goes is there a better option than the dimple mat for An interior cinder block wall before the rigid foam?
I get very minimal moisture coming through, just want it as easily as possible to make its way to the French drain.
Your approach is very good and often used by many pros. Dimple mat is good stuff. Also, most block walls have drain on the inside like yours vs on outside like poured foundation, so water is kind of moving to the inside of the wall anyway. Don’t skimp on the sealing of dimple mat on edges and seams. Need to encapsulate the moisture as much as possible and get water to the drain as you know. I’m confident with how you are proceeding, have used this method many times. I do however run dimple mat from the slab to the sill plate. I can’t speak on the performance of only going halfway up the block wall. My theory is might as well go all the way up b/c moisture always finds a way. The moisture may wick and condense higher up the wall.
Appreciate the response, and your theory does make sense. With my basement the way it is going up to the sill plate above grade would be minuscule on most walls, so i will take your advice and go all the way up. Thanks
My only worry was attaching the dimple mat causing more harm with the fasteners, and same with the attachment of the rigid foam to the mat, causing undo holes for moisture leakage.
Use minimal fasteners on the dimple mat and apply sealer over the fasteners when done, no worries. Glue the foam (no fasteners) to dimple mat with big dabs of glue. Just need to keep foam from falling down. Frame your wall tight to the foam to hold it in place.
You might find some good info here: https://www.finehomebuilding.com/2005/03/01/the-no-mold-finished-basement
It's been 15 years since I wrote that, and that particular basement is still in fine shape.
Great information Thanks.
What would your thoughts be on a basement floor with minimal headspace. I’m not opposed to keeping the ceiling open, but as for adding 2” to the floor, on 7’ tall basement even 2” seems like a lot.
I was contemplating just using an epoxy finish, and area rugs in the event of water easier cleanup.
But definitely planned on foam under sole plate for that break in the wall framing.
Basement temp really doesn’t fluctuate much but honestly havent put much thought into floor yet. Had been spending most of my effort on making sure the wall layers I’m planning were okay.
I hear you. Every project is a compromise. Go with the epoxy paint and save the headroom. It's what I did in my own basement.
Here is a pic of a simple basement I did awhile ago. You can achieve a very finished look w/out drywalling the ceiling. I do find that it looks better to wrap the main trunk and return of the hvac in drywall as it tends to be a bit hard and unkept looking. For the floor I prefer a concrete sealer in a matt finish, so the floor looks like stone in comparison to the shiny plastic look of epoxy. The sealer is a lot more forgiving in application as well and allows slab to breathe and moisture to evaporate into the atmosphere. If you do not have a dehumidifier I would suggest considering getting one and setting up a drain, so you do not have to empty containers all the time.
Thanks for all the input guys, definitely have answered my questions and opened my eyes a bit on the process.
I feel like I have a solid plan now going forward.
I noticed u went with black ceiling rafters in that pic. Was it difficult to paint, and I’m assuming u did the underneaths of the floor boards too. Also like the look of those recessed lights inside the rafters.
Yes, painted every surface of the underside of the first floor. It’s definitely a job for a paint sprayer. Was easy to paint, the hardest part was the prep, cleaning off all the years of collected dust. The lights are cylinder light fixtures which we installed in the joists space.
Appreciate all the help so far. I’m having some difficulty locating a dimple membrane product in my area PA. Everyone seems to only sell it by multiple large rolls.
I figured big box stores wouldn’t carry it unless I’m missing something.
If anyone has a name of another brand that can be found more readily online that would be great!
I know the cost is gonna be a decent amount with fasteners and edge seals but I feel it’s definitely needed.