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How to finish this basement

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How to finish this basement (post #216018)



I am new to these forums and could say I was a weekend warrior DIYer. I have doing projects for a couple years now since I moved from Europe and houses here in this side of the pond are so much easier to work on - my houses in Europe were solid concrete.

After last year building a deck, and also tearing down a stairwell which was load bearing in order to open up kitchen and living room and installing a 22 ft LVL beam, I thought for a project this summer, why not finish the basement? Sure enough!


 My question is on how to structure the outer walls of the basement. I have researched for so many hours and there is so much conflicting information it's hard to decide on what...
Ive seen people recommend moisture barriers, others saying they dont have a place in basements... others for vapour barrier others not for it...
Details of the house:
- Single Ranch House with basement
- Basement built out of cinder blocks
- Late 50s or early 60s house - no idea if there is any waterproofing or barriers from exterior
- Grade on the soil is away from the house
- House has 2-3 gutters and they all lead 8 ft away from house and are all working
- French drench drain around the inside perimeter of basement leading to a sump pump is present
- In the 4 years that I have been in this house, never I have seen any type of infiltration. EDIT - correction - there was some seepage on the walls coming from the windows but this was before the new windows were installed. Before this, they were the old iron, single pane, with lots of gaps windows. About 2 years ago I changed for double pane modern windows and sealed them correctly ... 
- Location is Central PA - hot and humid summers and cold winters.
My idea was to put the XPS foam against the cinder blocks and tape the seams with a good quality tape. As far I was able to see, because I have 2'' panels I shouldn't need a moisture barrier since the XPS at 2 inches acts itself as a moisture barrier. Then, on top of XPS just build the walls with studs - I would go for metal studs -, perhaps add extra insulation such as rockwool or just leave the gaps empty and apply a vapor barrier (is this still needed??) and then drywall.
My concern is with the application of the XPS and the french drain at the edge... i do have cinder block so there are grooves in them although staggered... would this be enough if water comes in, to slide all the way down the wall to the french drain? Or, should I use some sort of dimple mat between the XPS and the cinder blocks? If I were to do the whole wall, this would get expensive... 1000$ just for dimple mat... I have seen someone recommend, to just apply dimple mat the first 6 inches from the floor in order to make sure the french drain entry is open...
Also, should I use Drylok paint on the cinderblocks? My wife says her mothers basement used to leak a lot! and once they did the Drylok paint all issues were gone... again, online I have seen contradicting information about the use of this... granted, we don;t have a wet problem basement ... sure it's a bit damp but i dont see any runoffs, however I will be doing the plastic sheeting taped to walls test in order to assess moisture. 
Regarding installing the XPS onto the cinder blocks, what would be the best method? Glue? Tapcons? If I am to drill holes in to the cinder block isn't that counter productive since we are trying to keep water away from getting in?
Any feedback and advices would be greatly appreciated!

? (post #216018, reply #1 of 7)


All I know is that there are (post #216018, reply #2 of 7)

All I know is that there are a lot of differing opinions as to how to finish off below-ground basement perimeter walls.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Late 50s or early 60s house (post #216018, reply #3 of 7)

Late 50s or early 60s house would likely have only tar on outside of basement wall as waterproofing. Probably hardened and cracked by now.  Conrete block will let water travel through them.  French drains in basments were also not common to the age of the house.  Suspect there was water problems some time in the past requiring installation of the drain.
Given that, put up a drainage membrane on the wall from ground level down with clear passage way to the french drain.
XPS panels against the wall.  Friaming will support the panels, You can use glue to hole them in place untill framing is installed. Seal panels to each other for air barrier and to protect framing from condensation.
Frame walls and insulate,  If framing with wood, pressure treated for anything that touches the concrete.  If metal, use platics spacers / shims  so no contact with concrete.
You can also use thicker XPS panels, and then use 1x3 strapping to support the finish drywall.
If finish floor is the concrete slab, tiles or vinyl on top of concrete, space drywall 1/2" up from floor, use plastic baseboards.
If putting in DryCore subfloor or similar, put that in before framing. Framing to sit on the  DryCore.
Check minimum insulation requirements here:

Thanks great (post #216018, reply #4 of 7)

Thanks great info.


Yeah I suspected that... basement I think it leaked from those iron single pane sash windows because the block walls have stains right under the windows... ever since I never saw anything.

I have had poolysheet taped to my basement walls for the past couple weeks in 1x1 foot sections or little bigger... no moisture and we have had in the meantime 4 inches of rain where 3 inches were in a single 24-36 hour period...


Regarding the walls... Drylok ... yes or no? Is it worth to put it on since it would be "cheap" insurance for extra protection?


I am going to use metal studs ... I was thinking of using a EPDM sill gasket to go under the metal track ... I also already bought the tape to seal all foam seams as well the foam gun for all joints...

I would not use the epdm (post #216018, reply #6 of 7)

I would not use the epdm gasket under the sill plate. It will trap moisture and dam it up.  Unless you use short sections of the EPDM with gaps. Use the plastic shims suggested before that will keep the metal form contacting the moist concrete and in the event of water intrusion you will at least see it. On further suggestion consider using a fiberglass faced dry wall product such as Densearmor plus. The fiberglass will not support mold growth and if anything gets wet or damp you can dry things out without needing to remove drywall.

"Regarding the walls... (post #216018, reply #5 of 7)

"Regarding the walls... Drylok ... yes or no?"

Drlylok is good, if using this, install per manufactures instructions.

6 mill polyethylene sheet will do at less cost.  If you use this, suggest you tack it to the concrete with acoustic sealant.  Will stick  better than tape.  Continuous bead even with outside ground level.  A few dots at bottom to hole in place untill walls are in place. Fold on bottom along floor to direct water to the drain.

Drainage barrier is from ground level down to the French drain.  Above ground level, the basement wall should be left bare to allow any moisture to disipate.

I just sold a similar ranch (post #216018, reply #7 of 7)

I just sold a similar ranch and I still believe basements are risky to convert to living space.

That said, many people want to get as much living area as possible.

I won't get into the wall/ insulation disagreements, but I will strongly recommend grinding/polishing/staining the concrete floor.

Water is most likely to end up on the floor for so many possible problems with pipes, boilers, rain, water heaters,..... Water will eventually ruin any flooring buildup.

keep it simple and clean.