Question for you guys who frame basements.

[JelloStorm]

Hey guys,

I'm a first-time basement refinishing noob struggling to find the right insulation R-value for the interior basement walls of my house. My house is a relatively new build, built in 2005, that uses solid poured concrete slabs 2' in diameter. The majority of the wall is below grade.

I have not noticed any real issues with moisture. Only once during a torrential downpour did I see two wet-spots on the wall so I don't know if I need to spend the extra cash to seal the walls. Lowes has this latex Drylok stuff for ~$24.00 a gallon.

I plan on using the 4'x8' foam to insulate the walls since they would create a vapor barrier and don't absorb moisture, but living in Northeast PA, I'm seeing that I need an R-value of 19. The only problem is, the 2" thick 4x8 sheets of foam are only R-value of 10. Which would mean I would need to double them up just to get the correct R-value, right?

At $32 / sheet for R-10 2" thick I'll go broke since about 10 of them or 20 if I double them up. Or is there something I am missing here??

 

[Switchblade]

I'm in upper mid TN. Winters get down to the teens. The 1.5" I used is sufficient due to the fact 75% of the basement is actually under ground level and not directly exposed to exterior. The thinner R value works fine and we don't use much heat or AC to keep it nice. The morons that did the original work had the right idea, but their execution sucked balls. Sooner or later I am going to have to rip it all out and replace it

1. Check the entire surface for any hairline cracks or other places that would allow seepage. Fill these in with hydraulic cement
2. Paint the walls with basic white DryLok
3. Now do the same for the floor
4. Set your lines at 2' on center, all the way around the perimeter, making sure you add 1 to each doorway or window
5. Using construction adhesive, set the floor with 1" weep proof backed, insulated floor board
6. Set stud marks on the walls at 2' centers
7. Frame out the top
8. Using concrete sealing nails, and moisture barrier, set your studs on the flat, all the way around the room. Seal them along the edges, tops, and bases
9. Set your wiring, plugs, and other low to the floor items
10. Insert your 1' - 1.5" foam insulation, all the way around the room.
11. Set your drywall
12. Finish out your drywall and doorways
13. Set your ceiling

 

[Brian]

I'm in upper mid TN. Winters get down to the teens. The 1.5" I used is sufficient due to the fact 75% of the basement is actually under ground level and not directly exposed to exterior. The thinner R value works fine and we don't use much heat or AC to keep it nice. The morons that did the original work had the right idea, but their execution sucked balls. Sooner or later I am going to have to rip it all out and replace it

1. Check the entire surface for any hairline cracks or other places that would allow seepage. Fill these in with hydraulic cement
2. Paint the walls with basic white DryLok
3. Now do the same for the floor
4. Set your lines at 2' on center, all the way around the perimeter, making sure you add 1 to each doorway or window
5. Using construction adhesive, set the floor with 1" weep proof backed, insulated floor board
6. Set stud marks on the walls at 2' centers
7. Frame out the top
8. Using concrete sealing nails, and moisture barrier, set your studs on the flat, all the way around the room. Seal them along the edges, tops, and bases
9. Set your wiring, plugs, and other low to the floor items
10. Insert your 1' - 1.5" foam insulation, all the way around the room.
11. Set your drywall
12. Finish out your drywall and doorways
13. Set your ceiling

With the studs on the flats they're only going to be as straight as the poured walls are and once the board is up the waves and lines will come out

Why not set the studs conventionally independent of the poured walls guaranteeing a straight wall and insulate with the batts?

 

[Deerhunter28]

Use 1 5/8" metal studs.
Get your walls plumb.
Before this paint wall with drylok or there are others that are better.
Follow the instructions to the T.
May need to caulk some cracks?
Again do what water proofing manufacture recommends.
As far as insulation your are below grade.
If needed def go with a ridged insulation seen it up to 4" thick or multiple sheets?
Again you are under ground but I'm from the South not North.
HD Supply will be your best waterproofing friend and insulation.
CK supply will be your metal stud and drywall friend.
MR drywall would be a good idea or mildew resistant



Good luck




PSE EVO 60 Lbs.
Blacked out

 

[Punisher29073]

What's a basement?

Ryan

 

[Deerhunter28]

What's a basement?

Ryan

Top floor of the house


PSE EVO 60 Lbs.
Blacked out

 

[79jeepcj5]

However you decide to frame it, be sure to use pressure treated lumber anywhere the framing contacts concrete or block. Good luck!

 

[JelloStorm]

However you decide to frame it, be sure to use pressure treated lumber anywhere the framing contacts concrete or block. Good luck!

Yeah. I'm doing the taped foil to the wall test for the next few days so we'll see how that turns out too.

 

[jrassy]

If your test doesn't show a lot of moisture I wouldn't spend the money on waterproofing and rigid insulation. If your going to run electrical wiring and plumbing just go with a treated bottom plate and 2x4 studs. Hold your stud wall 1/2 inch off your basement walls, plumb your walls, nail your top plates to your first floor joists, insulate with R-13 batt insulation,Sheetrock with 1/2 inch rock if you go 16 inches on center. I would also use metal studs but then you might have to add wood blocking for base trim, no big deal really. There are lots of helpful videos for this. Keep your Sheetrock at least a1/2 inch off the floor so it doesn't wick up any moisture off the floor.

 

[Hookturnr]

Alright, being in western PA, I know the climate. Having done this for a living for the last 20+ years, I have an idea what you are trying to do. Above advice was interesting...some good, some extreme overkill, some just plain amatuer.
If your walls are 90% below grade, the needed r-value will be minimal for most of the wall.
All the sealing advice is way over the top in a monolithic poured foundation wall system.
Inspect for visible cracks/wet spots, if none, soldier on.. as for framing materials, take your pick.
I'm partial to 3 5/8" 20ga. steel studs but you can use regular SPF 2x4's if you like. All you need to do with the wood is use construction adhesive on the bottom of the bottom plate to isolate it from the concrete floor. When you frame your walls, frame them conventionally (16" centers normal orientation) unless there is some pressing need to do otherwise.
Make sure to stand your walls approx. 1/2" off the foundation walls.
Insulate with standard r-13 kraft faced batts.
If you're worried there may be a mold issue in your future, sheet the walls with 1/2" densglas. It doesn't have any paper content to feed mold, however it will require a level 5 finish to appear smooth. If you're good and dry in there, I'd just use regular drywall and rock on..
Your floor preparation will entirely depend on what finished flooring you choose....ceramic tile is my preferred product as it is impervious to the floor moisture issues that crop up and you can run electric floor heating so it's comfortable to throw it to the wife on the throw rug after your done..
All in all, just don't over think it. If you're not comfortable doing it yourself, hire a pro.
If you can't afford to have a pro do it, find one that will consult with you for a fee..

I have made a very good living coming in and repairing/replacing homeowner attempted projects over the years....don't be that guy..

good luck!

 

[79jeepcj5]

I agree with the advise hook gave you except for the waterproofing. Having already stated that you've had some moisture on the walls, don't skimp on the moisture prep. If water has a way in, however small, it's gonna find it.

 

[thrusty]

Did crazy amount of research on doing my basement.......

Insulate your rim joists - I used 2" foam board, sealed with caulk or foam and will put R30 fiberglass on top for added value.

Most of the info you will find here on keeping your basement dry and mold free:
BSD-103: Understanding Basements ? Building Science Information

I have poured foundation walls....
Ensure you do not have active leaks...if you do, fix them first.
Insulate your walls with 1" - 2" rigid foam board (whatever you can afford or depending on how much R value you want).
Use the appropriate adhesive caulk for foam board.
Use expanding foam to seal corners, top and bottom of rigid foam.
Tape the seams of all your foamboard....Tyvek tape is expensive, but this is an important step....
Foam board provides for a capillary break between concrete and all the other stuff that can mold if moisture contacts it.
MOST IMPORTANTLY: Foam board does not mold when it becomes damp/wet...so it allows for the moisture to evaporate on it's own and slows down the creation of moisture when you turn the heat up in the warm zone and the concrete is as cold as the ground outside.

On the outside of the foam board, frame your walls.
Wood or Metal framing is fine....
Any wood touching concrete must be treated...ALSO, use a gasket on the bottom of the bottom plate of your wall. Will help seal and keep moisture/water from running underneath.
I would use Tapcons to attach bottom plate to floor so you can take walls down more easily should you get a bad leak and need to repair...but Ramshot will work too.
Between studs, use fiberglass insulation...you should be around R20 by the time your done if you use 2" foam board and R13 Fiberglass.
Wire and close with drywall.
You do not need to use a vapor barrier -That is what your rigid foam is for. You also should not use fiberglass in the walls with a vapor barrier (kraft face) either.

I will note that I did NOT paint all my walls with Drylok or any of the other sealing items. I did however have a bad crack that was leaking...I widened the crack with a chisel, filled it with DryLok fast plug...then painted over that with DryLok...Hasn't leaked since.

It is REALLY important to note that you do NOT want fiberglass touching concrete behind a closed wall. Fiberglass will mold if it gets moist/damp...concrete does both - even when leaks are not present, concrete wicks moisture from the cold zone (outside) to the warm zone (your basement).

Check out this diagram for better description:

 

[wdebo]

Do not use fiberglass batts for insulation in your basement. Every county I build in that does not pass code for a reason. It will cause you problems down the road.
Use 2" foam glued to the concrete walls and stud walls built over that. The best option is to use closed cell spray foam. This is the method I always use but it's expensive.

 

[K2Ballistics]

Do not use fiberglass batts for insulation in your basement. Every county I build in that does not pass code for a reason. It will cause you problems down the road.
Use 2" foam glued to the concrete walls and stud walls built over that. The best option is to use closed cell spray foam. This is the method I always use but it's expensive.

This^^ . If you insist on using batts, your wall need to be far enough of the concrete wall so that the insulation is not touching and that there is air flow between the two. This will place your studs 2-3+" or so from the concrete wall not 1/2".

 

[Switchblade]

With the studs on the flats they're only going to be as straight as the poured walls are and once the board is up the waves and lines will come out

Why not set the studs conventionally independent of the poured walls guaranteeing a straight wall and insulate with the batts?

I forgot to state that the studs are set plumb slightly off the concrete to facilitate two things:
The ability to use 2" foam moisture blocking insulation with spray foam behind the studs, and once the frame is set, and the drywall is dine, it is still narrower than the 3.75 inches of basic 2x4 metal or wood. I refer metal frame because that is what I know, but wood works too

 

[Tough Guy]

Don't forget to add in the hidden room for guns and ammo.

 

[Brian]

...If you insist on using batts, your wall need to be far enough of the concrete wall so that the insulation is not touching and that there is air flow between the two. This will place your studs 2-3+" or so from the concrete wall not 1/2".

Correct.

Isn't this the correct way to do it though and not halfassing it?

With a kitchen or bathroom involved you not getting drain and vent pipes in the outer walls built on the flats unless you notch the walls and you still have to nail plate all the plumbing.

And with wiring you would have to nail plate or sleeve all the Romex or use Armored cable on any of those walls to meet the NEC unless of course your halfassing.

 

[meathunter1]

Use the pink/blue depends on retailer. Foam board adhesive. Tape the seams. Stud walls in normal fashion. Use PT plate on floor. They make a foam strip to put on the concrete. Its in a roll. Only a couple bucks. Tapcons or ramset you pick. I live near prospect, pa. I am 50% below grade and have no moisture problems at all. I am starting my "outside" walls now and will be using this method. I will post some pics throughout the process.