Building A Basement Storage Room
The basement storage room project is coming along nicely. I recently wrote a couple of posts, Finished Basement – Step 1 Insulation and Basement Framing and Insulation Update, about how to properly insulate a concrete foundation wall in a basement. Now that the walls are insulated I’ve started finishing off our new storage room. I’ve decided to put 1/4″ luan on the walls and ceiling in this room to keep the costs and labor to a minimum. Plus the room really is only for storage so it’s not like it needs to be super nice. One MAJOR disclaimer though is about using the luan in this application. The fiberglass insulation is kraft faced and it really should be protected against fire with drywall. However, seeing this is a storage room and I have no real source of fire I’m willing to take the risk.
Storage Room Shelving
For this project I’m planning on building two sets of 24″ deep shelves along two of the walls. Along at least one of the other walls I’ll build some book shelves for the hundreds of books my wife and I have accumulated. The shelves are pretty simple. I’m using a 2×3 along the wall and front edge of the shelves. I’ve used 1/2″ cdx plywood for the shelf and a 2×4 vertical column support at mid-span.
As you can see I’ve also divided up the wall height into thirds which gives me about 30 inches between each level of shelving. This room should give us most of the storage we need for items which we use seasonally. For long term storage we have a full attic in the new house that we can store things in.
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Todd,
Good post about basement storage. What a lot of people forget to do is insulate their basements. Heat loss through the basement can be significant if the basement is not properly insulated or sealed.
I am looking forward to working on my basement after we mitigate the water problem.
Paul,
Thanks. Basements are a real challenge when it comes to finishing them properly. The biggest gamble is always the water issue as you already know. I think the method I used will work really well and help keep moisture at bay.
Todd,
I insulated the concrete walls with polystyrene as you recommended and have a good jump on the framing. I'm using standard 2x4 walls for electrical reasons. My only question is why do you use faced fiberglass over unfaced? Doesn't the polystyrene act as the vapor barrier due to the 3 mil plastic on either side? I guess I'm concerned with having two vapor barriers and potentially trapping moisture in the wall.
@ Josh - The vapor barrier is an issue that isn't really definitive. Here's the scoop. Warm moist air wants to condensate on a cool surface. Let's say you only install 1" of foam board. You've not completely insulated the concrete to prevent that cool surface from condensating warm moist air coming from the finished space. So, some folks recommend the vapor barrier at the finished surface from letting that moisture into the framing.
The foam board should be stopping all moisture from coming from the concrete side. If that's true then there shouldn't be moisture traveling out towards the finished space. All of this is pretty subjective. It's a coin toss in my opinion. All I can say is I've done it this way successfully.
if you use the foam on the foundation walls, do you still want a vapor barrior between the fiberglass insulation and the drywall?
@ Joel - There is no perfect answer to that question. It really depends on how thick the foam is and if you feel it has created a sufficient vapor barrier. If you feel it is too thin then you should definitely use a vapor barrier.
House information: I have a 3-yr old house. I'm planning to insulate the poured concrete basement walls. Some basement walls are completely exposed to the outside air, some are partially and others are totally under ground. I had a 1" exterior foam board attached to the exterior concrete basement walls that were located below the ground level.
Proposed Project materials:
I'm planning to use Cellofoam North America Inc's Polyfoam board (1"x4'x8') sheets and glue them directly to the concrete wall. Then install a 2x6 wood framed wall directly next to the foam board. Then insulate the walls with R-19 fiberglass faced batts. Then place 1/2" drywall over the 2x6 framing.
Questions:
1. I have no water problems. The builder installed drainage pipes around the perimeter of the entire basement wall and the drainage pipe is exposed at the edge of the property. Do I need to apply Drylok to the inside of the concrete basement walls?
2. What are your thoughts of using the Polyshield product versus a extruded Polystyrene products from Dow or Lowe's version? I know the R value is less but I figured I will gain it back with the R-19 fiberglass. The Cellofoam website indicates the Polyshield board is mold and mildew resistant. Any other differences I should be aware of? Your thoughts?
3. What about faced versus unfaced fiberglass in the wooden wall?
Thanks
Tim
1. Drylok is one of those things that I think is probably ok at keeping some moisture at bay but it won't do a darn thing when cracks develop in the concrete. Having said that if you don't mind the cost and labor then it certainly can't hurt.
2. If you go to: http://www.cellofoam.com/Polyshield.htm and read the first paragraph you'll see NOT A VAPOR BARRIER in bold print. Basically I wouldn't recommend using this product in a basement. The whole point of insulating the walls in the fashion that I proposed is to use a minimum of 1-1/2" of extruded polystyrene which will act as a vapor barrier. You MUST stop moisture from the foundation from getting to your wall framing.
3. Ideally you'd install 2" or more of EPS and skip the fiberglass. Having said that it's not always cost effective for an honor. So the use of both products can be a good compromise if you've got a good vapor barrier (i.e. min of 1-1/2" foam). At that point the faced/unfaced arguement isn't that important. I say use what is easiest for you.
I hope this all makes sense.
Thanks Todd for the information. If I use a 1" EPS board with a 2x6 wall(R-19 faced fiberglass), will the 1" board be good enough for the vapor barrier? Lowes doesn't sell 1.5" EPS board. Please advise. Thanks.
Tim - Most all literature on the market says you need a minimum of 1-1/2". I would check with a local building supply company as they typically stock many thicknesses.
Is it always best to put the wood frame against the foam board? I've also read you should leave a inch as well. I'd rather put it against the board for saving space.
Brian - It really depends on how dry of a basement you have. If you've got the chance for water then leave the gap. If you've got a really "dry" basement I'd put it tight.
Todd,
My house is 6 years old. I am the 2nd owner. The house was built with the exterior foam insulation on the basement walls. The 1st owner put Drylock on the basement walls and had the basement framed in, but never completed the project beyond that.
I would like to finish the basement. It is obvious you always recommend the 1-1/2″ of extruded polystyrene which will act as a vapor barrier. In my situation, I do not want to tear down all the framing already completed to do this. There is just a minor gap (1/4") between the wall and the framing. Would you recommend a thick plastic sheets between the concrete wall and wood framing as an alternative vapor barrier? And if you do recommend the plastic, should there be a air buffer between the plastic and the fiberglass insulation? I have not decided on faced or unfaced insulation yet.
Thank you for the help.
Brian - I don't recommend that. Quite a few people have asked that question and the answer is fairly straight forward. While the plastic would act as a vapor barrier for moisture that wants to leave the foundation it also creates a problem for any moisture from the other side. The plastic will be cold (touching a cold foundation). If warmer moist air hits that cold plastic it will condense and turn to liquid. If that happens it's likely to get trapped in the insulation and promote mold.
If I were you I'd just cut the wall framing loose (cut nails top and bottom that attached the framing to the slab and or framing above). Tip the walls down, insulate properly, then stand the walls back up and attach. You may need to cut them down a bit on the ends for the shorter wall lengths.
Hey guys. I have a split level home built on a hill, the lower level is cut into the hill about 4 feet on the west side. Since the basement is not completely underground is the1 1/2 of foam insulation over the foundation and behind my stud wall still 100 percent necessary?
I could probably fit 1/2 inch foam in-between the gap that already exists between the stud wall and foundation. would that be sufficient considering I am not completely underground?
Ej - It doesn't really matter how much is below grade. You really need the thickness to prevent water vapor from leaving the foundation and getting into the framing.
Todd,
I have a similar situation to Brian L. above. My basement was framed with studs and heavy plastic behind the studs (between the studs and the basement wall). The electrical wires have also been roughed in. There is about an inch of space between the studs and the basement wall. I was thinking of having spray foam insulation installed (3" of open cell was recommended up against the plastic and partially behind the studs and partially into the stud cavities. I would like to get your opinion on this since getting foam board behind the framing is not feasible at this juncture.
Richard - I think that approach is fine but I'd be very cautious of the open cell foam. In this particular situation it might work considering you have the poly but I'd still worry. Once open cell foam gets wet it holds water like a sponge.
Todd,
Do you think that closed cell foam would work better then open cell foam? They can do either one but they claim that they usually use the open cell foam in that situation. They said they would use closed cell foam if the vapor barrier was not behind the studs. They said the closed cell foam is harder and more brittle.
Thanks,
Richard
Richard - Closed cell is much better in basements.
Todd,
My last comment was sent before completion, sorry - did you get the first half?
To recap:
I have already passed framing inspection and have insulated the storage room. I used a system I found on the Dricore website.
I installed a Dricore floor 1/4" from the foundation walls and then installed the framed walls on top of the Dricore. No need for a treated kick plate as the Dricore protects it. Less anchor screws into the slab as you can use the Dricore floor to help hold the walls in place. The walls are 1 1/2" from the foundation walls. This leaves an air-flow system where air can run around the walls and under the floor leaving the walls in a similar temperature zone to the whole basement. Dricore says you can even cut holes in the floor for registers to provide more air flow.
My home is around 10 yrs old and has a poured foundation and the builder painted the basement walls and floor. I have never had moisture on the walls. With this circulation system do you think moisture will still start after the dry wall goes on?
I was also discussing “comfort therm” by Johns Manville, which I have started to use. It is insulation wrapped in plastic where the warm side is a plastic vapor barrier and the backside is also plastic with perforated holes that allow the insulation to breathe and dry. The manufacture says that the insulation is for basement use. Given this along with the air flow system do you think I am ok regarding mold? I know your system is better as your way eliminates moisture all together, but as I have already framed the walls will my system work?
If I had it to do over, I would not use this system as I would rather not allow any moisture to form. Also, Dricore is an imperfect product. Its great for warming the floor but if any small amount of water gets under the floor the panels are that well protected, the plastic feet do allow drainage but the tongue and groove seams are not protected and water is wicked up at all the joints. Plus if ever get a lot of water in the basement and need to remove the floor its going to be very difficult with the walls on top of it. Live and learn.
My questions are:
1) Do you have any experience with Comfort Therm regarding its ability to better resist mold.
2) With the Dricore circulation system, Comfort Therm insulation, painted walls, do you think there is any merit to this system?
3) If not, do you think its possible to still get form panel behind the already installed 2 x 4s that have an air gap of 1 1/2" ?
4) Most the walls have a 1 1/2" gap from the foundation wall but one wall has a 5" gap due to a drain pipe running on the ceiling. If I install 2' form panel there will still be a 3" air gape between the form panel and the insulation - is that too much?
Thanks.
John
John,
Dricore is a decent basement sub-floor system. There are certainly merits to allowing good air flow under their flooring system. However, what they are neglecting to tell you is how much water vapor is stored inside concrete. You see concrete is like a huge sponge, millions of micro pores throughout that are filled with water. Throughout the seasons the water vapor migrates in and out of the concrete. As that happens it can cause serious issues behind drywall. When you paint drywall you are creating a vapor semi-permeable surface that has a hard time with letting out moisture.
I don't have experience with Comfort Therm, however, I would NEVER recommend any type of fiberglass insulation product up against a foundation wall even wrapped in plastic. The small perforations in my opinion can let water into the "bag" and cause problems. Now, if you installed this after installing a 1-1/2" layer of XPS foam I'd have no issue with it. You should read some of my other basement insulation articles including: How To Insulate Basement Walls
If it were my home.....I'd stop where you're at, move the walls forward enough to get the proper foam back there, then stand the walls back up. You'll be glad you did years down the road.