attaching drywall directly to concrete/foundation

i plan on attaching drywall directly to the foundation in part of my basement. the basement is extremely dry and theres never been any water down there since the home was built 4 years ago.

my questions are, can you use regular drywall for this? and what would i use to attach the drywall, is there a special glue? any other tips would be appreciated. thanks

 

You'd want to use drywall adhesive, generally is sold iin half gallon tubes and available at most decent hardware & lumber yards. You'll need to p/u a glue gun that works with the large tubes also.

 

telefunken,

One thing that was not pointed out is the moisture that may become a problem when you apply drywall over concrete block (exterior wall). Even though you say no problems in the past 4 years but it has been directly exposed to the room. Now that you intend to close this with a barrier, you may start a problem with moisture and without a vapor barrier, it is almost a guarantee that you will!

It is not recommended to adhesively place drywall directly over block. You could install rigid insulation with furring strips then drywall but the issue of moisture buildup will be a problem if this space is heated and moisture transferance. The other issue is finishing the drywall, block walls are not usually the straightest and having the ability to anchor your drywall at butt joints will be a necessity.

Vapor barriers should be installed although this is debateable to some. Most municipalities require it as if you don't, with this application, the drywall will be destroyed and the issue of mold and mildew will arise.

Last thing is the need to install electrical and/or posibility of shelving, pictures hanging cabinets. Furr strips or the traditional 2x stud walls will be better for this.

Hope this helps!

 

Doug has made some good points, if you're planning on doing a whole block or cement wall, his suggestion is correct. What I was thinking about is where you have a basement wall that is cement in some form on the bottom an studs on the top. In that sort of case I believe it is acceptable provided you do not have a moisture problem. I've done it lot of times and have never had a call back due to that issue here in the midwest.

 

when you say furr strips, would that mean something like 2x2 studs anchored to the foundation with tapcons, and the sheetrock screwed into that?

i guess the 2x2's or furr strips would have to be pressure treated if they come in contact with the foundation.

 

telefunken,

This is a general article I wrote, discard what you feel is not relevant to your project.

I guess this is the best and most economical way to construct walls that would be placed on the exterior. I prefer to see 2x4 but as mentioned by others they can get 2x3's. You still need that W/T BOTTOM PLATE. The best way is to attach WOOD TREATED BOTTOM PLATE to the concrete is to use either...
Concrete nails - Sometimes this is hard and time consuming!
Tapcon Screws - Relatively easy but again time consuming!
Hilti Gun with ramset nails - Rent the gun, buy nails and charges - Very fast and holds great! - No adhesive is needed.
Doing the wall framing 16" O.C. provides a solid base for your 1/2" drywall. If using traditional framing method, frame your new wall 1" from the vertical block/masonry surface if using R-13. The reason to keep the wood out from the walls is the moisture that could damage them. If using insulation like R-19 and only 2x4 studs, the insulation would touch the walls. I have stated before that if a homeowner did put thicker insulation in, and the wall was only 1" from the masonry surface, I have recommended hanging a vapor barrier between the back of the wall and masonry surface. This doesn't allow for the insulation to touch the wall and air movement is not restricted but at least you won't create damage to the insulation or wood.
Vapor barrier should be placed directly under the drywall. The warm inside air containing water vapor can get past the wall finish and insulation and condense inside the colder wall cavity. If enough of this happens, and the water cannot escape, wood rot, mold, and other moisture-related problems are likely to occur. For this reason, building codes often require installing a vapor diffusion retarder on the warmest side of the wall cavity. This is what is required in Minnesota;

"A 4 mill poly vapor barrier must be placed against all concrete or block exterior foundation walls prior to applying furring strips for full height of the wall. Another 4 mill poly vapor barrier must be placed over furring strips and insulation prior to covering with finish materials. (State Energy Code Requirement)" - MINNESOTA CODE

***PLEASE NOTE THAT YOU MUST MAKE SMALL SLICES AT GRADE LEVEL ONLY FOR WEEPING IN THE POLY IF POLY IS PLACED AGAINST THE BLOCK - ATTACH THE POLY WITH STAPLES TO YOUR JOISTS/FOUNDATION SILL PLATE***

If you do want to increase the R value, move the wall out further or use the R-13 and then apply a rigid insulation over the studs (warm side) then drywall (not paneling) *Code advises a 15 minute fire rated material over any rigid insulation - 1/2" Drywall*..

Kraft Faced insulation is fine to use in the above scenario. No need for the poly and you can do everything easily. You may find this easier and I would do this versus unfaced and vapor barrier because I don't like to play with it any more than I have to.

Let me add one other thing, rigid insulation used on a concrete/masonry surface is fine. Considerations to make in using this is;

1. If you are just using 1 1/2" rigid and furring strips - A. You need W/T strips to protect the wood. B. The strips can be adhesively applied but they must be solid - mechanical anchors may have to be used to insure that if shelving is installed it will hold. Problem with this is, the penetration into a sealed concrete/masonry surface is damaged and subject to leaking. C. Any electrical boxes will have to be shallow - sometimes makes it hard to wire. D. You must use a fire retardant material over this as per Code.

(Most books, articles about rigid and furring strips fail to say anything about the use of W/T and this will get destroyed and be a good source for mold/mildew with the slightest hint of moisture)

2. Alternative which does add cost is to apply full rigid sheets to the concrete/masonry walls, adhesively applied, then place frame wall against the rigid, then insulate between studs and cover with drywall. The Rigid insulation does then act as a the vapor barrier. Do not tape/seal the seams. This allows it to breath and dry up any condensation that may form.

So here is some more stuff....

W/T is wood treated. International Residential Building Code says "it must be used whenever wood is in contact with concrete and/or masonry". Check it out with your local inspector. This would also include furring strips applied directly to a vertical block wall unless you use the vapor barrier behind it.

If you are considering using 2x2's as furring strips I can only give you my 2 cents worth and you decide;
A. Are you going to have electrical in the walls? Short depth boxes make it difficult to wire. 2x4's would be better. B. Are you planning or foresee hanging shelves or cabinets on the exterior walls? Not alot of strength and may be subject to splitting easier than 2x4's.
C. I personally can't seen how 2" will make a difference in conserving space when you consider the hassle of doing electrical or other carpentry issues.
D. Depending on what you are talking about when it comes to the pre-cut polystyrene, the white foam board, which is the molded expanded polystyrene (MEPS) only is available in R-2 - 3/4" thick, it only costs about $5 per 32 SF. The better quality with R-7.5 is the pink foam - extruded expanded polystyrene (XEPS). This is great stuff but costs more.

Just a note, when you use NON-W/T stock as the 2x2's or 1x3's as furring strips, you have to place a vapor barrier between that and the block wall - you have to attached the furring strips to wall somehow, right? You can't adhesively apply them, you have to use a ramset - this obviously has drawbacks...you just put a hole through the poly making it useless which in turn starts the problem with moisture touching the wood. Second, is if you used W/T or Non-W/T stock and have a waterproofing sealer on your block walls, you just penetrated the block, puncturing the seal coating that was suppose to stop water/moisture...creating possibly a worse problem....water that fills the concrete block cores starts to drain out or will leak in heavy rains. Just thought I'd bring this up. I would do 2x4 walls with R-11 or R-13, insulation would cost about $.02-$.03 more per square foot than the white foam and be better all around. Leave the walls out 1" from the block when framing, apply your poly over the studs apply the drywall and be done. You'll have no problems then.

Hope this helps!

 

Doug,

The full version of your article should be posted such that is anchored to the top of this forum section. It is truly a valuable FYI piece that will answer a good portion of the posts in this section.

 

Jeff,

Thanks for the insight and suggestion. I didn't know if many would read, what we call the "stickies" that are permanently placed at the top of each topic. Most seem to want to get to the meat and potatoes of what the questions and answers are within the postings.

What do you want to call it?

 

I like the FAQ post in the Plumbing Section with hyperlinks to the answers and links back up to the FAQ list.

Your full basement framing piece provides the answers to many posts. It would let anyone planning a basement remodel know what is required, including some details they may not have even thought to ask about. Even if the "sticky post" is skipped, you can refer to it instead of having to paste your article.

 

jeff,

Thanks, I'll work on it. There are numerous items that we could do that to.

I appreciate the feedback, allot!

 

Doug,

What a fantastic article! I just ripped out old ceiling tile and paneling from a basement room (12x19x7), 1x2 furring strips were used. I was thinking of leaving them up, but I can see that for the long run this would not be be best solution.

There is some evidence of slight water damage to the bottom of the old paneling I removed on one of the exterior walls. There was no vapor barrier, it looks like a 1/4" block of wood was placed under the furring strips wherever they were attaced to the concrete block (so the strips did not actually touch, but it doesn't look like that 1/4" 'scrap' weathered particularily well). When I removed the paneling, the concrete block where it looks like water damage occured has the paint bubbling and/or peeling. The majority of the block painting seems fine and it looks as though most of this peeling was near the floor. Perhaps there was condensation and it collected at the bottom.

We've lived in the house for several years and I have never seen actual water leakage - even this year when it seemed we lived in a monsoon over the spring & summer. While I'm no expert, I would guess that this damage is more cumulative and not from a single or several particular instances. However that is just a guess.

With that in mind, do you think the method you outlined is the best? Should I try to treat the concrete blocks w/ a coat of a sealer of some sort?

So what I understand from you article is that the best results are from:

1. Use a wood treated baseplate for exterior walls (regular 2x4 would be fine for interior).
2. Frame by using 2x4s, 16" OC, 1" from the exterior wall. I imagine the W/T base plate would also be 1" from the wall.
3. Use a kraft faced insulation (R-13). Currently my walls have no insulation so 13 would be fine. However this is where I'm confused. Wouldn't the insulation touch the exterior wall & create a problem? I haven't seen R-13 in a while (I have R-19 in the attic), but maybe it's not as deep as I think. If I want more insulation, I could put rigid insulation over the studs.
4. Put a 4 mil vapor barrier over the insulation. Staple it to the studs.
5. Use 1/2" drywall & throw a party.

Does that sound right? You had a lot of info in that article, I just want to make sure I'm on target. Also I'm curious as to the need to treat the concrete block where it has peeled.

Finally, there are mabe a half dozen holes drilled into the concrete block - we used as anchors for a shelf system. Should I worry about those (i.e. fill them or anything)?

Thanks so much - what a great resource!

Bob

 

Bob,

I would say do it as I suggested except that you need not use poly if you are using Kraft faced insulation. The paper is a vapor barrier in itself. Use only poly if you are using UNFACED and then apply your drywall.

Personally, applying a sealer of some type is a good thing but it is not a necessity if you have not seen anything. The sign that you have had some moisture, even if it's condensation is that the paint is peeling. If you want to seal this, it will require some good wire brushing and you have to be sure that the wall is dry! There are sealers out there that can be applied to a damp surface but you are going to spend some money. Bear in mind, that a sealer is not a guarantee that it will stop water infiltration but if it is left unsealed, there will still be air movement behind this wall with the 1 in spacing between studs and wall. Most problems are solved by good outside landscaping and gutters. Again using R-13 for 2x4. Kraft faced is better as you don't have to worry so much about getting the itch!

R-13 is 3 1/2", R-19 is 5 1/2" so this won't touch the wall. There is really no need for more insulation that the R-13, it will be overkill to add more. Just ensure that your rim joist is properly insulated.

Hope this helps!

 

Doug, thanks for the clarification! When you say properly insulate the rim joists, do you mean just extend fiberglass batting high enough to cover the exposed joists?

Thanks,
Bob

 

Bob,

This will help and by the way, you're very welcome!

http://www.energy.iastate.edu/effici...n/basement.htm

Hope this helps!

 

Doug,

Thank you for all your knowledge! What a resouce!!!

I have a question for you. I live in Minnesota. I am slightly confused about the MN code you posted. Does it require a vapor barrier on the inside and outdside of any wall next to a concrete foundation?

Minnesota has some hard core building codes, and that is great in my opinion. Here is my situation. I have a new house with a brand new foundation. The exterior of the foundation is sealed. The house has great elevation and drainage.

I am just getting started on finishing the basement. I am going to use 2x4's and your 1" from the wall suggestion. So, do I need a vapor barrier between the wall and the foundation? I am also having a hard time with visualizing where to stop the vapor barrier. Does it stop at the top of the wall or extend into the floor joists. Same with insulation.

Thank you!

 

bulm,

The poly is place inside the basement to be placed against the foundation.

The vapor barrier as I stated below is to be stapled to either the sill plate or josit. Insulation would be to the ehight of your framed walls. Your rim joist spacing should already ahve insulation there.

"A 4 mill poly vapor barrier must be placed against all concrete or block EXTERIOR foundation walls prior to applying furring strips for full height of the wall. Another 4 mill poly vapor barrier must be placed over furring strips and insulation prior to covering with finish materials. (State Energy Code Requirement)" - MINNESOTA CODE

***PLEASE NOTE THAT YOU MUST MAKE SMALL SLICES AT GRADE LEVEL ONLY FOR WEEPING IN THE POLY IF POLY IS PLACED AGAINST THE BLOCK - ATTACH THE POLY WITH STAPLES TO YOUR JOISTS/FOUNDATION SILL PLATE***

Look at these and if need be, call your local builidng official.

http://www.ci.savage.mn.us/images/do..._Basements.pdf


http://www.whitebearlake.org/Buildin...ent%20Info.htm (by the way, I graduted from here, so where are you at?)

Hope this helps!

 

After looking at these urls and going to the code itself, I think we have an interpretation problem on behalf of the WHITE BEAR LAKE AREA DEPARTMENT OF INSPECTIONS . Looking at the energy code at http://www.revisor.leg.state.mn.us/arule/7670/0470.html it appears that whoever wrote the code for WHITE BEAR LAKE AREA took liberties with what the code actually says.

The quote in question is:

"A 4 mill poly vapor barrier must be placed against all concrete or block exterior foundation walls prior to applying furring strips for full height of the wall. Another 4 mill poly vapor barrier must be placed over furring strips and insulation prior to covering with finish materials. (State Energy Code Requirement)" - MINNESOTA CODE
Found at http://www.whitebearlake.org/Buildin...ent%20Info.htm
This is an interpretation of the State Energy Code Requirement.

What the code actually says:
Chapter 7670.0470 ENVELOPE THERMAL TRANSMITTANCE FOR ALL BUILDINGS
Subp. 6.
B. Vapor retarder. A vapor retarder must be
installed between the interior surface and the winter design
condition dew point location within each building envelope
surface to prevent diffusion of moisture into thermal insulation.


(1) If the vapor retarder is also intended to
serve as the air leakage barrier, then the vapor retarder must
be continuously sealed.

(2) EXCEPTION: A vapor retarder need not be
installed on rim joist insulation not susceptible to
condensation from moisture diffusion.

C. Air leakage barrier. A barrier against air
leakage must be installed to prevent the leakage of
moisture-laden air from the conditioned space into the building
envelope.


http://www.revisor.leg.state.mn.us/arule/7670/0470.html

There is a butt load of repealed laws in that portion of the code, and I can't find what they were. It very well could be the code WHITE BEAR LAKE had referred to was repealed.

My interpretation of this is you would hang a vapor barrier from the sill plate to grade level (dew point location) to prevent degradation of the thermal insulation. The vapor barrier under the drywall serves as the air filtration barrier.

I had to find out about this even though I don't live in MN. That plastic on an exterior concrete wall to the floor would cause a lot more damage than nothing at all.

 

But in fact, every new home I've worked in in Minnesota (not just WBL) has had poly to the floor between the concrete and the interior insulation and studs. Then a second layer over the studs and insulation. This is in fact required even if the basement is not to be finished (unless the masonry is insulated and has a moisture barrier on the exterior).

I can't say why, I'm not an insulater or mason, just an alarm & communications installer.

 

I am looking into finishing my basement. Are there any good books out there that someone would recommend that explains in detail whats involved as far as vapor barriers, mold issues etc. I know alot of this will be based on local building codes.