Basement Subfloor Q's


  #1  
Old 06-19-03, 05:08 AM
mechengineer
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Basement Subfloor Q's

Hello,

I am getting ready to finish my basement and I have a few questions.

When I built my house I upgraded to a 9' basement so I had room for a subfloor and a drop ceiling.

I have read 2 books on basements, and 1 says to frame all the walls and then install the subfloor, the other one said to lay the subfloor, and then install the walls, which one is right?

The books said to lay fireblocking between the sleepers for the subfloor. How do I do this? What is fireblocking (Is it a special type of material, or just cut 2x4's)?


Thanks,

--Matt
 
  #2  
Old 06-19-03, 05:52 AM
Doug Aleshire's Avatar
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mechengineer,

These links might just be what you need to make this easier. There are different products available for doing the subfloor if that is what you want.

http://www.subflor.com/floating-sys.html

http://www.dricore.com/english/home.htm

http://www.dricore.com/english/pdf/Brochure%20ENG.pdf

Other alternative ideas for flooring over concrete...

http://www.hardwoodcouncil.com/displ....asp?artID=139

http://www.tedsmithfloors.com/DIY/Gen_HW/default.asp

http://www.ntlfloortrends.com/CDA/Ar...,87335,00.html

This was done by one of our members....

Before you go spend a lot of money, please look into this. I'm glad I did.
First I found this product called subflor, which appears to be very similar to the Dricore product.
http://www.subflor.com/
Then I found that they wanted $9 a 2x2 piece (4 sq feet). WHOA. So I got some rolls of Delta-FL
http://www.deltams.com/deltafl/index.html and 4x8 sheets of 5/8 OSB which came out to be about a buck per square foot. I'm sorry I can't remember the actual price per sq ft for the Delta product, but I do remember it being less than a dollar.... Screwed it down with some tapcons and I'm good to go! Made my own 'Subflor' for half price!
I've looked into these two products as well. And had one comment. The big difference between dricore and delta-fl is that the dri-core panels will 'float' with thermal expansion and wouldn't take as much effort to 'level' them to irregularities in the concrete. Dricore is a subfloor on is own, But with deltams you need install a sub floor on top of it before your final finish.
I installed Dri-core, solid, VERY EASY to install subfloor!!! It took me and my wife (yes, my wife) about
5 hours for 300 sq. ft., with some cutting around pipes support poles etc. I thought it went well anf it looks and feels great. Just follow the installation instructions and ther will be no problem...Need to do the other 1/2 next weekend...will be putting wall up after that..i will keep all informed on how it goes...But I would recommend this floor to anyone...Thanks for all your input..
I like the idea of putting the walls on top of the dricore, which i will be doing..Should I get any dampness, (which I shouldn't bu if), the walls and toeplate are off the cement. I used 1x3's as spacers and the 3/4" space is just right. . Dricore suggest fatening the toe plate to the flooring and then fastening the flooring to the concrete with 3 fasteners every 16 ft. I think itll work out nice. Let me know what you choose..and I'll keep you up to date on how the walls go up. In addition, i am not using baseboard heat so I did not have that worry, I am using a gas fireplace. Good luck..

I never contacted a flooring contractor about dricore. I bought 2 panels to show my General Contarctor, and he liked it, he had never seen it. From my understanding, it is made in Canada and is only available exclusively at Home Depot in the US. It is $4.97 for a 2x2 panel.

Advantages is that it is easy, solid, incorporates your vapor barrier and sub floor in one piece, allows the panel to "breath" underneath should you get dampness. I will now feel much more comforatble putting down carpet. Another point, it is dricore is only 7/8" high, where a true subfloor with sleepers etc is 2-2 1/4"..a big deal for me because of my ceiling height...

Had to use a few piece of leveling kit near the sump hole..$3.97 for a package of 20 pieces...

Regarding wall framing/insulation....

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 plate. Doing the 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 all helps!
 
 

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