Deck floor in basement?

[TheScottman]

I'm reasonably handy, and want to start finishing off my basement. One part of the basement is really off level due to a bad pour of concrete (not my fault). I'm thinking the best way to solve the problem is to build a subfloor or a deck in this area. The area is approx 6' long x

12' wide. One of the 12' stretches has almost nothing to secure to except for maybe 1.5' of concrete wall.

I have levels, hammer drill, saws etc. I just don't know exactly how to put the floor together, and then how best to level/secure the floor.

The walls are cinderblock, not solid or poured concrete.

I'm thinking I could by about 4 12' and 2 6' sections of wood (2x4?) and frame it all out with brackets. Then level with shims and bolt into the cinderblock with lag bolts or tapcon screws.

I would love to hear any ideas on this. I don't think it's an overtly hard project. I just need a few pointers.

Thanks! The Scottman

[gregz]

I'm wondering how off is it. With a small area like that I would think about self leveling cement.

I've used that stuff before, but the mixture must be just right, else your in real trouble.

Greg

[Ed Pawlowski]

I doubt you need much fastening. What's the worst that can happen if it is floating? It can't fall.

I'd frame it out with taper in the 2 x 3s , Put some insulation between them, at best, I'd use some construction equipment to hold it. Then put the sub floor, etc.

[bob haller]

self leveling concrete is a far better choice, if you use wood use pressure treated wood since basements often have moisture issues.

if water has EVER been a issue fix that first....

[trader4]

One issue with basements is that putting down more flooring means less height, which usually isn't a good thing. So, depending on how out of level it is, I would definitely look at leveling material before going to wood.

[nestork]

Scott:

This area of rough concrete that's 12 feet long by 6 feet wide...

1.) is the concrete in that area lower then the rest of the floor, higher than the rest of the floor, or about level with the rest of the floor but very much rougher than the rest of the floor?

2.) Is it in the middle of the floor, near one side of the floor or in a corner?

Could you not simply set a laser level on your basement floor and mark the spots on the concrete block foundation wall where the laser dot was. Then lower the mark by 1/4 to 1/2 inch to mark the level of the basement floor on the concrete block wall. Now, finally raise each of the marks on the concrete block wall by 1 5/8 inches. Now, use Tapcon screws to fasten a 2X4 to the concrete block wall so that the top of the

2X2 is even with that final set of marks.

Now, pick out a straight 2X4 at the lumber yard and cut a 1 5/8 inch notch ot of one corner. When you rest the notched end of the stud on the 2X2, the bottom of the stud will be level and even with the basement floor.

Now just paint the surface of the old concrete you want the new concrete to stick to with an concrete bonding agent and an old brush, and then let it dry.

Now, within the time period specified by the manufacturer of the conrete bonding agent, have a helper mix up some concrete mix and throw it with a shovel onto any areas that need to be a bit thicker. You just keep working that screed to ensure that all the concrete remaining behind the screed is level eith the bottom of the notched 2X4.

Then, cover the concrete with plastic while it cures to get it to cure as hard as possible, and then remove your 2X2 from the wall.

Bags of concrete mix will indicate how thick a pour you can do with the mix in that bag. Typically each bag will render 1/2 cubic foot of concrete, but the thinnest layer of concrete you could apply using that mix might be 3/4 inch thick because the largest size stones in the concrete are about 3/4 inch in diameter.

Some concrete mixes have fiberglass strands in them that hold the cured concrete together so that it doesn't crack. I know the fiberglass reinforced concrete is more expensive, but it'd use it for a relatively small repair like this one.

[Jim Elbrecht]

*If* you've been there several years, including a really wet one, and there is never any water problem. . . . [if it has ever been damp, or you're new there-- search for how to damp proof your basement]

I'd use floor leveler or self-leveling cement - then cover it with those squares -- Had to look it up

You don't mention if it is a 10' ceiling or 6'1" -- nor do you say if "really off level" means an inch in 12'- or 3" in 3'. . . . or if it affects the whole floor, or just a section. All of those variables would be important to me.

Jim

[krw]

Wood does give the opportunity to add insulation, though. Some floorings are better/easier over wood than concrete, too.

That said, I really don't like the idea of finished basements. Too much chance of mold. ...and it takes up valuable shop space! ;-)

[willshak]

TheScottman wrote the following on 10/7/2012 7:45 PM (ET):

What I would do. Rather than going through all the steps and waste all my typed characters, I'll give a shorter example. You know how they build a house wall in stick built construction? They build it flat on the deck and then raise the completed wall to form the wall. Well, do all that and then don't raise it, just level it. :-)

[Doug]

I'm not a big fan of wood in a basement but it can be done. Keep in mind you might get water in the basement.

[hrhofmann]

You don't want concrete mix to level the floor, it has srones/ aggregate in it that will not allow you to completely level the floor. You a mix with only sand and cement. I sure wouldn't use wood, that is just asking for trouble, as well as losing ceiling clearance.

[recyclebinned]

I just got finished leveling a 10=92 x 16=92 concrete floor=20 in a room that was off between 2=94 to 8=94 without any help.=20 First I stringed and framed it into smaller sections,=20 mixed in a motorized mixer and poured concrete=20 one section at a time with a few days in between pourings.=20 It didn=92t come out perfect=20 but I smoothed out the minor imperfections with pure cement.=20 The rule of thumb that I learned from it=20 and my advise is if you=92re going to do it alone=20 don=92t do a section that is wider or taller than your height.

[Existential Angst]

There is a design for flooring called a floating floor. It has some advantages, altho I can't remember what they were. :)

Having said that, if the ceiling height is adequate, I'd leave an air gap of sorts between the concrete floor and new wood floor, to let the existing floor breathe.