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Old 11-07-2012, 11:45 AM   #16
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Holy cow! I didn't realize the laser levels had come down so much. Yeah, I'll be getting on of those for sure!

I've used the T&G CDX before. It is pretty nice stuff! I think I may go that direction.

It's very possible that the slope was planned for wash-down reasons, since it was intended to be a flower shop. It made for some strange and unfortunate modifications to the house (that I'm slowly, but surely, UN-doing). There is actually an end door in the construction that will be going away before we do this floor project. There's also a flat roof (er... very low sloped roof) on the addition. But THAT is a WHOOOOOOLE 'nother story! HAHA! There will be a post on that eventually as well.

Last night I was telling my wife about the education I've been getting from this thread and I mentioned the heated sub-floor... Yeah. I guess we'll be doing that as well.... HAHA! So if any of you can refer me to a good thread on heated sub-floor products that would work for this application, it would be much appreciated.

Can of worms opened...

Thanks everyone!

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Old 11-07-2016, 09:58 AM   #17
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Re: Floor Joists Over Concrete Slab


Okay! I'm finally updating this thread. We are back on this project. We are all-in on this! End wall has been removed and roof is being completely reconstructed.

When demo'ing everything, we got a good look at the slab. There were two slabs poured at two different times. They are on-grade and there is no vapor barrier. We found two floor drains (one is plugged one will need to be plugged).

We reclaimed 1-1/2"x3/4" oak flooring that matches our flooring and now it's back to focusing on what to do about the slab when they're done with construction.

Latest thinking:

1) Level the slab with self-leveling compound (if possible), put a vapor barrier down, lay my subfloor plywood, and put down the floors

2) Sleeper system as already discussed with vapor barrier down, PT 2x4 sleepers, foam board in between, subfloor over, floors down over that

3) Any combination of the above but adding radiant floor heating of some kind

With construction under-way, I can't check the floor until later this week to see just how out of level it is, but I suspect it will be beyond what I can level with self-leveling compound, so focusing on a sleeper system with or without radiant floor will be the continued focus, I think.

NEW QUESTIONS!

Should I use a standard 6 mil vapor barrier, or are there new vapor retarders available that provide a level of insulation as well?

I may as well put some kind of insulation under the floor. What type of foam board is recommended to provide some added comfort?

Should I really consider the radiant floors if I can do some good insulation? NC winters are pretty mild and I'm concerned about types of radiant floor for this project as well as the cost associated with them. I would really like some feedback on this.

Thanks guys! Happy to be back working on this again! It's getting pretty serious and I'm trying to make a huge dent in the project by the end of the year so we can use this space.

CHEERS!
S
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Old 11-17-2016, 08:08 AM   #18
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Re: Floor Joists Over Concrete Slab


Another update. I finally was able to get in to the room last night with the laser level and get an idea of what's going on with this slab.

The original part of the slab that was built in the 40's is about 1-1/2" higher than the portion that was added later. There is quite a bit of slope. Total displacement from one end of the room to the other is 3" on one side and 4" on the other. The newer portion has slope in two directions. Clearly this room was intended to shed water towards a drain that was in the lowest corner. This will be too much for leveling compound.

It appears that the original portion has slightly less slope than the later added. That might work in my favor for sleepers.

I see a couple different methods...
1) PT lumber glued and Tapcon'd directly to the slab with vapor barrier between the sleepers and the sub floor.
2) Vapor barrier down first, then PT lumber OVER the vapor barrier and Tapcon'd down with subfloor over that.

Which makes more sense for my situation? What about shimming the heights? Is there any clever pre-made shims out there for this application? Which side of the vapor barrier does the insulation need to be on and what type of insulation board should I consider?

So back to the top with this! Thanks guys!
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Old 11-21-2016, 10:52 AM   #19
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Re: Floor Joists Over Concrete Slab


what i would do is use the 2X6 you mentioned and cut for slope. its really doesnt take long. all you need to do is set board on floor and lift the low end up till its level. use a large compass and scribe the board to the floor and cut. i would have a bundle to cedar shingles for shimming for the area that didnt cut right or floor dipped too much in one area and circular saw couldnt follow your scribe. I love the cedar shingles as its tapered nice and long and wide. put down the vapor barrier on the concrete and floor joist on that. no need for tapcons unless the wood is cut down to 2 inch or less on the tapered end. use lots of blocking. block the whole floor in 2 preferably 3 rows. run your wiring under the floor to area you needif you cant go around the walls then insulate it with foam boards. if you can spring the cost have it sprayed in. then you can cover up with tg subfloor and be sure to glue the heck out of it with lots of screws so it wont squeak when you walk in it. remember the blocking ? that should help with squeaks.

If you decide to use sleepers -- remember the sleepers will flex more unless its been shimmed the heck out of it 'every foot or less and tapconed thru sleeper and shim. if your floor only slopes less say 1 1/2 or less then i would use sleepers but you say you have 3-4 inches - that is alot. you need a proper floor.

your other option is to call in a concrete guy and have them pour a new floor on top of old. this way you can can two options after doing this - one use snaplock floors with the Pergo GOLD 100-sq ft Premium 3-mm Flooring Underlayment or lowes brand or simalar ( i used it and love it) or two - use sleepers like you said and glue and tapcon it with hopefully little shimming needed.
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Old Yesterday, 07:57 AM   #20
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Re: Floor Joists Over Concrete Slab


Quote:
Originally Posted by radioman99 View Post
what i would do is use the 2X6 you mentioned and cut for slope. its really doesnt take long. all you need to do is set board on floor and lift the low end up till its level. use a large compass and scribe the board to the floor and cut. i would have a bundle to cedar shingles for shimming for the area that didnt cut right or floor dipped too much in one area and circular saw couldnt follow your scribe. I love the cedar shingles as its tapered nice and long and wide. put down the vapor barrier on the concrete and floor joist on that. no need for tapcons unless the wood is cut down to 2 inch or less on the tapered end. use lots of blocking. block the whole floor in 2 preferably 3 rows. run your wiring under the floor to area you needif you cant go around the walls then insulate it with foam boards. if you can spring the cost have it sprayed in. then you can cover up with tg subfloor and be sure to glue the heck out of it with lots of screws so it wont squeak when you walk in it. remember the blocking ? that should help with squeaks.

If you decide to use sleepers -- remember the sleepers will flex more unless its been shimmed the heck out of it 'every foot or less and tapconed thru sleeper and shim. if your floor only slopes less say 1 1/2 or less then i would use sleepers but you say you have 3-4 inches - that is alot. you need a proper floor.

your other option is to call in a concrete guy and have them pour a new floor on top of old. this way you can can two options after doing this - one use snaplock floors with the Pergo GOLD 100-sq ft Premium 3-mm Flooring Underlayment or lowes brand or simalar ( i used it and love it) or two - use sleepers like you said and glue and tapcon it with hopefully little shimming needed.
Hey! Thanks for your response! I appreciate it! Thanks for the tips.

At the minimum, I will put a 2x4 flat at the top of the slope, and work out/down the slope from there. I love the cedar shingle idea. Certainly rot resistant.

I was going to price out spray foaming everything, so there are no air gaps. The guy will be out to do the rest of the room, so the cost will probably be minimal to have him do the floor while he's at it. I'll use the gray electrical conduit under the floor for wire runs, where needed. The room will have surround sound, so I figured this was the best option.

The other good that comes from this, although sort of strange, is that the feel of the floors over joists/sleepers just seems to have a better feel than over a solid slab. Odd detail, but I like it.

Thanks! Keep the tips coming!

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