Proper Sleeper Joist Installation for Subfloor

[scootermcrad]

Hey guys!

I didn't see much on the topic of sleeper joists over uneven slab floors for subfloor installations. For those of you that have done this, maybe you can give me some input.

I'm going to be installing a reclaimed T&G 3/4" Oak floor over an existing older slab. The slab is all over the place and even has a small floor drain that's been back filled many years ago and sealed. A bit too much for leveling compound. My plan has been to level up the floor with sleepers for the subfloor and oak flooring as well as provide some insulation.

My plan is to put an 8mil vapor barrier down, ramset my 2x4 shimmed sleepers down with TruBoard subfloor attached over that. Are there any interesting vapor barriers out there that would provide some R-value as well as vapor protection? What would be recommended for insulation? Flat foam insulation board of some kind? How about lumber. Does this need to be pressure treated lumber or something else?

Thanks for any help guys! I know this isn't pertaining to drive-over surfaces, but I've seen a few people put nice wood flooring down in their shop, so I figured someone would have messed with this at some point.

 

[scootermcrad]

Did I put this in the wrong place? I probably should have put this under General Discussion. Please move if that makes more sense.

 

[Radix2]

Have you tried Ramsets into that floor? I'd use one of the concrete screws which I think will give better results. The biggest r value is one of the foam boards, so not much choice there, also easy work with...

Pressure treated would be good, but I would only use kiln dried since you don't want to have to go crazy trying to keep it flat.

Is the slab on grade or below?

 

[scootermcrad]

Have you tried Ramsets into that floor? I'd use one of the concrete screws which I think will give better results. The biggest r value is one of the foam boards, so not much choice there, also easy work with...

Pressure treated would be good, but I would only use kiln dried since you don't want to have to go crazy trying to keep it flat.

Is the slab on grade or below?

Thanks for the reply!

I haven't tried Ramsets on the floor. There were tack strips for carpet on this slab once (yes, it was weird and gross) and I didn't really take note how they were fastened down when I pulled them up, but they definitely weren't screwed down.

I was thinking Ramsets would be a lot easier than drilling and screwing. Is there a concern that maybe the Ramsets may crack the floor or something?

Thanks for the tip on the kiln dried! Good thinking!

The slab is on-grade and poured inside a brick foundation. I will know more soon about how the brick foundation and slab interact. Contractor is in there today demo'ing.

THANKS!

 

[tab2]

About 10 years ago I was working on a 40,000 square foot new construction house (no that is not a typo) that did something similar.

The framers were doing the subfloor and they put down chalk lines where their sleepers were going (every 16") and then used a laser to measure every 16" on that chalk line. They took how far it was high or low on the laser, wrote it down and then going 1" in from the endgrain of a 2x4, they would use a straight edge and draw the contours of the floor onto the 2x4.

So let's say the end was low 1/4" on the laser, 16" from there it was 0, and then the next 16" was 1/8 high of the laser. They would write this down and use a straight edge on the 2x4 and mark every 16" what the difference should be. So for my example, they would start they 1-1/4" from the edge, the next 16" would be 1" from the edge and the next 16" would be 7/8" from the edge. Next they used a circular saw to connect the dots.

They used rotary hammers and Tapcons for fasten them down. LOTS of Tapcons. They they put down subfloor, and then the floor guys put down a wide plank oak. They checked for squeaks before that went down though.

I remember it being time consuming, a pain to clean and a pain to walk perpendicular too. They did use foil backed foam between the sleepers too.

 

[Radix2]

Thanks for the reply!

I haven't tried Ramsets on the floor. There were tack strips for carpet on this slab once (yes, it was weird and gross) and I didn't really take note how they were fastened down when I pulled them up, but they definitely weren't screwed down.

I was thinking Ramsets would be a lot easier than drilling and screwing. Is there a concern that maybe the Ramsets may crack the floor or something?

Thanks for the tip on the kiln dried! Good thinking!

The slab is on-grade and poured inside a brick foundation. I will know more soon about how the brick foundation and slab interact. Contractor is in there today demo'ing.

THANKS!

In my experience ramsets don't work very well on old hard concrete. May be the local aggregates...they spall out big chunks, they underdrive, they overdrive, ect. Just not a predictable quality connection.

With the availability of cheap SDS drills, drilling and screwing is fast and painless.

 

[Shiftless]

I agree with Radix2

tab2:
Wow! 40,000 sq. ft. garage. Amost an acre under roof. I'm wondering if a guy builds a house of that size how big would the garage and shop be?

I know Bill Gates' house is 66,000 sq. ft.

 

[scootermcrad]

In my experience ramsets don't work very well on old hard concrete. May be the local aggregates...they spall out big chunks, they underdrive, they overdrive, ect. Just not a predictable quality connection.

With the availability of cheap SDS drills, drilling and screwing is fast and painless.

Ah! Gotcha! That makes sense. Tapcons it is, then.

Thanks!

 

[scootermcrad]

About 10 years ago I was working on a 40,000 square foot new construction house (no that is not a typo) that did something similar.

The framers were doing the subfloor and they put down chalk lines where their sleepers were going (every 16") and then used a laser to measure every 16" on that chalk line. They took how far it was high or low on the laser, wrote it down and then going 1" in from the endgrain of a 2x4, they would use a straight edge and draw the contours of the floor onto the 2x4.

So let's say the end was low 1/4" on the laser, 16" from there it was 0, and then the next 16" was 1/8 high of the laser. They would write this down and use a straight edge on the 2x4 and mark every 16" what the difference should be. So for my example, they would start they 1-1/4" from the edge, the next 16" would be 1" from the edge and the next 16" would be 7/8" from the edge. Next they used a circular saw to connect the dots.

They used rotary hammers and Tapcons for fasten them down. LOTS of Tapcons. They they put down subfloor, and then the floor guys put down a wide plank oak. They checked for squeaks before that went down though.

I remember it being time consuming, a pain to clean and a pain to walk perpendicular too. They did use foil backed foam between the sleepers too.

WHOA! 40,000 sq. ft. is a cubic ****-ton of sleepers to install! Thankfully the area I'm working is only about 16x23. I cannot imagine working that job!

Stupid question. If I'm drilling and using Tapcons is there a sealer that should be used along with this, since screwing through the sleeper into the concrete means breaking through the vapor barrier?

 

[EdT]

I suppose you could put a strip of butyl tape flashing on the edge of the sleeper or pre-drill them all and put a blob of sealer you like around each hole. I'd use PTL for that. It'll get damp and that may last longer. I pulled up a basement floor like that at my son'r house and discovered something you should consider. Take all the precautions you want to prevent water from coming through the concrete and there will sill be some. In addition, if there is ever a leak onto the floor from above, you will end up with a real biology project under the floor. The poly will create a festering pond of ick. The plywood will get soggy and what's on top will come of and it'll stink like a mud flat at low tide. If you can, notch or space the sleepers so that, if it does get water under the floor, there is a path for it to evaporate out. Even consider some provision for forced ventilation to help. I'm sure there are a lot of floors just like you are planning, so my comments are based on dealing with only one and it was a mess.

 

[rpenner54]

When basketball floors are done often times the sleepers are just floating. In fact the only way I have seen wood floors over concrete done is with random sleepers, random sized and spaced just put down and a floor nailed to that.

 

[scootermcrad]

I suppose you could put a strip of butyl tape flashing on the edge of the sleeper or pre-drill them all and put a blob of sealer you like around each hole. I'd use PTL for that. It'll get damp and that may last longer. I pulled up a basement floor like that at my son'r house and discovered something you should consider. Take all the precautions you want to prevent water from coming through the concrete and there will sill be some. In addition, if there is ever a leak onto the floor from above, you will end up with a real biology project under the floor. The poly will create a festering pond of ick. The plywood will get soggy and what's on top will come of and it'll stink like a mud flat at low tide. If you can, notch or space the sleepers so that, if it does get water under the floor, there is a path for it to evaporate out. Even consider some provision for forced ventilation to help. I'm sure there are a lot of floors just like you are planning, so my comments are based on dealing with only one and it was a mess.

Ooo yeah! Interesting point! Maybe I'll put like 17 layers of Poly on after the floors are refinished!

Thanks!

 

[scootermcrad]

When basketball floors are done often times the sleepers are just floating. In fact the only way I have seen wood floors over concrete done is with random sleepers, random sized and spaced just put down and a floor nailed to that.

Hmmm... interesting thought. That would even allow them to expand and contract without issues. I suppose the weight all by itself would keep everything in place.

 

[tab2]

tab2:
Wow! 40,000 sq. ft. garage. Amost an acre under roof. I'm wondering if a guy builds a house of that size how big would the garage and shop be?

13 bay U shaped carriage house. I think it was 4000 feet. I think they did epoxy in there. Another big bill!

 

[scootermcrad]

So what are my options for insulation here? Is foam board simply the best solution?

Radiant heat flooring is also something I'm thinking of here, if I can swing the extra cost. It will depend on how bad the budget gets destroyed on the renovation.

 

[scootermcrad]

Hey guys! I'm bumping this back up. I need some help.

I'm right smack dab in the middle of this and did some last minute research before securing pressure treated sleepers down and found out that I may be going the wrong direction.

I have NO vapor barrier OR insulation below my slab. I was going to put a 6 mil poly sheet directly over the slab with sleepers on top, insulation in between, and subfloor over that. I just read a good point about if I don't have the poly sheet completely adhered down to the floor, the pockets will create a mildew problem thus causing a smell problem and probably many other problems. Is there an adhesive I should be using between the poly sheet and the slab? Some other kind of product??

Need help! Thanks guys!

 

[scootermcrad]

Can I just use a tile adhesive like Henry's, or some other kind of mastic, to glue the VB down? Seems like that would eliminate the bubble/void issues.