# Sleeper joist over existing subfloor



## philcav7 (Jan 15, 2009)

Project involves expanding a kitchen into a enclosed porch area. The porch is 2x8 joist (spanned 11') with 3/4" T&G strip (likely syp or fir). I need to raise the floor nearly 7" to match the height of the existing kitchen floor. 

I had initially thought to cut out the existing floor and add/sister new joist to increase height. It will be covered with tile so the deflection of the 2x8 is maxed out. 

Would installing sleepers directly over the existing floor be an option? It would be much easier, but I'm concerned the strip flooring is not as dimensionally stable as plywood/osb. My fear is if a board would buckle, it could compromise the sleeper assembly carrying the new 3/4" plywood, CBU, and tile. However, dimensional joist carrying traditional subfloors are not exactly dimensionally stable either. I've seen sleepers done over plywood before, but never strip. Is it plausible?


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## Tom M (Jan 3, 2007)

I hear sleepers I think on the flat. You say you need 7". I cant see the whole situation but I assume you dont want to pull the existing joists because the walls are framed up on top of the perimeter.
Could you leave the joists in place, pull the T&G then add 2x10 in between? Dont forget you can notch the rim joist ends 1/4th.
Its a bigger job if you didnt plan on this but then your tile is safer moving forward.


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## elementbldrs (Sep 26, 2010)

We do tapered sleepers on our older historic retrofits regularly. Joist over decking over joist. Shoot laser, mark lines, snap line or worse connect points, rip, repeat.

Heres a standard archi deg. Pretty straight forward.


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## philcav7 (Jan 15, 2009)

I had originally planned to rip the subfloor, install new joist to meet elevation and put new plywood down. Sleepers was a secondary consideration. I know sleepers are common for leveling, but wasn't sure if there's a hidden risk (excluding deflection) of this method over plank. I would have no concerns with going over plywood with sleepers.


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## Tom M (Jan 3, 2007)

I think I would install to the new elevation so be done with it


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## Dan_Watson (Mar 1, 2008)

What footings are under the porch framing?


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## TimelessQuality (Sep 23, 2007)

I'd probably add a beam midspan, screw the t&g tight and add the tapered sleepers with PL and pocket screws right on top of the other joists...

What's the joist spacing?


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## philcav7 (Jan 15, 2009)

Dan_Watson said:


> What footings are under the porch framing?




It's mixed. The kitchen area and most of the porch is on CMU, the remaining porch section is comprised of a ledger and 4x4post/beam. I'm going to get my mason out there to see about extending the foundation outwards to enclose the section. The current 4x4 configuration doesn't work for me. 

Spacing is 16"OC.

Attached is the area that is supported by ledger/post. The remainder of the 130"x140" porch is over the foundation.


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## Dan_Watson (Mar 1, 2008)

Three new footings and posts, zip, insulate, and then sleepers. Wouldnt think twice as long as the footings are helical. :thumbup:


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## philcav7 (Jan 15, 2009)

I'm not sure what footings are under the post, if any. They just closed on the house this past week so it will need an invasive inspection to assess.

It's a short span that the post carry so the tributary load is minimal. Dan how much do helicals run?


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## Tom M (Jan 3, 2007)

I would be considering any tile until I knew that beam was solid


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## philcav7 (Jan 15, 2009)

The only thing that I found suspect is the short cantilevered section on the front. It looks like it was scabbed onto the rim without proper bearing on masonry. Extending the foundation under this area would leave the rims fully supported. The 2x8 span does meet L360, but new joist would bring deflection up.


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## TimelessQuality (Sep 23, 2007)

I'm not seeing much worth saving there... Shore the roof up and start over


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## Dan_Watson (Mar 1, 2008)

philcav7 said:


> I'm not sure what footings are under the post, if any. They just closed on the house this past week so it will need an invasive inspection to assess.
> 
> It's a short span that the post carry so the tributary load is minimal. Dan how much do helicals run?


We average $240 a post for a typical footing.


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## Tom M (Jan 3, 2007)

With an up charge for fewer than 4....


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## Dan_Watson (Mar 1, 2008)

Tom M said:


> With an up charge for fewer than 4....


Depends on the travel distance, I said average.


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## Tom M (Jan 3, 2007)

Salesman :laughing:


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## Dan_Watson (Mar 1, 2008)

Tom M said:


> Salesman :laughing:


Ouch.


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