Building Over A Concrete Patio

[pktraylor]

The client has a 14' x 14' patio that has a 4' stim wall and footing. He now wants to add an addition over the patio.

In order to do this we will need to build up the flooring 14" to meet the existing floor level.

We need to use 12" floor joists but that leaves us only 2" inches between concrete and Joists.

How would you design the job? What would you fill the 2" space with and would you use a vapor barrior and mud sill foam?


Appreciate your thoughts,


Paul

[chuckgar]

I would use the a sill seal for sure. Because the slab is on a stem wall I would guess that is level and flat around the perimeter but I would check it regardless and shim as needed. If it is exactly 14" you need to come up I would use a pressure treated 2x12 joist (11-1/4"), a 2x4 mudsill (1-1/2"), and a piece of treated 1/2" ply on the top of the mudsill to get the overall 14". I would also seal the slab with a tar type sealer (like they use on foundation walls), or just use treated ply for the subfloor. You may also consider nailing a strip of ply for under the walls and sheathing in between using screws to fasten to the joists in case you ever need to pull it up.

Oh, and this space should be vented as well.

[Jay Malaspino]

The client has a 14' x 14' patio that has a 4' stim wall and footing. He now wants to add an addition over the patio.



In order to do this we will need to build up the flooring 14" to meet the existing floor level.

We need to use 12" floor joists but that leaves us only 2" inches between concrete and Joists.

How would you design the job? What would you fill the 2" space with and would you use a vapor barrior and mud sill foam?


Appreciate your thoughts,

Paul

My thoughts are finding the perfect CAD program...... Oh you mean thoughts on your situation?

I'd use 9 1/2" i-joists. They are far more than adaquete for a 14' span. That will give you a 4 1/2" space under the joists. (1) PT sill and (2) KD plates over then the joists = 14" or so with the larger than 1 1/2" sills.

jay

[Tim O'Donnell]

for your climate, you need to put down the vapor barrier as well...i would consider using 2" of foam to isolate and insulate the room from the ground as well

[dcdavis]

I would make sure the footing for the original stem wall meets code for the addition before I did any thing.

[HARRYBSTANFIELDJR]

you need to leave 18" from joist to cement

[tony33770]

Harry's right on - the question is local code - will they permit the proposed new floor system without the usual minimum clearance.
Obvious solutions - step down to present slab - combination of both platform at house with step down to present slab - etc.
Finally will the construction as you propose be considered a "sleeper floor assembly" by the building officials, if so your home free.

Good luck

[pktraylor]

All great ideas! Thank you!


I will consider all the ideas before starting and check the codes for clearence.


Again thanks to all!



Paul