need help, who to level out room addition floor

[roermo]

Ok this my be out of place here but maybe not, because I am going to use a tractor to haul off building debris .

Ok here it is, years ago I raised a porch floor 6 inches to match the rest of the house. Porch 12x26 on 2x6 12 ft long 16 inch centers, on hangers. This week I took out all the air leaking windows and knocked out the brick wall and opened it up to the main part of the house. Now for the question. I am 1 ½ inches to low.
I am thinking a can put a ¾ in strip down then ¾ plywood, or two sheets of ¾ plywood. What would be better. If I use the strip idea I am afraid it will not be strong enough and might wobble. I like the idea of tw0 layers but the cost is much higher.

Any ideas.

Thanks

roger

 

[inveresk]

My preference is for 1" flooring particularly if joists centres are 24" instead of 16" - less bounce - but 3/4" ply cut into 2" wide strips and fixed through the existing floor to the joists then overlain with 3/4" flooring grade ply rebated all round should work fine. If you screw rather than nail, it's less prone to squeak and should also help the stiffness.

 

[CurlyDave]

If there is access to under the porch, I would think about raising it 1-1/2".

Either new hangers, shim the bottom of the old ones, or pull the nails & raise them. This is really the right way to do it, but might take longer.

Just take it slow & easy. Raise each joist 3/4" until they are all raised that far and then go for the full 1-1/2" one at a time. I have done this kind of thing with a 5 ton bottle jack and it worked out pretty well.

 

[Henro]

I would consider using some kind of strips like you mentioned, say 3/4 inch, 24" on center, and between them put some 3/4 inch foam insulation. Over this I would put the 3/4 inch plywood. The pink or blue stuff you can buy at Home Depot or Lowes in 4x8 sheets and cut on your table saw into strips, or with a circular saw or whatever.

The foam would give the plywood a lot of support (try putting a square foot of foam under a square foot of plywood, and jumping on it, you will be surprised at how much it supports). The foam would give some insulation value also. And be cheaper than plywood by half or more.

Just an alternative thought... /forums/images/graemlins/smile.gif

 

[EddieWalker]

I did an addition where the homeowner wanted to extend their living room onto their porch. The porch was solid, but it started out an inch below the floor at the house and droped away from the house.

I used strips that I cut from 2x4's at an angle to level it out and spaces a foot apart. I glued and screws the strips down, then did the same with 3/4 inch plywood. It was rock solid.

If your totally level and just need to build up the area. Rip a 3/4 inch sheet of plywood into two inch wide strips. To keep it as solid as you can, I'd put them at 12 inch centers, but 16 inch will be fine. Glue and screw so it will never flex or move, which will make sure you never have a squeeky floor.

Eddie

 

[roermo]

I failed to mention that the joist are on a slab and nailed in with ring shank nails no taking them apart. The floor was down with ring shank, (used them before the day of screw).

I had to cut up the floor to run two heat runs and found water on the inside on the floor. 1 from an old hot tub, two from wall size trailer type folding type windows. So I had to pull up all of the floor. Fix the damage and now trying to level it out.

So I am afraid of putting down ¾ inch strip of wood on top of the 2x6 thinking it could work loose. So the other thought is 2 layers of ¾ plywood. Which is better. This time I will screw every thing down instead of ring shank. Heck even my new stud walls are screwed. When I put the door in I screwed it. Good thing because I have to take it out and raise it because of the floor being or will be higher.

Thanks again for the input.

From all thumbs in Missouri

Roger

 

[inveresk]

I can't see why strips should work loose if they're properly screwed. On roofs it's perfectly normal to fix firring or declavity pieces on top of joists to introduce a fall and I've never experienced them working loose. I don't see this as being any different.

Bear in mind the floor is only subject to downward loads - self weight and any live loads (furniture, people). I can see the floor being liable to work loose if it were subject to sideways or upwards forces but not downward only.

As a rule of thumb if the screw bites into the joist by 2X the thickness of the material you're trying to secure, you should get a solid fixing so use min 2.5" screws at, say, 12" max c/s.

 

[roermo]

Inveresk: thanks for the input. I understand your point. I always doubt my thinking. The good thing using screws this time around if I have to pull up the floor for any reason I can do it with out the use of a 30 pound hammer that I used this time on perfectly good plywood.

Again thanks for the info.

Roger

 

[Glenn9643]

Roger,
If you're not into square-drive screws yet, I suggest you try them.

 

[roermo]

Ok last post before I hit this project head on.
I am going to use ¾-furring strips on top of the 1x6 floor joist then ¾ inch tongue and grove on top of that to bring the floor up with the living room and dining room. Screwed down very 4-6 inches along the joist.
The floor is a slab of concrete, then the 2x6.
Now for my last questions. When I built the floor I put the joist on hangers then insulation the 6mil plastic then the plywood.

Do I need the plastic as a vapor burrier? /forums/images/graemlins/confused.gif

Thanks again guys.

Oh I use the star screws 6 sides is that the same as a box screw.?

Roger