Building a block stem wall

[brad900]

I will be building a 2 x 6 wall on top of a 8" cinder block. I would like to have my inside walls flat so is it ok to put the 2" exposed lip of the block wall on the outside as in the pic. The blocks will be filled with concrete & at a angle to slope the water away from the sill plate

 

[srmofo]

From what I know which is admittedly very little, you really dont want to do that.

Basically you build so the outside of the wall ends up flush with the stem wall. Then whatever exterior siding you choose over hangs the stem wall just a bit. This keeps any water from landing on the stem wall and creeping under the bottom plate.

I know you said you would fill with concrete and angle away, but both concrete and wood shrink and eventually you will end up with tiny gaps where the 2 meet. Eventually you will end up with a rotten bottom plate.

Why are you so set on having a flush interior wall? With a 6" wall and 1/2" interior cover on an 8" block, you will have a 1.5" hanging over. Thats the perfect distance to keep whatever is in front of the wall like a work bench or tool box from damaging the wall

 

[brad900]

I thought it would be easier when building a workbench & cabinets. Also when I put my tool box there there wouldn't be a gap for things to fall into. I see your reason for not putting the lip to the outside

Thanks

 

[dwp99]

You can always nail furring strips to the 2"x6" to build the wall out to the 8" block.

Or use 2" x 8" studs.

 

[Doug B]

On my garage,we layed an 8" stem wall up to grade,then added 2 courses of 6" block,keeping the oustide flush. Back filled and compacted up to the top of the 8" block and poured the floor inside the 6" blocks.Framed up with 2x6 for a nice flush wall inside. It's kind of hard to see,but here are a few pics.

 

[PittsS1]

On my garage,we layed an 8" stem wall up to grade,then added 2 courses of 6" block,keeping the oustide flush. Back filled and compacted up to the top of the 8" block and poured the floor inside the 6" blocks.Framed up with 2x6 for a nice flush wall inside. It's kind of hard to see,but here are a few pics.

I did the exact same thing, and it worked great. Drywall flushes perfectly with block in the inside. An added bonus is that it gives you a 2" lip on which the slab can rest, so it really ties the slab to the foundation and helps prevent settling... I'd definitely go 8" up to just below slab height and switch to 6".

 

[joes169]

I did the exact same thing, and it worked great. Drywall flushes perfectly with block in the inside. An added bonus is that it gives you a 2" lip on which the slab can rest, so it really ties the slab to the foundation and helps prevent settling... I'd definitely go 8" up to just below slab height and switch to 6".

This is the best reason to convert from a wider block below grade to a 6" block above grade, BUT, it's best to leave the ledge inside rather than outside. This is fairly common in many parts of the country, and is referred to as a "floor ledge". I can see no benefit to having the ledge on the exterior, but I can see a huge benefit to having it on the interior. Actually, I've replaced a number of existing garage floors that failed because they didn't have an interior ledge.........

 

[Mudbone]

On my garage,we layed an 8" stem wall up to grade,then added 2 courses of 6" block,keeping the oustide flush. Back filled and compacted up to the top of the 8" block and poured the floor inside the 6" blocks.Framed up with 2x6 for a nice flush wall inside. It's kind of hard to see,but here are a few pics.

I did the exact same thing, and it worked great. Drywall flushes perfectly with block in the inside. An added bonus is that it gives you a 2" lip on which the slab can rest, so it really ties the slab to the foundation and helps prevent settling... I'd definitely go 8" up to just below slab height and switch to 6".

For you guys that have done this I am wondering how the widths worked out. A 6 inch block is 5 5/8s inch thick. A 2x6, (5.5 inches) plus 1/2 inch drywall inside and 7/16 OSB outside gets you to 5 15/16s inch or 5/16s wider than your block.

Edit: I did the math wrong here, long day. A full 2x6 wall with OSB and drywall is going to be 6 7/16s which is 13/16s wider than the 5 5/8s block...Hmmmm

 

[Doug B]

For you guys that have done this I am wondering how the widths worked out. A 6 inch block is 5 5/8s inch thick. A 2x6, (5.5 inches) plus 1/2 inch drywall inside and 7/16 OSB outside gets you to 5 15/16s inch or 5/16s wider than your block.

I flushed the framing up to the outside of the block.Let the OSB and siding set proud of the block,leaving a little overhang out there. Variations in the 2x6( I have seen 5 1/4 up to 5 5/8) end up on the inside.I will hang the drywall to the bottom of the framing.

 

[Mudbone]

I flushed the framing up to the outside of the block.Let the OSB and siding set proud of the block,leaving a little overhang out there. Variations in the 2x6( I have seen 5 1/4 up to 5 5/8) end up on the inside.I will hang the drywall to the bottom of the framing.

Since your OSB is proud of the external wall, do you do anything to keep it, specifically the edge, from exposure to moisture?

As an example,
Around here, (NC), for house construction, the mudsill and floor framing is set in from the edge of the brick/block by approximately 1/2 inch. Then the OSB is run all the way down the band boards, flush with the outside of the brick. (This helps tie the wall to the floor as well) Then a strip of horizontal flat flashing is put on covering the edge of the OSB and brick. Finally house wrap is applied, covering the top half of the flashing strip. Then the siding is run past the flashing overhang so you only see brick and siding. If water gets behind the siding and on the house wrap, it runs down, across the flashing and onto the brick without the OSB being exposed to it.

 

[PittsS1]

Since your OSB is proud of the external wall, do you do anything to keep it, specifically the edge, from exposure to moisture?

As an example,
Around here, (NC), for house construction, the mudsill and floor framing is set in from the edge of the brick/block by approximately 1/2 inch. Then the OSB is run all the way down the band boards, flush with the outside of the brick. (This helps tie the wall to the floor as well) Then a strip of horizontal flat flashing is put on covering the edge of the OSB and brick. Finally house wrap is applied, covering the top half of the flashing strip. Then the siding is run past the flashing overhang so you only see brick and siding. If water gets behind the siding and on the house wrap, it runs down, across the flashing and onto the brick without the OSB being exposed to it.

Hold the bottom plate to outside of block so sheathing is overhanging. Then run weather resistant barrier (Tyvek, etc) down to about 1/2" past bottom of sheathing. I prime exposed edge of sheathing to seal it. Siding then hangs about 1/2" below bottom of sheathing. If water is running down the WRB it should drip down without soaking bottom of sheathing. Seems to be working so far- not sure how others do it. This put my drywall flush with block on inside, which is really nice.

 

[camarotoolman]

Why not just make the hole wall block? Probable about the same money, strong, no termites, etc. Or maybe I've been in Fla. too long!

 

[Doug B]

Since your OSB is proud of the external wall, do you do anything to keep it, specifically the edge, from exposure to moisture?

As an example,
Around here, (NC), for house construction, the mudsill and floor framing is set in from the edge of the brick/block by approximately 1/2 inch. Then the OSB is run all the way down the band boards, flush with the outside of the brick. (This helps tie the wall to the floor as well) Then a strip of horizontal flat flashing is put on covering the edge of the OSB and brick. Finally house wrap is applied, covering the top half of the flashing strip. Then the siding is run past the flashing overhang so you only see brick and siding. If water gets behind the siding and on the house wrap, it runs down, across the flashing and onto the brick without the OSB being exposed to it.

No special precautions. There is house wrap over the OSB and the siding hangs down about 3/4" below the sheathing.

 

[Mudbone]

doug and pitt, thanks for the explaination. And I am with you guys, I like a nice flush wall on the inside as well. Of course here in NC we have the opposite problem. Very few 2x6 walls. So you end up with appromiately a 4.5 inch wall sitting on a 5.5 inch wide block.

EDIT: Guys I just realized that I did the math wrong above. If you flush your framing lumber to the outside of the block, that only gives you 1/8 left. How is your 1/2 inch drywall flush?

Why not just make the hole wall block? Probable about the same money, strong, no termites, etc. Or maybe I've been in Fla. too long!

Cost and insulation. In addition, most folks are going to want some type of siding to match their house which means running furring strips. This doesn't get done a lot so builders don't have as much experience doing it. I have seen some really bad wavy siding jobs where siding was applied to block walls. I think they must have tried to put the siding directly on some type of exterior hard board insulation without furring strips. Of course down in Fla. you can stucco the wall and it matches everything else.