Not Exactly a Basement


  #1  
Old 11-28-05, 12:28 PM
highlander
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Not Exactly a Basement

The first "story" of my home is actually 3300 square feet of horse stables (plus tacks room and horse shower). All cinder block walls about 12 feet high, and cement slab floor. The second story is the actual living area.

I'm wanting to make all but a small portion into more living space, and I'm wondering the best way to go about finishing the cinder block walls. Keep in mind that these walls are not below ground! I'm thinking the best approach would be to nail up furring strips to the cinder block, then attach board insulation - how exactly do I then attach drywall on top of that? Do I need to nail up more furring strips atop the insulation? I assume I still need to put up a vapor barrier even though these walls are dry?

One other question: the interior walls of my downstairs are cinder block as well. This means that, when insulating all my exterior walls, there will be portions that I can't get to (where the interior wall "T" intersects the exterior wall). Is this something to worry about considerably? If so, would you recommend insulation ALL the walls downstairs?

Any help or insight would be appreciated!
 
  #2  
Old 11-28-05, 04:13 PM
M
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I would nail up the furring strips, install 3/4" foam between the strips and hang the sheetrock over the foam directly to the furring strips.
 
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Old 11-28-05, 04:40 PM
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I built a concrete block home with a brick exterior, so I could give you some help. When you do this, you have to change some preconceived ideas since in some ways it is like a small commercial building. This is something a traditional stick builder fails to do.

I have no idea of what your exterior is and that can make a minor difference. My suggestions may be overkill for insulation for most locations, but the details and finishing work out very well. What is your exterior wall made up of beside concrete block?

If you are in a cold climate, I hope you have rigid polystyrene under the floor. This will be your major heat loss.

I would attach 2x2s to the exterior walls at 16" on center with construction adhesive and a few ramsets or masonry nails. This gives you a better surface attachment for everything without much of a decrease in insulation because of the wood. Nailing is very easy of you have lightweight block for better insulation with the same strength. For normal or heavyweight block a ram set works better but is not necessary. If you have lightweight block, nail into the block - if you have normal weight block, nail into the mortar joint.

I would use 1 1/2" extruded polystyrene between the studs. If you run eletrical in the exterior walls, you have to use shallow boxes. Where I ran romax, I used 3/4" rigid insulation and covered it with another 3/4" thickness to maintain the 1 1/2" thickness. After that, it is typical interior finishing.

A friend of mine ripped a few 2x4s so he could use thicker foam. This allowed him to use standard boxes, but he still used two layers where the romax was.

Some people think that UF romax is required, but the inpector did not require that because my romax was above grade and inside the primary moisture barrier (1 coat of Thoroseal on the wall).

It is not necessary to use PT lumber in an above grade application as this. Actually, most designers perfer normal kiln dried be cause of the lower moisture content and stability.

Because of the mass of the walls and the absence of infiltration, your actual level of insulation will be much higher than using the pink tinted R-values common in light construction. There are tables for the additional effective insulation depending on you climate.

Good luck with your project.

Dick
 
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Old 11-28-05, 04:55 PM
highlander
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Many thanks for the info - to answer your question, the exterior is stone atop the cinder block.

Should I worry much about where the interior walls meet the exterior walls? There's not much I can do about it aside from insulating those interior walls as well. Thoughts?

As for the floor: it's not insulated, and I'm a bit torn about how to handle it. It's concrete, and I've never seen a wet spot on it from ground absorption. I live in the piedmont of North Carolina, so we don't get much frozen ground in these parts - even in the dead of winter. I had thought about simply tiling directly onto the concrete. Is this not a good idea?
 
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Old 11-28-05, 07:09 PM
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Not Exactly a Basement

Where the interior and exterior walls meet, I had a 3 1/2" strip of rigid foam insulation between the studs on the exterior wall. Where the insulation was not on the exterior wall on one side of the intersection, I just in a 2x2 to protect and contain the insulation.

If I had my choice, I would go for some kind of carpet and pad for comfort. That is only because our natural soil temperature a few feet down is 55 degrees even in the summer.

Dick
 
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Old 12-08-05, 10:45 AM
highlander
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OK, re-thinking per some discussions I've had. Please give me your thoughts:

First of all, it was pointed out to me that if I nail up 2x2, firring strips, or anything to my walls, then try to finish them, it could be ugly. The odds of my cinder blocks being nice and flat and plumb everywhere are slim. I'm sure they're mighty close, but not perfect. Now I'm thinking about the following:

Build the wall frame using 2x2s 16 inches on center. Tilt the frame up against the wall, then use straps at the top and bottom to fasten to the wall. Make holes with hammer drill in the cinder block and attach with mason screws.

As for the insulation, I could either attach fiberglass roll the same way (mason screws) directly to the wall OR - what if I simply stapled it to the wall frame itself on the sides of each stud??? Then I wouldn't have to poke more holes in the cinder block AND I wouldn't have pinched-off insulation areas (screwpoints) where there'd be heat loss. Thoughts?
 
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Old 12-08-05, 05:20 PM
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Not Exactly a Basement

You did not mention how much insulation you want for your climate. Since you have a stone exterior, you are limited to the exterior.

You can nail 2x2s to the wall if it is reasonably plumb. 2 bys and 1 bys are frequently used to get a level ceiling when the joists are not level, so it is nothing new. You don't need a perfect wall masonry wall.

Do not attach fiberglass to any wall with screws or you will lose even more heat through the connection than you lose through the wood. Between the wood stud loss and the connectors, a R13 could be an average of R5 or R6 for the fiberglass/stud combination.

Before deciding how to build, you should decide what you need for insulation.

Dick
 
 

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