Insulating stone walls

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  #1  
Old 11-25-08, 06:53 AM
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Insulating stone walls

My stone house in SE PA (philly area) has 18 in thick stone walls (2 courses of field/rubble stone). I am re-doing most of the interior rooms which involves removing the plaster walls down to the studs. Of course the house never had any or really needed that badly any insulation; however, i think it would help quite a bit none the less.

What is the proper type and setup for the insulation since the walls are stone - the insulation would have to be stapled to the studs and I guess I would want some vapor barrier between the drywall and the insulation? and the insulation side facing the stone?

Any help appreciated.
 
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Old 11-25-08, 07:06 PM
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Build a wall about 2 inches from stone wall. Add insulation and sheet-rock like normal. The 2inches will let the stone wall breath.
 
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Old 11-26-08, 04:04 PM
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It's funny how many of the big old building have survive for, well, 120 years with out moisture, mold or other air quality problems. Now we decide to tighten them up. It's a delicate issue. Too much air flow between your wall and the old wall, and your insulation will be of little value. Too little and you increase the potential for condensation.

The only other approach, which I've only seen used on stone foundation walls, is spray foam. It might be worth talking to them.
GL
Bud
 
  #4  
Old 11-29-08, 05:36 PM
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Good for you. I did one built in 1890 in Denver.

The key for structural brick or stone is the foundation. Keep that water away by pouring concrete walk 4 foot wide all the way around that is well drained away for the foundation. Water and moisture comes from the bottom up. You want the foundation dry, dry dry, all the time.

18 " block wall is R6 add to 2X4 stud cavity R13 batts vapor barrier to inside as normal and you get an R19 and you are good to go. I would go ahead and staple polyethylene over the batts for additional vapor barrier in shower rooms and hot tub rooms. I installed polyethylene on all exterior stud walls in Denver home because I used my hot tub to humidify my whole house and I had another 3000 gallons of water storage inside in other tanks for whole house solar thermal heating during the winter. And with this added insulation to the walls your HVAC system will be bigger than needed.

Now don't deface the old stones. in another 120 years somebody might want to do something different.

Now with that much thermal mass if you have a broad expanse of wall which faces south with plenty of sunshine you could turn it into a passive solar trombe wall and harvest a lot of BTU's in the winter. Sourcebook Passive Solar Guidelines1-2

FYI Home Energy conservation DIY check list
1. Increase Insulation, and eliminate air infiltration
2. Other home thermal performance improvements, windows, attic venting, window shading.
3. Home energy audit data collection using blower door and infrared measurements and inspection
4. heating, ventilation, air condition (HVAC) reeneginnering to calculate new HVAC size.
5. Ground Source Heat Pumps (GSHP) with solar thermal assist. and/or
6. Active and passive Solar Thermal (ST) whole house heating,
7. Insulated Concrete Form (ICF) new home construction

PS In Denver I didn't need an A/C the structural brick helped keep the house cool and there was no summer humidity to contend with. The hotub I kept covered and only heated domestic hot water. Question! Does your stoner home have air conditioning????? Your A/C might not stay on long enough to remove the summer humidity after you add all this insulation.
 
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Old 11-30-08, 12:12 AM
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thanks so far for the advice - a few others have told me to check out spray foam directly onto the stone..but it sounds like a straight-forward approach will work fine as well
 
  #6  
Old 11-30-08, 02:05 AM
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I use spray foam for those old and brand new loose fitting stick frame homes. Especially vinyl sided 2X4 stick frames. The foam in 3.5" space has R24 and fills all the air holes created after the house has settled and shrunk or makes up for the lack of a house wrap. On structural brick the cost of foam isn't justified as it serves none of these purposes.
 
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