R Value of stone

radmix

I have a project that I would like to do a heat loss on. The house is late 1800s with

exterior walls that are 2 feet of stone and plaster on the interior walls. The home owner aslo said that there is horse hair in the walls. what is the best way of doing this heat loss.

icesailor

Heat Loss:

You have a difficult building to do an accurate heat loss on.

2' of stone is basicly uninsulated. It isn't much different than a poured concrete wall. A 8" wall equals 0.670 and a 12" wall equals 0.560. Therefore, there is some factor of resistance to the other foot of thickness.  A 12" brick wall is 0.33. But brick has more resistance.

As far as "horse hair", that is most likely in the plaster. It was used to bind the lime/sand plaster together. What I have seen in some New England is eel grass, placed in bags and stitched together to form rolls and rolled in like modern fiberglass insilation. Burns good too.

You can use the IBR/GAMA H-22 heat loss guide to walk you through but I wouldn't recommend using it for a first try. You have a very difficult building to do a accurate heat loss. The new guide is not as easy to use as the old one.

Good luck. 

bill_105

The tough ones

I had a tough heat calc. to do last month. This house was about 3500 s.f. and has 2 ninty degree corners. It's a real geometry quiz. I've since been wondering, Would it be possible to use a thermal imaging camera to do a heat calc.??

meplumber

Thermal Imaging is the way to go.

We had a "Summer Cottage" up here on the coast that we were doing some major reno work to.  Trying to guesstimate the wall construction wasn't something that I was comfortable with.  Hired a company out of Portland, ME to do some thermal scanning.



They gave me a great report with infiltration and heat loss data for the wall and ceiling system.  The engineering company took that and produced a plan for me. 



As intelligent as we all feel about our trade, I have gotten more willing in recent years to lean on the "Learned Professionals" when it is more than just a standard structure.



Let us know what you find out.

icesailor

Stone:

I don't quite understand what the shape is but, I would visualize a roo, that is curved, and divide it up into one, two or three walls, Whatever works. Take the overall length for infiltration and amoount of walls. That determines how many air changes per hour you have. Then, you must make some calculation for room volume.

I don't see how a thermal imaging camera would do much. That's not how it is done.

Remember, it is the length of exposed wall, area of windows, and the volume of the room with infiltration added in.

Dave Yates (GrandPAH)

R-value of stone wall

I use the same value as for concrete: .08 per inch, although that would be for a 'tight' masonry wall. Loose-laid stone gets derated. A 2' thick stone wall would, therefore, get slightly less than a R-2 value. If re-building, an air-gap of 3/4" and Tuff-R insulation-board will grant an R-10 to R-12. Just commisionned a radiant job in a stone home from the 1700's. With the exception of the concealed Tuff-R and hydronic radiant heating, it's an historically-accurate rebuild utilizing old-world construction techniques.



Next up: a zero energy new home project that's under construction! The air-to-air HX has a built-in mini-geo unit that utilizes PEX tubing wrapped around the home's foundation. PV, thermal, & passive solar flesh out the remainder of the home's energy needs.      

onequartersaw

I get about R3.5

with my modeling software (Hot2000). That's with a 3/4" @24" o.c. furring layer beneath the plaster. The depth of this cavity makes a difference. Its about R2/inch.

onequartersaw

I get about R3.5

with my modeling software (Hot2000). That's with a 3/4" @24" o.c. furring layer beneath the plaster. The depth of this cavity makes a difference. Its about R2/inch.