Old Stone Wall - Renovated

Patrickof

Looking at a cert for an apartment built in a renovated corn store, c. 100 yrs old.

If I select the wall type as stone c. 1900 then the U-value is worse than the reality - the wall is dry - lined and possibly insulated but I've no evidence to back up any insulation.

As the corn store was renovated and converted into apts around 2000 then is the stone wall c. 1900 or c. 2000 in DEAP?

(The only evidence I have is the occupier claims the apt gets quite cold if the heating is off for a day or two so that would make me lean towards little or no insulation).

dunie001

My guess would be that dry lining usually has about 50 to 70mm of insulation between the timbers.

You should try to contact the builder who renovated the corn store to see if they can shed some light on the situation.

As for the U-value you need to use the U-value of the stone wall, invert it i.e. 1/u-value to get the thermal resistance.

Then add the Thermal resistance of the drylining (by working it out) add it to the resistance of the stone and then work out the u-value again as per the normal method...

However you have to have some proof of the insulation e.g. letter from builder stating what insulation there may be in the dry lining etc.

Patrickof

Yeah, I have the formula for the u-value but am confused:

(i) I haven't had any luck tracking down the builder - neither the occupier or landlord knows who it was, and there's no record on the local planning site - probably pre-dates their digital files

(ii) Assuming I can't find evidence I must go with a stone wall, in that case as it has been dry-lined is it a stone wall built 1900 or a stone wall built 2000 in the building elements of DEAP?

dunie001

You would probably have to select "Other" and type in the description "stone wall circa 1900 with dry lining no insulation."

Then use the formula I said above to calculate the drylining and stone as a whole...

remember that you have to use upper resistances and lower resistances (like in the roof formula) to account for the air cavity/timber in the dry lining.

you could use a fraction of bridging of 35/400 = 0.0875 for the fraction of timber.

I worked this out roughly and the u-value should work out at about 1.19 or 1.2.

dunie001

When doing the new u-value write down the u-value of a stone wall in 1900 (i think it's 2.10)...

Then you have to:

1. Get inverse of u-value of stone to find out the thermal resistance.,
2. Work out upper resistance and lower resistance of air cavity (resistance = 0.18) vs. timber and (include plasterboard as well), but leave out all the surface resistances when doing this as they are already accounted for in the resistance of the stone.
3. Then add the two resistances together to come up with the new u-value, which should look like this:

1/(Rw + Rdry) = new u-value.

Rw = Resistance of stone wall
Rdry = Resistance of the dry lining.

Patrickof

Thanks, I get a u=value of 1.33 based on a stone wall of 600mm with timber batens as you outline above.

dunie001

The thickness of the wall is irrelevant! as you already have the thermal resistance, you don't need the thickness of the wall or the conductivity...

joebre

I was looking at a similiar type building. Somebody had put their boot through a wall on a landing. It was plasterboard on metal studs with no insulation.
This is why I believe that it would be wrong to assume insulation, just because it was done only 10 years ago.
Has anybody asked SEI on this or does it take too long to get a reply ?

In the same building, 100mm concrete block walls were built to divide the apartment from the unheated corridoor. What wall type would you pick here ?

Would you choose "other" and calculate the U-value or would you tick the box as semi-exposed and select the same wall type as the external wall "stone"

Joe

d'Oracle

joebre wrote: »

I was looking at a similiar type building. Somebody had put their boot through a wall on a landing. It was plasterboard on metal studs with no insulation.
This is why I believe that it would be wrong to assume insulation, just because it was done only 10 years ago.

Its just wrong to assume insulation full stop.
If you dont have proof that the wall is insulated, you must assume Stone.
Thems the rules.