Does cavity injection complicate damp treatment?

[Hank]

My house was built in 1899. I'm thinking of having the cavity walls injected with some kind of thermal insulation, as my local council is offering to do it at a cut price.

However, the house has a bit of a damp problem on two sides of teh house at ground level (detectable inside, up to about 3 feet above ground level). I'm wondering if injecting the cavities will make it more difficult to treat the damp issue at some future date.

I think ideally, I should have the cavities cleared of debris first, but that's a job I don't want to tackle just yet. I suspect the cavity-injecting people won't bother to do it. The dampness is not serious enough to be a real problem. It does not create any mould on walls, but you can certainly detect it with a damp meter. I would probably want to get it treated immediately prior to selling the house.

Thank you.

Hank

[Dave Fawthrop]

|! |!My house was built in 1899. I'm thinking of having the cavity walls |!injected with some kind of thermal insulation, as my local council is |!offering to do it at a cut price. |! |!However, the house has a bit of a damp problem on two sides of teh |!house at ground level (detectable inside, up to about 3 feet above |!ground level). I'm wondering if injecting the cavities will make it |!more difficult to treat the damp issue at some future date.

In fact the cavity injection will *help* with the damp problem a *little bit*. The inside skin of the wall will become warmer and any damp will evaporate faster. from both the inside and outside of the inner skin.

[meow2222]

damp treatment is unlikely to be the solution, so its moot.

explain the games and the real solutions.

NT

[Ed Sirett]

The oldest houses I know with cavity brick walls were built in 1915 and they are uncommon on houses built before 1930. I think 1899 would be a safe bet you don't have cavity walls.

[Andrew Gabriel]

I believe cavity walls go back to around 1880 in exposed coastal areas, and gradually spread from those to the rest of the country over the following ~50 years.

[Andrew Mawson]

council is

Well strictly speaking it goes back a long way further than that. Vetruvius describes double skin walls for damp control in his books on architecture written just BC for use by the roman army in constructing forts all over the Roman empire ! In the UK I believe in more recent times cavity walls were used in the late 1890's in Lancashire.

AWEM

[unknown]

Would the cavity of such old properties not be sufficient to gain any benefit from being filled in the first place I wonder?

[The Natural Philosopher]

every little helps..and inch of insulation is as good as a foot of brick usually..or more...

I solved a condensation problem with 3mm of cork tiling. Made a huge difference to a solid 9" wall.

[<me9]

My parent's house was built in 1902 and (together with most in the area) had cavity walls. My Sister's was even older (Victorian, but I don't know the date, 1880s I think) and had cavity walls.

It depends where you are in the country (and the prevailing weather there) as to when cavity walls were introduced.

[meow2222]

Cavities were usually half inch to 4" in brick walls, and larger in stone. neither half inch nor 4" are suitable for filling, but 2" ones are.

Its a popular myth that houses before 1900 didnt have cavities. Some do, for damp control, not insulation.

The idea of cavities as insulation and cavity insulation fill were not generally known at the time.

NT

[Phil L]

As are 3, 4 and 5 inch ones...some new build now are built with 100mm cavities which are blown with CWI instead of using the normal batts - We used to get double meterage for them when i was an installer, although bizzarely, we got feckall extra for a 75mm cavity.

Correct - they were originally built for the control of damp

[Phil L]

Not really, unless the lower part of the walls are filled with debris like broken bricks, mortar snots etc. If this is the case, the only sure way of getting rid of the dampness is to have the cavity cleaned, but if it's just rising damp, then CWI will not make matters worse

They will, but at a hefty price.

CWI won't make it better nor worse, but if it does turn out to be the bottom couple of feet of wall filled up with debris, this will eventually have to come out, and if the walls above have ben insulated, you may lose a small amount of insulation, plus the newly cleaned parts will be uninsulated.

[Mark]

No you are quite wrong in this. There are thousands of houses on the south cost built before 1890 with both cavity walls and a DPC This is from personal experience as I have owned a few dozen and still let three of this type and age.

[Hank]

Thanks - but how can evaporation occur on the *inside* of the inner skin if the cavity has been filled with insulation?

Hank

[Hank]

I know for a fact it has cavity walls. I have seen for myself, during a repair once. The cavity is about 3" wide. The house is on the South Coast, where such houses do exist.

Hank

[meow2222]

A 4" cavity on a Victorian brick wall means rattrap bond, and rattrap is a bond not suitable for CWI.

NT