Cavity walls insulation 1900 detached house

[robbie77]

This is following on from a post I had on the plumbing forum.
House is circa 1900 and I believe it has cavity walls although I know that most houses around this time were not.

I know for a fact that at least 2 of the original walls have a cavity but does it generally follow on that the others will be to?

The reason I ask is that I am considering cavity wall insulation but some of the walls where the bedroom windows on don't look wide enough.

I have noticed that one bedroom window gets condensation quite badly, (single glazed) not sure if that means anything.

I am worried about getting the insulation as I have no damp problems that I know of and the house has had no modern damp proof course (aint broke don't fix it philosophy) so I am worried about someone hacking into the unmolested for 125 year old walls, injecting or doing whatever they do and then me having problems.

I am aware of the grants available.

I want a more efficient house but I am worried about the consequences.
What do I do!?

Any suggestions or recommendations?

P.S Have insulated and boarded the loft myself to help.

Many thanks................

 

[r896neo]

Just get your tap measure out and check the reveals. I cavity wall should come out in the region of 13 inches whereas a solid 9inch wall will be around 10.

 

[robbie77]

Thanks neo. Will get tapemeasure out.
Any other experiences with old house and cavity walls or suggestions? I noticed I can get grants from most big energy companies. I guess all much of a muchness.

Do they just drill a hole at the top of the wall and pump it full of insulation?

 

[r896neo]

they drill lots of holes approx every 1.5m apart width wise and at least one sometimes 2 per floor height wise.

If you get them to come and quote they will often remove a brick to double check cavity dimensions and suitability.

being so old your cavity walls may be an odd size like a 75mm or even less gap in which case they might not be suitable.

 

[ajrobb]

Be aware that cavities prior to 1930 often indicate a wall exposed to driving rain. These cavities probably use iron ties. Cavity wall insulation exposed to driving rain might get sodden and cause iron ties to rust and fail. Wet insulation is no good. There are horror stories of people having to have the CWI removed.

I think a modern cavity wall exposed to driving rain might have insulation against the inner leaf AND a 75mm empty cavity.

Mineral wool can be coated with silicone to prevent wicking. Check what product they intend to inject.

It's your wall, your decision.

 

[stuart45]

Old houses normally have cavities of 2-3 inches. This size cavity was used until the 90's when a 100mm one was more common.
If your cavity is less than 45mm they probably won't fill it.
They usually drill holes at 3 different heights to check and also make sure there isn't too much debris in and on the wall ties.

 

[robbie77]

Thanks for the replies everyone.

These cavities probably use iron ties.

Spot on. I have iron wall ties. Around the rear porch one has rusted and swelled lifting some of the brickwork.
I am going off the idea....

 

[stuart45]

If your ties are that bad they won't fill it.