Dirty Cavity Insulation Problem.

harryhound

The situation and story so far is as follows:

Circa 1970’s, an early retired postal worker, took on a countryside shack as a retirement project.
The property was a four room wooden shack from 1930.
As it is in the “green belt”, he had to resort to propping up the roof and rebuilding the walls below it.
He built in mainly brick-cavity-block. Though his work is hidden behind render and internal plaster, I could not call him a “craftsman”! He then put in plans for a grant assisted bathroom and kitchen, cooking on the living room stove being a bit primitive, and built a large extension at the rear. This appears to have been built to local council inspection standards and pebble-dashed to match the rest. It is fletton brick-2”cavity-block; but parts of the top of the cavity have not been closed.

At his stage the original renovator died. I took on the still to be fitted out renovation, in the mid 1970’s, and completed the job.

During the next 10 years I managed to get permission to extend in two directions, building in 225mm “Durox” blocks. The property has changed from the original 50 sq metres of shack to about 160 sq meters of bungalow. At the time, I was thought of as a bit of “a nutter” for putting 125mm of insulation in the roof, double glazing the big wooden “Sunshine” window frames (re-done this year in 4-6-4 mm Guardian glass low e coated sealed units). I even put 50mm of expanded polystyrene under the screed, in the extensions I built.

So now on my route to saving 20% by 2020%, I’ve arranged to have my loft insulation topped up to a depth of 275mm.

BUT about 1/3rd of the external wall of the bungalow is still a nominally 2” cavity structure. That is the North – Eastern corner measuring about 2.1 x (7 + 10) = 36 sq meters (less window area).

As the utility companies are being forced by government levies to subsidise insulation, I asked a local South Essex firm to come and take a look.

The young “surveyor” turned up and we drilled half a dozen holes through the 17 metres of wall to confirm with his “endoscope” lighting/viewing gizmo, that there is indeed a cavity in there somewhere. So I signed up at a price of 150 GBP.

A fortnight later a big van arrived, with a crew of two. Already an hour late, because they seem never to have heard the words “Internet” or “Tom Tom”, their mood did not improve as I tried to explain where the cavities were. Eventually the senior of the two set off to drill rows of holes round the bathroom while his mate was still preparing the flexible hose. They were trying to inject [EMAIL="instafibre@instagroup.co.uk"]instafibre@instagroup.co.uk[/EMAIL] . This looks like little yellow blobs of fibre that could have been scraped off the end of a “cotton bud”. The injecting pump works like a petrol pump; when it thinks the cavity is “full” it cuts out.

Well we tried two different holes and the pump cut out after about a half pint of fibre blobs had been injected.

A small drama then developed as we re-sealed the holes:

-[FONT=&quot] [/FONT]“Are you sure this wall is not “brick tied? - by this I think he meant “rat-trap” bond ; looking down the cavity I cannot see anything.
-[FONT=&quot] [/FONT]“Where is the surveyor?” – “off sick!!!”
-[FONT=&quot] [/FONT]“I told you this place would be trouble when we came up the drive; we’ll be lucky to clear 100 GBP after a start like this”.

As I watched the van disappear down the lane, I was only too aware that I was dealing with subcontractors of a sub-contract from National Power. No way was I the “customer”.
So where do I stand?

How can I insulate this section of wall?

Can someone do a realistic detailed survey of my wall and of its problems?

Would foam do a better job?

What about polystyrene beads (though I am concerned that there are some drop down lengths of PVC wiring in there and styrene makes PVC hard & brittle) ?

Can I expect a surveyor with an infra red camera to check my heat leakage through this section of wall?

Would it be cheaper to take down one of the leaves of the wall and rebuild?

OMG – any sensible advice or experience would be gratefully received.

Harry.

PS I’ll post this on the forums of
http://forums.moneysavingexpert.com (Where I can be contacted as “harryhound”)
http://www.screwfix.com/talk/
http://www.greenbuildingforum.co.uk/

harryhound

ping ping ping

adaze

without being an expert or having anything to look at, I would say that there isn't a proper cavity there, maybe some voids that have formed through settlement, especially if this is an old brick wall, and if it is, then the answer is you can't - well not unless you would consider "fixing" insulation to the inside or outside of the wall?