Wires in cavity - cavity wall insulation

[bernardgreen]

Uncommon.

https://www.bbc.co.uk/news/uk-wales-42165358

http://cavitywallcheck.co.uk/ “Inappropriate cavity wall insulation in homes has become ‘a scandal’ according to the UK government. The UK Government is working closely with selected partners to address and improve the situation.”

 

[JohnD]

I don't see the numbers you have in mind.


"Not unique" does not mean "common."

It's strange that the BBC article includes pictures of damp internal walls.

The advertising page you quote includes words attributed to the UK government. Where is the government statement?

 

[bernardgreen]

Quoting from HERE

Can cavity wall insulation allow rainwater across the cavity?
Despite the constant insistence by manufacturers and installers that cavity wall insulation cannot allow rainwater to cross the cavity, the Building Research Establishment has found that it can. Their findings have been published in a number of BRE publications, notably BRE Good Building Guide 44: part 2: “Insulating masonry cavity walls – principal risks and guidance” (available from www.brebookshop.com). This states, “There can be an increased risk of rain penetration if a cavity is fully filled with insulation, ie moisture is able to transfer from the outer to the inner leaves resulting in areas of dampness on internal finishes. Rainwater, under certain driving rain conditions, can penetrate the outer leaf of masonry leading to wetting of the cavity insulation, a reduced thermal performance and damage to internal finishes.”

 

[JohnD]

No numbers.

Does it contradict what I said?

No.

The advertising page you quote includes words attributed to the UK government. Where is the government statement?

 

[sparkwright]

Yes the power socket is a spur not on the main ring.

I doubt there will be a massive effect on the cables themselves, the main worry would be the issue of changing them in the future, without much knowledge of CWI, is it possible to run wires through it? In other words, would I still be able to pull the wires through and replace after CWI has been installed?

Knocking the bricks out won't be too much of an issue because I had to knock bricks out and replace to brick up the hole left by the flue, this was 4 full bricks in the end. It's enough space to get some trunking in but it sounds like it might not even be worth it.

In terms of the type of insulation, the quote we've received so far has quoted Energystore BAW 18-057-S-A-UK but I'm not sure whether that's related to the type of insulation or not.

I honestly never knew about the risks of damp in houses with CWI, I assumed it was a "no brainer", every day is a school day!

The house was built in the 70s, it's a detached dormer with a damp proof course and lots of air bricks underneath that.

Edit, the quote includes having all the cavities cleared of rubble

Yes, you should be able to draw in new cables very easily, by tying onto the old ones, without the CWI being a problem.

Just make sure sure you tie it on well .

 

[JohnW2]

... it's a detached dormer with a damp proof course and lots of air bricks underneath that.

As a matter of interest, what is a "detached dormer"?

Edit, the quote includes having all the cavities cleared of rubble

Again as a matter of interest, is there a reasonably non-destructive way of doing that?

Kind Regards, John

 

[Harry Bloomfield]

Again as a matter of interest, is there a reasonably non-destructive way of doing that?

It depends what you call 'destructive'. When we had our cavities inspected, cleared out - they removed three bricks, every yard or so, to get a scraper, a light and a mirror in. After which, removed bricks were replaced.

 

[JohnW2]

It depends what you call 'destructive'. When we had our cavities inspected, cleared out - they removed three bricks, every yard or so, to get a scraper, a light and a mirror in. After which, removed bricks were replaced.

I suppose I would call that 'fairly destructive', and I'm far from convinced that it woukld always be adequate ...

... as I've said, I have not lived with cavity walls for many years (just 13½" and 18" solid brick walls!) but, in the cavities of other houses I've seen, the so-called 'rubble' is often not simply bits of broken brick etc. - but is also at least partially bits of mortar which which were dropped into the cavity, which, when set, often become 'well stuck' to the bricks/blocks and, worse, sticks a lot of the true bits of rubble together, and to the bricks/blocks!

Kind Regards, John

 

[siross85]

Keeping in mind the warning about polystyrene dissolving PVC insulation on cables, if it is a loose fill type of insulation, you will have no problems pulling in a new cable using an old or existing one as a draw wire. Chances of your adding a cable without a draw wire, once the CWI is in place are almost nil.

I've emailed the company asking them to clarify what type of insulation is being quoted for but they have not got back to me yet. The wires are already there to act as a draw wire so that shouldn't be an issue then, I ran the wires prior to all plastering and have since just used existing wires as draw wires.

Yes, you should be able to draw in new cables very easily, by tying onto the old ones, without the CWI being a problem.

Just make sure sure you tie it on well .

Ha, good point. I've fallen foul of that before, it's infuriating thinking you've got it through only to be very disappointed!

As a matter of interest, what is a "detached dormer"?
Again as a matter of interest, is there a reasonably non-destructive way of doing that?

Kind Regards, John

Hi, probably a poor choice of explanation. It's a detached bungalow which has a dormer on it

 

[JohnW2]

Hi, probably a poor choice of explanation. It's a detached bungalow which has a dormer on it

Thanks for clarifying. Some rather odd images were going through one mind when I tried to imagine what a "detached dormer" might be

Kind Regards, John

 

[siross85]

Hi guys, I've had confirmation that the material quoted for is the Energystore Superbead https://energystoreltd.com/energystore-superbead/

This is the polystyrene stuff which I'm assuming is a no go with wires in the cavity? The video does look good in terms of moisture management though, or is that marketing nonsense?

 

[Harry Bloomfield]

This is the polystyrene stuff which I'm assuming is a no go with wires in the cavity? The video does look good in terms of moisture management though, or is that marketing nonsense?

Polystyrene does not absorb water, so they will not transmit damp from outer to inner leaf. I understand the same is now true of other blown in insulations now though. Originally there was a problem with the insulation used being moisture absorbent.

 

[JohnD]

expanded polystryrene contains a chemical that attacks the PVC sheathing and insulation from ordinary electrical cables, so they must not be in contact.

Or maybe it absorbs one of the constituent chemicals from the PVC.

Either way, it wrecks the cable.

 

[sparkwright]

Hi guys, I've had confirmation that the material quoted for is the Energystore Superbead https://energystoreltd.com/energystore-superbead/

This is the polystyrene stuff which I'm assuming is a no go with wires in the cavity? The video does look good in terms of moisture management though, or is that marketing nonsense?

Tell them you want the other stuff.

I don't why these chancers insist on bunging in this polystyrene stuff that attacks cables.

The bottom line is these cavity wall insulation people do not care one bit.

 

[crystal ball]

expanded polystryrene contains a chemical that attacks the PVC sheathing and insulation from ordinary electrical cables, so they must not be in contact.

Or maybe it absorbs one of the constituent chemicals from the PVC.

Either way, it wrecks the cable.

I spotted this in a loft, someone had emptied some polystyrene packing (Quavers) to top up the insulation, the cables had an oily feel to them