Extension

[davethsparky]

Re: how not to wire your extension

You can get rockwool cavity batts, but they are a lot more solid than that stuff and they have to be pinned back to the outside skin with big washer type things that go over the wall ties.

 

[jonwade]

Re: how not to wire your extension

ah, I had not realised at the time that was rock wall! - so that's a problem too.... moisture could soak through the bricks into the cavity insulation and into the room?

I am amazed that building control do not check all this stuff if it is so important.

 

[jonwade]

Re: how not to wire your extension

OK, found a photo I took of the product, it is Earthwool DriTherm37, which is described as:

Application: Earthwool DriTherm Cavity Slabs are for the thermal insulation of masonry cavity external walls and are installed to fully fill the cavity. They are approved for use in buildings up to 12m high in any exposure zone and for use in multi-storey applications up to 25m in height.

Read more: Earthwool DriTherm Cavity Slabs Earthwool DriTherm Cavity Slabs
Follow us: @KnaufUK on Twitter

So, does that mean it is OK?

 

[ExArmy]

Re: how not to wire your extension

yeah ok it looks like it's being used as it was intended to, so don;t panic. but i would certainly not be filling the cavity right up.

 

[davethsparky]

Re: how not to wire your extension

Building control should be looking at these things if they have been called in by the builder at the correct times in the job.

According to the data on that website yes that is the right stuff, just doesn't look like any cavity batt i've seen used before!

 

[saveloy]

Re: how not to wire your extension

Dritherm cavity batts are a perfectly acceptable form of insulation.
This type of insulation is known as full fill and is a standard building
system. There is no need for clips and it wont transmit damp from outside to inside.

 

[ExArmy]

Re: how not to wire your extension

Dritherm cavity batts are a perfectly acceptable form of insulation.
This type of insulation is known as full fill and is a standard building
system. There is no need for clips and it wont transmit damp from outside to inside.

debatable. they said the same about the "new" cavity fill beads" that are used for retrofit cavity insulation, but they cause problems still! i'd be interested to see how both of them perform back to back, and the cost difference (dritherm vs 50mm cavity batts)

 

[saveloy]

Re: how not to wire your extension

debatable. they said the same about the "new" cavity fill beads" that are used for retrofit cavity insulation, but they cause problems still! i'd be interested to see how both of them perform back to back, and the cost difference (dritherm vs 50mm cavity batts)

Well it is a system that has been used in millions of
houses and extensions all over the country for the past 30 odd
years. Problems with damp transmission in cavity walls will
almost always be down to poor construction methods
ie cavitys bridged with mortar or poor pointing rather than insulation transfering moisture.
Granted a partial fill system will almost guarantee no damp by virtue of a free air gap, but only if constructed properly.
If full fill caused that much of a problem then there would be millions of homes with problems amd it would have been abandoned by now.

 

[danzor]

At least they have a Gary Neville

 

[pepparz]

Re: how not to wire your extension

Think hes taken pictures for when he has to take the builder to court!