New build deviating from plans…

[blueg33]

Zarco said:

Do any new build sites use blown insulation? I've never heard of it. Seems like a right awkward and crap way of doing it.

Not as a rule.

[Toaster Pilot]

AlmostUseful said:

I’ll get back in my box then

Still reckon it was just the wrong drawing used.

Yeah I agree, they’ve more or less said as such when discussing remedials.

[Zarco]

mcg_ said:

Zarco said:

Do any new build sites use blown insulation? I've never heard of it. Seems like a right awkward and crap way of doing it.

why awkward and crap?

Easier to just install insulation board in the cavity as the wall is built by the brickies, rather than having another trade involved (insulation blower?).

Can be inspected as works progress, and be sure the whole wall is insulated.

No need to leave a hole to blow insulation in. How do you know its even been filled properly with blown insulation.

If you need to make a hole in the wall retrospectively (whether during the build or after occupation) board doesn't all fall out.

I honestly thought this was a technique only used on existing buildings without any cavity insulation.

[anonymous-user]

I’ve got a 60s bungalow I extended. The old parts have empty cavity walls which I keep considering for blown insulation. Would love to do it but too many scare stories put me off.

[OutInTheShed]

blueg33 said:

Zarco said:

Do any new build sites use blown insulation? I've never heard of it. Seems like a right awkward and crap way of doing it.

Not as a rule.

Some years ago, I knew a bloke doing foam injection to cavity walls, quite a lot of his work was on new builds.

[blueg33]

PianoManYork said:

I’ve got a 60s bungalow I extended. The old parts have empty cavity walls which I keep considering for blown insulation. Would love to do it but too many scare stories put me off.

Its not designed to have insulation. The cavity will need to breathe.

[Equus]

OutInTheShed said:

blueg33 said:

Zarco said:

Do any new build sites use blown insulation? I've never heard of it. Seems like a right awkward and crap way of doing it.

Not as a rule.

Some years ago, I knew a bloke doing foam injection to cavity walls, quite a lot of his work was on new builds.

The last major housebuilder I worked for, directly, used 'ecobead' insulation (the grey polystyrene balls sort of stuff).

It can be cheaper to have a specialist company do several houses at once as you're building an estate, rather than have bricklayers buggering about fixing insulation as they go along.

blueg33 said:

The cavity will need to breathe.

This is not the case.

Depending on cavity width (it needs to be a minimum of 50mm., not for breathability, but to reasonably obviate the risk of moisture bridging) and exposure, it can be fine. There is no technical need for the cavity to 'breathe'. See pages 32-35 of Approved Document C

[anonymous-user]

Equus, are there specific blown retrofit options you would recommend/avoid? As I said, I am tempted because the old rooms do have very cold walls in the colder months and must be leaking heat terribly.

[Pflanzgarten]

Story Homes used blown in insulation, miles cheaper than solid and quicker.

Not sure if it'll get them to the new regs now though, this was last year.

ETA I'm not saying it's better than solid.

[mikey_b]

My 1958 house has blown-in cavity wall insulation. It also has a large extension built about 8 years ago which has the modern standard slabs of rock wool type insulation added during the build.

We have zero issues with damp transfer (or any other problems) where it was retrofitted. It’s a sort of white fluffy stuff, looks a bit like cotton wool. Seems to be very effective though, the older part of the house is generally warmer than the new, although to be fair the new part really needs another rad installed, and the bedroom has three outside walls and a garage under it, so perhaps I’m being unfair to blame the insulation.

[Equus]

PianoManYork said:

Equus, are there specific blown retrofit options you would recommend/avoid?

I prefer the 'Ecobead' (polystyrene balls) type to the 'blown fibre' type.

Although theoretically both types are waterproof, my experience is that you're more likely to suffer problems with damp tracking across the cavity with the blown fibre type... but in any case, the 'Ecobead' type gives slightly better levels of insulation, when it is done properly.

IME, most problems are down to either pre-existing defects or application to an inappropriate property (too narrow a cavity or too exposed a location), rather than the type of insulation used, though.

[blueg33]

Equus said:

OutInTheShed said:

blueg33 said:

Zarco said:

Do any new build sites use blown insulation? I've never heard of it. Seems like a right awkward and crap way of doing it.

Not as a rule.

Some years ago, I knew a bloke doing foam injection to cavity walls, quite a lot of his work was on new builds.

The last major housebuilder I worked for, directly, used 'ecobead' insulation (the grey polystyrene balls sort of stuff).

It can be cheaper to have a specialist company do several houses at once as you're building an estate, rather than have bricklayers buggering about fixing insulation as they go along.

blueg33 said:

The cavity will need to breathe.

This is not the case.

Depending on cavity width (it needs to be a minimum of 50mm., not for breathability, but to reasonably obviate the risk of moisture bridging) and exposure, it can be fine. There is no technical need for the cavity to 'breathe'. See pages 32-35 of Approved Document C

You are right. I got my dates wrong. Pre 1930’s cavities are not usually suitable for cavity wall insulation

[anonymous-user]

Equus said:

PianoManYork said:

Equus, are there specific blown retrofit options you would recommend/avoid?

I prefer the 'Ecobead' (polystyrene balls) type to the 'blown fibre' type.

Although theoretically both types are waterproof, my experience is that you're more likely to suffer problems with damp tracking across the cavity with the blown fibre type... but in any case, the 'Ecobead' type gives slightly better levels of insulation, when it is done properly.

IME, most problems are down to either pre-existing defects or application to an inappropriate property (too narrow a cavity or too exposed a location), rather than the type of insulation used, though.

Many thanks.

[smokey mow]

blueg33 said:

Zarco said:

Do any new build sites use blown insulation? I've never heard of it. Seems like a right awkward and crap way of doing it.

Not as a rule.

In my experience Persimmon Homes and Charles Church do on their Essex sites, or at least all the ones I’ve looked at in the last 5 years or more.

[blueg33]

smokey mow said:

In my experience Persimmon Homes and Charles Church do on their Essex sites, or at least all the ones I’ve looked at in the last 5 years or more.

They didn’t when I was there but that was longer ago

[smokey mow]

blueg33 said:

smokey mow said:

In my experience Persimmon Homes and Charles Church do on their Essex sites, or at least all the ones I’ve looked at in the last 5 years or more.

They didn’t when I was there but that was longer ago

They had a lot of issues with theft of cavity batts by the sub-contractors for their own projects so switched to blown cavities around 2016.

[blueg33]

smokey mow said:

blueg33 said:

smokey mow said:

In my experience Persimmon Homes and Charles Church do on their Essex sites, or at least all the ones I’ve looked at in the last 5 years or more.

They didn’t when I was there but that was longer ago

They had a lot of issues with theft of cavity batts by the sub-contractors for their own projects so switched to blown cavities around 2016.

They should choose better subbies................ Its not an issue I can ever recall having.

[smokey mow]

blueg33 said:

smokey mow said:

blueg33 said:

smokey mow said:

In my experience Persimmon Homes and Charles Church do on their Essex sites, or at least all the ones I’ve looked at in the last 5 years or more.

They didn’t when I was there but that was longer ago

They had a lot of issues with theft of cavity batts by the sub-contractors for their own projects so switched to blown cavities around 2016.

They should choose better subbies................ Its not an issue I can ever recall having.

Like the subbies who built toaster pilots window ?

In my experience it’s a race to the bottom in terms of price with little site control or concern about quality.

I heard a rumour recently that one local developer (who I won’t name) is now charging an additional £500 premium on their new homes if you appoint your own snagger so as to cover the cost of additional works and rectifying the defects they find.

Edited by smokey mow on Monday 20th February 17:52

[blueg33]

smokey mow said:

Like the subbies who built toaster pilots window ?

In my experience it’s a race to the bottom in terms of price with little site control or concern about quality.

I heard a rumour recently that one local developer (who I won’t name) is now charging an additional £500 premium on their new homes if you appoint your own snagger so as to cover the cost of additional works and rectifying the defects they find.

Edited by smokey mow on Monday 20th February 17:52

Site management, is, as ever, they key to a good build

[crofty1984]

Mark V GTD said:

The criticism of new build houses does amuse me. I was brought up in a 1930's semi - it was a new build in the 1930's - 9" brick outer walls, rendered and pebble-dashed, single glazed windows holding up the bay windows to the front elevation, zero insulation. In other words, simple construction but still standing today with replacement roof tiles, windows and loft insulation, re-wired and new plumbing. Basic structure all original though.

I'm sure the vast majority of todays new homes will be around for as long with a similar level of replacement and upgrading.

Edited by Mark V GTD on Monday 13th February 13:07

They built these old houses like mine to last a hundred years!

... But now it's 100 years old and needs a bit of extra care in its dotage!