Is this cavity insulation enough?

[redbrickman]

My first post so please be gentle

I'm buying a new house, currently being built. Every week I pay a visit and take some photos, unfortunately I can't get too close because of the screens.

My queston concerns the cavity wall insulation. I have attached a zoomed picture of the cavity, and I am concerned that the insulation looks to be only about 15-20 mm thick.

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• redbrickman
• 28 Feb 2010
• 1

Is it enough considering the regulations now are a lot more stringent than a few years ago.

I'm suspicious that the builder having had the original designs energy checked (top of C Band 80) may have dropped the spec on the insulation.

How often do the building control visit to check and at what stages?

Grateful for any advice.

 

[PrenticeBoyofDerry]

That does look a bit on the skimpy side, I wouldn't be happy with that. I'd expect at least 50mm.

 

[freddiemercurystwin]

I can't really tell from that photo, depends what insulation it is too. You could always ask the builder?

 

[Nige F]

Large National builder or local guy - Must be national if it`s screened and you can`t see In that case I would say it`s OK. . Just watch out when the Gas Safe ( plumbing) Redskins arrive

 

[noseall]

Looks more like a kind of fabric to me.

I wanna know what it is and i would like to see a better photo' please?

 

[redbrickman]

It's Celotex and they appear to be tiles about two feet square.

I managed to look at another similar house and confirm the material. Still don't know what the thickness is but will be inspecting it on Fri as I am meeting the site manager. I am none to happy with what I have seen, including some of the tile hanging free from the wall

Will ask him for full spec of brick block and insulation.

 

[freddiemercurystwin]

Its like no other Celotex I've ever seen then! Unfortunately tis often a bit of a reality check when you see your new home purchase being built, the photos on the trade webistes and reality are rarely in the same league!

 

[redbrickman]

A picture of another hosue nearby showing the foil panels taped and secured by red fasteners.

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• redbrickman
• 2 Mar 2010
• 1

 

[freddiemercurystwin]

Well no one can deny that that's Celotex although they look slightly peculiar sizes although photos can be deceiving, standard sheet size are 1200x450, assuming they're standard size blocks they look about 900x450. Anyway, that aside the only 25mm thick cavity wall insulation available from Celotex is the CW3000 http://www.celotex.co.uk/Products/Celotex-Products/Celotex-CW3000 and if they're only using 25mm that doesn't sound anything like enough to me. It does depend what kind of blocks they are too and nowadays technically the rest of the insulation used throughout the property. Get your ruler out on Friday, find out the make and model of the inner skin and exactly what the insulation is. Try and get a gander at a drawing or specification when you see the builder, he should have no problem showing you if he has nothing to hide. Don't tell him you've been on a Forum, that'll go down like a lead baloon! On the plus side the workmanship looks ok, just don't look after the external skins gone up at all the snots of mortar sitting on the wall ties and the empty drinks cans and bags of crisps in the cavity!

 

[mikric]

The blocks they are using look to be 115mm thick ones to me, celcon solar or similar I would think.
The thing to bear in mind is that the spec could have been passed and approved years ago, this is common on large developments that were passed years ago and the specs are below current standards.
If it is 25mm celotex and 115mm blocks I would roughly guesstimate a u-value of around 0.32W/m2k - 0.35W/m2k after doing the u-value calcs using celotex calculator, which is fine and nothing to worry about.
But I think you are right it looks thinner than 25mm to me.

 

[PrenticeBoyofDerry]

Have a word with the builder, as stated could be up to a old spec, I would want 50-75mm if it was my new build.

 

[Nige F]

then they would tell you to take your deposit back They are National firms- not your friendly local bespoke builder Like Noseall , whom I would seriously ask to come down and lodge nearby if I needed an extension, etc.

 

[alittlerespect]

Hi

Not sure what your builder has used but the proposed construction is unlikely to meet the requirements of Part L (Conservation of Fuel and Power) of the Building Regulations.
Whats worse is the fact that it appears that you have a cavity that is quite capable of taking 50mm thick insulation material and still leave a gap of 50mm for the cavity between the insulation and the facing brickwork. Which is a bit of a tell tale that all is not right!

Information on the insulation characteristics for the building should have been provided at the time of the planning permission and there must be a record of the design U value. As freddymercurystwin has already mentioned it may be that the plans have been on file for a while (maybe a couple of years or so) and the builder has stayed still while the insulation standards have moved on - for new build the U value should be a maximum of 0.30W/m2K.

Before jumping the gun you should find out the designed U value for the building, and chase up whoever is responsible for Building Control and if you are getting an NHBC guarantee get on their case as well!!


Final comment - as already mentioned you would be well advised not to mention that you have had any support from this forum - as it is bound to put the Builders back out of joint, and he won't be a happy chappy!!

Regards

 

[Nige F]

Hi

Not sure what your builder has used


Final comment - as already mentioned you would be well advised not to mention that you have had any support from this forum - as it is bound to put the Builders back out of joint, and he won't be a happy chappy!!

Regards

Yeah, we`re likely to get a bloke in a helicopter after us . Or a solicitors letter @ least. Maybe that`s why they put hoardings round sites now . Then you get the punters on here who say never fill a cavity with `owt

 

[ajrobb]

Let's assume that it is 30 mm Celotex and something like Thermalite block:

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• ajrobb
• 4 Mar 2010
• 1

So it could be OK.