second storey extension : insulation

24 Sep 2005
Reaction score
United Kingdom
I have recently built a new second storey extension to my house , previously a flat roofed property .The pitched roof has 200mm. x 75mm. rafters ,bird mouthed onto new steel purlins , which will allow insulation to a depth of 150mm. , with a space of 50mm. for ventilation through permeable roof felt .My question is this ? Is the new type , bubble silver backed foil , better than insulation board ?
Sponsored Links
Mikeyboy said:
bubble silver backed foil , better than insulation board ?
How thick are the bubble silver backed foil?

Is this a loft conversion or just a loft area?
Several other forums have hot debate on the effectiveness ( or not!) of multi layer/ bubble type insulation.

I can only comment on my own experience of an extension built and insulated with a multi layer foil!
2 months later we had cavity wall insultaion injected- much warmer!

Oh and your mobile phone or wireless internet won't work in the room either!
we used the tri iso 9 in our loft conversion. Very cosy, good noise reduction as well. Ive just moved my office upstairs and its just improved the signal on my wireless router for the internet, i thought it would be the other way round! Its easy to put up and quicker, however you have to batten across it, its not that easy to cut and you cant put a screw into it.
Sponsored Links
I've used 100mm of Celoxtex between rafters with 30mm below the rafters as a thermal break. This is nice and cosy warm even without the radiators installed in the upstairs rooms.

I can't comment on how good Tri-Iso 9 or similar is but take a look at the following for some background information (just remember who commisioned the 'independent' test)

Also, our local BC will not accept any of the foil solutions as they say that it does not achieve the required level of performance.

I would have loved to have used Tri Iso in my own extension as it could have made life much easier however it was not to be :(

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local