New Extension advice on external wall insulation

[roboughton]

Hi all I am after some advice on insulation my extension as I am getting conflicting reports

I should point out I have not started the build yet but planning passed and all funds in place. I am happy to go above and beyond min spec insulation.

300mm wall with 100mm cavity (potential to change if required)

So to the question

What is the best form of insulation in the cavity? Full fill (dritherm) or partial fill boards (kingspan)? I ask as several people have said go with full fill it cheaper and does the same job then I see one most of these tv programs that they put solid board partial fill in so I am confused.

I currently have spec of 50mm kingspan in my plans but I was thinking of maybe going with dritherm 32 and then putting a 50mm insulated plasterboard on dabs on the internal walls. Or maybe I should just put 150mm cavity with full fill dritherm?[/i]

 

[noseall]

Full fill every time.

Quicker, simpler ,cheaper and does pretty much the same job.

 

[roboughton]

Full fill every time.

Quicker, simpler ,cheaper and does pretty much the same job.

Should I use insulated plasterboard to give me more insulation? I live at the top of a hill in Wales and the existing dwelling is known as the cold house.

 

[freddiemercurystwin]

Additional insulation is worthwhile up to a certain point. That said, you will still lose loads of heat through the existing if uninsulated so had you considered upgrading that instead?

 

[roboughton]

Additional insulation is worthwhile up to a certain point. That said, you will still lose loads of heat through the existing if uninsulated so had you considered upgrading that instead?

The rooms in the exisitng dwelling with no insualtion will be upgraded as and when the rooms are refurbished, a few of which will be done when the extension occurs, luckly I have already done the upstairs rooms that are not connected to the extension so no waste of cash there.

As for the cavity and the extra insualtion my thoughts are still to go

100mm full fill in cavity with 50mm insulated plasterboard bringing the board 62.5mm off the internal wall on dabs.

 

[tony1851]

Without doubt full-fill Dritherm 32.
50 kingspan will give the same standard, but at greater cost, and a slightly increased risk of damp penetration if the workmanship is not 100%.