Side extension with 150mm cavities.
- Thread starter excited
- Start date
None physical. But I'd guess one could question whether spending more elsewhere in the property instead would provide better value for money.
You would be increasing the insulation thickness by around 50mm above normal.
That 50mm might be better applied in the roof.
That 50mm might be better applied in the roof.
I'm not sure whether you can get cavity lintels or housing ties for that width.
You need to ask the question - at what point does a wider cavity become ineffective?
As the guys have said there will be a point at which making the cavity thicker than say a standard 100mm will only boost your thermal resistance by smaller and smaller percentages, the wider you go.
Look at building more robustly, i.e. making sure your builder does all he can to alleviate drafts around openings, floors abutments etc. We use foam, mastic and tape wherever we see a hole, crack or gap!
You need to ask the question - at what point does a wider cavity become ineffective?
As the guys have said there will be a point at which making the cavity thicker than say a standard 100mm will only boost your thermal resistance by smaller and smaller percentages, the wider you go.
Look at building more robustly, i.e. making sure your builder does all he can to alleviate drafts around openings, floors abutments etc. We use foam, mastic and tape wherever we see a hole, crack or gap!
You can, although they are normally used in commercial construction.
Probably not though, as insulation obeys the law of diminishing returns...so increasing from 100mm to 150mm in the walls would give more benefit than increasing from 300mm to 350mm in the roof.
Would it be possible to build the wall using 75mm blocks to keep the wall to 300mm thickness, I wonder...
If it's single storey, why not use timber frame for the inner skin? Lots of space to pack insulation.
Ah, sorry, I was thinking of full fill insulation.
I wonder why 75mm block is not used. I'm sure structurally at least it would be fine if well tied together.
Ancon make some heavy duty, thermally efficient wall ties for large cavities.
Easiform housing was made with 75mm inner and outer skins and a 50mm cavity. Solid concrete admittedly...
Did build an extension in the early 80's with 75mm blocks on the outer skin, but was told that the render was included in the thickness, unlike tile hanging or cladding.
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