Renovation of a Thermal Element

[Gizzydash]

Hi All,

Hoping someone can help me make sense of guidance re renovation of a thermal element, specifically replacing a timber suspended floor.

If you replace all the joists, I'm reading it that you have to meet the u-values of say a new build as opposed to renovation u-values (0.22 versus 0.25-0.7). Is that correct?

In relation to this paragraph:
Where more than 50% of the surface area of an individual thermal element or more than 25% of the total building envelope is being renovated (through undertaking an activity listed in paragraph 3.67), the whole of that element should be upgraded to the improved U-values given in column (b) of Table 3.4.

This means if you expose joists say on more than 25% of the total building as part of renovations, you should upgrade everything to renovation u-values? Equally though replacing a floor is renovating >50%, so do you go by the renovation u-values or new?

Thanks!

 

[John D v2.0]

You only have to do your best, basically aim for the recommended values but it doesn't always make sense to get all the way there

 

[Notch7]

Hi All,

Hoping someone can help me make sense of guidance re renovation of a thermal element, specifically replacing a timber suspended floor.

If you replace all the joists, I'm reading it that you have to meet the u-values of say a new build as opposed to renovation u-values (0.22 versus 0.25-0.7). Is that correct?

In relation to this paragraph:
Where more than 50% of the surface area of an individual thermal element or more than 25% of the total building envelope is being renovated (through undertaking an activity listed in paragraph 3.67), the whole of that element should be upgraded to the improved U-values given in column (b) of Table 3.4.

This means if you expose joists say on more than 25% of the total building as part of renovations, you should upgrade everything to renovation u-values? Equally though replacing a floor is renovating >50%, so do you go by the renovation u-values or new?

Thanks!

Is the rest of the work you are doing under building regs? - if not, do what you want.

 

[^woody^]

If it's inside, who will even know or notice?

Do your best (which is the actual requirement), but don't worry about it and don't bother with an application.

Pay attention to draught proofing.

 

[tony1851]

This goes to show how ridiculously complicated thermal insulation is becoming.
In the Good Old Days of Building Regulations 1965, we were told what insulation material and thickness was required, and that was that.
No faffing about with cold bridges, vapour barriers and lambda values.