regularisation of Building control for loft conversion

[dogbotherer]

In 2001 I converted my part of my loft and turned the rest into a vaulted ceiling over a living room. The loft room opens onto a balcony over the living room. Stupidly, I didn't get building control involved. I have now gone back to them and tried to regularise it. They have rejected my application on a number of grounds, most of which I think I can deal with. The bummer is the roof insulation. I put in 30mm at the time - they say it should have been 50 mm. They also say that there should be a 25mm gap between the insulation and the breathable roofing felt. Any suggestions as to whether there is anything I can do other that a massive re-insulation of the whole ceiling of both the loft room and the vaulted ceiling?

 

[freddiemercurystwin]

I doubt it, you could try upping the insulation elsewhere in the property to compensate but obviously this is likely to cause even more hassle/expense.

 

[dogbotherer]

I suppose the question I need to find out the answer for is whether the regs did specify 50 mm back then. I didn't think it did.

 

[^woody^]

The regs would not specify a thickness, but would specify a value, and it will depend on what type of insulation was used which would determine what thickness it should be

Otherwise a whole house [SAP] calculation may be able to prove that heatloss through the roof is acceptable as it is

 

[dogbotherer]

I used Kingspan silver foil backed extruded polystyrene - I now think it's 35mm - I just measured it.

 

[freddiemercurystwin]

As mentioned, find out what U Value they require for the roof (probably 0.35 I think but your Building Inspector will tell you what he’s expecting if its not in your correspondence) then contact Kingspan technical 0870 850 8333 and ask for a U Value check to confirm what your 35mm gives you, if its not too far off the target you may get away with it. Certainly the first thing to try!

 

[jeds]

To save you looking it up, the min U-value of a roof with insulation at rafter level in 2001 was 0.20. Which is the same as it was up to three weeks ago.

 

[freddiemercurystwin]

I thought where it was a sloping ceiling jeds it was 0.35?

 

[jeds]

The 2000 issue of Part L just says pitched roof with insulation between rafters. Doesn't mention anything about sloping ceiling. Below is cut and paste from the table.

Element U-value
Pitched roof with insulation between rafters 0.2
Pitched roof with integral insulation 0.25
Pitched roof with insulation between joists 0.16
Flat roof 0.25
Walls, including basement walls 0.35
Floors, including ground and basement floors 0.25
Windows, doors and rooflights (area-weighted average),
glazing in metal frames
2.2
Windows, doors and rooflights, glazing in wood/PVC frames 2.0
Table 4: Maximum U-values in 2000 Building Regulations (England and Wales)

It was the same in 1991 but only if the overall SAP was below 60. If above it was 0.25.

How about this then; it was apparently 0.25 in 1985. Now I'd have lost money on that one.

Edit; looking at that now I suppose a sloping wall would be 0.35. But are we not talking about a converted roof here?

 

[freddiemercurystwin]

OK, 1995 Regs, table 1 (page 8 ) underneath the table note 2 says 'sloping parts of room in the roof 0.35'. Or is there another table for extensions, didn't think there was?
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL_1995.pdf

 

[dogbotherer]

Ok - I've got a glimmer of hope - thnks a lot guys - much appreciated. Jon