50% repair rule for insulation

[Bill35]

The building regs say that if more than 50% of a roof (or thermal unit) is being replaced, new insulation must be fitted in line with current standards and it requires a building control application.

 

My q is how do they calculate the 50% figure in practice? For example, I am looking at replacing the front of my pitched roof which is smaller than the back, so would be < 50% of the total roof. If it came to it, would Building Control want to count each pitch separately, or look at the total area of the roof?

[SteamyTea]

Why would you not improve the current insulation to at least current regulations.

 

[ProDave]

I read the question as would I be expected to upgrade the insulation on the bit of roof that is not being replaced as well?

 

But what sort of roof is this?  If a normal pitched, tiled, cold roof you are not touching the insulation in any case, so you must be talking of some form of warm roof?

[Bill35]

It's a pitched roof with multiple leaks and other issues and so we are looking to replace the front pitch of it on a very limited budget, the focus being on restoring it's integrity.

 

We would rather not retrofit insulation given it's a very old house and the front roof is a dormer loft conversion, I think the only way to insulate it would be pulling plaster back and doing it from inside which we can't afford at the same time as the roof.

 

Focusing just on the front roof, which is less than 50% of the house's total roof area, could we do this without building control and forced insulation work?

[Ferdinand]

What's the plan for the house?

 

If you or relations plan to live there then I think you will regret *not* doing it, as it will inflate the heating bills forever. And this may be your only chance.

 

With Building Control, you are probably best asking them directly. I would just make a phone call to them and ask without mentioning the address. My BCO is quite sympathetic to constraints.

 

Someone here may be able to advise on how to do it from the outside tout disturbing the plaster, and without costing too much. Presumably this is DIY - getting other people working on your roof is always expensive.

[ProDave]

If stripping the roof to re tile, you could strip it completely, old tile battens, felt and expose the wall structure and re insulate from outside without disturbing the plasterboard.  If it were me, I would take the once in a lifetime opportunity while doing that to over sheet the roof with a layer of external insulation before membrane battens and tiles.  That will vastly improve what is probably a cold and leaky dormer at the moment.

 

If you just patch up the tiles and ignore the rest you will regret it later when it will be very much harder, more expensive and more disruptive to upgrade the insulation.

[Roger440]

Whilst doing some upgrade to your insulation while you are there makes sense, im not sure why anyone would ask building control either way.

 

id just crack on and do what you need to do.