Building Regulation for Flat Roof Replacement

pred02

Hi,

I need to replace my flat roof. It's currently I believe a cold zinc roof, want to replace with either Felt or GRP.

I written and tried calling my council to get more information on BR, but could not find a clear answer.

Reading online as I am replacing the type of material and insulating then I do need BR paperwork as its more than 25% of the roof however when I ask the roofers that came in (and I already have a few come in) they mentioned this is not required as I am not making structural modifications to the roof.

I want to make sure I have paperwork when I sell the flat.

1. I know I need to file for BR planning permission. At what other stages do the inspectors come?

2. Is there an additional cost above and beyond filing the paperwork with BR?

3. Is a warm roof the only/preferred option or can I insulate the rafters by putting in 50mm between joists?

4. If the existing boards are in good condition/not rotten, is there any benefit of replacing them with OSD3 if putting up a felt roof?

I cannot get in touch with my council (Lambeth) so any steer on this is appreciated.

Thanks,

Mistral001

If you are changing the roof covering to that covering that is not heavier than the one that is one it now, you should not need Building Control Approval. If it is heavier, then that would be a structural alteration as the structure below the covering would have to be checked to see that it can take the heavier load.

pred02

I finally go through to the council. They said if BR is required is a 'grey' area and that they cannot enforce it. However, they said to avoid any issues when selling the property I should file (and pay).

They said to file 72 hours before beginning work, and up to 3 inspections are required though she was not sure if this is the case.

If replacing Zinc with felt it should weight less, however if I do end up putting 120MM boards on top for the warm roof then the weight will likely increase.

I wish there were clear guidelines for this.

FreeBear

pred02 wrote: »

3. Is a warm roof the only/preferred option or can I insulate the rafters by putting in 50mm between joists?

50mm of Celotex/Kingspan type insulation will get you no where near meeting BR requirement. You'll want 150mm of PUR or around 270mm of fibreglass/rockwool.

andrewf75

I'm no expert but you surely don't want to be doing a roof in felt. EPDM rubber is the modern equivalent.

Doozergirl

FreeBear wrote: »

50mm of Celotex/Kingspan type insulation will get you no where near meeting BR requirement. You'll want 150mm of PUR or around 270mm of fibreglass/rockwool.

And they expect warm roof build up now, or certainly do in Birmingham.

pred02

andrewf75 wrote: »

I'm no expert but you surely don't want to be doing a roof in felt. EPDM rubber is the modern equivalent.

The cost fo doing EPDM or GRP roof is twice as much as doing felt. I will be selling the property in <5 years so I am not sure it warrants the return on investment.

Majority of the roofers I had over recommended felt or GRP, they said EPDM blisters up, rips etc. I only got one quote for EPDM and did not feel the roofer was competent and the quote was near the GRP ballpark.

£9000 for GRP roof, £4500 for felt warm roof. 30 sq meters, South London.

Mistral001

pred02 wrote: »

The cost fo doing EPDM or GRP roof is twice as much as doing felt. I will be selling the property in <5 years so I am not sure it warrants the return on investment.

Majority of the roofers I had over recommended felt or GRP, they said EPDM blisters up, rips etc. I only got one quote for EPDM and did not feel the roofer was competent and the quote was near the GRP ballpark.

£9000 for GRP roof, £4500 for felt warm roof. 30 sq meters, South London.

If a felt roof is done properly it can last for decades. My felt roof lasted 40 years before it had any signs of a leak.

ric1982

I think you wanna look at Building Regs L (for energy efficiency stuff). This is now required when you change the roof. (not for minor repairs). There are youtube videos about this.
Personally I dont like the idea of either felt or EPDM. I dont know how much DIY you want to do but you can get GRP roof kits and you can go for a day worth of training. Personally I think its doable. But it really depends how much hassle you want to take on.

Good luck.

Doozergirl

pred02 wrote: »

£9000 for GRP roof, £4500 for felt warm roof. 30 sq meters, South London.

Wondering where the person is who was telling me that a 15 square metre roof costs £14,000...

It's your choice. If you're moving on, you may not feel the benefit. How visible is the roof? Is going to make a difference visually?

MX5huggy

If you’re looking to sell do a proper job a large flat felt roof would set off alarm bells on future replacement costs, or if still looking newish what other corners have been cut.

As said Building Regulations apply because of Part L.