Pitched Roof renewal - how to satisfy BRegs?

[keyzjh]

Hello, we have a Victorian terraced house and are considering a roof renewal which includes replacing roof tiles, flashings, membrane and battens. The roof tile replacement is like-for-like and the roof is pitched.

I understand that we may need to apply for a BReg inspection, as the roof renewal is not a structural change and the loading doesn't change, but it covers >25% of roof area. However the Part L insulation bit is confusing.

Existing roof has old felt underneath without insulation, and loft insulation is at ceiling level (but this is old and thin).
The main question is how do we satisfy the BRegs inspection about insulation?

1. New roof insulation e.g. the Kingspan Pitched Roof boards between the rafters?
2. New ceiling insulation between the ceiling joists?

Or will the exterior roof work (tiles, membrane, battens) alone satisfy BRegs?

Thanks!

 

[RandomGrinch]

New ceiling insulation between the ceiling joists?

Do this.
Not just for building regs, but given current energy costs, with the decent cost/benefit ratio - it's a no-brainer.
It's usually suggested to have at least 100mm rockwool (or equivalent) between the joists, and 170mm running perpendicularly above the joists.

 

[keyzjh]

Do this.
Not just for building regs, but given current energy costs, with the decent cost/benefit ratio - it's a no-brainer.
It's usually suggested to have at least 100mm rockwool (or equivalent) between the joists, and 170mm running perpendicularly above the joists.

Agreed! We do want to do this, but probably after the exterior roof works is complete, as we have roofers ready for next week.

Assuming Building Regs inspection needs to be done prior to and after the roof renewal works, if no insulation was present at the time of inspection - this will fail the inspection right?

 

[RandomGrinch]

Assuming Building Regs inspection needs to be done prior to and after the roof renewal works, if no insulation was present at the time of inspection - this will fail the inspection right?

My local inspector was decent and pragmatic - that might not always be the case!
He was happy to provide final sign-off when I emailed him photos of the finished job.

Talk to them, if you're unsure

 

[keyzjh]

My local inspector was decent and pragmatic - that might not always be the case!
He was happy to provide final sign-off when I emailed him photos of the finished job.

Talk to them, if you're unsure

Really hard to get hold of them on the phone, so wanted to be more ready beforehand!
Do you think the ceiling insulation suffices and satisfies the building regs? Or will I also need the roof insulation between the rafters?

 

[freddiemercurystwin]

No need for any insulation at rafter level, as mentioned 100mm between the existing ceiling joists, then 170mm or thereabouts laid on top perpendicular.

 

[jeds]

if no insulation was present at the time of inspection - this will fail the inspection right?

It won't fail, it just won't be complete yet. You could arrange an interim inspection and then another when the insulation is installed, although, frankly, one at the end would be sufficient. My advice is 300mm laid at ceiling level as RandomGrinch above, which gives you a u-value of 0.14. Minimum u-value under L1(a) 2022 is 0.15.

PS. Or even 400mm. In the old days, the diminishing benefit of extra thickness was a factor. With fuel costs these days it probably isn't.

 

[keyzjh]

It won't fail, it just won't be complete yet. You could arrange an interim inspection and then another when the insulation is installed, although, frankly, one at the end would be sufficient. My advice is 300mm laid at ceiling level as RandomGrinch above, which gives you a u-value of 0.14. Minimum u-value under L1(a) 2022 is 0.15.

PS. Or even 400mm. In the old days, the diminishing benefit of extra thickness was a factor. With fuel costs these days it probably isn't.

Thanks for the confirmation!
I was trying to submit a Building Control Notice which my local council says requires details of proposed work, relevant drawings and structural calculations.
Does a roof renewal without structural changes require relevant drawings and calculations?
It almost seems easier to complete roof + insulation then apply for regularisation!

 

[jeds]

Bear in mind that the person at building control telling you you must provide x, y, z is admin who is probably working from a checklist and may know very little about roofing. In reality, a description of the works in writing is perfectly adequate. The only part that requires any 'structural' input is the difference between the existing and proposed tiles. So, you need to establish exactly what the existing tiles are and the gauge? The gauge is how much the tiles overlap, so giving you the actual coverage of the tiles. You then need to same information for your proposed tiles. Compare the laid weight of existing and proposed tiles. If your proposed tiles are more, you may need to justify with a calculation. If the same or less, then that is sufficient.

 

[jeds]

It almost seems easier to complete roof + insulation then apply for regularisation!

And what it it doesn't comply? You'll be re-doing works or adding structure afterwards.

 

[keyzjh]

And what it it doesn't comply? You'll be re-doing works or adding structure afterwards.

Bear in mind that the person at building control telling you you must provide x, y, z is admin who is probably working from a checklist and may know very little about roofing. In reality, a description of the works in writing is perfectly adequate. The only part that requires any 'structural' input is the difference between the existing and proposed tiles. So, you need to establish exactly what the existing tiles are and the gauge? The gauge is how much the tiles overlap, so giving you the actual coverage of the tiles. You then need to same information for your proposed tiles. Compare the laid weight of existing and proposed tiles. If your proposed tiles are more, you may need to justify with a calculation. If the same or less, then that is sufficient.

Thanks for the reminder. Annoyingly the local council doesn't let me talk to anyone to discuss this until I pay the application fee and submit an application first, whereas I'm unsure what documents are actually required! Thanks for the tips!

 

[Old Salt]

Talk to your local councillor and tell him your planners are being d*ckheads and wont talk to you when you just need some advice prior to submitting your application. Remind him you are a regular voter with loads of friends living locally if you have to.

 

[keyzjh]

Managed to get through to the council, and they insist I will require roof insulation between the rafters to pass building regs inspection. Ceiling level insulation is not sufficient.
Are they mistaken or do I need to save up for more budget for the roof insulation?

 

[freddiemercurystwin]

You haven't got a room in the roof or loft conversion have you?

 

[keyzjh]

You haven't got a room in the roof or loft conversion have you?

None, the loft is unused and not boarded at all.