2.4m height for attic conversion

sackedlunch23 · 05-05-2021 03:39PM #1

Hi All. There are a few posts on this but I can't find any recently, and I'm aware regs change etc.

We live in a 4-bed semi built in 2017. Looking at getting the attic converted as a habitable space. We're engaged with an engineer and likely with a architectural-technician shortly. I should add that I'm familiar with the other pre-requisites of having it as a habitable space.

As attic conversions go, most of the structural work has been confirmed as already completed by the engineer. Hallways and landings are 30 minute fire resistant etc. Fire doors and self closing hinges will need to be installed.

The attic itself is about 34sqm. Double trusses are in place for the windows and to support the new stairs (I believe).

The engineer has measured the floor to attic at about 2.38m. This height is in place for about 80% of the floor space. This seems like a massive oversight by the builder. Having made so many allowances to hand it over as 'ready-to-convert', having the ceiling height under 2.4 is disappointing. Adding in 10/15mm ceilings and it could be as little as 2.37m. The existing 20mm plywood flooring will be swapped out.

Our engineer believes there is some element of a judgement call to be made. I have seen in other threads where engineers will offer their opinion that it meets the guidance.

My question is; is it possible or likely when we sell the house, and the bank sends their own engineer, that they will take issue with the ceiling height being 2.37m?

Gumbo · 05-05-2021 04:08PM

The 2.4m height is suggested as part of the Ventilation requirements (Part F).
If the ventilation requirements can be met by other means such as mechanical or similar then the 2.4m may be relaxed.

sackedlunch23 · 05-05-2021 04:42PM

Gumbo wrote: »

The 2.4m height is suggested as part of the Ventilation requirements (Part F).
If the ventilation requirements can be met by other means such as mechanical or similar then the 2.4m may be relaxed.

Thanks for taking the time to reply. Could you give any examples of other means? Are you referring to something as simple as air vents similar to those on the ground and 1st floor, or something more engineered?

As to my original question. If our engineer gives an opinion of compliance with the relevant regs, how common is it for other engineers to offer contradictory opinions, for example for 2.37m clearance v 2.4m in an attic. Is everyone generally on the same page?

Calahonda52 · 05-05-2021 04:45PM

Massive sight is a little OTT
\ can you raise the collar ties, bolt/screw in new ones first and the remove the lower ones
check with you adviser

sydthebeat · 05-05-2021 04:54PM

What could have been originally signed off as 2.4 could easily become 2.37 with a thick flooring material.

These regs are very obtuse and opinions differ daily

sackedlunch23 · 05-05-2021 04:55PM

Calahonda52 wrote: »

Massive sight is a little OTT
\ can you raise the collar ties, bolt/screw in new ones first and the remove the lower ones
check with you adviser

Thanks. The attic at present is just a big empty room, surrounded by timber frame, Insulation, membrane wrap etc. Tackling any structural work diminishes the advantage and likely cost savings from having the structure already in place, if that makes sense? The builder has gone above and beyond what would be expected to make it easy for us to convert, so in that respect not having a clear 2.4m+ feels like an oversight. That's all.

sackedlunch23 · 05-05-2021 05:13PM

sydthebeat wrote: »

What could have been originally signed off as 2.4 could easily become 2.37 with a thick flooring material.

These regs are very obtuse and opinions differ daily

This is a factor. It's roughly 2.39m throughout with 20mm plywood. It varies due to uneven plywood boards. When the ceiling plasterboard is added it'll likely settle around 2.37/2.38m.

It would have been ideal for opinion to be taken out of the equation by having an extra couple of cm to play around with.

PMBC · 07-05-2021 09:08AM

It would be worthwhile talking to your local B C Officer. The 2.4m is a recommendation only. You have gone most of the way to achieve that and B C fellows I know would be very helpful. It will come in handy, in the event of a future sale, to have a confirmatory email from them.

Gumbo · 07-05-2021 10:43AM

PMBC wrote: »

It would be worthwhile talking to your local B C Officer. The 2.4m is a recommendation only. You have gone most of the way to achieve that and B C fellows I know would be very helpful. It will come in handy, in the event of a future sale, to have a confirmatory email from them.

Most BCO will not confirm anything like that in writing as it goes them down to the design that may or may not be in compliance.

They will direct you to Part F, the diagram associated with the room below the roof and then tell you that it’s the responsibility of the Building Owner to achieve compliance. If they can’t comply with the mandated figures in the TGD, then the other means will need to be demonstrated by calculation by the Building Owner or the Professional involved.

Been there done that.

2.4m height for attic conversion

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