Garden Room - 'substantially non-combustable'

[having a go]

Hi,

 

I'm looking for some advice in relation to building regulation compliance for outbuildings. 

 

I'm looking to build a garden office of over 15m2 but less than 30m2 it will be sited within 1m of our boundary on 3 sides. I understand that while this does not need to be compliant with full building regulations the building must be  non-combustible  due to proximity to the boundaries.

 

I'd like to understand what would need to be done to make the building fire resistant.

 

My plan is to construct the building using a timber frame or SIPs. Are these completely non compliant since they are combustible materials or is it more about the external cladding, which in this case would be sheet steel to the 3 sides facing the boundary and composite / Canadian red cedar to the front.  

 

 

I've seen similar issues posted on this forum but nothing conclusive on what level of fire proofing or is required in this situation. 

 

Many thanks in advance

[oliwoodings]

You ultimately can't tell conclusively without consulting your local BCO and asking what their own interpretation of 'suitably non-combustable' would be in your situation specifically.

 

In general, having the external cladding as either cement board cladding/sheet steel/rendered is enough, especially if it's only bordering garden fences (i.e. isn't next to other people's houses), which is usually the norm for garden buildings. But they may also be fussy about the internal wall finishing as well.

 

For my own, I didn't bother asking our BCO and just went with cement board cladding all round (Hardie VL). Slight gamble? Yes. Likelihood of building control giving a shit? Practically zero.

Edited February 25, 2024 by oliwoodings

[Nick Thomas]

Feels like there's a lot of garden rooms going up at the moment ^^

 

https://www.legislation.gov.uk/uksi/2010/2214/schedule/2 is the legislation - basically, the different types of exemption you can get. You're trying to fit within Class 6:

 

 

If you're within 1M of the boundary and the construction is timber frame, you don't fit into (1) on either count, in my view.

 

If you're going to work from it, (2) isn't a goer, which is a pity.

 

And you're too big for (3).

 

 

( https://www.legislation.gov.uk/uksi/2010/2214/regulation/9 describes how the schedule is used, and what building regs you do still have to comply with even if you manage to fit into schedule two one way or another)

Edited February 25, 2024 by Nick Thomas

[having a go]

Thanks. So, I've written to local building control let's see what they say. 

If they come back negative I see I have two options go for a steel frame or build smaller. 

 

[Bruce]

On 26/02/2024 at 08:00, having a go said:

Thanks. So, I've written to local building control let's see what they say. 

If they come back negative I see I have two options go for a steel frame or build smaller. 

 

We are about do the same but with a garage. What was your BCOs response? Ours are being awkward and I don't get any good responses from them.

[ETC]

If it’s within 1m it needs to be substantially non-combustible material.

Timber frame on its own with metal cladding won’t give you the FR you need.

The rules for FR for a building within 1m require the wall between you and your neighbour to have 1HRFR and that needs to be from BOTH SIDES.

More than 1m away and the FR is required from INSIDE only.