Buildings reg on wooden summer house?

[GettingThereSlowly]

Hi All

We are looking at putting in a log cabin/summer house in our garden, which is approx 7.7m wide. We had a design done for a building that is 6m wide (and 3.95m deep) and so it cannot sit 1m away from the side boundaries and is obviously made of combustible materials (56mm logs).

When we asked about building regs, the company stated:

"Due to the fact that the cabin is under 30 sq.m internal floor area, and not being used for living/sleeping accommodation, then the project is exempt from building regulations approvals. The only aspect in which you should comply with building regs is satisfying class 0 spread of flame. As mentioned over the phone there are two aspects to this:-​

• The inherent char rate of the wood must give 30 mins char rate. Yours quoted is a 56 mm log at 0.7mm char/minute = 80 minutes
• Reduction of spread of flame. This is achieved by applying HR Prof which is a fire retardant. This only needs to go on the walls within 1.0m of a boundary. Where this is applied you do not need to apply the preservative also as the HR Prof contains preserving abilities. HR Prof will advise how much you need, and then it is a simple case of applying layer by layer until you run out."

The company indicated they had installed 100s of log cabins of sizing >15sqm < 30 sqm without needing building regs done.

Does applying HR Prof really make wood be classed as non-combustible and therefore avoid building regs? Or are building regs just not needed if it is not living/sleeping accommodation despite being 15-30sqm, made of wood and within 1m of boundaries?

Notes: Ridge height of gable roof would be ~3.5m and therefore planning required for sure. We intend to have electrics & networking in there but no water or sewage.

Many thanks in advance.

 

[^woody^]

That company don't seem to know the regulations that apply to the product they sell, nor how to meet them.

No-sleeping is not the only criteria that exempts a garden building - if so, you can't have an afternoon nap in your summer house. It is the actual use which determines whether building regulations would apply or not.

The problem with using a coating to try and achieve fire resistance, is that the coating will wear or weather off in what could be very short time, and you don't know this until the thing goes up in smoke. So its never a good thing to rely on.

And you can't just rely on char rate or how long anything may take to burn- you are being misled. What about the joints, the junction with the roof, the eaves, the roof material? All these can allow fire or hot smoke to spread across or into a building

And you need to comply with not just surface spread of fire , but also how heat/flame may spread out (or in) across the boundary. Again, misleading.

 

[GettingThereSlowly]

Thanks for the reply @^woody^, most appreciated.

It will be mixed use, I'll possibly work from home in there, likely to put a threadmill in there, use it for storage to declutter the house, have a load of kids stuff in there when they have friends round, that kind of stuff, possibly even have the rabbits housed in there over winter rather than outside.

Are you saying that a 6m wide wooden building, (thats greater than 15sqm but less than 30sqm) in a 7.7m wide garden would definitely need building regs? Or that it depends on usage?

 

[^woody^]

Obviously, no one knows or may not care what you use it for once you say "It's a summer house for a few hours use in June and July". But the principle of how it is used and for how long should apply as that will create the risk to user's safety - on which the requirement for building regulations is based.

So things like working from home - does that mean business use and business use regulations will apply? And will work from home be an hour or so in the morning like everyone else, or 6AM to 2AM with 15minutes for lunch?

And even if it's expedient for you to declare that building regulations may not apply, would your home insurers take a different view in the event of any claim - and the claim may not have anything to do with the summer house!

So it's always best to get things clarified by either the council or such like and not the people who just want to sell you the thing - unless they want to provide something more in writing to back up their claims.

 

[GettingThereSlowly]

Thanks again @^woody^.

Usually I am office based but covid means I have been working from home rather than the office and our office wont be open again until March while they move. When the office does open back up, I will likely work from the office maybe 2 days a week at most and the rest from home, possibly from the summer house, in my normal working hours say 8 or 9am-5pm with lunch break. I am not running a business from home at all, no work related visitors or anything like that.

So in my case the only people who can truly tell me if building regs are needed for my proposal are my own council?

 

[^woody^]

Lots of people can give an opinion though!

It depends what you want to rely on

 

[GettingThereSlowly]

OK thanks @^woody^

I guess I was hoping for a clear yes/no but it seems that is not the case so I will try to talk to building control in my council and see what they say.

 

[^woody^]

It can be a clear yes or no but someone would need to consider the factors involved to comment formally.