Large Garden Room - Help with BR

[Roomba]

Hi all.

 

Complete noob questions incoming so sorry in advance.

 

I’m planning to build a large garden room 11m x 6m. It will contain two offices, a toilet and a games room.

 

It will be 1.5m from side and rear boundaries and will be 2.5m heigh at it’s tallest.

 

I know I need to meet thermal U values but am struggling to work out exactly which ones I need to meet. The design I’m hoping to use has the following values.

 

Floor      0.17U

Walls     0.21U

Roof      0.17U

 

I know about substantial fire resistance so am planning on using Cedral fire resistant cladding outside and fire resistant pasterboard inside.

 

I’ve worked out joist spacing and unsupported distances for the roof.

 

Electrics I’ll have a qualified person sort out so that’s ok.

 

Drainage falls I’m happy with.

 

Will I need structural engineer drawings with loads worked out/shown? And are there other building regs I’ve not mentioned I need to meet?

 

I know that’s a huge question so don’t expect people to spell it out letter by letter for me, but if anyone is able to point me in the right direction as below it would be very helpful.

 

Thermal U Values
Roof Pitch
Drainage slope
Electrics
Unsupported distance requirements
Fire spread resistance

Thank you, and again really sorry for the huge questions!    

[mr rusty]

Why don't you build it as two separate units with perhaps a canopy between and save yourself a lot of heartache - <30sqm internal and it is BR exempt.

[Big Jimbo]

As above. save a fortune and build Two units, with a not quite connected covered walkway between.

[Roomba]

Thanks both, the games room would still be 45+sqm at the size we want (smaller wouldn't work for us) so even splitting would still hit BR.

Edited August 9, 2023 by Roomba
spelling

[DevilDamo]

The u-values would be based on the outbuilding being an extension to the existing dwelling.

[Simon R]

On 08/08/2023 at 17:23, Roomba said:

I know I need to meet thermal U values

Don't forget to look at solar gain. It can be a real problem if you don't get your window shading correct.

[Space Race]

20 hours ago, Big Jimbo said:

As above. save a fortune and build Two units, with a not quite connected covered walkway between.

Genuine question, Would the savings be significant? What areas could savings be made by keeping it under BR sqm? Very interested as we'll need a large space in the future and I'd being weighing up a single larger build vs two smaller 

[Big Jimbo]

Building regulation fees. Structural Engineers fees. Foundation Costs. All the money you save, you can put into the build and build a better product.

[Roomba]

13 hours ago, DevilDamo said:

The u-values would be based on the outbuilding being an extension to the existing dwelling.

 

Thank you, damn that means only my Floor meets regs.

[Roomba]

13 hours ago, DevilDamo said:

The u-values would be based on the outbuilding being an extension to the existing dwelling.

 

Just one point on that, would it be classed as a dwelling as there's no sleeping provision? Not saying you're wrong just asking  

[Space Race]

3 hours ago, Big Jimbo said:

Building regulation fees. Structural Engineers fees. Foundation Costs. All the money you save, you can put into the build and build a better product.

Thanks, Plenty to think about 

[kandgmitchell]

Just to be clear, up to 30m2 internal floor area and more than 1.0m from the boundary then the building is exempt building reg control so you choose how to insulate it. Two separate 30m2 buildings placed close but not touching could therefore save you a lot.

 

Over 30m2 and under 50m2 the building regulations apply (foundations, damp proofing etc) but not the "energy efficiency requirements" so you choose the insulation. Beyond that you need to comply with everything and the regulations set the standards even if you are not sleeping in it.

[DevilDamo]

23 hours ago, Roomba said:

 

Just one point on that, would it be classed as a dwelling as there's no sleeping provision? Not saying you're wrong just asking  

It would be deemed as an extension to an existing dwelling where there is a lesser and more relaxed approach to u-values. 

[Roomba]

Thanks for all the replies people. I have a meeting with one of the local building control officers to go over my plans and what exactly I'll need to do to meet all regs. From our emails he seems a really helpful guy and happy to guide me through each requirement.

I'll let you know how we get on  

[ProDave]

Just an off the peg suggestion.

 

11M by 6M is within the size limit for a "caravan" so build it as a moveable structure and call it a "caravan" and no building regs needed.

[ETC]