Outbuilding - WorkShop

[Giant90]

Hello All,

I have scoured the interweb for information on designing, planning and eventually building an workshop for myself.

I have been granted planning permission to build a 5m x 8m at 3.3m high outbuilding with a flat roof. Now I need to apply for building regulation which is where I am getting stuck and would be grateful to any advice.

I am confused on U-Values - What is the maximum for an Outbuilding?(Have searched but not found a definite answer.)

I have looked at L2A from BR approved document - Is this correct?

Roof:0.25

Wall:0.35

Floor:0.25

I will use u-valuecalculator.co.uk is there a better option as it seems sponsored by kingspan.

Based of those U-values:

Floor - 150mm Hardcore> 50mm Blinding Sand>DPM>150mm Concrete Slab>50mm Insulation>Separation Layer> 65mm Screed

Cavity walls - 10mm Polymer render>100mm dense block> 55mm clear cavity > 35mm Kingspan Kooltherm K108 Cavity Board>100mm dense block?>12.5mm plasterboard>3mm skim

Warm Flatroof - GRP>18mm OSB3>90mm Insulation>VCL>12mm Plywood deck>firring>75 x 225 joist>12.5mm plasterboard>3mm skim

Thanks you, Giant.

 

[Nakajo]

What's the heat source?

 

[TicTac]

Well you can use lightweight blocks on the internal wall, and you don't need the separation layer under the screed. But why aren't you using insulated plasterboard on the inside of the outer skin instead of a cavity wall setup.

 

[Giant90]

What's the heat source?

I was thinking for heat source an electric fan heater or oil filled radiator, haven't put much thought into it.

Well you can use lightweight blocks on the internal wall, and you don't need the separation layer under the screed. But why aren't you using insulated plasterboard on the inside of the outer skin instead of a cavity wall setup.

Dense block to hang cabinets, storage etc. There is no plasterboard on the inside of the outerskin cavity...10mm Polymer render>(External)100mm dense block> 55mm clear cavity> 35mm Kingspan Kooltherm K108 Cavity Board>(Internal)100mm dense block>12.5mm plasterboard>3mm skim

 

[Notch7]

do building regs specify thermal specifications for outbuildings which arent habitable?

I dont know, Im interested to find out.

 

[Giant90]

do building regs specify thermal specifications for outbuildings which arent habitable?

I dont know, Im interested to find out.

Thats what I am trying to find out, spoke to BC and they referred me to L1B. I stated I'd use it as workshop and heat it during winter.

 

[^woody^]

If it's a workshop for DIY - aka a "shed" under 30m2, then b/regs wont apply other than those for combustibility near to boundaries.
If over 30m2 floor area, and same useage, then only the additional b/regs related to structure apply. Other sections will only apply if you install specific things - electrics, windows/doors (safety glass only), steps etc .
Resistance to moisture ( ie damp proofing and including cavity walls) and insulation wont apply.

If it's a proper workshop for a business, then all relevenat b/regs will apply.

 

[Giant90]

If it's a workshop for DIY - aka a "shed" under 30m2, then b/regs wont apply other than those for combustibility near to boundaries.
If over 30m2 floor area, and same useage, then only the additional b/regs related to structure apply. Other sections will only apply if you install specific things - electrics, windows/doors (safety glass only), steps etc .
Resistance to moisture ( ie damp proofing and including cavity walls) and insulation wont apply.

If it's a proper workshop for a business, then all relevenat b/regs will apply.

It is within 600mm from boundary.
If only necessary building parts apply why would BC advise me to go for:
Roof:0.18
Wall:0.28
Floor:0.22

Just spent the morning redrawing insulation and editing labels as I have been advised to apply for full plans.

 

[^woody^]

If only necessary building parts apply why would BC advise me to go for:
Roof:0.18
Wall:0.28
Floor:0.22

Because they are silly?

There is no difference whether you keep your lawnmower in there or stand in there filing down a bit of metal. It's a shed, an out building.

Unless it's a habitable room, then it wont need insulating. And you have not got permission to build a habitable room.

 

[Giant90]

Because they are silly?

There is no difference whether you keep your lawnmower in there or stand in there filing down a bit of metal. It's a shed, an out building.

Unless it's a habitable room, then it wont need insulating. And you have not got permission to build a habitable room.

Thanks for the advice woody, it make sense as the permission granted is for an outbuilding.

No this has confused me - Do I need to put in for Full Planning permission or building notice?
Electrics will be done by a qualified electrician.

I have drawn up plans to BC U value but will clarify and let them know it is only an Outbuilding.

 

[^woody^]

You already have planning permission. You can do this on a building notice as long as there are no public sewers below or near it.

But if building on a notice, you need to know what to do before you do it. Full plans once approved, will tell you what to do of you are unsure.

 

[Notch7]

Thanks for the advice woody, it make sense as the permission granted is for an outbuilding.

No this has confused me - Do I need to put in for Full Planning permission or building notice?
Electrics will be done by a qualified electrician.

I have drawn up plans to BC U value but will clarify and let them know it is only an Outbuilding.

You might find an independant building inspector an alternative. They can be easier to get on the phone and more pragmatic. With BBS building control, you can submit your plans and start work 7 days later.

 

[Giant90]

You already have planning permission. You can do this on a building notice as long as there are no public sewers below or near it.

But if building on a notice, you need to know what to do before you do it. Full plans once approved, will tell you what to do of you are unsure.

Thanks for the speedy reply, I think I will go down the Full Plans route - I have drawn the plans on sketchup and created a spreadsheet for costs.

When I submit an application for Full Plans - can I change insulation size? for example instead of 120mm for 50mm. Or would I need to reapply and submit new plans.

 

[^woody^]

When your plans are checked, if the inspector is not happy with any items he will send you a list and either ask you to change them or clarify. He'll most likely include advice on what he thinks the items should be to make them conform.

You then either agree and change the things or put your points across as to why you think the items do conform.

Say you put insulation on despite it not being needed, the plans will just be approved. However if you leave insulation off and it is needed, you will be asked to specify it.

But it's not just a way to get the inspector to tell you what to do. If the plans are significantly incorrect or lacking in detail, they just get rejected.