Converting outhouse

[hudster]

The house we bought has an outbuilding adjoined, basically an old storage building with toilet room.

The previous owner got building regs to convert it to 'utility room with access to house'. We have since knocked a doorway through.

The outbuilding walls are single layer brick, so no cavity walls.

Do I need to get any kind of permission now before insulating (I thought probably foam backed plasterboard)?

 

[DevilDamo]

The building regulations approval should have covered the upgrading of the existing walls to comply with current u-values as the area will become a habitable space.

If the existing outbuilding walls are built on a concrete slab, the easiest way to achieve the thermal requirements is to form an internal stud wall. This will consist of leaving a 50mm gap between the inside of the single skin wall and the timber stud, fill the vertical studs with insulation and then some additional insulation across the face of the studs. That is just a basic guide. There's ply/plasterboard/plaster on top of that.

Upgrading of the walls will only be one element. How about the roof?

 

[hudster]

silly question maybe but how can I find out what was approved? all we have are the papers from the solicitor which state that permission was granted

 

[DevilDamo]

(Sorry, I added a little more to my post above, which you may not have seen before making your post)

If you have the documenation, you "should" have the building regulation drawings/specification. if not, contact your building control department asking if they have any copies of drawings/specifications and request copies, which you will be charged for.

However, that is of course providing drawings/spec's were submitted as part of the application. Sometimes, applications are submitted using a building notice, which does not require full drawings/spec's while a full plans requires everything.

 

[hudster]

there is a concrete slab (we put in with 50mm insulation underneath), but yes it's walls and roof that I'm looking at now

 

[freddiemercurystwin]

Are you getting confused between Planning Permission and Building Regulations Approval?

 

[hudster]

haha yes I think we are both furiously typing away at the same time

thanks for your advice I think the first stop is for me to find out exactly what he submitted

 

[hudster]

Are you getting confused between Planning Permission and Building Regulations Approval?

no, this is what came up in the searches: "BC/07/xxxx Convert lean to outbuilding with toilet to utility room with access to dining room/kitchen. Undated"

I assume this BC number will mean something to the local building control office

 

[DevilDamo]

That does sound like a building control reference number so just give them a call to see what information they have. You can tell them the application was submitted by the previous occupier and you're wanting to take it over and complete it.

As for the concrete slab. It's very rare for insulation to go below the slab, especially if the slab already exists Just out of interest, what is the difference in level between the outbuilding and the house at present? Obviously you'd want to line it all through so putting insulation and a screed or even a timber deck on top can be used to achieve the levels.

 

[hudster]

When we moved in the floor in there was just original brick laid on earth (not even any mortar). Obviously very damp etc, so we dug that up, laid 50mm foam + DPM and poured the slab on top.

The level of the floor is about 150mm below the rest of the ground floor but we decided not to raise it as it would have meant raising the waste for the toilet and having to raise the exterior doorway, plus it actually looked appropriate as there is another step down to the garden.

The room feels much drier now due to the DPM, but walls + ceiling still uninsulated

 

[DevilDamo]

Oh I see. Apologies. I thought you were implying there was already a slab but it's understandable if it was just some kind of brick paving.

Was 50mm under the slab sufficient in achieving compliance?

I have just run a quick calculation through the Celotex website for the wall insulation...

Hope that makes sense?