Garage conversion

[RLJ]

Hi all,
I'm looking to convert my new garage into additional room used for working in.
It's single skin detached with a pitched roof newly built (if that makes a difference).

Obviously I want to make this into a normal room adequately insulated and holds off the mould that seems to appear after a while currently.

I will get the garage door bricked up with a upvc window. I will board it all out myself and then get a plaster in to skim it over.

My idea was to use 25mm celotex on the walls between studs and plasterboard over the top. Understand 25mm is the smallest size and arguably won't do much? (Let me know what the minimum you'd realistically want). With rockwool or thicker celotex above the roof.

Does this seem okay or am I missing anything obvious?

There Is damp proof membrane above the damp course bricks but I have also brought dpc gel to insert into the brickwork. The internal brick walls are also painted over if this makes any difference.
 
Thanks in advance..

[oliwoodings]

25mm celotex on its own won't do much, you should aim for more. Perhaps do 50mm battens, which will allow you to first run services in (electric and water if applicable), and then infill with 50mm rockwool. Put a vapour barrier over this (stapled and seams taped) before boarding over the top with insulated plasterboard (25mm probably enough).

 

For the ceiling, we need a bit more info. You say it's pitched, is it a truss roof? Has the ceiling already been boarded out? Any form of insulation yet? You should probably aim for at least 200mm of rockwool up there - most heat is lost through the roof.

[Russell griffiths]

With anything like the 25mm you propose it will be a cold miserable place. 
50mm min in walls, 50 in the floor and 150loft roll

it will still be under spec but will make it useable without having to spend a fortune on heating. 
it does depend on what you want it for and how big it is. 
I have a lovely cosy garden room, but it’s only 9m square so a small area to heat. 

[RLJ]

It is a trussed roof yes not boarded or anything yet. I will chuck plenty of insulation up there.

 

I hadn't actually given the floor any thought. I was planning on keeping the rubber click together type flooring in place. Will moisture come up through the concrete slab? Do I need to insulate the floor as well?

 

I'll aim for 50 on the walls then.  You say under spec is there anywhere I can actually find the spec?

 

I'd like to see where I can get it within or near the spec but under what circumstances will this matter if its in my own garage anyway?

 

Thanks 

 

[Mr Punter]

For the floor you can cover it with DPM, then Celotex, thin polythene and top it with T & G chipboard.

[Russell griffiths]

It’s not a garage if you brick the door up 😂😂

depending on size you might need planning for change of use, and depending on that change of use will determine what regs you need to comply with. 
it could be a craft room, home office, gym, torture dungeon or an extra bedroom. 
 

everything hinges on what it’s for and the size. 
 

[oliwoodings]

2 hours ago, Russell griffiths said:

It’s not a garage if you brick the door up 😂😂

depending on size you might need planning for change of use, and depending on that change of use will determine what regs you need to comply with. 
it could be a craft room, home office, gym, torture dungeon or an extra bedroom. 
 

everything hinges on what it’s for and the size. 
 

I believe you can get around this by leaving the garage door in place and just building a stud partition against it on the inside.

 

 

[kildienesaule]

Hello everyone, my husband and I want to convert the utility room into a living room for guests. We no longer want to deal with repair work ourselves, so we are looking for specialists who would do their job well. Maybe you have contacts? I read on another forum about https://www.cledemaison.co.uk/en interior design services, but other specialists are needed as the interior will be the last job.