Detached garage conversion - my plans and some questions

Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
Hi all,

We have detached garage at the end of the garden with its own sloped drive way. We're looking to get started with a conversion in the coming weeks. I've confirmed with the council that it doesn't need any form of building notification as its under 30m2 and won't be used for habitable space and has no water line. It has a preinstalled 45amp supply which will be sufficient for our use as an office.

So it's a pitched roof structure and there's no boarding up to cover up the loft area, there are some family members wanting to retain this as an 'open ceiling' conversion so we'll completely see the rafters once done. It's a lot more work but open to hear any thoughts on this approach. The alternative would simply be the traditional boarding up to create a ceiling and an insulated loft area.

We will be getting large double french doors to replace the large garage door, this will help with getting some natural light in. I'm trying to get some second hand given the cost of these new.

First question is, how we would go about insulating the roof if we decide to opt for an open ceiling design. I know we will need to insulate between the joists, but wondering whether we need to put in any waterproofing membrane to start?

With the study walls what's the standard size batten that's used for the walls - we have a single brick construction so looking to get the building as well insulated as possible. I understand a membrane will need to be affixed to the wall first, but how is this affixed securely without compromising the membrane itself and what type would be needed?

There's a pillar that protrudes from the brick wall about 10cm I've considered to bring this wall's insulation to the same thickness so the pillar no longer protrudes. All other walls would be the standard cavity/insulation thickness, what ever that is.
 
Sponsored Links
Joined
22 Jul 2016
Messages
5,227
Reaction score
888
Country
United Kingdom
Pictures would be good
Obviously better insulation if you fit a flat ceiling
However a mate converted a garage and we looked into (and dind't do ) a vaulted ceiling.
What we considered was creating a "fake" ceiling, actually two 45°corners and then a flat part higher up.
We were using rockwool. But if you used celotex or similar you could insulate the whole thing roughly as is, then add a structure that will take the weight of the new PB ceiling, adding more insulation once the PB is in situ.
 
Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
Will try and get pictures, but I think the slud walling (size of battens used and insulation type) would be the same regardless?

I understand what you mean about the flat ceiling a bit higher up. I think I need to take a look at how the rafters are positioned to see if it would be feasible (and also look nice). But it sounds like it might take even more effort trying to create another flat ceiling higher up than trying to insulate and board up an open ceiling as the structure is already there to be insulated and boarded.
 
Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
Can I get any suggestions for the wall membrane and how this is normally affixed to the wall?

It's also a single wall construction, wondering whether any foil based board will be needed when erecting the stud walls.
 
Sponsored Links
Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
Pictures are on the way. Not at home at the moment so had to request them.

But aside from the open roof query, regarding the wall membrane how is this normally affixed to the wall itself - is it the battens which are screwed into the wall, do they hold it in position?
 
Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
Good introductory video, thanks for that.

Is it also possible to tack the membrane directly to the wall, and fixing in the studs as you go along to the shape of the wall (instead of building the structure beforehand)?
 
Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
So here are the internal and external images.

IMG-20190821-WA0005.jpg
IMG-20190821-WA0002.jpg
IMG-20190821-WA0001.jpg
IMG-20190821-WA0003.jpg
 
Joined
11 Jan 2004
Messages
38,891
Reaction score
1,871
Country
United Kingdom
I'm confused. You say it won't be used as a habitable space.

So why the insulation and french doors?
 
Joined
17 Apr 2015
Messages
2,599
Reaction score
420
Location
Warwickshire
Country
United Kingdom
Given it’s a trussed roof I don’t think you can do anything with that without major alterations or you’ll weaken the structure
 
Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
I'm confused. You say it won't be used as a habitable space.

So why the insulation and french doors?

It won't be used for sleeping accommodation, just as an office.

Given it’s a trussed roof I don’t think you can do anything with that without major alterations or you’ll weaken the structure

What about if we lined the inner part of the roof with a membrane, insulated between the studs in the usual way and then plasterboarded over it (leaving the other truss beams as they are).
 
Joined
2 Feb 2006
Messages
46,236
Reaction score
3,220
Location
Staffordshire
Country
United Kingdom
What about if we lined the inner part of the roof with a membrane, insulated between the studs in the usual way and then plasterboarded over it (leaving the other truss beams as they are).
For goodness sake fix a plasterboard ceiling - it's a pig ugly truss roof! Besides it is lined with non-breathable membrane so (between rafter detail) insulating and venting is a non starter - unless you remove the roof tiles of course.
 
Joined
6 Aug 2019
Messages
78
Reaction score
1
Location
West Midlands
Country
United Kingdom
It's really not that ugly, which is why having an opened up ceiling could've been an option. But if lining it and insulation will cause issues then we might just have to have a normal ceiling.

Can I can any suggestions on what membrane I need to use on the walls and floor? Perhaps with an example link to one
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top