Detached garage conversion - help please!

[NutcaseOReilly]

I’m looking at doing a DIY conversion of our detached garage. We had a quote of £10k + VAT for a builder to do this, but reckon I could do it myself, with a bit of help. It would include:

• 1/3 laundry room accessed from new insulated 2/3 side opening garage door
• 2/3 garden office, accessed via existing pedestrian door to the rear

See attached rough sketch and photos - red lines on sketch are where I'd like the new walls to sit - see below.



The garage already has power, with its own garage consumer unit and a new roof (although the fibreglass was botched by whoever did it before we moved in - getting this replaced soon).



I’m fairly confident about doing this myself in terms of stud walls, insulation, floating floor etc, but have a few questions:

Plumbing

• I’m going to get a water supply fitted and a soil pipe etc. for the washing machine. I’m assuming I should do this before boarding and insulating, then board and insulate around the pipes?

The walls

• There are some pillars in each corner of the garage, and half way down on each side. My plan was to follow the Restoration Couple garage conversion videos on YouTube, and build stud walls with celotex insulation in-between the stud work so it’s flush with the pillars, then more celotex over the top all the way down so we have straight walls - my question is if I fit a breather membrane to the outer (garage wall) side of the stud walls, can I leave a gap between the garage wall and the studs?

The ceiling

• The roof looks like it was replaced before we moved in - the flat roof seems new with new joists and boards sitting on top of the existing garage walls and a fibreglass finish and plastic fascias around the outside. The fibreglass has failed and recently has leaked in places, so will be replaced but our roofer said we can leave the joists and boards as there is little damage and we can dry it out once it’s repaired.
• There are a few gaps between the top of the garage walls and the plastic fascia - do I need to leave this gap for airflow or should I fill these in with expanding foam? Next doors rose is growing through one of the gaps!
• How should I insulate this kind of roof - if I fill the gaps as above, can I fit Reticel in-between each joist, then celotex and plasterboard?

Electrics

• Electrics and garage consumer unit are currently fixed to the garage walls and also run along ceiling joists - I’m planning on unfixing them, boarding and insulating and then fitting all the wiring back in to the most inner layer of insulation behind the plasterboard. Does this seem feasible or would I get away with leaving the wiring fixed where it is behind the stud/breather membrane (and in the ceiling along the joists and just pull forwards the sockets and consumer unit?
• I’m going to need an electrician to come and alter the lighting points - I’d like to move the existing strip light into the laundry section, and then fit spotlights in the office ceiling.

I think I just need some pointers here, then I’ll be happy cracking on and giving it a go, so any advice is much appreciated. Thanks.

 

[sxturbo]

You need to find out where the drain will go, then build the studs then do first fix plumbing. Then once the stud wall is built etc do 2nd fix plumbing.

The ceiling, fill with rock wool or whatever insulation you want. You might need a vapour barrier, and leave a small gap between the insulation and roof, leave the plastic as it is. Hopefully someone with more experience will answer this bit.

Yes the garage walls with the pillars bring out with stud and insulation as you have stated.

The wiring needs to stay fixed to the joists.

I do t believe you can move the consumer unless your qualified, even if it's just pulling it forward.

I'm not sure for what your planning whether it will come under a new circuit install.