Garage conversion

[p111dom]

So it's starting to get colder already up in Scotland and the garage it unusably cold in the winter. It's been exclusively been used as a workshop for 5 years now so I think it's time to bite the bullet and convert it properly but how? It's a single walled brick double garage attached to the house. I want to retain the garage door for access and security (no windows) but will replace the current one with an insulated roller door. Can I just take the US route by battening out the single wall, insulate in between, vapour barrier over the lot then board on top? Would this be acceptable to building regulations? Does anyone know of a good step by step guide? Sorry for all the questions in one go but I can't seem to find the answers easily. Many have made bespoke workshops but very few seem to have converted a single walled structure.

 

[Brooky]

building regs vary fron councils but bsically if you are going to heat it with a combustable sorce ie;gas boiler from house and radiator,then legally you will have to comply to strict regulations and insulate to `u`values for walls 'floor and roof.however there are loop holes !

 

[p111dom]

I don't mind doing it properly even though I want to leave the garage door. If I ever moved I'd rather it were a plus point (as in all you'd need to do is replace the garage doors with patio doors to make it a habitable room) than a negative point (would cost money to rip out as it's not up to code). I'm as interested in good U values as the council as the point is to make he garage usable heatable and warm.

 

[dickm]

A lot to be said for insulation up here! That's why (to quote a friend) I have a large well insulated workshop with a bit of a house attached!

Basically, as far as I know, from the council's standpoint, a garage is not a habitable room even if you use it as a workshop, so it doesn't matter what you do about the walls for insulation. Your scheme sounds fine, and the thicker the insulation you can get in, the better.

But, if you consider putting in a stove or any sort of flame-based heating, then I think you do fall foul of Building Control. Don't know what BC are like down with you, but up in Aberdeen area, they seem to be quite helpful. So if you are going to do this, probably a quick but careful 'phone call would help.

In my last workshop, which was also well insulated, I went down the storage heater route with offpeak electricity, which avoids flue problems but will now presumably fall foul of Part P.

 

[Brooky]

ok your next step is to contact someone local that can draft drawings showing the alterations and calculations.i must say you are doing the right thing by doing it to building control as work carried out will go on the price of your house,as a half hearted make do job is money spent with no real return.last point ,it is very dangerous to work with cold hands!

 

[Ed68]

The way I've known it to be done is to strap the walls with pressure treated timber with dpm between the timber and wall. Its usually the 100mm roll bricklayers use.

The main thing to avoid is trapping any water that is shed from the dpc level (on the occassions the wall gets saturated with persistant rain) so any battens should be fixed just a little bit above this.

The insulation you use would have to be water resistant like polystyrene or foil backed then moisture resistant plasterboard or plywood.

HTH

 

[RogerS]

....but will now presumably fall foul of Part P.

Thought Scotland was maintaining its' sanity and Part P didn't apply up there?

 

[p111dom]

Quite correct, no part P in Scotland although many rouge sparkys up here claim there is and threaten to "shop you to the council" if you don't use them. You still have to be a "competent person" according the the regs but there's no definition as to what a competent person is up here. Think I will go and talk to building control or the local planning office first. Cheers for the advice.

 

[cadders75]

I'm starting a garage conversion pretty soon and I've recently had the local BC guy round to go over my options, I was expecting to have to stud wall the entire garage with batts in-between the studding.

However he's advised me that fixing 1" tile battens to the single brick skin walls, fix tyvek to the battens (making sure that the tyvek is tucked under the vapour barrier for the floating floor). You can then line the walls using insulation backed plasterboard with insulation of no less than 40mm.

I've hunted round for the cheapest prices for the insulated plasterboard and this is the cheapest site I can find, I haven't used them as yet so I cant comment on the service.

http://www.just-insulation.com/index.html

My only concern is how to run the electrics and plumbing for the radiators with such thin wall.

 

[Carlow52]

Forgive my intrusion into this thread....

Your post is silent on the roof structure and your plans for same

On the roller shutter, I would reconsider the insulated option and instead put a set of insulated doors inside the existing R/S with possibly a small window therein to allow for some natural light.

The rigid PU/PS type insulations are now being replaced by wood-fibre type ones due to the concept of temperature decrement delay.

The issue is essentially about the inability of the PU/PS types to hold heat or cold and is illustrated by the way the dishwasher retains heat after the wash is finished as it has fibre insulation http://www.viking-house.ie/decrement-delay.html

The other issue is that fixing insulation directly onto the inside of external walls is now frowned upon due the the high risk of condensation at the interface, with mould etc.

Better building practice is to leave a gap between the insulation and the exterior wall.

 

[p111dom]

The roof is the easy bit it's pitched on all 4 sides and while I use the eves for storage it's mostly empty product boxes that can go out. Basicall I just need to plaster board it out with loft insulation above. I'll add an insulated hatch for access but the only query would be whether to continue the vapour barrier from the walls across the roof. I would have thought so if only to stop moisture getting in front of the wall membrane. Really my first problem is the floor. For some reason I thought there was a step down into the garage from the house but there's not. The floor was poorly laid, rough and uneven complete with trowel marks and slopes from back to front by about the height of one brick over the 18 feet. Despite this slope towards the door and also despite the fact that my drive is slightly uphill to the door, 10 inches from the door it slopes down very slightly. The consequence is that I do get a little water in the garage when there's driving rain. The house has concrete floors so my plan would be to put a batten behind the garage door by about an inch and pour in some sort of levelling compound making the floor flat and creating a 60mm vertical barrier that water could not get past. I'm planning to get a door that lowers into waterproof bottom track. The garage already has a window In the side wall. The current floor is painted which was a mistake as it was really slippery when I first did it. I'm worried about adhesion of any substrate over this due to the paint. It would also be very thin at the back so I worry about break up. Any ideas on a product for this?

 

[dickm]

For some reason I thought there was a step down into the garage from the house but there's not.

That rings alarm bells. Not sure of the exact reg, but the garage floor should be at least 4-6" (or it may be more) below the house door threshold for building regs. I assume it's to do with leaking oil/petrol from any car.
So maybe a casual question to BC about this would be in order.

 

[p111dom]

Ok well there is a step down. I meant I thought there was a physical step. Still there's not enough depth to add joists, top boards and insulation in-between. Hence the query about levelling the floor.