Garage conversion

[Simon B]

Just moved into a new house and I've got a single garage to play with. I've bought 3 lots of kitchen cabinet to create a 3m long work bench, put an ikea unit in for storage and a long Ikea table for a second bench. I'll pop some pics up soon.

I've got a corrugated plastic roof and would like to insulate it and bought 7 sections of celotex foil covered foam panels for the job. Would i be able to glue them to the roof? I'm loath to put bolts through in case it brings water through.

[Rich too]

I have a similar problem, a corrugated asbestos roof and I am going to use the bubble wrap type insulation and secure with some very thin battens using the existing roof structure - no fixings...

[Allan Bennett]

Presumably the roof sheets are on some kind of joists. You'll get the best insulation if the celotex sheets are attached to the undersides of the joists -- with extra battens added across the joists if the spacing is too great for the sheet sizes. That will create an air gap between the roof and insulation sheeting, which will improve the insulation slightly.

[John F]

I've got a garage with a corrugated cement sheeted roof.

The condensation from winter through to spring forming on the roof is a real problem some days and it is quite hot in the five days of summer.

Even if I were to insulate this the damp would still form, apparently, so the roofing beams would eventually rot. The sheets are cracked anyway and leak at times so I bit the bullet and got some quotes to replace the roof.

Agreed yesterday, after many quotes, to have the roofing replaced with ply boarding and 3 layer roofing felt. My garage is 28 x 9 ft and quoted £1660 all in.

Might this be an option for you?

[rcaddict]

if putting insulation below or between roof rafters then you should have air space to prevent condensation and fitted with vents,

you will note on modern flat roofs the insulation goes on the outside

warn roof v cold roof !

[Rich too]

 

Posted by John F on 05/07/2016 08:22:39:

I've got a garage with a corrugated cement sheeted roof.

The condensation from winter through to spring forming on the roof is a real problem some days and it is quite hot in the five days of summer.

Even if I were to insulate this the damp would still form, apparently, so the roofing beams would eventually rot. The sheets are cracked anyway and leak at times so I bit the bullet and got some quotes to replace the roof.

Agreed yesterday, after many quotes, to have the roofing replaced with ply boarding and 3 layer roofing felt. My garage is 28 x 9 ft and quoted £1660 all in.

Might this be an option for you?

There are two issues. In the winter, if you have lots of gaps you will get damp air in from outside. You need ventilation but not too much, and I have been sealing all the gaps in my garage apart from the around the door, with expanding foam. The air is already much dryer in there. I used to get mould forming on the steering wheel on a car stored in the garage. So that was not a good place to store models!

My roof structure is steel, so it won't rot anytime soon, but if you leave an air gap you should not get rotting wood up there. You need a water proof membraine so that the condensation cannot get right through the insulation. That's why I am using the foil backed plastic bubble wrapping insulation. It is pretty cheap and will allow any condensation go run away and not fall in the garage - which it currently does now.

[Rich too]

Posted by oldgit on 05/07/2016 08:45:47:

if putting insulation below or between roof rafters then you should have air space to prevent condensation and fitted with vents,

you will note on modern flat roofs the insulation goes on the outside

warn roof v cold roof !

Exactly

[cymaz]

Don't forget to insulate the floor. I'm lucky to have an integral garage with pitched roof. But the floor is solid concrete. Unbearably cold on the feet during winter. I can't put insulation down as cars get peaked inside now and again.

Edited By cymaz on 06/07/2016 08:14:44

[Simon B]

You've all given me a LOT to think about. I think the best plan is to get a professional in, as I'm totally out of my depth!

[Dave Bran]

I researched my "garage as workshop" situation and the "proper" deal was so much even doing much myself that the increased heating costs would never pay for the upgrade in my expected lifetime. Mine is a 1930's built onto the house at the time of the house brick and thin block structure with what was Asbestos but is now a concrete corrie roof.

So, all I have done is to draught proof around bad gaps as much as possible, and have no condense issues at all.

[Simon B]

In modeller terms i'm a veritable spring chicken at 37, so i should get a good 40+ years out of it. The main thing is less a cost thing and more that i want to make it feel comfortable enough to use regularly and doesn't feel like a cold garage.

[Jack Banner]

Seal the worst gaps and buy a big, blower type, heater. Rubber horse matting placed where you will be standing and walking will also help avoid the cold feet issue.

I have my heater on a timer so it comes on an hour before I expect to use the shed.

[Mike T]

I cleaned and sealed the (concrete) floor then laid some 2nd hand (ex work) carpet tiles. Not much in the way of insulation, but it does make standing for long period easier - use localised, thicker matting (per Jack) near worksurfaces.

Walls were insulated with gyproc that had 2" thick foam bonded to it (with a layer of Al. foil in between). You could woodchip and paint this (but I didn't bother).

I built benches (some with drawers under) on 3 walls and a mobile walk-around bench for the middle - which is a godsend. I used an old 600mm kitchen base unit for this, topped with 18mm MDF, with hinged flaps either side (7' long when deployed). The whole mounted on large castors for mobility - and also helps raise to a comfortable working height. A multi power outlet is screwed to the back. A 1KW fan heater under one of the benches keeps it all snug.

[Erfolg]

If the garage was built some time back, it probably will not have a Viscreen or similar membrane, under the concrete. I would take a bet that the floor, under the concrete has no insulation , such as Kingspan, Dow etc.

If so, damp is always a issue. If you put something down such as Vinyl sheet, you will almost certainly find that after just a few days, that there will be a puddle of water underneath.

Damp is something you will have to live with, controlled by a degree of ventilation. Even then, the storage of electronics may not be desirable.

The best solution is to find an excuse to dig out the floor, put in a membrane , plus insulation, covered with concrete. I have done this for a very large kitchen in the past, it is not as difficult or as expensive as it sounds. The requirement is probably two skips for the waste. At a similar cost is the insulation. With access to a cement mixer the remaining cost is trivial.

[rcaddict]

erfolg - a bit OTT for a garage/workshop (non habitable) , I would put down kingspan K3 flooring on top of existing concrete (with a membrane)

[ben goodfellow 1]

you can put 1200 gauge visqueen .then pir board on top of your existing floor

[Erfolg]

If there is the height available, I would also go for it. The problem that I see is that the insulation thickness to meet building regs, leads to a pretty thick build.

Probably my main concern without a membrane is how damp concrete floors actually are, if the water vapour is not vented away.

At the end of the day, we cannot always do what we think is the best long term solution. Having to live with and manage the resulting issues.

[ben goodfellow 1]

100mm is what bc said we had to use on an extension . generally its said anything over 150mm is not worth it . very little gain for any work involved

[Erfolg]

Ben, if something is worth it is always debatable, more often than not either driven by a statutory requirement, or a personal opinion, formed formed by functional needs, convenience, time and finance.

The important aspect here is usage, how the structure performs and any limitations that are or could be a consequence.

For years, I used a well ventilated (unintentionally garage, although my radio etc was not kept in it. Some metallic items did however show some signs of damp damage. In fact I still use a garage for general storage, although my modelling is generally done else where..

[Simon B]

Thanks for all the suggestions chaps. I'm particularly interested by the suggestion about insulating the floor using visqueen and celotex. Found some useful videos on youtube. I've got someone coming to quote for the roof insulation on Tuesday, so we'll see. If it's too pricey i'll have a go myself!

[Martin Whybrow]

I insulated my garage floor with 100mm Celotex on top of a 1200 gauge Visqueen membrane; because I have machine tools in the workshop, I built a grid of 2"x4" timbers on edge, then covered the whole lot in 22mm OSB and finished it off with a couple of coats of epoxy floor paint. The walls are isnulated with 50mm Celotex then battened over and plasterboard on top; this gives an easy route to run wiring without needing conduits or trunking. The internal pillars in the garage were insulated / finished with plasterboard with an integral 25mm Celotex layer. The roof will be insulated with 50mm Celotex with plasterboard attached to battens strung between the roof frames; the pitched roof already has a felt membrane, so I'm not too worried about moisture and there will be a good air gap above the insulation anyway.