Hello I am going to attempt a "mostly" self-build of a double garage. I can do a 6m x 6m single storey, with pitched roof and gable ends with no planning permission. It is unlikely this will ever hold cars, unless I build one. It is going to be a workshop/man cave and will be used a fair bit in the winter months, so I would like it to be warm and toasty. Having had a cold concrete floor in a previous garage, I was thinking about under-floor heating powered by a wood burner, but also wondered weather I should use block walls with a cavity, or single block built around wood frames and Kingspan. Cost is a consideration but not if it ends up being a fridge like my last garage. I will get a brickie to do the blockwork, I could do it but not in a reasonable amount of time, so I will just do the rest. Does anyone have any thoughts? or am I missing lots of other information? Thanks Andy
UF heating from a wood burner ain't an option, I don't think. The idea of UF heating is that it works at a low temp - probably around 45-odd degrees? If you are going to fit a wood burner, then simply use that - the smallest should easily heat that size. But you really should install this properly, either getting a Heatas to do it, or else running it past your BCO and then they'll inspect it. If max insulation is the aim - and it's a good one - I'd personally go single skin (rendered on the outside so's it's 100% damp and water proof) and then line the walls with Kingspan/Celotex. You will get FAR greater insulation values from even an INCH of Celotex than you would from a cavity and extras block skin. If you clad with say 2" of Celotex, you'll be as cosy as a cosy thing. The floor won't need as much attention, and you could get away with a few inches of cheap Jablite (expanded Polystyrene) for this if you wanted. Make sure you provide for trickle ventilation (actually, a lot MORE than 'trickle' if you fit a stove...) but guard against draughts - that'll be what cools you down more than anything. Is it going to have a proper garage door? If so, that's your main issue right there.
Whilst you probably haven't fixed the size of your garage you may want to do a scale drawing as with a 6m width pitched roof the rafters will be quite long and therefore quite expensive. Underfloor heating isn't the best for garages/workshops as sometime you will want to fix things to the floor - partitions, power tools etc. Always best to have insulation in the floor and roof space and then concentrate on the walls. Consider things like a warm roof and putting the insulation on the outside and then a latex render. This way the inner wall surface is better to work with for shelving, benches and fixing to. Whilst not permitted without building regulations, you may want to consider having a storage platform within a part of the roof space. A wood burner is very expensive to install the flue components alone can cost around £1,000 alone and unless you are producing lots of sawdust and offcuts, could be quite expensive to install and run
If your pitched roof is open - vaulted - on the inside, also bear in mind that most of the heat will end up there... So worth considering an insulated ceiling, with storage above - you'll prob need an insulated hatch to access this.
Thanks for your replies, the information about the heating was very useful as is the insulation advice. I am glad about Celotex being better than blocks, it will be something I can do myself which means cheaper. The regs here (Isle of Man) state that I can put up a 6m x 6m single storey garage without planning permission, subject to some restrictions about its position in relation to the house and boundaries. The inside I can do what I like with, apart from use it as accommodation. It must have a pitched roof the same angle as the house, so putting in a ceiling and making loft storage is definitely a consideration. I would make a hatch, then also put in a small access door at the front , high up, to slide in long lengths of stored timber etc. My previous garage had a floating polystyrene and chipboard floor over concrete which was warm enough, I don't plan on walking around bare foot anyway, too many sharp things lying around ! I hadn't thought about the type of door - something I can line with insulation I suppose. If I do put heating in , I will use a small wood burner or rocket stove. I know a fitter and can get it put in correctly. I don't produce enough off-cuts to power it, but I do have a free supply of softwood logs that are rotten, damp, and never to be used in a normal fireplace. Thanks again
Interesting about the internal platform and size. Where I am, you can a domestic building with a ridge height up 4.5 but only 2.5 at the eves but no internal platform without building regs. I have a vaulted ceiling in mine and even with the ridge at 4.5m sometimes it gets awkward moving timber around, certainly need 3.5m to carry a full sheet of ply in.
I haven't thought about moving ply around, it will be a problem if I cant do that. I don't use loads, but this is a newly bought house and no doubt there will be a lot of ply and plasterboard sheets with the corners knocked off! I think the stipulation about the pitch angle means they couldn't stipulate a ridge height as well, but 4.5m wouldn't be far off. If height is needed, I could do a vaulted roof and suspend some racks out of the way, but I don't know how to make a vaulted roof. I understood that the joists keep the rafters from spreading or something like that but I will have a read and see if I can find out more. Thanks
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