Hi there,
I'm just going through the same process - I'm looking forward to the results. Here's a few tips I'd offer up:
10ft by 12ft will be great for a layout. No need to worry there!
Prepare the site well. Put the shed onto a sound, well drained base.
Order your shed with tongue and groove walls - avoid shiplap style. T&G forms a proper barrier to the outside world, shiplap is like a garden fence.
When the shed arrives, regardless of what it's sold as having had, treat all the surfaces of each section before it's built.
For the underside of the floor I'd recommend using bitumen paint. It's nasty and messy stuff but very little gets through it.
For every other surfaces paint well with Cresote. Don't use a water based treatment - get a decent chemical based one.
Consider insulating under the floor - where you've just covered in bitumen paint. Putting in a thin Kingspan layer of insulation may make a bit of an improvement.
Build the shed.
Once it's done as per the manufacturer's instructions, it's time to insulated.
I would recommend Kingspan insulation - it's rigid foam with metallic coverings on both sides.
I'd recommend 50mm thickness.
Do for the walls and the roof.
(This is *really* very important for a shed to hold model railway stuff year round)
If you want hidden electrics, now's the time to get them installed.
Lightly carve out channels in the foam for where the wires will go and for the back boxes for the sockets. Use conduit for the cabling.
Do make sure that there is a switch / fuse box where the electrical supply comes into the shed so you can turn it off if needed.
For the walls you will want to have a covering over the insulation. Plywood is fine, or you could use pine cladding.
Do mark where the beams are behind the covering so you can screw things into those areas in the future if needed.
For the roof you may wish to leave the Kingspan showing as the metal surface reflects the light well.
If you do, tape up the joints, especially the roof crown, with aluminium tape. This prevents heat loss.
If you put another layer on the inside of the roof the tape is less important but still a good idea.
If you don't mind surface wiring you can install the mains power now.
I think it's "Steve's Law" that says you never have enough power sockets so put in double the number you think is necessary!
I'd also recommend one waterproof socket on the outside for general garden use.
Lighting is important. Don't think that a single bulb in the middle will work. All that will do is cast a shadow over the bit you're looking at!
I've gone for 4 lights, two on each side wall mounted just below the roof. There are many other ways to do this but this works for me and never casts awful shadows.
Finally, once it's built check that you've got a decent lock on the door. Modelling stock isn't cheap and it's well worth protecting. At the very least get a good quality latch and padlock.
Ideally get a multipoint lock and some form of alarm.
(Also, to remain completely legal you shouldn't do any of the mains electrics yourself - get a professional electrician.)
Hope this is helpful,
Mr Toad
--- old post above --- --- new post below ---
Oh, to answer the original questions a bit better:
Get a "standard" size shed - these are cheaper than custom made ones.
Typically, these are in 2foot increments, eg 6ft by 8ft, 8ft by 10ft, 10ft by 10ft or 12ft by 10ft.
Wooden sheds are cheaper and easier to find than metal buildings.
Also I think wooden sheds look nicer but that's an individual preference.
Don't skimp on the construction quality. Shiplap style is cheaper and perfectly fine for keeping garden tools in but T&G is far, far better for model railway use.
To get the size you want and in the style you want either find your local shed retailer (specialist ones do exist all around the country!) or you'll need to look online.
Here's a few suggestions:
http://www.shedstore.co.uk/garden-sheds/wooden-sheds/traditional/traditional-heavy-apex-shed-10-by-12
http://www.gardenbuildingsdirect.co.uk/Timber-Garden-Sheds/Tongue-and-Groove-Sheds
http://www.buyshedsdirect.co.uk/garden-sheds/wooden-sheds/
http://www.tigersheds.com/product/tiger-xl-heavyweight-workshop-shed/?option=439&utm_source=Google_Products&utm_medium=Google_Products&utm_campaign=Google_Products&gclid=CMvzzfX7jL8CFSEcwwodvBIAKw
(The last one is very close to the last shed I had before I moved)
Cheers,
Mr Toad
