David, You havn't said what sort of structure the workshop will be, wooden shed, brick or block, pre-cast etc. Whichever it will be I would consider making the slab thicker and re-inforced and do away with any sort of wooden floor. I am not up to date on modern building methods but you could even have insulation under the slab, most likely will also need some form of damp proof course. Machinery will be easier to site and more stable on the solid floor. You can apply suitable finishes to the top surface or even polish the concrete to get a good smooth finish. Consider the site for water/damp it may be that the top of the slab should be raised well above the soil level. When in doubt consult a local builder perhaps.

John

Edited By Journeyman on 04/06/2018 17:08:16

My workshop,and sometime garage was built on a 6" slab with insulation underneath,the surface being polished.

The builder thought I was mad going to such lengths but it,s hard to beat a smooth floor when you need to move stuff around. Damp proof underneath,of course. Floor ends up just slightly over ground level,so no problem getting machines in or out. Roof height might be worth thinking about though,more important than you might think,to go by some early posts. Sometimes that extra few inches can make all the difference.

My wooden workshop is at least 12 years old and has a concrete floor with gravel under it and a damp proof plastic membrane between. There is a small, shallow, ditch around it that drains away any water to a lower level. I have an old carpet on the floor and it is always dry. The concrete is about 3" thick and supports my heavy machines adequately. Colin

Waterproof chipboard tongue and groove underflooring boards make a perfectly satisfactory and more than adequately warm floor when laid on top of a concrete slab with an insulation layer included. I used the good quality green stuff which has proved non-dusty. Well up to supporting industrial style machine tools too, Bridgeport, Smart & Brown 1024, P&W Model B 12 x 30 being the major heavyweights. Stands up to the odd welding mishap well. Generally tools don't chip if dropped, which is nice. Use the spare bits for shelves and cold work bench tops. Slightly rough finish is great for stopping stuff rolling off but isn't so rough as to prevent deliberate sliding.

Was told the brown equivalent is dusty, so I didn't use it.

Put up over 12 years ago so I don't recall how deep the insulation layer was laid. Basic floor is re-inforced concrete with total depth of around 9". Overkill but its not going anywhere. Stub walls up to timber frame. One brick above entry "patio",which is at highest point, so taller round back. OSB both sides of 4 x 2 timber frame, insulation between, I used fibreglass Celotex or similar sheet would have been easier. Shiplap outside painted with Sadolin has proved durable and smart. White emulsion direct on OSB inner walls keeps things bright. I had the height to put a flat ceiling in under a pitched steel sheet roof. Insulation under both. Cheap over-makes / second hand double glazed household windows and doors help keep it warm and damp free. Needs heating only at snow time and foggy, dreary winter days.

Fit plenty of electrics. I used ex-industrial metal clad distribution boards rather than ordinary sockets. Cheap, real cheap 'cos I had them!

Clive.

I have just googled shed planning turning up

**LINK**

and this doesn't seem to mention the max area permitted for sheds anymore, apart from the 'half size of house' bit. It used to be restricted to garage size in wood, or twice garage size in 'non-combustible' when next to boundary.
Has there been a relaxation recently ?

David make sure any timber of the construction is well clear of the ground level to prevent water damage, my workshop outer walls, which are wood, stand on 9 inch high blockwork. Internal floor is concrete much more practical and stable for the machines.

Dave W

My workshop was a single garage with a concrete floor. When I moved here, I first laid a DPM, reaching up the sides to just above the final floor level. Then 2 x 2" battens in a 4 x 2 ft matrix. The 'holes' were filled with 2" polystyrene foam slabs and the whole lot was covered with flooring grade T & G chipboard. To cap it off, the floor was covered with industrial grade vinyl flooring.

I have had some heavy machinery standing on it with no problems. It is warm and comfortable to stand on and also it is easy to keep clean. 15 or so years on, I don't regret getting a hard-wearing, comfortable floor, even though it may not have been the cheapest solution at the time.

If you use a wooden floor, you need to seal it in some way to prevent oil ingress. The vinyl (non foam backed) is an easy solution. Choose a light colour so that when you drop a small screw or the like, it can be (relatively) easily seen.

Dave
The Emerald Isle

Dave – if you were wondering what a 'polished floor' meant for concrete, it means a floor that has been power-floated. You can hire power floaters by the day. The trick is to wait until the concrete has nearly gone off so you can walk on it but is still a wee bit soft so a little of the 'fat' will rise to the surface when troweled. Then go over and over it with the power floater, maybe adding a little water spray if it's too dry, until a nice flat polish is achieved.

It's well worth the extra effort, you get a nice flat smooth floor. The snag is that there is usually a long wait until the concrete is ready. Lay the concrete at the wrong time of day and you can be power floating at 2-3 am! Not really neighbour friendly. Perhaps get a builder/ground works guy to do it, he will know the right sort of time frames and can plan the job accordingly.

That's how I've seen it done, no doubt someone else will point out where I'm wrong!

Chris

Edited By ChrisH on 06/06/2018 11:59:20

Had same problem David in the winter the cold comes through the floor and up your bones.

Easty fix for little is the cheap 3mm rubber matting should do that for £30 region.
Its easier and quicker to warm up, what used to take 4 hrs now takes 1hr.

Over time even thick board will wet and or bellow at any centres, more so with heavy machines on top stick with thicker concrete you wont regret.
Boards good for the walls though on battons, just make sure the shelf brackets are made specific spreading the load 1"x1"x1/8" good for 1/4 tonne spaced accordingly around 2ft. (3 over 4ft)