Workshop build pre build

[technium]

Hi

I am getting rid of my metal 10x 8 shed and 8 x 6 wood shed and having a new workshop built in the same area (roughly 17 x 9).

I wont be building the shed as no idea where to start but have had a few quotes for a build and erect onsite so probably will go down that route.

The area under the new workshop will be a concrete base which I am in the process of digging the ground, but want to make sure the shed lasts so wondered what you all thought would be best.

The metal shed had a concrete floor so I will use that but next to it is mud so I am digging down 5" and am planning to fill that space with crush and use a whacker plate to level it to the same level as the concrete base. Then I will shutter the whole area and concrete on top of the existing concrete aswell as the crush to make a solid foundation for the workshop.

is there any membrane or anything I need to put down either before laying the concrete or on top of the concrete before putting the workshop down or even is there anything else I can do to help protect the floor of the shed?

Not sure if anyone wants the progress updated with pics or not as shed builds etc seem to be plentyful on here.

thanks in advance.

 

[Monkey Mark]

I'm no expert here, but i'd be concerned about cracking between the new concrete and old unless you intend to put a pretty thick layer over the top of the existing one. Maybe break up tge top layer of the existing one before going over the top.

You could put down a damp proof course and could also add a layer of polystyrene before the shed floor otherwise the concrete base could hold the cold.

 

[Phil Pascoe]

Make sure you think about where any services are coming in.

 

[technium]

Thanks guys.

The concrete base going on top is going to be 6" thick so hopefully should be ok? When you say polystyrene, do you mean lay the floor on polystyrene, wouldnt it just squash and break up under the weight?

No services other than electric but that will be coming in along the wall to the workshop location and then just be drilled through to the inside then probably have a fuse box fitted inside the shed with a main switch to enable me to turn off ALL power inside when I leave the building.

cheers.

 

[Adam9453]

I'd put some rebar in to help hold all the concrete together, particularly where the join would be.
Rebar isn't expensive and will add an enormous amount of lateral strength to the concrete slab.
You'd want a damp proof membrane as well.
Damp is the enemy in a woodworking shop

 

[technium]

by damp proofing is the black plastic sheet stuff screwfix sell ok 1200GA for a tenner? What I dont understand about that is the damp proof will stop the moisture coming up from the concrete but surely then the damp proof also keeps all the moisture on top of the plastic with no where to soak so creating a pool of water under the shed or am I looking at it wrong?

thanks again

Colin

 

[sunnybob]

Definitely use rebar to keep the concrete in one piece. Use a big hammer drill and drill lots of horizontal holes into the joining side of the existing raft and force rebar in there as well, or the new build WILL slip away from the old as the newly compacted earth settles under the weight of the new raft. Cross hatch 6 or even 8 ft x 3/4" round rebar all across the join. That is going to be the weak point, regardless of depth poured over.
I would suggest you cost out removing the existing altogether and lay all new, it be much longer lasting.

The DPC should be about 2 bricks above the highest earth touching the raft, otherwise you will get water pooling as you fear.

 

[technium]

While the weather is pants Ive been thinking about wether or not I should self build the workshop instead of getting it pre-made for me, I mean would it work out cheaper, would the materials the company use by lesser quality to what I could buy from local timber yard?

Ive been looking around for some plans and found this link and wondered what your thoughts were?

https://ruralgardener.co.uk/2008/12/30/ ... op-part-1/

My only question is that they mention about doing the roof from a template and mention tommy walsh using an OSB board for the template but I cant find any info on it, does anyone here have a link to what they are talking about?

Also what are your thoughts on self build.

 

[sunnybob]

If you get someone else to build it for you, you want to see other work they have done and speak to the owners.

"Professional" builders come in all types, from bodgit & scarper upwards. And the price is NOT an indication of quality.

 

[Fitzroy]

Currently i'm in the early stages of a workshop build, just about got the base down. I'm enjoying the self-build, and in the end i will have a great workshop for a much lower cost, but i have found there is a lot to learn, the devil is in the detail, and I've had to spend a lot of hours of research and planning to get the outcome that I want.

 

[technium]

Currently i'm in the early stages of a workshop build, just about got the base down. I'm enjoying the self-build, and in the end i will have a great workshop for a much lower cost, but i have found there is a lot to learn, the devil is in the detail, and I've had to spend a lot of hours of research and planning to get the outcome that I want.

Thanks Fitzroy, do you have any plans you are going by or are you just freelancing it? Any thing you think I need to be aware of?

Im still sorting the base at the moment but once thats done then I need to make a decision about the workshop itself either buy in or build it myself. Also I want to build right upto my boundary so ideally I need to be able to put the sides on the sides (if that makes sense) and then lift the whole side into place, any tips on that?

thanks

Colin

 

[Stanleymonkey]

Where are you based Colin?

I'm sure you could find a few 'locals' on here to give you a hand and speed up the process for you.

Martin

 

[technium]

Im Portland, Near Weymouth Dorset mate. Does this site have a members map? Im hoping with the weather I might get out tomorrow and do some more digging to clear some more of the ground.

 

[Fitzroy]

Colin.

My build can be seen at 6mx3m-pent-workshop-build-t97540.html slow going at the moment though!

Shed design is my own. I used sketch up to work out the detail (shout if you want a copy of the file) ie what timbers and boards I needed. Shed is 6m x3m, mainly 4x2 framework 18mm Osb floor and roof and 11mm Osb sheathing, and timber/boards was £900 ish. I had to go for a suspended timber floor on block foundations as I couldn't have a slab for planning reasons, mature tree root zone. Base timber was about £120 out of £900.

Other main costs to come:
EPDM rubber roof £250
Larch cladding £550
Electrics £400 (inc 6mm armoured cable 75m from house, new grounding rod)
Insulation and internal boarding £400
Windows and door £300 (but making myself as pre made would be £750+)

Aiming for £3 built cost, a ready build of similar quality would be c. £6k and the cheapest shed only (no electrics no insulation) was c. £1500.

I'm building the wall frames flat then lifting in to position, don't see why you could not clad etc first then lift into position, although my walls would be insanely heavy at 6m X 2.5m.

Anything to be aware of? It'll take longer than you think, especially if you have a 3yr old and a 5yr old 'helping'.

Fitz.

 

[technium]

Thanks Fitzroy.

I have no idea of costs but for 17' x 9' shed pre built and installed on site i was quoted about £1900 and that was 22mm Tanalised loglap cladding, floor is 2x2 bearers as is the framework and the floor has T&G on it. not sure if a self build would beat that price.

Ignoring the fact I have to do the crush layer, damp course, then cement base which is planned anyway for the pre built build.

For the self build I was thinking of the following. a layer of cement blocks and then sit the framework on that. so I guess 4 x 2 framework, then OSB on outside followed by the damp proof sheet, then some kind of cladding? Not sure about how to do the roof but want Apex as I can use abit of the roof space as storage. Felt on top. I guess I can knock up square frame for windows and I have plenty of sheets of glass here I can cut to use for the windows.

I like the idea of fitting the clad first then lifting into position but my concern would be the corners as how could I make sure theyre sealed? And if the price isnt going to be much cheaper then maybe I should just go with the pre built option.

 

[Stanleymonkey]

Dorset is lovely, but a bit too far for a shed I'm afraid.

 

[technium]

LOL thanks Stanley. Youre right it is lovely.

 

[Fitzroy]

I think you could complete a self build 17'x9' for less than £1900, but you'd have to do the build yourself! There are a couple of 'stickes' in the workshop forum that contain lots of info regarding the how to, especially if you are building on top of a slab, ie build-a-shed-mike-s-way-t39389.html.

With regards to precladding the panels i'm sure it could be done by allowing the cladding to overlap the end of the frame by the depth of the framework. It would mean that the membrane is not continuous, and I doubt you could tape the corner. However if you compare this to your log-lap pre-built version i'm sure it will turn up on the back of the truck as a set of complete panels that are nailed together and a simple overlapping corner trim nailed on.

btw I'm not putting the pre-built option down, or saying you should built it, just that I've been through a lot of the same mental arguments and and often you're just not comparing apples with apples. If you want to build it yourself to the same standard as the pre-built, then you have to build out the same materials, ie 2x2 bearers, 2x1 wall frame work, 22mm loglap whitewood walls, 19mm t&g floor etc etc. I expect you could build it cheaper on this basis but for me the decision was to spend a bit more but end up with something of much better quality and to a design of my choice that will be much more visually pleasing at the end of my garden for the next 20yrs.

 

[DennisCA]

Thanks guys.

The concrete base going on top is going to be 6" thick so hopefully should be ok? When you say polystyrene, do you mean lay the floor on polystyrene, wouldnt it just squash and break up under the weight?

My house and garage are built like this, it works fine. In the finnish climate this is necessary or you'll never ever get a warm house in winter.... But even in britain I imagine it'd help a lot.

 

[technium]

Thanks all, still not sure which was to go but as im still at the breaking ground stage its not an issue yet. Still confused about the polystyrene aspect that was mentioned above.

I think id like the self build idea as I think I would learn alot in the process and get alot of satisfaction out of it but its the time needed to do it and the "asking friends to help" part that concerns me.

Still plenty to think about.

thanks
Colin