f you're over 15m^2 (which I will be, there's no point otherwise) and withi n a metre of the boundary (which I also will be - the garden is long but na rrow and I really need to use the full width) then you're not allowed to bu ild in wood under the BR exemption.
adjacent to the boundary without needing to satisfy any fire-regulations?
houses, and a shed is not a dwelling house.
Ah yes, I found this on planning portal:
"If you want to put up small detached buildings such as a garden shed or su mmerhouse in your garden, building regulations will not normally apply if t he floor area of the building is less than 15 square metres and contains NO sleeping accommodation."
Sorry it's taken me a while to reply - when you're not reading a group regu larly it's easy to forget to check in. Thanks for the useful replies - the heads up on fire-resistant fake cement planks hopefully means it's still a goer even if the BCO insists on not using wood cladding. I know I need to c ontact him (the Southampton council website seems to make that reasonably e asy) but I haven't got round to it yet.
On access - the house on one side does have an alley and gate, but there's a brick wall between us. The house is a student let, and I've never met the landlord. It's not totally impossible, but neither is it as simple as aski ng a favour from a neighbour you see every day. On the other side are two o ther houses (mine is part of a unit of three, where one of the original big semis was pulled down) and then I'm not sure if there's a gap at that end either.
I have had a rough estimate for the concrete part of the job - a boom truck that can reach right over the house and to the end of the garden would be about four hundred quid for a short day and that is a price I am willing to pay to avoid barrowing several cubic metres of concrete through my living room. The main reason I'm coming back (as well as to say thanks) is to ask about making the base. Assuming I have concrete descending from the sky on request, what should I be putting under (or in) it?
I have the old slab patio which needs to be broken up and disposed of, so I guess I have a certain amount of hardcore in situ. I want to limit the amo unt of other sand/gravel/etc involved where possible, because that can't be magicked over the house. If that can be traded off against more concrete ( within reason) then I probably want to do that.
I know I need to set up formwork around the slab site, and have a long batt en reaching right across to level the surface. I don't know much else about laying concrete. Would a slab this size (4.5m x 7m) need any kind of reinf orcement within it?
I had been assuming that the base would be wider than the shed, but I've si nce read something that advises against it - for the same excellent reason that you don't want your groundsheet sticking out from under your tent. If the body of the shed effectively shelters the slab, then it will help preve nt damp inside. This is a very important consideration, as I will be storin g a lot of stuff inside, from fabrics to electronics, and also plenty of to ols which I don't want to rust. I guess I should also be using some DPM som ewhere in the mix?
I'd prefer to have a plain concrete floor rather than lay wood on top of it , but how smooth am I likely to be able to get it when laying the slab? Or is it inevitably going to require some kind of screed on top? Doesn't need to be skating-rink smooth, but I'm thinking of having a couple of movable t ool-chests on say 4" wheels and I want to be able to push them around.
I plan to embed a couple of L-shaped conduits for wiring (one for 240v, one for anything else I might want later). I would place these with a slight d ownward slope towards the underground end, so that they don't fill up with water. I don't have in mind any plumbing beyond perhaps a waterbutt and a s mall soakaway under its tap.
Any other advice on preparing and laying the slab is welcome.
You could smash the concrete up and run a vibrating plate compactor over it to get you a well walloped base for the concrete.
I would. Mesh is not expensive nor heavy for 2 people to carry through the house (8x4' sections).
Yes - if you can, sizing it for the shed so you can curtain the shed walls over the edge will keep water from pooling under the shed and will make the floor bearers last forever.
If you wanted DPC you would need to blind your hardcore with sand, vibro-tamp that down then lay sheet then pour concrete.
A simpler solution would be to paint the shed floor with epoxy paint which will form a DPM on top of the concrete and give you a good surface. You will need to let the concrete cure, dry (several weeks), wire brush it to get the laitance off (cement/salt bloom).
A cheap solution would be to lay some cheap vinyl on top and accept it may need replacing from time to time (I expect it will last quite a long time).
If you can get some, some larger bore blue MDPE pipe would give you a continuous (jointless) tube with a nice smooth wall to pull SWA or other cables through. Lay several. You're right about the downward slop to outside - good move :)
That's the kind of thing I had in mind, yes. Although the planned slab is j ust over twice the size of the existing base, so it will be spread relative ly thinly. How thick a layer would be recommended if I was starting from sc ratch? Also, how thick the actual concrete slab itself? The company I got t he estimate from said they'd assumed 100mm - that about right?
OK. The stuff I've found with a quick google is quite pricey, but I think i t's massive sizes meant for serious civil engineering. Will have to come up with some better search terms.
That's what I had in mind, together with gravel in the half-metre gap betwe en the base and the foot of the surrounding wall and fences. I wasn't plann ing a raised floor though...
To be clear, if I did this I wouldn't need the DPM under the slab, and so w ouldn't need the sand blinding layer? And it would provide just as good pro tection against damp? If so, it sounds like two birds with one stone, and w ell worth doing. Remember, I attach a high cost to any additional aggregate s because they have to come through my living room!
I can probably manage the curing time, as I plan to bodily shift the existi ng shed onto the main house patio to store the contents while the slab is p repared. Remove the contents, and the internal boarding, and bolt some hand les on the outside. Then undo the anchor bolts and, with a few mates, walk it up the garden!
How would I go about wire-brushing the surface? I assume you don't mean spe nding hours with the kind of hand brush I clean rusty metal with :-)
That's more or less what I did with the existing shed (actually it was DPM laid directly onto the paving and OSB on top of it - real bodge job). But I want to make a proper job of this one, and since I'm planning to install a lot of built-in furniture (benches, racking, even a small internal room fo r dust-free varnishing) I don't want to ever have to take the floor up.
I'd also worry that anything not actually bonded to the concrete would fail to keep the damp out.
I was thinking of 40mm solvent-weld waste pipe, with a swept bend at the co rner. Originally it was going to be a single conduit of 100mm, as I have so me lurking in the shed from a bathroom refit, but I realised that sharing t he conduit between 240v and, say, ethernet, was not best practice even thou gh with SWA the risk seems minimal.
Yes - you are just moving the DPM to the top surface.
Yes - it only takes a light brushing (usually) to remove laitance - and you may not even get any. If the surface is solid and not powdery, paint straight on. Too wet concrete can get laitance and too dry can have sandy surface. If the mix is right, and you don't overdo the final floating it should have a good surface - especially as you will be dropping it into hardcore so excess water will not pool.
You could look at:
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I used F75. All of those assume you will put something else on top, however it's pretty tough stuff and I would think it would stand up to foot traffic pretty well.
But it might be worth looking at some epoxy floor paints (rather than DPMs) - you may find something more suited.
Make sure the bend is very swept - the bends I'm familiar with will be a little tight. Don't overlook the fact the joints will act as a snag point right where you don't need snags. I had this with even a straight coupling in ordinary conduit.
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