My "shed" build (first timer!)

Help Support

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Established Member
3 Sep 2016
Reaction score
Hi all,
Just wanted to start a thread for the workshop/shed I've started.
I have to admit this is the first time doing anything like this and no doubt I may have done/plan to do things incorrectly so please feel free to steer me in the right direction if you see any vital errors, I'd really appreciate any advice anyone can offer along the way.

So the story is we've just moved from a top floor flat to a lovely fully refurbished and extended ex-council end terrace 3 bed house and finally we have some outside space for us all to enjoy, my 4 year old son love having a garden and simple things like being able to wash our own cars, hang out washing, put on a BBQ and so on are just so nice, it's amazing what simple pleasures you miss living in a flat!

So, I really need a decent size outdoor building, the tin shed at the bottom of the garden is leakier than a leaky thing and has to go ASAP as all my camping gear, expensive bikes, power tools and so on are currently at the mercy of the weather and we want to utilise that space in a total revamp of the garden starting next year. Ideally the previous owners kept a caravan at the bottom of the drive, it's an area built up with sleepers and ideal for the 14x9 "workshop" I've started. Sadly I'm limited to 2.5m max height as the building will be within 2 foot of the neighbouring property.

I've looked at pre-fab "sheds" and have either been extremely unimpressed or blown away with the cost of some of them and I'm convinced I can do as good, or hopefully better than the offerings and for a lot less then some of the higher end stuff, I'm keen to keep it under £1500 (not including some tools I've purchased) and it's to be fully insulated with power and more than a shed, would be nice to have a proper little outdoor "room" that can house an iMac computer, all my tools, good workbench space and so on. I have amassed a fair amount of tools over the years, mostly car related as i work on my own and friends cars regularly but I have the essentials I need for doing this too I think.

Anyway, on to some pictures which I'll explain on the way:

This is the area in question, picture does not show it very well here but essentially minimal slabbing, approximately 18 foot long by 9 and a bit foot wide (retaining sufficient space to access the cars and drive and get the bins out).


So the groundwork starts, removed nearly 2 tonnes of chips from the area alone, the ground under them was very uneven and they just threw as many chips as it took to level it out I think


Originally I'd planned building it 16 x 9 and much closer to the monoblock drive and also having a wood store to the rear however upon lifting the existing slabs and breaking up the mortar pads they sat on I uncovered a bloody manhole cover, and a new one at that!?? Odd thing was that our drain is further down the garden and upon opening the manhole it was pretty obvious it had not been in use for a very long time, there was debris, bits of brick and all sorts in the channel where the waste would run, so why the new cover?? So a quick email to the previous owners and it was explained that many years ago the council re-routed the system and this had been "decommissioned", the reason for the new cover was that there was a very old, large and thick domed iron cover on it and they changed it to a low profile one simply to allow them to get their caravan in there and they simply fitted it and then slabbed on top of it!!?



Anyway, wouldn't be at all comfortable building on top of that, knowing my luck they would want in there at some point and the shed would have to be dismantled so now unfortunately it's got to be 14 x 9 and further down.

So I put up a little shuttering just to section off the area and keep the chips from collapsing in and ended up excavating down about 6 inches or so in total and made it as level as i could by eye, got 3 tonnes of type 1 sub base, lined the bottom with a layer of driveway fabric/weed control barrier and started barrowing in the sub base then borrowed a whacker from my neighbour and whacked it down. Took the full 3 tonnes to get it to the level I wanted too!







So, sub base sorted and i had to decide if I wanted to go the poured slab route or re-use all the 2x2 and 3x2 "council" concrete slabs I had dotted around all over the bottom of the garden, in the end for cost reasons I decided on the latter, may as well use them and save the £300ish I was quoted it would have cost in having concrete delivered. Also saved me the hassle of having to get rid of all these slabs at the same time.

So I ordered up a tonne of sharp sand and some bags of cement and laid the slabs on a 6/1 dry mortar mix, now this again was the first time doing this and a couple of the slabs were off level a bit, certainly not perfect but I have a plan for that which I'll explain in a bit but on the whole not awful for a first attempt I hope?


So next up was to get the timber for the base, gone for tanalised 4x2" framework which is sitting on 4 - 4x2" tanalised bearers laid flat to spread the load and support the joists whilst giving a clear 2 inches of ventilation space under the whole base, I'm hoping that is sufficcent?



And here's the finished base framework, the joists are at 16" on centre spacing.


Now you can probably see that I've chosen to screw it together rather than nail. I've since been reading that possibly this is not ideal and nails are better however I wanted to be able to correct any errors I made easily and as I'm going to be doing this over a period as and when the weather allows the cost of hiring a Paslode for a day or two at a time, multiple times, was going to just be too expensive.

I've gone for TurboUltra A2 Stainless 90mm screws with pilot holes and used 3 per connection, I hope I'm not making a terrible mistake doing this, seem to be mixed opinions, plenty use them plenty say not to?

So that's where I'm at, I've 5 sheets of 18mm exterior plywood waiting to go on just as soon as my 50mm polystyrene insulation sheets arrive in the next couple of days and I can fit them.

I've also got 250m of C16 treated 4x2 timber coming tomorrow for the rest of the framework and roof.

The plan is to fit 2 second hand UPVC windows door on the side and one UPVC window at the bottom end, thinking this should work nicely and pretty cheap to pick up on Gumtree and the likes, because of the height restrictions I'm limited to the roof will be pent sloping using 4x2 C16 but I'll double it up full length or use sister joists giving me the span strength and maximising internal head room as much as possible (I'm already going to be 8 inches to floor level with the ply on!) plus the C16 4x2" was a fantastic price on special from my local timber place. I'm hoping that doubling up is acceptable?

One question I do have.....

As I mentioned a couple of the pavers are a little lower than the others where the bearers run over them, I've taken some 4x4 slices from a tanslised fence post and I've treated them both sides with Ensele End Grain Preservative (same as I used on the cut ends of the tanslised framework), I was going to shim the areas that are a little low with these treated slices, it's just a few areas maybe 1cm or so, am I bonkers doing this or is that acceptable?

Anyway I'll update as I go, appreciate all comments good or bad and any advice would be greatly appreciated.

Looks good, if I where you I would have carried on regardless and made and access hatch above the drain. Also it would be good to put a membrane between the slabs and timber, as they will rot quite quickly from rising damp.

nice work so far, but before you go too much further can I suggest that you purchase some DPC, the 6in wide rolls, not the large sheets and put that under any bearers that are in contact with the slabs. that will stop any moisture seeping up into the wood. if you can fix it at each end and not have any fixings along the length so much the better

edit adidat types quicker than me....
My roof is 6x2 on 600mm centre with 18mm Osb on top, span is 308cm and walking on it is fine. If you look up joist span tables online they will give you a better idea on your plan. You may be better have narrow joist spacing rather the doubling up each joist. I'd do a test with a few lengths between bricks at the expected spacing and see what you think. With 150mm floor and ceiling joists on my build there would have been noway to stay under 2.5m.
Cheers for the replies.

I was originally thinking the same re: DPM but the timber merchant I got it from assured me as it's pressure treated tanslised timber that there was no need, they're specifically designed to be used outdoors just like their sleepers they sell for garden use? I suppose it's next to no cost so I may as well do it, thanks for the heads up!

Re: the drain, it's too high with the cover on, I'd need to raise the enture area aother 2 inches and that would eat right the overall height, the only way would have been to remove the cover entirely, take a layer of the brick course away and cover it with a steel plate or something and that's a faff and too permanent for my liking. so the plan now actually is we're going to utilise that area there as a bin store, the council have now given us 4 full size wheelies to use as of October so we can tuck them away around there out of the way and close to the street rather than sitting in the garden. Might even manage a little woodstore in there too.

Fitzroy - Regarding the roof span, according to the tables even at 16" centres (400mm) I'm limited to less than 2m, but at my 9 foot span (assuming you take the span as the distance between the supporting walls with no overhang included) I'm actually 2.75m. In the same boat as you regarding the height limit so every inch counts, hence either doubling up on the 4x2 C16 or maybe screwing and gluing ply to one side of each. It's not going to be a heavy roof by design, I think I'm going to go 12mm ply and EPDM but we can get a lot of snow here. I like your suggestion though, if I went to 12 inch centres I bet that would be fine, not sure where to check that to be certain though as the tables show fixed centres?

There is an online calculator called the sagulator which does the bending calculations for shelf sag. Using this I compared the sag on a 4.5 X 14.5 beam vs a 4.5 X 9.5 beam. For the same span and loading the shallower beam deflected 3.6 times as far, which shows why beams are deep. All the maths is linear so you'd need 3.6 times as many joists for the same deflection. So if 6x2 is ok for 600mm centres you'd need 4x2 at 170mm centres.

Edit: I've a bit of spare time this morning I'll see if I can find some other calcs.
I wouldn't shim with timber, I'd either find some slates or bed the timbers in mortar where they need building up - I wouldn't chance small sections of timber in a place where they can't be replaced without serious work. Sleepers are treated for years of full ground contact, treated 4" x 2"s aren't. When you look at your cut ends, you'll see where the colour changes - that's where the protection ends, which is why you treat the ends. It doesn't take more than a little damage or for much of a crack to open up to get through this layer, which is why it's wise to use a DPM.
It's a pity this Country doesn't use a H Rating system like NZ, where you know what you're buying. H = hazard, and it goes from one to six, with six being for permanent ground contact. So simple.

For above ^^^ -
Halo Jones - I cant believe I never seen this before, this could change everything, looks like an apex roof is definitely an option then, I'll need to do some calculations, thanks!

Fitzroy - Thanks for that info re the sagulator, that helps loads cheers, certainly confirms that doubling up will work but looks like an Apex might be on the cards anyway, never realised Scotland's PP rules were different!

phil.p - That sounds like wise advice and as it happens I've a load of slates sitting at the back of the garden, brilliant idea, thanks!
Thanks for the link, confirms what you said, good news! :D

Took the advice from the first two posters and fitted a DPM to the 4x2 bearers. I used stainless staples to secure it and also a bead of silicone right along the external edge and ends, the DPM edges on the outside will be overlapped by the cladding anyway but better to be safe than sorry I guess.


You might have spotted the Paslode, it's an IM350+ and I picked it up on Gumtree yesterday for the bargain price of £200 in superb condition and I used it to secure the bearers to the frame from the bottom (now protected by the DPM) which has made the whole thing extremely solid and holding square perfectly, great tool, will make this whole build a lot easier I think.

Also took delivery of nearly 250m of 4x2 for the rest of the framework/roof and whatnot, probably ordered too much but I'll use the extra elsewhere once this is done.

Muzza, I don't want to be the bearer (no pun intended) of bad news but pretty sure the DPM needs to be between the concrete slabs and the bearers. The issue is that the ground and concrete slabs are fundamentally porous, so moisture will be continually wicked up through the slabs and into your bearers, so the bearers will be constantly wet which will shorten their life. Yes, you can get rain on top of the dpm, that will soak into the bearers, but this will be an occasional and temporary issue as there should be some airflow under the shed that will dry this situation out between inclement weather periods.

Envious of the pasload, i looked out for one on gumtree for my build for ages but one never came up at a good price. Ended up nailing my by hand, with the resulting blisters for my keyboard jockey hands, bet you never knew you can use Compeed on your hands, it works a treat to get back to nailing when the weather is good and you have to keep going.

Fitzroy":1timfrkd said:
Muzza, I don't want to be the bearer (no pun intended) of bad news but pretty sure the DPM needs to be between the concrete slabs and the bearers.
ITYF he's turned the base upside down to attach the DPM.
I would have just laid it on the slabs, not stapled it to the bearers.
Fitzroy":3ohvu8f0 said:
Hmmm, now i feel stupid :oops: . So temping to delete my post

Not at all, I'll make daft errors along the way I'm sure so please feel free to point anything out no matter how obvious!

Yes that's the base upsides down, I needed to attach the bearers to the base anyway and rather than toenail from above, seeing as I was going to be lifting it and fitting a DPM anyway I decided to do it all neatly and essentially encapsulate and seal the bearers from the elements, I was thinking thinking laying strips of it on the slabs and just laying the bearers on top would potentially allow run off water, rain, snow melt over the top of the DPM and then in turn into the bearers?

Mabye over thinking it but not much extra effort to do it this way and it's nice and neat too ;)

Fitzroy":3ohvu8f0 said:
Envious of the pasload, i looked out for one on gumtree for my build for ages but one never came up at a good price. Ended up nailing my by hand, with the resulting blisters for my keyboard jockey hands, bet you never knew you can use Compeed on your hands, it works a treat to get back to nailing when the weather is good and you have to keep going.


Yeah it was a great buy at that price, I'm planning doing some fencing and decking in the garden too next year so it will pay for itself I'm sure, I'll always be able to sell it on, probably for more than I paid for it once I'm finished with it too, win win really. :)
Insulation arrvied.

It's 50mm EPS70 and i got 18 sheets for £150 delivered, not bad.


Weather's been horrendous so no more progress on finishing the base, so this morning I went on the hunt for windows, picked this up from a local UPVC place for £45.


It was a mismeasured unit, frosted glass, tilt and open, 850x750, brand new with sill, handle, vents and so on, ideal for the end wall.

Also got a lead on one double wide one, opens out, again brand new with sill and so on, £50, ideal for the side facing the house where the door will also be.
So, finally a couple of days of decent weather this weekend, managed to get the base insulated and covered with 18mm exterior grade ply.

Also built 3 of the walls and test fitted the window I picked up last week.







Need to find a door now, cant continue until I do, also need to pick up the double wide main window I sourced on Gumtree.

To give you an idea of what I'm aiming to achieve, this is pretty much what I want but without the door on the end.

So a little update if anyone's interested.

Got the other window, door, 9mm OSB for outside sheathing, Permavent breather membrane, batton for the cladding (yet to be purchased) and also decided to go with 6x2 for the roof in the end.



So yesterday I enlisted the help of a friend and for all the walls up, sheathed and wrapped in breather.....





The windows and door I'm wrapping in a dark grey vinyl for a more modern look rather than the brown, I've done a fair bit of wrapping on cars in the past so windows and doors are pretty straight forward in comparison, here's something to give you an idea....


Now to make a start on the roof!
Wow - great progress! Coming along really well. Although seeing the chop saw and stand filling up the footprint really gives it perspective
MattRoberts":ggav2eq4 said:
Wow - great progress! Coming along really well. Although seeing the chop saw and stand filling up the footprint really gives it perspective


To be fair the saw/stand are big, but no, it's not a huge building, just 14ft x 9ft but really very adequate for what I need and should be nice and light with the windows and door being quite big.