CocoCabin - my new studio, shed, workshop build

Height>2.5m and proximity to a boundary for planning.

If you read from the start, most of your questions are answered.

Hey Alan,

I've attached the budget as it stands so far. This not entirely comprehensive, but it is accurate to within £100 I'd say. It also doesn't include a few tools I've bought for the project, which probably total a couple of hundred quid on top.

Sounds like a cool plan, I went for a dual pitched roof because I wanted extra ceiling height (I will occasionally use it as a studio space for my work, photography) and also because it looks cool as fuck. Single pitch roofs are much more common for garden rooms because they're a bit simpler, I think. It seems like people mostly use waterproof membranes to roof them, I don't know much about it. One of the best resources online for this is a youtube channel by a guy called Ali Dymock who made a single pitched, almost flat roofed, garden room and made VERY detailed videos about all the different stages. He's very informative and it's nice because almost everything to do with DIY construction on youtube is from the States, and he's British.

RE planning, there is something called 'permitted development.' this is a certain set of parameters — building height, building footprint, building footprint in relation to house footprint etc – and if your proposed building falls within these parameters you DON'T need any sort of planning, just crack on.

However, and this is where it got me, if you are building you're proposed structure within 2m of a boundary of your property these parameters shrink.

So, to use the example of the parameter that I felt limited by, an outbuilding on your property can be up to 4m total height for a dual pitch roof or 3m for any other roof type, with a maximum eaves height (wall height) of 2.5m, with no permission of any sort needed

If your building is within 2m of a boundary, however (which anyone with any sort of normal garden is going to need to do) you are limited to a maximum height 2.5m overall.

If you're building a shed that's fine, but if you want proper headroom 2.5m isn't a lot, and I had no choice but to be within 2m of a boundary. Once you start planning you gain height quick. You want your sub floor a few inches off the ground for ventilation. Then the sub floor is 200m deep, then 18mm for osb floor, then you want a decent amount of headroom so the walls are maybe 2.2m tall, you're already at 2.5 and you have even started on the roof.

You can save some of this height by doing a concrete slab instead of a raised subfloor but that has it's own costs associated with it that probably cost more than planning...

It's an easy but slow process

1 Attachment

Is the ceiling vapour sealed behind the MDF? I can see a load of foil tape behind the battens. You want to avoid condensation on the OSB.

Nope, it's just insulation then MDF. Where is the vapour coming from though? There's a vapour barrier externally, is that sufficient?

You need a vapour barrier on the warm (inner) side of the insulation, and a vapour permeable membrane on the cold (outer) side of the construction - your building paper wrap. The foil on the insulation is a vapour barrier, but you should tape up all the gaps as well to make a continuous barrier on the warm side.

The vapour comes from inside - the inside of the room is relatively warm, you're breathing, the air is holding that as water vapour, and there's a sort of low level air pressure gradient from inside to out. The insulation means that the inner face is warm, and the outer face is cold - the bit touching the OSB. So if the relatively warm, humid air gets to the OSB, there is a risk that the water vapour condenses onto it and causes damp.

In reality, if you're not running a bath in there on a regular basis, and importantly if the building wrap really is breathable, then the OSB shouldn't get that damp and any low level dampness should evaporate out the other side. Assuming there is some kind of air-flow between building wrap and roof cladding.

Thanks for the information. Realistically I'm not going to get to this now I don't expect, but if I did, what would a suitable vapour barrier underneath the MDF be? Something breathable or just plastic sheet?

The floor...

I wanted to try and get some flooring down asap after I'd finished the dusty ceiling jobs. I had an enormous metal cabinet full of tools that had been living in the lounges of our various houses for the last five years and it was an exciting prospect to have that out of the house, along with lots of other crap. But I didn't want to fill the new room up with junk only to have to take it out again when I do the floor.

My friend had a load of old Canadian maple gym flooring at his studio from a Zara shoot we did a few years back. The production had paid for it so it hadn't cost him anything but when I mentioned it he said he wanted to sell it to me. With some cajoling he eventually agreed to let me have it.

I needed 8.6m2. I searched through my emails and eventually found the original email regarding flooring for the Zara shoot and we'd ordered 9m2. Hurrah!

It was way more covered in old adhesive and crap than I remembered, and when I dug it out of storage I thought I'd probably just have to scrape it all off.

When I actually started laying it though I soon discovered the bituminous substance was not going to come off easily, and was caked on the tongues and grooves. Really bad bits I chipped away at, but mostly I just said fuck it, It's just a shed, and laid it gappy.

In the end, there wasn't quite enough, some must have been binned or damaged during the shoot. When I got about half way I would be sorry and so I left a door matt cutout of 1m x 50cm, you can just see that starting in the second picture.

3 Attachments

It's part of the job of the foil on the insulation, so let it do that, and then tape up any gaps with foil tape. You want to stop humid air getting to the cold zone, so gaps between the insulation boards and also gaps around the edges of the ceiling to wall. If you buy separate vapour barrier it's usually a thinnish polythene or foil-backed sheet.

Oh I see, well maybe I have got one then... All the gaps in the foil are taped with foil tape, the rafters and any damaged insulation etc. I didn't realise that's what you meant

All sounds good then!

Oh, I could have lent you my porta nailer.
https://www.building-supplies-online.co.uk/porta-nails-angled-floor-nailer-with-mallet-in-case-por402a.html?utm_source=google_shopping&gclid=CjwKCAiA-f78BRBbEiwATKRRBFnNSNNMEGOs6okB90Sb0hTHjwbBy1uLdX2tRfvkbLkxZOitOPbbTRoC1JEQAvD_BwE

Thanks mate, nevermind though, regular nail gun is good enough for the shed!

I can relate.

DISCLAIMER ABOUT ALL ELECTRICAL DISCUSSION: I DON'T KNOW WHAT THE FUCK I'M TALKING ABOUT...

With the building sealed, the ceiling insulated and boarded, and the floor laid, it was time to think about power.

In a previous shed project when I was living back at my mums I had wired together a few sockets and a fluorescent strip light and simply ran this all into some standard electrical cable with a plug on the end. Whenever I wanted to use the shed I would drop the plug out of the window and plug it into the house's outside socket.

Surprisingly, I never had any problems with this bodge method, and my teenage self frequently sat in there late at night with the lights on, with an electric fan heater on, getting really stoned and watching skate videos on the TV/VCR, even boiling a kettle at times for tea.

However, I wanted to do things a little more properly this time round. I was unlike to put much draw on the power out there, I have a few workshop tools (band saw, pillar drill etc) but mainly my power tools are on 18v battery now, and so charging would be the main concern, along with lights. However, I did want to future proof the space thinking future house owners might want to use the cabin as an office, gym or whatever.

So, while building the cabin my plan had always been to get a professional in to do it properly — run a new ring off of the house's CU, with it's own protection and sufficient power.

When I actually finished the cabin we were deep into lockdown and I was months out of work, and so I had to rethink this. I tried to research the process of 'doing it properly' myself, but generally DIY and constructions forums where people ask these sorts of questions are overrun by Electricians arguing about cable capacities and making it abundantly clear to amateurs that electricity is kin to magic and cannot be fathomed or manipulated without the correct qualifications. Eventually I found a suitably knowledgable friend though, and he advised me that running power 'properly' with correct protection and directly out of my house's CU was actually pretty easy, not that dangerous is a certain logical process is followed, and quite good fun.

Step 1.
My house CU was at capacity, with no slots left for new MCBs or RCDs. So, I bought a 1-way shower CU from screwfix and there was exactly enough space for this in the cupboard next to the existing house CU. I just installed it on the wall at this stage and didn't wire anything in.

This unit has a 63A RCD where I would bring the power in from the main CU, and then a 40A MCB from which I would run the power out to the shed.

It is about 50m from here to the shed and the CU in the house is on an internal wallso routing the cables was going to take some though, but I though I'd get the shed wired and ready first...

1 Attachment

It is notifiable under part P though, isn't it?

probably

I won't tell if you won't

Actual lol

So next I got a garage CU also from Screwfix. This one has an RCD for the power from the house and come pre populated with a 16amp MCB for the shed sockets/ring and a 6amp MCB for the lughts.

I'd already left those two cables routed along the ridge board and down through the studs on the gable end wall.

I decided to house it all in the cavity immediately adjacent to the door, so that when the internal cladding is up it will be tucked away.

I put some mounting points into the cavity using old studwork and plywood, and then attached the garage CU. Then I added a double switch at normal height operate the two ceiling lights I wanted, and I third switch higher up for the security light that I'll eventually out outside.

1 Attachment

@Josh012 for inspiration!

I put an LED striplight along the ridge line and then halfway down the front slope of the ceiling I put a pendant fixing in above the window corner.

I ran a radial from the garage CU round to three double sockets, one at floor height just below the CU, next to the door for operating power tools outside, on the back wall above my workbench, and at floor level over by the window corner for the easy-chair/laptop area.

Next I routed cable from the house CU all the way to the shed.this involved running 4mm2 unarmoured cable from the CU down to the skirting board, through the wall into the lounge, along the skirting behind the TV unit and to the front wall of the house. Then I drilled a 20mm hole out of the front wall of the house at a slightly downward/outward and and lined this with PVC conduit.

On the outside of the hole I put a watertight junction box and ran my 4mm2 armoured cable into this. This then went straight up the front wall of the house to first floor level, around the side, down again and then all the way down the fence line to the shed. Learning how to gland the armoured cable into the junction box was particularly fun!

3 Attachments

Wonderful read - so impressed by your skills/knowledge !!

Thanks very much!

With the electrics done and connected to the house I was pretty keen to get all my tools down to the cabin and get going on some projects, particularly my new bike build - I had all the components lined up and was just waiting on my pre-order Brother Kepler.

Firstly I need a work surface and some extra storage. I have a carpenters workbench with vices and such back in the shed at my mum's I'm Norfolk, but I wanted something a bit more all purpose.

I had been hankering after some German-made Auer storage crates for a while so I put in an order for some 40x60cm crates in various thickness. I ordered 12 crates and 6 lids so that the bigger ones could be sealed storage for larger stuff,and the slimmer ones could be drawers and tool trays for various sets of tools.

1 Attachment