Building a SIP workshop.

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  • Not been very active on this forum over the last couple of years, COVID and two nippers kind of put pay to riding bikes for fun, mostly ridden now to the bakery and take sprogs to the park! I wanted to document this somewhere and seems like there’s some appetite for this content and plenty of folk who’ve done it before.

    Our garden is slightly odd in that it’s wide and not very deep so the workshop will be tucked off to one side against the boundary (see photo of area with rough position).

    It’s going to be 6x4.2 meters (basically as big as I can make it in the space I have), on a concrete slab and build from SIPs, with a pitched insulted box profile roof, supported by a 6m glulam ridge beam (most of which I already have lying about the garden / in the garage)

    Today is Feb 25th, groundwork’s start on Monday (27th). It’s the only bit I’m not doing myself, I wanted to, but I don’t really have enough people available to help me on pour day, and the slab is a trek from where the concrete truck will be, so got a couple of quotes and figured once the base is down I’ll have no excuse to get on with the rest.

    I’ll try and stick some more photos up of the design and other bits when I can dig the photos out.

    Hopefully I’ll update this next week! Not sure how regular the updates will be after that though!

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  • I always like a thread like this, what orientation is it- south facing ?

  • For clarity, acronymns should always been fully expanded in the first instance.

    aka wtf is a SIP jfgi ok


  • I found this online because I didn't know either:


  • Yeah apologies, you’re right.

    As already mentioned SIPS = Structural Insulated Panels

    They’re not that prevalent in the UK yet, but with the focus on U-values and air tightness becoming more and more of a focus in house building, and the explosion of people building timber structures in their gardens, they have gained a lot of popularity in recent years.

    In a nutshell it’s a sandwich panel, usually OSB on the outer faces, with some kind of rigid insulation in the middle, bonded together under massive pressure and heat. They essentially replace whatever would have formed the structural element of a building whether it be stick framing or masonry, with a near continuous run of insulation within the fabric of the building. The panels have a rebate cut all round the edges that accept either jointing splines (mini sips that are the thickness of the rebate), or timber, which is what attaches the panels together.

    The roof sheets are basically the same but with a profiled steel sheet bonded to the outsides instead of OSB. Used extensively in commercial building of warehouses etc.

  • Following with interest, good luck with the build.

  • Subbed. I want to build something like this. Lack of a garden is currently the limiting factor.

  • subbing in. I'm hoping this will be the year I build a big shed. I've been looking into sips as an option as well.
    have you got any drawings?

  • Cheers for the subs.

    We’re having some internet issues and I’ve also currently got my 1 year old sleeping on me at the minute so I’m limited to the photos I can find on my phone.

    This is a rough idea, it’s an earlier design, and has changed a little since but it’s ballpark (the size is correct). I’ve reduced it to one larger window on the left and added a personnel door to the right hand side of the same wall. The long back wall is against the boundary, the short wall on the left is south facing (as is our garden), the main front wall with the window and personnel door will be east facing looking out across the garden, and the right hand wall with the large door (probably end up being a roller door) faces north, towards the front of the property, because we have a wrap around garden I can bring the car round the side of the house and through the big door - no more fixing cars on the drive in January when they inevitably choose to go wrong!

    The roof pitch might end to being a bit lower but if you imagine a big timber beam from one gable end to the other.

    Also pics of SIP mountain (tarped), roof panels, and Glulams chilling in the garage!

    I’ve decided to throw a water pipe in as a last minute addition, it may never get connected but nows the time to put it in before the concrete goes down, which also means sticking a soil pipe in for the drainage. Hopefully the ground workers don’t mind and by end of play tomorrow it’ll be in and ready to pour concrete. I’ll try and timelapse it all.

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  • Particularly for anyone who’s looking to do something similar, in a bid to keep costs vaguely sensible, the build has been quite heavily influenced by “stuff I found cheap on marketplace”.

    For example, ALL the wall sips were a job lot from a guy nearby who’d just done built his own workshop, this was the leftovers, I paid £640 for the lot and it’s enough to do the whole build (I think!) - when you consider that effectively replaces all your framing, all your insulation and all your sheathing, it’s very economical.

    The roof panels were the same, a job lot of leftovers from someone else’s build, I paid £1000 for enough panels (inc. most of the trims/flashings/guttering) to do the whole roof, and I’ll have some left over.

    The Glulams were the most recent addition. I priced up a new glulam (£530 delivered), a steel ridge beam (£500 delivered), buying new timber from Travis Perkins to do a cut roof (approx £3-400). I found these at a reclaim yard and got all 3 (going to double up the ridge beams as I’m unsure on the structural calcs, 1 probably would have done it but 2 certainly will) for £160!

    I realise I’m lucky to have the space to store all this rubbish but if you can be flexible and keep your eye out for deals, there are ways to do either a higher spec or lower cost (or both) build than you otherwise might if you were just placing a big order with the merchants.

  • Good friend of mine is an architect who works with these a lot for the building of schools and is always raving about how ridiculously quick they are as a construction method.

  • Sounds amazingly economical so far, impressive bargain hunting!

  • Progress!

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  • And a better idea of the plan, still moving things about a bit, going to bring the door in a bit, realised having the door tight to the wall is going to create a tiny slither that I'll have to clad on the corner, plus the ducting for the electric and water come in at that corner so I need clearance for those.

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  • Nice update. How much did the concrete slab cost?

  • Loving the reclaim aspect of this!

    Is there any reinforcement in the slab? Will there be any brittle finishes (eg plaster) inside or out?

  • £3600, but I have gone a bit overkill because I've got some big trees quite close (probably closer than is ideal, but they are mature trees), and I want to park a car on it. especially considering they dug our road up to fix a burst pipe and I saw how thin the road surface was (probably about 50mm subbase and 75mm tarmac) and we get a fair few trucks and tractors going up and down to the farm down the road. But I'd rather have it over-done than under-done.

    It's dug out 250mm, 150mm hardcore/type 1, 150mm reinforced concrete with fibres and A142 reinforcement mesh. Plus I had them dig a trench from one corner to a corner of the house (about 5m), for electric and a water supply, and stick in provision for a soil pipe (drainage) whilst they were at it.

    I very seriously considered doing it myself until recently, but after seeing how hard the two of them worked and how long it took them (they allowed 2 days and basically ran out of time and came back for another half a day to finish off and tidy the site up), I reckon it would have taken me a solid couple of weeks worth of man hours working mostly alone, and it'd likely not be as good.

    I priced the materials up to do it myself and it was around 2k, could be less if you did it all by hand with no machines but it'd take forever, with machine hire etc. you could easily clear 2k all in doing it yourself. I had quotes from 3.2k to 5k (I'm in Norfolk), but these guys came highly recommended.

  • Yes, lots! (see my post above). Nope, it's a workshop so it'll be OSB (maybe painted) inside, and clad outside.

  • Thanks for the detailed answer.

  • so cool, so many questions!

    where did you learn more about SIPS? I'd like to read as much as I can about the process.
    how and when do you cut the window apertures?
    what goes on the outside? tvyek?
    what goes on the inside? pain the OSB straight, or add ply?
    what are you cladding with?

    good luck with the project!

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Building a SIP workshop.

Posted by Avatar for ThePeginator @ThePeginator