Workshop with ground screws and SIP structure? Comments?

[MusicMan]

I am hoping to be able to build a new, larger workshop in the spring, so am starting the design thoughts and would like comments. I have some constraints.
- the site available is 5.5 x 4.5 m, perhaps 5.5 x 5.5 (external) if I go for planning permission and go right to the boundary. I don't think the neighbour would have a problem as long as it was fire-resistant etc.
- I am NOT going to build it myself, so please do not suggest this unless you are willing to come along and provide the labour! I'm 80 and simply not able to manage large sheets or large beams alone, and have no gang of fit young friends who could help. OTOH a custom build is more attractive than a bought shed, and I can do the internal fitting out.
- Given that I will be hiring people to do the work, it seems to me that it is wise to choose a build method that is fastest and uses least labour. I am therefore very attracted to SIPs for the floor, walls and roof. These have the reputation of being assembled in days rather than weeks.
- I am seriously considering the use of ground screws for the foundations. This is partly for simplicity but mainly to avoid the use of concrete where possible, for environmental reasons. Carbon footprint of a concrete slab is around 1.25 tons compared with 300 kg for ground screws. I will ensure the ground is properly tested (I had problems with the existing 16' x 8' workshop, where I skimped on foundations, settling on one side) and the screws properly specified. I will probably get the ground screw company to build and install the timber frame for the base, with SIP panels going on directly.
- I would prefer a pitch roof, which would require planning permission given the site, but I might have to settle for a flat roof.

I would be grateful for any comments or advice based on experience or training with ground screws or SIPs, good or bad. Please refrain from speculations, though!

Thanks, Keith

 

[Cabinetman]

Hi Keith whilst trying not to speculate, I relate this as something you may not have thought about. A restaurant near where I live was built using the insulated boxes from the backs of old articulated frozen food trucks, (cheap and I think 45feet long) all put side-by-side with the central ones having the sides cut out of them, how they joined them I do not know, what they are sat on? Again I do not know, but I do know it was the quickest build ever and when you are inside you don’t have the faintest inkling of what it is you are actually sat in. (Frozen) food for thought. Ian

 

[Jameshow]

Several men's sheds have used two 20 x8 containers bolted together. Gives a 6mx 5m area in a day.
You can specify then with elec windows and cladding. About £5k
Worth thought.

Cheers James

 

[MusicMan]

Several men's sheds have used two 20 x8 containers bolted together. Gives a 6mx 5m area in a day.
You can specify then with elec windows and cladding. About £5k
Worth thought.

Cheers James

It's a good thought thanks, James, but I don't have access to get them in, not without a crane that could lift them over the house and into the back of the garden.

Keith

 

[Jameshow]

Fair enough they wouldn't be my choice either!

Cheers James

 

[Ollie78]

I have considered this same issue and the ground spikes look very good to me as a quickly installed solution.

Another quick but surprisingly good method is adjustable galvanised "feet" set on plastic ground stabilizers with gravel. They are a flat galvanised steel plate about 300mm by 200mm with a large bolt welded to the centre, the height is adjusted using a pair of nuts on this bolt and the joist sit in a steel cradle.
They were very quick to install.
My Mum has a very large log cabin which sits on these things. When we were building it I must admit I was skeptical about the method but after 10 years it is still flat and level. The rest of the log cabin has been less successful but the base method worked great.

Ollie

 

[OldWood]

Ollie - could you expand on the feet you are talking about a bit please. My brother is about to build himself a shed predominantly for storing materials in and is cutrrently talking about a concrete pad and I suspect hasn't any knowledge of these other 'feet' options.

Thanks Rob

 

[gmgmgm]

I was building a structure recently and evaluated ground screws vs. concrete pad vs. small concrete post supports. The ground screws came in as very expensive and the time could be quick - or could be slow, depending upon what they find underground. And most builders aren't familiar with them, so I think you are being very sensible getting the screw company to assemble the base as well. You will also have a potential haven for rats underneath the building (as you would with small concrete supports for each individual post).

 

[Tris]

Would it be possible to use duckbill anchors to hold your frame down? If so you may be able to have small holes dug down to subsoil, filled with compacted hardcore and topped with a suitable slab or block. Less impact than concrete and removable if required.

I have no expertise in this area but have seen it done on a timber framed house before.

 

[Inspector]

I built a couple decks off the kitchen and another off the shop using helical piles (screw piles) ground screws to you. The shop deck is attached to the house on one edge and the other on to a couple screw piles it is 8 1/2' x 12'. The kitchen upper deck is also attached to the house on one edge and on to the lower deck on the other with the lower deck using 4 screw piles. Upper deck 10 1/2' x 12' and the lower 14' x 16'. So 4 screw piles for both kitchen decks. The screw pile contractor came with both the smaller diameter 2 3/4" and larger diameter piles 3 3/4" I think and used the larger piles because of the rocks in the ground. The smaller wouldn't have made it to the 10' depth to get past the frost line. The 6 piles were in place in about 2 hours including welding the adjustable saddles on top. My alternative would have been to get a contractor with a power shovel big enough to dig down to 10 feet, put in forms for concrete with rebar cages, get concrete delivered, strip the forms and backfill the concrete. The screw piles were about $2,500Can and were a lot cheaper than the concrete not to mention not disturbing the ground. Get the screw piles. I did the rest of the deck work with the exception of the rubberized decking on the upper decks and the aluminium railings. The 16' beams were built up of 3 of 2 x12s and a layer of 3/4" ply to get the width for the saddles on the piles, by me in situ.

I wanted to build the place with SIPs but the rat bag builder talked me out of them (more profit for him) in favour of double walled 2 x 4 construction. Still nice and warm but took months for them to put it up. If I do another house it will definitely be of SIPS.

Pete

 

[MusicMan]

Thanks very much for your experience and advice, Pete. Here they seem to use shorter piles but more of them, but then we don't have a frost line to deal with.

I couldn't pick your beams up!
Keith

 

[Inspector]

The architect had 14 or so screw piles and 2 x 6 joists for the decks. With the small screw piles costing about $250Can installed each and the bigger about $350Can each I baulked. While using 2 x 6 would have made it all easy I could buy a lot of 2 x 10/12 material and had money left over so I got her to rework it to the bigger stuff. I'm 66 so still have a little grunt in me and none of the lifting was over 4'. Since you are getting the contractor to do the frame on which to build if they used fewer piles you might have some room under the structure to store stuff like wheel barrows, canoes, lawn chairs etc, depending on the slope. The screw pile machine was no bigger than an Auston Mini and on rubber tracks. The operator walked with it using a remote so they are the answer for getting in and out of tight places. Depending on the slope they might be able to put tall piles on the lower end and weld braces so you would only need beams for the floor to sit on and not have any timber framing to get everything level. Their engineer should be able to give you prices for both ways of making it.

There were 2 SIP companies I could have gone with for the house. One used 4' x 8' OSB and foam. The other used sheets of OSB that were 8' x 28' and the foam with it cut to size and all window / door openings cut in with their big CNC router. The former would be ideal for a few people to put up and the later was strictly a crane job but with houses taking 2 or 3 days at most to put up. Simpler shapes going up the fastest.

Pete