Workshop planning: from small acorns...

[DaveMac]

Right; here goes. Thanks to much of the wisdom and experience shared here already, I've kidded myself that I can pull off a new workshop. And that a new workshop is more pressing than a fully functioning bathroom.

At the moment I'm only in the early planning stages, and as Donald Rumsfeld famously (or infamously) said: "There are known knowns... There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know."

First to the known knowns. Whatever I do I'll need planning permission (in an AONB and a conservation area, and the cottage is listed). That is going to limit the materials and appearance to a large degree. To avoid building regs I'll need to build a certain distance away from the boundary, and under a certain floor area and height. With those things in mind, I've made some very rudimentary sketches (don't laugh too much) based very heavily on the work of Mike G. There would be a 4m x 6m main workshop space, and separate 3m x 3m space for use as an office. Height at the ridge would be 3.9 m.

Western elevation:


Northern and eastern


Floorplan


I know it looks massively OTT, but it's going to be seen from every angle in the garden and needs to fit in with the surroundings without dwarfing them and offending the neighbours and planners too much. Hence natural stone fronting for the plinth, which could massively complicate things, and slates on the roof. The overhangs will protect from the helm winds from the north and provide a bit of space to store wood and sit out during the five days of high summer. The other thing is that there's a good chance we're going to end up looking after at least one older relative, and the cottage seemingly was made for hobbits. So I wanted to leave the option open of potentially converting to a partly habitable space in the future. I've already lived in a lot worse than my current temp workshop, but I need to do a lot more research to work out how feasible this really is, if at all.

The site is tricky. It's currently occupied by a dilapidated and slowly collapsing timber garage, spliced with a 1/2 stone garden room thing. The garage sits on its own slab a foot from the boundary fence (which will be replaced with a dry stone wall). I don't know how thick this slab is. The "garden room" sits on a different, lower slab, and is built on the boundary line. To the north there is patio. Pictures are worth a thousand etc:

Looking south


Southwest


Looking west


So to avoid falling foul of building regs the new building would need to be 1 m to the north of the boundary, and due to the overhangs about 0.6 m to the west of the current buildings. Plan below, with new building outlined in green.



So known unknowns. The ground conditions are a bit weird, and I'm completely and utterly clueless when it comes to foundations. Two types of existing slab of unknown thickness and none; a slope from south to north. So my first question is, is the only option ripping out all existing slabs etc, or is there feasible a way to cut and excavate channels into them to form some kind of trench foundation? The soil is clay but I think quite shallow, and there is one small ornamental holly tree nearby. The garage slab is still level and hasn't cracked. The village was built circa 1850 and there don't seem to be any foundations to speak of, but nothing has moved.

For the floor, I was thinking of a suspended floor but this would mean 200mm C24 joists to make the 4m ish span. But a lot will depend on what's feasible for the foundations. I've got a builder mate who did 10 x 7 m garage nearby, who should know a lot more about how to take the path of least resistance and on the groundworks. Hopefully I'll at least be able to get drawings in to the planners in the next couple of weeks to get the ball rolling.

All ideas, reactions, and unknown unknowns extremely welcome. Thanks in advance and tread carefully, for you tread on my dreams.
Dave

 

[Mike G]

That's an excellent start, Dave. Frankly, my drawings in the "How to Build a Workshop" thread contain very little additional information.

I've got to shoot off and do something else, so this will be quick. I'll come back to it later. My initial comment would be that if you have a solid base of an existing building in place already, then I would bend over backwards to build off that, even if it meant complying with Building Regs. Compliance is less onerous than you'd imagine. If the existing buildings are the right sort of size, then taking them down and replacing them would remove far and away the most challenging part of any build: the stuff in the ground.

Further, you've got a builder friend. That's your plinth sorted!! After that, it's just simple 4x2 studwork (and any competent DIYer can do that), and a roof (and I can design that for you in its entirety such that the only effort is actually cutting it and erecting it). Again, with a bit of help, that's within the reach of most DIYers, although it's better to have some help, and access to some scaffolding of one sort or another.

More later....

 

[AJB Temple]

Sounds like a great project.

Personally IMO if you are forced to get planning permission, then you may as well do building regs as well.

From personal experience, if there is any way of making the building inside a bit wider than 4m (say 5m) then I would push it with the planners as it makes handling sheet goods and big timbers in the shop a lot more manageable. My shop in the garden is approx 4m wide, (but quite long) and I find it a bit confining with machinery, storage and so on, especially with large beams and full size sheet goods. If you fit in say a planer / thicknesser, band saw, lathe, drill press, sliding mitre saw, table saw (or track saw bench) and a sanding station of some sort, plus extraction, then space gets to be at a premium. Helps if you can open double doors or a hatch (like Mike) to have outfeed for P/T and table saw.

It is super handy to lay water to the building and a beefy armoured cable or ducted power supply capable of all machinery including 16amp. Overspec that and run internet cable with them. Think how many sockets you could possibly need, and then double that. Costs peanuts extra and it is amazing how much kit we accumulate....

Insulate like mad. Helps to stop your gear rusting and makes the shop usable year round.

 

[DaveMac]

Thanks both for the rapid replies. Plenty to think about.
AJB: the internal space is something I've been agonising about. The problem is less with the planners than with my partner. The garden is her domain, and she's convinced this thing is going to shade out her flower bed. With the move one meter north to avoid regs that's limiting, but if I could comply with regs and build on the boundary that might change things. The problem is, I assume the only fire resistant material that the planners will countenance will be stone because of the conservation area business. I don't actually have much machinery at the moment, just bandsaw, lathe and pillar drill. A mortiser would drastically improve my life. I plan to follow all your other advice to the letter.

Mike: the problem is the size of the goodish slab would limit things to about 3.5 m in width. Not the end of the world. And then the weird garden room thing sits on a different, presumably much thinner slab. Is there a way to cast something additional to extend the length and width of the original slab, or is that just a world of pain? As for the builder mate, he'll come for a beer and tell me to make do working in a barn. The earliest I'd get him to lay a brick would be 2025.

 

[Mike G]

I would suggest a couple of holes......one hard-up alongside each of the slabs.....so that you can measure their thickness. But as you say, 3.5m is a bit restricting.

Building a building on a slab of a different size is a nightmare. I just wouldn't do it (well, wouldn't do it again......don't ask). So if the slab is the wrong size and shape then it will need to be removed. A clue as to its thickness will help, but you'll almost certainly have to break it up with a Kango. If it's say 9 inches thick, though, you'll probably need a digger and breaker.

Alternatively, you might cut off the spare concrete, and cast another slab over the existing and extending over the ground (in the ground) to your new wall positions. This will leave you a biggish step up into the workshop, which is also the downside of building a timber floor.

Of course, if there is an alternative location for the workshop other than in place of the old shed, then things would be quite a deal easier.

 

[DaveMac]

Brilliant, thanks Mike. I'll set to digging and see what horrors lurk beneath. If an encapsulating super slab is doable then a chunky step up might be a price worth paying, as there's no alternative site that I could square with the gardener. The only other possible site would be where I have the current temp workshop, but that would be fraught with its own issues and limitations (it's the building on the north-south axis just to the north and east of the proposed site). Really it's too small, on the boundary, has a dodgy and badly cracked existing slab, and I'd have nowhere else for a temporary workshop.