Worrier's Workshop

[Weekend worrier]

I'm currently packing my tools into boxes with (as yet) nowhere for them to go - the space I had in the basement now has to be put to other use as of Monday. So now my head is filled with ideas of a more dedicated space in a garden building.

I've read through a lot of the threads on here, thanks for all the advice generously given so far. I'm desperate to turn this from just a pipe dream to reality, but very aware of the gaps in my knowledge (and ability), and would gladly welcome any input.

 

[Mike G]

Always happy to help advise on workshop builds. The place to start is always with a site plan if possible, but at the very least some photos.

 

[Weekend worrier]

Thanks Mike, very kind. Your sticky posts above have been an invaluable resource.

Which neatly brings me to...

The Site:

We had some landscaping work done in the garden a couple of years ago, and I had the landscapers pour a concrete layer in an area I intended to use for some kind of building / shed in the future. I didn't really know much about the requirements at the time so don't think I ended up with the right thing: its a level area of concrete, but isn't a building-sized foundation as such, which in hindsight would have been much more useful.

To maximise building size I'll need to be within 1m of the boundary, so limited to 15m2 floor area, but as part of the landscaping we dug down from the surrounding garden 700mm to level this area, so I've gained some extra permissible height above the 2.5m restriction I believe?

Here's what I'm working with:

 

[Mike G]

You're only limited to 15 sq m if you choose not to go for Building Regs approval. This is a bit of an artificial limit, and achieving a BR -compliant building isn't difficult even within 1 metre of a boundary.

The 2.5m height restriction is also an easy obstacle to overcome, simply by applying for planning permission.

I suggest you have a think about the size of building you would ideally like, and then see what bureaucratic hurdles require jumping.

 

[Malc2098]

My plot sloped in two directions. I had a plan for a non PP but BR compliant workshop.

I asked both Planning and Building Regs at the council that in view of the slopes, where is the datum for height.

They said they would have to survey following a PP application. So I upped the apex of the roof and the eaves a bit and applied for PP, and it was granted.

In the end, I build 1.1m from the two relevant boundaries and didn't need BR.

 

[the bear]

I was always under the impression ground height is measured from the highest ground adjacent to the building. I'm sure a search of the planning portal will confirm or otherwise clarify

Mark

 

[MY63]

I had a similar question regarding height when I built my workshop. I spoke to my local council and their response was "it is your garden you decide where to measure the height from" I took measurements in a number of areas, and then chose the mid point. I sent this in an email to the council but never received a reply.
Before I started I had no experience of building I followed the instructions in Mikes posts and listened to the advice given by others. My workshop is coming up to 4 years old and still looks fantastic. I now store all of my leather in there and heat it with a small oil filled radiator in winter.
Michael

 

[Steve Maskery]

If you do decide to go for a larger building that requires BR, make friends with your local Building Control Officer as early as possible in the process. BCO can be very helpful or they can destroy your project. I was lucky, mine was fantastic and helped me out of more than one hole I'd dug myself into. But I know of someone who needed to rebuilt his (external) chimney and the BCO insisted he built the footings considerably deeper than the foundations of the original house.
I also know of one person who built his workshop on the QT and the council made him tear it down.
You want your BCO to be your ally, not your enemy.
S

 

[Malc2098]

My plot sloped in two directions. I had a plan for a non PP but BR compliant workshop.

I asked both Planning and Building Regs at the council that in view of the slopes, where is the datum for height.

They said they would have to survey following a PP application. So I upped the apex of the roof and the eaves a bit and applied for PP, and it was granted.

In the end, I build 1.1m from the two relevant boundaries and didn't need BR.

It was my BCO who showed me how to build without requiring BR.

 

[Weekend worrier]

Thanks for the input so far everyone

Here's a pic of the site (concrete area from retaining wall at the back up to the decking in the foreground):



In the space available I wouldn't get much more than 15m2, especially if I leave a little gap for access / cleaning - there's a willow tree overhanging the site and it seems to dump a lot of leaves and twigs at all times of year. So I'm thinking to stay within permitted development, with the option of going higher due to the dug-out floor level.

In peoples' experience, what is a better workshop shape with regard to arranging benches and machines inside? Is something squarer or rectangular more preferable?

 

[the bear]

If you leave a gap all round I'd want to be sure that the higher ground at the back still counts as the land immediately adjacent. After all strictly speaking the land immediately adjacent is now all the same height if a gap is left. I don't know the answer, but I'd want to know for sure beforehand.

My old workshop was rectangular, my current one is almost square as its partitioned off from a bigger building. I'd say the rectangle was possibly a better shape at the size it was, but the square workshop is a bit bigger and therefore fine as well.

Mark

 

[Mike G]

I don't think shape matters a lot, Dan, unless you are working with long lengths of timber......which would naturally suggest a longer workshop. A longer narrower building generally makes for an easier roof, but these buildings are so small that it doesn't make much difference.

 

[Weekend worrier]

If you leave a gap all round I'd want to be sure that the higher ground at the back still counts as the land immediately adjacent. After all strictly speaking the land immediately adjacent is now all the same height if a gap is left. I don't know the answer, but I'd want to know for sure beforehand.

A good point, immediately adjacent probably means butted up to the building wall, so I’d need to incorporate that into the build if I was to use it as a means to increase the roof height above 2.5m. I’ll ping an email to the local council to check.

 

[Mike G]

If you plan to incorporate the retaining wall into the structure of the workshop, you'll need to re-build it. It's quite a detail to get right.

 

[Weekend worrier]

Thanks for all the replies so far, this has been rolling around in my head over the last week, with no building experience I only ever seem to come up with more basic questions than answers...

I'm now looking to keep the build within PD, the idea of rebuilding the retaining wall to form the rear wall of the building to gain some extra height is beyond my ability / budget. Any sheet goods I couldn't stand up on end in the building I can always work immediately outside on etc.

Regarding the foundations, as you can see I have a level concrete 'area' but not a dedicated slab to build directly on (I so wish I knew more about what I needed at the time it was laid down :eusa-doh: ) I've seen the Quickjacks HS system to suspend the floor and fix it to the concrete - anyone got any experience of these?

Exposing the build to the elements whilst it is ongoing is another question I had - what do people do to manage this? Does it need covering etc?

 

[Mike G]

I would avoid any sort of suspended floor arrangement for 3 reasons. Firstly, you are operating within limited headroom to start with, and putting in a suspended floor may cost you a foot or more of headroom. Secondly, it would mean a step up into the workshop, and annoying as that is it's nothing compared to the hassle of trying to get a heavy piece of machinery in. Finally, it produces a void which is almost impossible to keep vermin-free.

What do you know about the concrete base? How thick is it?

Oh, and most building materials are perfectly OK getting wet. The only things to watch out for a mortar, which is fine once it's dry, plywood, and fibreglass insulation, which should always be kept dry. Timber, OSB, and most other common building materials are unharmed by getting wet now and then during construction.

 

[Steve Maskery]

For your floor I would heartily recommend the way I did mine. From the ground up:
Concrete slab
DP membrane
50mm Jablite
18mm OSB
22mm Caberfloor

The caberfloor is not a lot more expensive than regular chipboard flooring and it comes pre-finished with a non-slip polyurethan coating. Not having to paint the floor is a boon for speed and ease, as well as saving the cost of doing it.

If you want a very, VERY, long read, I blogged my workshop build on UKW. It will definitely cure your insomnia.

 

[Mike G]

For clarity, what Steve is describing is a floating floor. It's a way of insulating on top of a concrete slab, and achieving a "wooden" floor". That decision may be a step or two away just yet, as we are only just starting to look at the type of construction.

 

[Steve Maskery]

Thank you, Mike.
S

 

[Cabinetman]

My two favourite reads in woodwork, workshops and benches. Following with interest.
Just guessing but if doing a floating floor as described would it be beneficial to carry the membrane up and over the rear retaining wall to prevent moisture problems? Just hope the slab doesn’t slope back towards that wall!
Ian

 

[Mike G]

My two favourite reads in woodwork, workshops and benches.

...if doing a floating floor as described would it be beneficial to carry the membrane up and over the rear retaining wall to prevent moisture problems?....

No design I have in mind has the internal floor level at the same level as the external slab, and if we aren't re-building the retaining wall, then we'll be building away from it.

 

[Weekend worrier]

Again, thanks for the input everyone.

I pulled up the decking board adjacent to the concrete, although there was still framing timber from the decking pretty close up against the slab it looks to be around 110mm thick from what I can tell.

 

[Mike G]

OK. That's good enough to build on top of....but we can't build directly on top of it because water will run straight in through the lower mortar joint. I think the best answer is to lay another slab of concrete on top, to the size of the shed. That will give an upstand which will prevent water getting in, and will produce enough strength to be able to support a proper shed on a plinth. I'll try to remember to do a sketch this evening. If I forget, feel free to remind me.

 

[Weekend worrier]

Thanks Mike, from a bit of YouTube research it looks like a bonding agent is needed to get the new pour to adhere to the existing one, but not found any specifics as to how to make the form when the base is existing concrete as opposed to hardcore and sand. What depth would you recommend for the new slab?

 

[Mike G]

It's not actually critical to bond the new concrete to the old, but there is no harm in it.

The thickness of the slab will depend on the size of the proposed building. The formwork would be just a simple timber structure, which will need bracing back to (something) to prevent the concrete bowing the wood in the middle. This is normally achieved with 2x2 pegs bashed into the ground, and a prop screwed between them and the formwork. In your case, with a timber retaining structure at the rear, that's one side that's very easy.......but I don't know what is off the existing concrete

 

[Steve Maskery]

Don't underestimate the force of a slabful of wet concreted. That bracing needs to be very robust.
When we poured mine, we thought we had it all wrapped up nice and solid, but when we started to pour, those substantial timbers started to bow and we were frantically trying to brace them against the concrete fence posts. Not something you want to be doing when you've got a few m3 of wet concrete to deal with.
S

 

[Weekend worrier]

In your case, with a timber retaining structure at the rear, that's one side that's very easy.......but I don't know what is off the existing concrete

There's a retaining wall made of sleepers to one side (same as the rear but lower, ~300mm high), pull-out fence panels in concrete posts on the other. To the front of what would be the building is a deck, so I guess I could screw some kind of anchoring into that to brace the front of the form against.

 

[Mike G]

OK, that all sounds very useful for providing anchoring points for the formwork, but it also sounds like we could have a building in a potential pond. If a whole load of rain dumped itself on that concrete, would it get away, or would it puddle-up?

 

[the bear]

Workshop with a moat would be cool

Mark

 

[DaveL]

Workshop with a moat would be cool

Mark

First project, build a draw bridge?

 

[Weekend worrier]

Workshop with a moat would be cool

Mark

First project, build a draw bridge?

I could work on my hand-cut lap joints with a portcullis

 

[Weekend worrier]

OK, that all sounds very useful for providing anchoring points for the formwork, but it also sounds like we could have a building in a potential pond. If a whole load of rain dumped itself on that concrete, would it get away, or would it puddle-up?

There is a small area of water on the existing surface after rain (from the photo I posted upthread it’s a about half a m2 , couple of mm depth, over to the front left) the rest appears to drain well. The area in question would be pretty much covered by the building / any new base that was poured I think.

 

[Weekend worrier]

... wow those 2 1/2 years went quickly.
So, after a couple of chunky curve-balls and a bit of time out I find myself back in the position to build a workshop!
I'd like to sense-check my thinking with those who have knowledge and experience before going ahead and booking a crew to do the groundworks, if I may?

Right back at square one this time, need to get a small tree removed and some groundworks done, the space I now have available should give me an internal dimension of 4.4m x 3.4m:



Should that give me just enough room to get around the building / clad the outside etc, or should I be looking at more?

The site is on a slight slope, which falls 130mm from front to back. I was wondering if the following build up would work (dig out the slope for full covering of DPM, a 100mm concrete slab with a 2 course brick retaining wall around it)?

Yes there'd be a small step down into the building but I could live with that and it would maximise ceiling height within PD, providing it doesn't create a whole load of problems down the line:


Is this a feasible starting point and not opening myself up to other problems?

 

[Cabinetman]

This part of the process isn’t really my thing- sorry, but I will just say that removing the tree stump will need a bit of thought as the ground will be very disturbed which could come back and cause problems after the slab is poured?
Ian

 

[Weekend worrier]

The tree isn't huge - a bay with a trunk of 8-10in diameter, and some of the spoil from levelling the ground could go towards filling the hole i guess?