Workshop Design questions

[kdampney]

The time has come to finalise the design of my workshop, and your wisdom would be greatly appreciated!

Having followed Steve Maskery's build thread, and Mike G's on The Wood Haven, I have come up with the following (cladding needs completing but my Sketchup skills aren't up to it!).

PP would be required as the roof is higher than 2.5m while being nearer than 2m to the boundary. BR won't be required as it's at least 1m from the boundary. I may also shrink it to be less than 15m2.

A few questions:
1. Any advice on getting planning permission (e.g. phrases to avoid such as 'woodworking workshop')?
2. The lowest (rear) part of the site is perhaps 150-200mm below the highest part - presumably as long as there is sufficient hardcore and sand underneath, having deeper concrete on one side won't matter? Shuttering may just be a bit more tricky...?
3. Can random garden rubble (broken up bricks, paving slabs, etc.) be used to bulk up the hardcore a bit?
4. Steve put his mud sill straight on the concrete, Mike G did a few courses of bricks and some blocks - what have other people done to fix their mud sill (or the bottom bit of wall) to the concrete base? Pros & cons?
5. Are the housewrap, DPM and DPC all in the right place?
6. How best to frame the windows? That is, how do double-glazed units fit the walls? I may go for something simpler than in the image above.
7. Ridge beam as Mike G went for, or trusses as Steve did?
8. What have you used for roof tiles/EPDM? Which is most cost-effective/easiest to do/most durable?
9. I'm hoping to do as much of this as possible myself, but am an enthusiastic DIYer at best - apart from electrics, where else do you think I will need help?

Thank you very much!

P.S. I've just realised that having the insulation within the concrete obviously won't work - it should be on top of it.
P.P.S. It goes without saying that a WIP and photos will be forthcoming when I actually start (may be 2020...!).

 

[Petey83]

i could be wrong but for a single story structure i am not sure that you need planning permission as long as its not ridiculously big - i would suggest a bit of reading on google for this point but sure i read it a few months ago as a pre made outbuilding or space to build one is top of my list when we start house hunting next month

 

[AJB Temple]

This is obviously a garden store and potting shed, used for storing and keeping secure garden tools and for hobby purposes as you are an artist. It is non habitable.

If you have concerns about planning, I would be tempted to show shed style double doors in the planning rather than what you now show, as it does have something of a habitable look about it.
Presumably you will be compacting the hardcore and sand.
If you are going to put machinery in there such as a PT or bandsaw etc, I would be inlined to re-inforce the slab.
Rubble is fine in the hardcore as long as it is very well broken up. You don't want voids.
At your size I think you would be fine with either ridge beam or trusses as long as you have sensible timber spec. Your planned roof loading looks low.
If it were me I would probably use cedar shingles on the roof for looks, if I wished to keep the loading down.
I would also probably run 3 or 4 courses of bricks on the slab with DPC at say course 3 (not lower).

This kind of build at this size is easily a DIY project. Have fun. I would beef up your floor and wall boarding personally. Make it plenty strong enough to hang things off.
Ideally plan for a small lean too ("log store") in which to house your extractor. Keeps the noise and dust out of the working area.

 

[kdampney]

i could be wrong but for a single story structure i am not sure that you need planning permission as long as its not ridiculously big - i would suggest a bit of reading on google for this point but sure i read it a few months ago as a pre made outbuilding or space to build one is top of my list when we start house hunting next month

PP isn't required if it's away from the boundaries. The Planning Portal specifies:

Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof.
Maximum height of 2.5 metres in the case of a building, enclosure or container within two metres of a boundary of the curtilage of the dwellinghouse.

See also https://www.ukworkshop.co.uk/forums/workshop-shed-planning-permission-t35073-60.html for lots of other PP/BR advice. I added some examples on there that may be helpful.

My garden's only 7.4m wide, so keeping the roof 2m away from the boundary means a fairly small (or low) workshop. Or applying for PP.

 

[kdampney]

This is obviously a garden store and potting shed, used for storing and keeping secure garden tools and for hobby purposes as you are an artist. It is non habitable.

Exactly

If you have concerns about planning, I would be tempted to show shed style double doors in the planning rather than what you now show, as it does have something of a habitable look about it.
Presumably you will be compacting the hardcore and sand...

Wouldn't changing the doors count as not complying with agreed plans? Or are they fairly flexible?
Yes to compacting, though not with a wacker-plate if I can avoid it. I guess I could hire one for a day if needed.
If there is insulation and ply on top of the slab, what thickness battens and ply would support that kind of machinery?
You mean head height? I think it's around 2.3m. I can raise it, was just thinking storage above would be useful.
Good idea for keeping the extractor outside, guess I need to make some modifications Thanks for all the comments.

 

[Dave-Jeffo]

How heigh is your roof going to be (to the ridge) and how heigh is your frame work going to be?

 

[kdampney]

How heigh is your roof going to be (to the ridge) and how heigh is your frame work going to be?

Around 3.65m, and 2.35m. Although both can be easily modified.

 

[Fitzroy]

I had to apply for planning permission for my shed as my house is in a conservation area, so "permitted development rights" are cancelled. To be honest I did not find the planning application process particularly onerous, even in a conservation area I got permission for a 6m x 3m x 3m ridge pent design. So, so long as you're not proposing a palace then I doubt it'll be turned down. If you can use sketchup (which you obviously can) then doing the drawings and plans (use google earth for the site map etc) is easy. Yes it'll add a couple of hundred quid and 6-8 weeks onto the cost/schedule of the shed but you can potentially get a much better design by giving yourself 50cm of extra head room or some extra width by pushing closer to a boundary. Just a thought ;D

Fitz

 

[Dave-Jeffo]

your pitch should be fine. I agree with the above, if your putting planning in. Why not make it as wide and as large as possible.
Dave

 

[sunnybob]

There are housing estates in this country that arent up to that spec!

 

[kdampney]

I had to apply for planning permission ... you can potentially get a much better design by giving yourself 50cm of extra head room or some extra width by pushing closer to a boundary. Just a thought ;D

Thanks Fitz, though if I go any closer to a boundary (ie. within 1m) I'll run into building regs, or have to make it substantially non-combustible.

There are housing estates in this country that arent up to that spec!

One of my colleagues bought a Redrow new-build recently and moans all the time about it - a large bathroom sink (no pedestal) was mounted on two sheets of plasterboard with a small bit of ply in the middle - the whole wall was bending! So yes, this workshop, I mean potting shed, should be more substantial!

 

[mindthatwhatouch]

Looking good.
For simplicity I would be tempted to level the sand blinding and pour the slab on one level.
Roof options? I am very happy with the Decra metal tiles on mine, maybe an option. What is the wall cladding going to be?
Looking forward to the build.

 

[Phil Pascoe]

Don't forget - if you are putting in a duct from the house or an underground power (or even water) supply, think about them before the foundations and floor are in. A duct can be handy - I wired the lights in my 'shop two way (three actually) back to the house as I got fed with darkness coming and then realising I'd left the lights on. The power went down it as well, as did a phone line. I left a loop of rope in it so I could pull anything else down as well if needed.

 

[AJB Temple]

Without a shadow of a doubt I would hire a compactor for a day when you do your groundworks. They are very cheap and you will get a better job with a nice smooth finish on the sand. I have just done two twin garage slabs and a 100m2 parking area as well, and compacting this twice took half a day at the most (type 1 first then sand layer) and this included spreading the sand.

I doubt planners would care if you changed the doors, but what I would avoid is making it look too much like a habitable adjunct to the house. I would also max out your planning permission if you have to do it anyway. You can always build smaller if you want.

Are you having concrete delivered ready mixed, or doing it yourself? Quite a big difference in your labour.

Also, if you need a path to your potting shed and garden store, hardcore and compact that whilst you are at it.

 

[kdampney]

What is the wall cladding going to be?

I think cedar feather-edge, unless anyone has a better recommendation? I've heard T&G can expand and 'pop out' so to speak.

Without a shadow of a doubt I would hire a compactor... Are you having concrete delivered ready mixed, or doing it yourself? Quite a big difference in your labour.

The only trouble with a compactor (and mixer and mini digger etc.) is our side passage does a 90' turn, between the house and an outhouse, so I'm not sure anything big (even a loaded wheelbarrow) will fit down there. So I was thinking of having the concrete pumped. I guess it might be possible to have 2 wheelbarrows, and tip one into the other (at 90'?). Or does anyone have any other suggestions, short of hiring a crane?

 

[RobinBHM]

I think you would get a whacker plate around there, they arent very big. You would also get a belle mixer as they come apart, with drum and legs separate.

ready mix concrete and a pump would be a quick way to cast your slab. From memory a concrete pump is about £350+vat for a trailer one with driver. Goes 40 metres I think. Dont stand near it when the cleaning ball is sent down!

 

[AJB Temple]

I would forget pumped concrete except as a last resort. Apart from the cost of the concrete at say £90 a cube ready mix, you will have to hire a pump lorry (or the mix company will charge you instead sometimes). It can easily run to £500 to get the pumping set up. I have just had 18 cubic metres pumped which was worth it for me as I had very limited labor on site. But for a slab your size and thickness, I would probably mix it myself. I have a Belle mixer and my wife and last Autumn I did a couple of cubic metres for 12' by 8' shed base in a day, including barrowing the concrete about 60 metres from where we had the mixer, aggregate etc. You should have no trouble especially if you have a helper so that you can keep the mixer going. A whacker plate is only about 2 feet wide and will go around that corner easily.

Ps your level change is no big deal. For shuttering I tend to use gravel boards. My local Merchant does boards that are about 5m long from memory, 6" deep and an inch thick for £4.50 plus VAT each (after a bit of discount). 3ft stakes are about 60p each. I then re-use the boards and stakes for making raised beds.

 

[kdampney]

I would forget pumped concrete except as a last resort. Apart from the cost of the concrete...

From my calculations, 4m x 4m x 0.15m means 2.4 cu m. The sand, gravel and cement (priced up roughly from Wickes and Travis Perkins) comes to around £400-450, which is the price of ready-mixed. I think I'd be prepared to pay £350-500 for pumping to save 60+ wheelbarrow trips to the bottom of the garden (including transferring from one wheelbarrow to another to get around the 90' corner).