New Workshop

[defsdoor]

If I don't dig down then the lowest the underside of the floor joists could be is a couple of inches above the soil. The soil is already 18 inches higher than all the surrounding ground (lawn, neighbours etc..) and the old shed concrete floor. This old shed floor is the natural ground height. The higher ground is many many years of rotted leaf soil (incidentally I had 6-8 inches of this soil on the roof of the old shed!)

So if I don't dig out the soil, the new shed floor surface will be 2.5ft above the ground (it will just about reach the edge of the lower lawn). That itself adds a whole additional bunch of problems to the build and how to get in and out of the shed.

The current path is ground level with the old shed concrete floor and this is where I will be putting the main door - I really don't want this over 2ft above the path.

Also, this raised soil bed is 18-24 inches above the fence that the bottom neighbour has recently replaced. If I don't lower the ground level my side this fence will be rotted through in a year - otherwise I will be keeping the gap he dug out clear.

Ideally I want the base of my new foundation to start at the level of the existing concrete floor - this will give me a 6-8 inch step up (depending on the floor joist size).

 

[johnny]

That makes perfect sense now. :wink:
sorry I didn't mean to give you a hard time over this ,I was just trying to be helpful.

If we were talking together I would have known your reasons but there is only so much that we can explain in a forum message ,about all the little details that guide our choices .

If I was nearer I'd come over with my spade and give you a hand sounds like you've got a lot of work just preparing the site.

 

[cammy9r]

Nothing wrong with that plan. Get digging and if you can still lift a camera afterwards then a progress pic would be nice. A little funny that I spent hundreds of pounds buying in nearly 15 tons of topsoil to do the lawn and you are possibly spending hundreds to get rid of it.

 

[defsdoor]

Cleared all the rubble from the inside of the remaining couple of courses of bricks so I can take some more meaningful pictures -

Skip nearly full

Path to old door (its there honest)

Side view of height difference (although the camera seems to lose it)

Low view of different even by side of path

And low view to the side also

The soil is above that slab boundary in places.

The long side will be in this direction. The start of the new building will be 1m approx in from the edge of the current shed (it was built practically up to the boundary)

The narrow length of the shed (I keep calling it a shed - its my workshop!) will be up to approximately where the far side of the ladder is.

I figure I could leave the current shed floor where it is and add a small pier to rest some beams on. This would be my datum point for the overall level and determine how much needs to be removed elsewhere.

I'm fine with an all wood floor as long as I can insulate it well. The beam and block was a suggestion from my builder friend who would install it for mates rates (and get me trade on the materials)

 

[johnny]

great shots ! now we know what you've been up to :lol:

i had exactly the same build as you.
i needed to replace an existing 12'0" x 8'0" (3.6m x 2.4 ) timber shed which sat on a concrete base with a much bigger 16'.0" x 10'.0" (3.0m x 7.0m )

I did exactly what you propose. I dug out some holes to level and placed some hollow concrete blocks . I then placed some 250mm x 125mm reclaimed sleepers on the piers until the finished level of the top of the beams was level with the top of the concrete base . Then its simply a matter of using some treated 75mm x75mm treated bearers (c £1.50 perM ) across the lot to support your workshop walls and floors.
I had a very tight budget so for cheapness I covered the bearers with treated T&G cladding I salvaged from the old shed ,then put 18mm chipboard on top of that but you could put some celtex between the two

Might be worth looking for a local Company supplying timber fencing as they generally treat all their timber on site and will probably stock everything you need including reclaimed sleepers if you choose to go that route.

I know that you are intending to build within Permitted Development criteria but just to be on the safe side and anticipate possible problems run through this interactive Planning guide .
I thought I had covered all the bases but one of my neighbours complained (Parish Councillor) and I ended up having to lower my shed roof by 3" ! ruined the felt and was a lot of work.http://www.planningportal.gov.uk/permission/commonprojects/outbuildings/miniguide

 

[cammy9r]

Thats a fair amount of work there but the right thing to do. As you say leave the old base and work from it. Have you got a budget in mind. Wood is never cheap even though it grows on/in trees :?

 

[defsdoor]

My accountant (the wife) agreed to 10k a long time ago and I am holding her to that. I'd like to come in below that as once this is complete I will need a couple of purchases to go in it.

Totally knackered after this morning's exertions and the wife wants to go out Have to drive to Devon and back over the weekend to collect my daughter so won't get any more done till monday.

 

[cammy9r]

:shock: 10k :shock:
Im sure it will come in well below that even with the beam and block floor. I bet you will build something beautiful with that budget, perhaps not just a typical shed.
Enjoy the weekend off.

 

[johnny]

10K :shock: strewth !...... I could build you a 2x storey extension to your house for that ! :lol:

Seriously that must include all your new toys and equipment yes ? :wink:

My shed cost a little over 2K and I lined mine out with mdf . Its true I only used some cheap insulation off a roll to fit between the studs and rafters but 10k !..........crikey .
Well done anyway with what you've acomplished so far you deserve a bit of R&R

 

[defsdoor]

Shush - she might hear you !

 

[No skills]

Good luck with this. Even at the size your building I would be aiming to get the build cost sub 4k, the rest of the budget is quite a motivator

 

[Ollie78]

I will follow your progress with interest. I am planning a very similar building in my garden. I for one am not at all surprised by your budget. I have not finalised my design exactly but it will be on the 30m2 limit, 7m by 4m ish. I plan to do a concrete slab with timber frame, sawn 100 by 50mm framing osb outside with house wrap and timber cladding. Inside celotex 100mm with 25mm air gap (for electrics to hide in and for sound attenuation) and plasterboard lined. Using reclaimed doors and windows I worked out costs to about 8k if I do everything myself. My current sticking point is the roof, either totally flat with an upstand and epdm or a slight fall front to back and insulated metal roofing panels.
Also I am considering metal joists for the roof to reduce the thickness of the roof and thus increase inside height.

Incedentally I am interpreting the planing portal rules of 30m2 as the internal floor area so will be putting walls on the outside edge of this measurement.
Good luck.

Ollie

 

[defsdoor]

I'm doing some designs and basing it so far on a wooden framed floor on 6m * 5m layout, made from 75mm * 220mm joists. If I stick with wood floor structure I will put the insulation in between the joists as this saves me height.

Is it typical to put the floor in first and fix the walls down through the floor to the joists below (this is what I did with my shed) ? I can see plenty of plans where they do this but I, for some reason, have reservations about this.

I can see that not doing this would require additional wall-side floor support, but am uneasy about a floor that cannot be lifted (easily).

 

[defsdoor]

I've done a first draft of the floor - sizing everything to sensible multiples -

 

[johnny]

you need to design your base first .!

Are you intending to put your floor joists straight onto a concrete base ? or will they be supported on concrete piers ? if so at what spacing ?
Show us the base that you intend to use and how you intend to put your floor structure onto it

your joists are massively over specced ......no wonder your shed is expected to cost £10,000 :roll:
have you even done a costing on these ? Are they spanning ? if so what distance ? are they treated ? class 3 ,class 4? what specification is the timber ? C16, c24 ? what is the actual distance your joists will be spanning ? its not going to be 5.00 M for sure.
What is your anticipated loading on the shed floor of your whole structure including roof loads point loads evenly distribiuted loads, dynamic loads etc
You appear to have your joists on 350mm centres which is crazy . Are you intending to use 18mm or 22mm chipboard flooring ? If yourjoists are spaced at 450mm or less, you can use 18mm boards. If the spacing is greater than 450mm, use 22mm thick boards.

I think you need to show us exactly what you are proposing to construct from the ground up so that we can best advise you. If you have a website with some images of the construction , sections etc it would be very helpful to post them .

ps no its not advisable to put your entire structure on top of your chipboard floor . Put your stud wall sole plates onto your floor joists first ..then put your flooring in between the sole plates.

 

[defsdoor]

That is the base

In this design I'm suggesting block supports on each corner and at the mid point of the long edges only.

The width-ways span is 4650mm so I can use 45 x 220mm c24 joists. I have them on 400mm centres on this design.

The floor panels in this design are 18mm

Note at the moment I am just knocking up draft ideas - non of this is committed.

 

[johnny]

ok well a simple sketch of section through your structure would be very helpful to you and us. You seem to be designing this bit by bit as you go which is going to cause you compromises and major problems right through the build. I always look for ways to economise where possible to reduce wastage and redundancy so I guess I am looking at this shed build from an entirely different perspective. If it were me i would draw up the entire shed to scale in elevation and section with dimensions so that I can use them for costing and as a construction aid. that way you can construct your entire shed on paper first before committing a single penny and there are no surprises.

Chipboard is as cheap as chips whereas graded timber is very expensive. I would suggest that you settle on using 22mm chipboard .its stonger and less likely to warp,bend or be damaged by liquid spillage etc At least that will be one thing settled. :wink: The benefit of using 22mm is that you can now space your joists at 600mm centres not 400mm . That will save you 5x joists and about £150.00 !
If you place your chipboard flooring between the studwork you will have the option of removing and replacing damaged boards should you need to do so.

If you place your joists at 450mm centres with 375mm gaps you could then cover the joists in treated timber t&g cladding then lay your uncut sheets of insulation board on top of that and then put your chipboard flooring on top of that. then your chipboard will be protected from damp and insect damage from below and your insulation will not need cutting to put between the joists and it will be more effective because of the protection from the t&g from the cold air .


.

 

[defsdoor]

I'm not sure why you think I'm doing this bit by bit. All I've done to date is clear the old shed and rubble out of the way and started doing some preliminary modelling :O

But I won't be ordering a single plank of wood until I've got a complete design that I am happy with and I fully expect there to be many iterations. I've still not given up on a beam and block base - my builders coming over this weekend and we will discuss more then (I started out wanting a concrete slab).

I'm not keen on putting the insulation above the joists as this will add extra height from the outside ground floor and reduce valuable head room - but I hadn't considered protecting a chipboard floor (not decided on a chipboard floor yet either ) Can a vapour barrier be put down beneath it first ?

I'm not too fussed about an over engineered floor - especially if I do end up with a wooden floor structure. I'd like the floor to be as solid and bounce free as is feasible.

I'm doing the design of this in onshape so I can easily tweak the dimensions and spacings etc.. (simple variable change) I'll post more as I get time to work on it.

Appreciate your feedback though - I've never done something of this scale before and I'd like to get it right.

 

[Wuffles]

That is the base

Lol 8)

Good work. Are you intending to have any seriously heavy kit in there? Ever? Best think of the future in my opinion.

My base is solid concrete as it was an old stable, but without that I would have struggled with my old cast iron table saw.

And the Pool table, pile of bricks I (for no reason) keep in the corner, enormous pile of junk in the other corner, vast array of enormous pieces of wood decomposing in the other corner. Busy bloke me.

 

[John15]

Hi defsdoor,

Good to see you are doing things your way and in your own time, and not succumbing to pressure.

John