Workshed build wip 20'x12'

[zchais]

Setup:
20ft x 12ft mesh-enforced, insulated and DP'd, concrete slab to build workshop atop.

Slab has 2% fall / 70mm slope along 12ft sides.

Dense block perimeter (140 x 440 x 215). Flat roof. Land excavated lower than all 3 neighbours.

 

[NickWelford]

Now I'm no expert, and I'm sure some who know best will be along shortly, however, I'd consider two things - are the foundations sufficient for block walks so tall, and will a concrete wedge be strong enough to support the walls? I do think that putting the brick/block walls level is important. Have you considered a low wall and wood upper?

 

[RobinBHM]

You will need ot be a minimum of 1.0M from your boundary for building regs unless you are going to make the building substantially fireproof (I think Steve Maskery had this issue, so he may have some advise about what the building inspector adivses.

You will need to know whether your slab base will be strong enough for a brick or block base before going any further.

 

[Bm101]

You could still insulate and soundproof a wooden structure fairly comprehensively with something like this http://www.insulationexpress.co.uk/Prod ... wgodYUoEfg and it would be cheaper than a block or brick building. It all depends what you want to spend. If you're looking at blockwork etc then you might want to think about the costs involved using an online building calculator (can be found on most builders merchants websites). Would you want to render it? Can you do the work yourself etc. I have a wooden shed/ chalet type affair that was here when we bought the house. Tbh, I find its plenty warm enough if I have the door shut and keep a hat on. You can install a woodburner with no issues if you plan it right. Unless cost is not really an issue, which of course it might not be, I'd be wary of going to a solid structure unless you have definite reasons especially if you plan on having a wooden front anyway. Maintenance on a wooden structure might be a little more labour intensive I suppose. But a coat of paint every couple of years on a pressure treated timber and it should be fine.
(Dont forget gutters though and a decent rainwater runoff away from the slab. A slight fall on the roof is essential even if it's just a few inches. If you can overhang the eaves it will keep all but the most driven rain off most of the exterior most of the time.)


(I'd also change (in your profile) your location from your postcode btw to somewhere a little bit less definite. You never know who looks at the internet). :wink:

Keep us posted, Workshop builds always go down well!
Regards
Chris

 

[AJB Temple]

3" is a pretty fall over 12 feet. Most building control departments on a standalone garage spec would have a 1 in 80 fall specified. Here is a building control example. Look at page 15. http://www.fdean.gov.uk/media/Assets/Pl ... TION_5.pdf

This is basically just a shed. I would not use engineering bricks. I would cut blocks to make the first layer level, or do a few courses of bricks, also cut to level inside 2 courses, then put DPC to stop moisture above slab level wicking up the wall. This is dirt cheap so I am not sure why you would leave it out.

You don't give details of your foundation structure but if you are building a block wall you will need to make sure the perimeter foundation including the sub layer is deep enough and strong enough. There is a lot of construction info on the .go.uk planning portals so might be worth you perusing that before you start building.

 

[zchais]

Sketchup diagram of base in following post.

 

[zchais]

Slab: 6" type 1, 2" sand, DPM, 2" kingspan, DPM layed over kinspan, 3 x A142 Mesh overlapped and tied, on chairs, 3.7m3 of C20 concrete (5" at front to 8" at back, flat - not thickened edges/footings).

 

[Woody2Shoes]

+1 for the idea of using 7N dense concrete blocks cut with an angle grinder (or cold chisel if you're feeling brave) to get yourself back on the level, as it were. You could maybe render these to make them look slightly nicer and to reduce the risk of frost damage over time. I'd then bed on a length of DPC along the top before placing a timber 'plate' for the base to the wooden part of the wall - or further masonry, but your footings may well not be strong enough for a heavy masonry wall all the way up (it would need to project beyond the outer face of the masonry and would be better solid concrete, without celotex in the load-bearing part).

Engineering bricks are relatively impermeable and can form a so-called "type 2 DPC" which is suitable for non-habitable spaces e.g. you often see the first few courses of garden walls using them - the advantage being that you have continuous beds of mortar "gluing" the brick courses together, slightly increasing the resistance against sideways forces like wind (esp. today!) - mortar sticks to bricks better than it does to plastic/bitumen DPC.

Cheers W2S

 

[zchais]

Opt1: One course 7N dense blocks, angle cut to level, DPC.
Opt2: Feather-levelled concrete wedge, dense blocks, DPC.

 

[blackrodd]

I'd keep it simple and stick to you're original plan, build in wood.
If you're local council will allow you to infill you're existing concrete post fence with cement based panels, much like Steve Maskery did, you will have a fire resistant fence, and as I see on you're pic, you have no building behind at the present regs should be satisfied.
Masonry is slower and expensive, you're damp course arrangements aren't ideal, you'll likely have water ingress by capillary action as soon as you lay the first bed on the slab, with or without a dpc on the slab or 1 brick up.
engineering bricks are not necessary nor 7 n blocks they're designed for a weight factor of 2 floors above.
You certainly don't need the extra weight as you've no footings or foundation, only the slab itself.
The foundation should have been dug all round the perimeter and cast in One pour with the slab.
I have to say, you have done a nice job so far, everything looking good for a timber building, with strong foundation etc.
Stick to plan "A" but persue the fire resistant fencing
Regards Rodders

 

[Woody2Shoes]

Hello again! - I only suggested the blocks because they're pretty cheap and easy to cut fairly accurately - personally I don't like aerated blocks near the ground (and definitely not timber!). I guess you could use solid or perforated - I think solid would be better. You'll find cutting (usually perforated) engineering bricks much less easy (they're brittle and hard). Normally, you'd bring the DPM (from under the slab) up the wall and tuck it in under the DPC - a bit like the diagram here: http://3.bp.blogspot.com/-os7WXEJpMvs/T ... 1600/9.gif so you have continuity. Another versatile option with damp-proofing is the paint-on SynthaPrufe type gunge.

I take the previous point about the cost and effort re. masonry - yes you could perhaps more simply just build the timber straight up off the slab - but if it were me, I'd 'go the extra mile' with masonry up to the DPC before timber and hope that my timber structure would last a lot longer as a result. Good luck whatever you decide, cheers, W2S

PS there are some quite good details here (found by Googling "DPM overlap"): http://civilconstructiontips.blogspot.c ... chive.html

 

[mindthatwhatouch]

Even if you do not build the whole wall out of brick or block a course or three will elevevate the timber frame off the ground.
This is what I would have done if I did not come up against the non combustable problem.
Made an error on my build, had some excellent advice from Rodders regarding interenal damp proofing of the blocks see his post end of August 2015. yep-it-s-another-workshop-design-questions-t84326-60.html

 

[NickWelford]

Lots of advice to peruse. For gods sake, never ask about sharpening!

 

[zchais]

DPM outside of the slab. No room to manoeuvre in terms of building up around the slab: re-routed land drainage pipe around back, and electrical provision pipe along left.

Blocks to be rendered. DPC under framing.

 

[mindthatwhatouch]

Why the 9"?
4" block will be fine with piers at doorways.

 

[zchais]

Why the 9"?
4" block will be fine with piers at doorways.

Thanks. Blocks to be 140mm wide. Front elevated (blocks on top of) dense coursing blocks: 215 x 140 x 65.

 

[Bm101]

You've done your DPM (membrane), thats great. What you need for you blockwork base is DPC (course). Its literally a roll of plastic that gets laid between courses in your brick/block work to prevent damp rising.
Personally I think you've cracked it.Although I'd use the the money for the block work on better timber walls myself but there ya go. Each to their own and rightly so.
Relax a little if that doesn't sound patronising, its not meant too. You have the best of both worlds. I don't know why you'd need piers if you're building a wooden building on top of a block footing.
If it was me I'd ask 3 or 4 recommended local builders to come and give me a quote. I'd question them on various methods of construction. This will give you an idea of prices but better still you're not obliged to contract but what it will give you is some excellent ideas. Gratis. You're obviously committed, make it work to your benefit.
Also, as you progress we want photos! Thats the cost of advice lol.
Good luck and don't forget to enjoy it in all the mayhem.

Can I ask if you're planning on doing the work yourself?

 

[mindthatwhatouch]

The advantage with blocks is you won't have to mess around with slate and shaving the bricks.
One block high at the lowest part of your slab and take a little off each one to get the top level. More uniform appearance, can be painted or rendered. Wooden stud wall bolts straight on top, DPC first as mentioned above, you can fit a builders strap under the blocks to tie to the studs if you wish.

Just to throw another option how about casting a small wall!!

 

[zchais]

Wall built. Coursing blocks along front level with raised sides below blocks.

Framing: 47 x 150 x X (was 38 x 140 x X), 600 c/c.

 

[mindthatwhatouch]

Try a local wood yard (greater range of material and should be cheaper than wickes) ask for a discount.