New Brick\Block Workshop - 4M x 4M

[Skeety]

Hi All,

I’m finally (After many years) in a position to build a workshop (4M x 4M)

This is probably the first of many questions, have read through other threads, Google etc.

It’s going to be built out of a mix of single skin brick and blocks (Blocks where they won’t be seen) and bricks where they will. The reason for this is cost. The bricks matching the house are about £700 per (500) 450 allowing for breakages advised by the manufacturer.

Anyway, do any of you know where I could find out or know how to construct the foundation\floor?

I want the base insulated with PIR but am getting lost with how deep to go on the edges vs the centre. Addition of rebar etc.

Any pointers most welcome. I’m planning to get it built by someone but want a good idea of what needs to be there so I can draw it up.

Cheers,

Jon.

 

[Spectric]

I would get the advice from your builder who is doing the brick / blockwork. I assume you have allowed for brick peers in your design as it is only single skin and the walls need support.

 

[Skeety]

I would get the advice from your builder who is doing the brick / blockwork. I assume you have allowed for brick peers in your design as it is only single skin and the walls need support.

Thanks,

Yes, I have allowed for piers.

Still trying to find a builder, early days but so far I have 1 quote which was £18K to build it in wood and me supply the doors and window!

Cheers,

Jon.

 

[Spectric]

Looks like builders down south know how to charge customers !

 

[Fergie 307]

For what it's worth I would probably avoid single skin. By the time you have insulated it effectively and clad the inside it probably wouldn't cost an awful lot more to do it double skinned, and you will have a much better building. Having had a number of single skinned concrete and brick buildings over the years they are a PITA for damp and condensation. If you are looking to keep cost down I would go for wood every time, especially for a relatively small building. You can get a good, well insulated wall only around 150mm thick, so maximising floor space. It's lighter too so less substantial base needed, and should be cheaper, a lot cheaper if you do it yourself as your only cost is materials. My main shed is 10x7 m. Once the concrete base was down I just made the wall frames on the floor, then lifted them into position and bolted together. It really is quite straightforward.

 

[Fergie 307]

Looks like builders down south know how to charge customers !

Have to agree, and not just builders. Having had a look around at a local garden building place, the prices they wanted for some of the tut on offer were unbelievable. " Here we have the prestige garden buildings barbecue house, knocked together out of wood you wouldn't use to make a pallet, and looking as though it was put together by a monkey with a nail gun, yours for the bargain price of £8k"

 

[Doug B]

I’d agree with Fergie re the double skin, my previous workshop was single brick with pillars when I built my present one I went for cavity block wall with insulation in the cavity & it’s so much better.
Which ever type of wall you go for I’d opt for strip footings then over site concrete with a dpm below for the floor pir insulation on top of that then a floating floor of moisture resistant chipboard, so much more pleasant to stand on for long periods than concrete.

 

[Adam W.]

Looks like builders down south know how to charge customers !

Reassuringly expensive.

 

[Fergie 307]

With you on the standing on concrete. I spend hours at the lathe and have a really good quality thick Yoga mat to stand on, makes a heck of a difference, must be getting old

 

[Dave Moore]

Hi All,

I’m finally (After many years) in a position to build a workshop (4M x 4M)

This is probably the first of many questions, have read through other threads, Google etc.

It’s going to be built out of a mix of single skin brick and blocks (Blocks where they won’t be seen) and bricks where they will. The reason for this is cost. The bricks matching the house are about £700 per (500) 450 allowing for breakages advised by the manufacturer.

Anyway, do any of you know where I could find out or know how to construct the foundation\floor?

I want the base insulated with PIR but am getting lost with how deep to go on the edges vs the centre. Addition of rebar etc.

Any pointers most welcome. I’m planning to get it built by someone but want a good idea of what needs to be there so I can draw it up.

Cheers,

Jon.

Hi,
search on YouTube, there are many builders etc on there and loads of info.
Regards,
Dave

 

[Jameshow]

Without knowing your ground conditions I woul think you want a 200/100 raft.
200mm at the edge and 100mm across the floor, perhaps with some mesh in it too.

I would agree with others on here though and go for a wooden structure on a 100mm base.

Simpler and cheaper too.

 

[pauljhaigh58]

Isoquick is a insulated slab floor no need for shutter to side as all included give them a ring I have no association with them and there are others this system can be done diy by competent person hope this helps

 

[RobinBHM]

It’s going to be built out of a mix of single skin brick and blocks

the lack of a cavity makes a problem with damp arrangements

to avoid the thickness of a double skin you might consider using breathable membrane externally, then 50 x 25mm battens vertically, then cladding (say timber on the garden sides and rendaboard or metal box section on the fence facing sides

that way you get a 25mm cavity that allows a wind and watertight structure

 

[Skeety]

Thanks all,

Making a bit of progress on this, bricks and blocks arrive today. Found a builder that smokes cheaper crack lol. Hopefully start digging out for the foundations\insulated slab next week!

 

[Skeety]

Well, it now exists I still have a lot to do but the box exists

 

[Fitzroy]

Looks fab, get in there and start making stuff.

 

[Skeety]

So in terms of the original footing\slab question this is what we did:

Excavated footings, filled with 300mmx400mm C35 concrete with steel mesh. Allowed to cure then laid 2 courses of 7N blocks belly down then a final course of brick to finished floor level. We then dug the centre down to 350mm, put in 100mm of type 1 (original plan was 150mm but seems ton bags are no longer a ton so a bit of recalculating required) which was compacted, then 25mm of sand, DPM then 100mm of PIR\Celotex (decoupled around the edges with PIR) then 125mm of C35 concrete. Ended up with 125mm slab instead of 75mm due to the shortage of MOT. We had calculated 0.98m3 at 75mm, when we had the MOT issue we already had concrete booked for later in the day. As it was volumetric the minimum was 2M3 so we went for a 125mm slab as it was basically free. we ended up using 1.98M3.

Barrowing it through on a hot day was not fun for this desk dweller lol. We had just finished floating it when one of my cats appeared on the fence directly behind. Before we could react we had a cat in the concrete, followed by another 3-4 cat craters as he escaped. Cat in the shower with us trying to fix the holes. As sods law dictated the hole was the absolute furthest point from us and inaccessible by foot to easily fix.

~30 tons dug out by hand then about 20 tons of concrete in.