Building a brick garden shed - foundation and footings

[Farooko]

Hi All

I am planning to build a brick shed in my garden. I just need some help in terms of laying the foundation. So my approx size will be 30-35 sq meter and I am going to have a double skin walls with a pitched roof. I just want to know how deep do I need to dig the trench and do I need to have concrete underneath the whole structure or just in the footings.

I did try and search for it but cant find any specific info on this forum.

Thanks and regards

 

[Bonni]

Out buildings of 30 square metres and more require building regs. So the spec is in the building regs.

 

[jfg]

You need to know what type of soil your garden is comprised of. this will give you an idea how deep you need to dig. You should dig a test hole to assess how deep before you find solid substrate to work from.

 

[ban-all-sheds]

Out buildings of 30 square metres and more require building regs. So the spec is in the building regs.

Farooko - you can do what jfg suggested if you really want to do something other than what your council's Building Control dept want you to do, but it is probably not worth the effort.

 

[Notch7]

Building regs apply in interior area, so you could make it 29.9 sq metres.

The foundation required is determined by the ground bearing capacity and stability where the shed is going.

If you have good ground and no trees such as leylandii or oak nearby, then probably 700-800 deep x 450mm wide will be fine. Possibly even shallower as its a shed.

Thats the depth to bottom of trench. The actual concrete only needs to be a few 100mm deep, it depends in whether you want to fill the trench with concrete or build up with blockwork.

If it was me, I would build the foundations to regs, then you know you have a stable base. Its not worth skimping on such a big structure. Modern brick and block construction is not forgiving of any movement and will crack easily. Timber frame is much more forgiving -if you have lots of trees nearby I would choose timber frame over brick, esp if you have shrinkabke clay soil........

Timber frame on a brick plinth will have a very long lifespan, you could clad the non seen sides with rendaboard and paint.

 

[Bonni]

I'll try to clear all these posts up.

There's a frost line of some 600mm to 650mm. Foundations should be below this. This is why house foundations are some 700m below ground level. Also, you need to hit solid ground, so sometimes you need to go deeper. That's why gate pillars and garden walls lean due to frost heave.

Planning is applicable to outbuildings, even sheds. They have to be under a certain height if you're in within a certain distance of your boundary. Your local council will help.

Building regs only applies to outbuildings greater than 30 square metres and electric cabling to such buildings. I only know because I deal with building regs and they told me so.

 

[ban-all-sheds]

They also apply to any ones with sleeping accommodation, and any in the 15-30m² range which are < 1 metre from any boundary and not constructed of substantially non-combustible materials.