I plan to build a summerhouse. What should I use for foundations?

It's a half-oval / elongated D shape, about 12' x 8', and I need a
dwarf brickwork wall about 2' high. Between the walls will be paving
slabs. Ground is flat, well-drained sandy soil. The structure on top
will only be light, maybe 350lbs.

Should I run the slabs _between_ the walls? Or simply slab an oval
and then site the walls on top?

Thanks

Andy Dingley wrote:
I plan to build a summerhouse. What should I use for foundations?

It's a half-oval / elongated D shape, about 12' x 8', and I need a
dwarf brickwork wall about 2' high. Between the walls will be paving
slabs. Ground is flat, well-drained sandy soil. The structure on top
will only be light, maybe 350lbs.

Should I run the slabs _between_ the walls? Or simply slab an oval
and then site the walls on top?

Thanks

Too many 'slabs' here for me to envisage what you mean.

Do you mean you intend to lay flags as a floor inside the house?
And the other 'slab' is actually the footings of the wall?

If it were mine, I would dig a trench 18 inches deep and a spade's width and
put in 9-10 inches of concrete.
Build wall and erect summerhouse, making a one or two brick step up into
inside.
Remove turf etc from inside and lay 3-4 inches of sand, then flag over...you
can put a membrane down underneath the sand if you wish, to keep some of the
moisture from penetrating up into the floor.
It also keeps some worms / slugs out.

On Jan 22, 3:10*pm, "Phil L" wrote:
Andy Dingley wrote:
I plan to build a summerhouse. What should I use for foundations?

It's a half-oval / elongated D shape, about 12' x 8', and I need a
dwarf brickwork wall about 2' high. Between the walls will be paving
slabs. *Ground is flat, well-drained sandy soil. The structure on top
will only be light, maybe 350lbs.

Should I run the slabs _between_ the walls? *Or simply slab an oval
and then site the walls on top?

Thanks

Too many 'slabs' here for me to envisage what you mean.

Do you mean you intend to lay flags as a floor inside the house?
And the other 'slab' is actually the footings of the wall?

If it were mine, I would dig a trench 18 inches deep and a spade's width and
put in 9-10 inches of concrete.

If it were mine I'd probably lay a raft of concrete nowhere near that
thick. Provides a stable base and solves the flooring problem too.
If you put the brickwork on top of the slabs I'd imagine that over
time you'd get some movement and cracks.

On 22 Jan, 15:10, "Phil L" wrote:
Andy Dingley wrote:
I plan to build a summerhouse. What should I use for foundations?

It's a half-oval / elongated D shape, about 12' x 8', and I need a
dwarf brickwork wall about 2' high. Between the walls will be paving
slabs. *Ground is flat, well-drained sandy soil. The structure on top
will only be light, maybe 350lbs.

Should I run the slabs _between_ the walls? *Or simply slab an oval
and then site the walls on top?

Thanks

Too many 'slabs' here for me to envisage what you mean.

Do you mean you intend to lay flags as a floor inside the house?
And the other 'slab' is actually the footings of the wall?

If it were mine, I would dig a trench 18 inches deep and a spade's width and
put in 9-10 inches of concrete.
Build wall and erect summerhouse, making a one or two brick step up into
inside.
Remove turf etc from inside and lay 3-4 inches of sand, then flag over...you
can put a membrane down underneath the sand if you wish, to keep some of the
moisture from penetrating up into the floor.
It also keeps some worms / slugs out.

WOW, go another 6 inch down and you could get building regs on a two
storey house with those foundations :-0

Staffbull wrote:
On 22 Jan, 15:10, "Phil L" wrote:

If it were mine, I would dig a trench 18 inches deep and a spade's
width and put in 9-10 inches of concrete.
Build wall and erect summerhouse, making a one or two brick step up
into inside.
Remove turf etc from inside and lay 3-4 inches of sand, then flag
over...you can put a membrane down underneath the sand if you wish,
to keep some of the moisture from penetrating up into the floor.
It also keeps some worms / slugs out.

WOW, go another 6 inch down and you could get building regs on a two
storey house with those foundations :-0

Not a spades width you couldn't, and definately not 2 ft down, at least not
around here, it's normally a minimum of a metre in depth and 600mm wide at
the bottom.
Apart from anything else, he doesn't give the size of the structure, nor
whether it is to be a 4 inch, 9 inch or cavity wall, coupled with a sandy
soil...hence my overcautious footings :-p

On 22 Jan, 15:10, "Phil L" wrote:

Do you mean you intend to lay flags as a floor inside the house?

Yes. Timber is more work, and higher. For the use I envisage, paving
slabs on sand would be just teh job.

And the other 'slab' is actually the footings of the wall?

Yes, although I'm not sure whether the floor will be above the
footings, or will actually be the footings.

Could I _really_ cut corners, just lay slabs and then lay bricks/
blocks on top to make the wall? Or is that too cowboy?

Otherwise I guess I need to lay some sort of footings in a spade-sized
trench, brick onto that, then lay paving slabs to span between the
bricks. Obviously I'll also need to cut the slabs into an oval to
match.

I don't like the poured concrete slab idea. It's a bit over-complex
for what I'm planning, the structure on top is very light (a
fibreglass dome) and so doesn't really need much, and I'm also
concerned about possibly lifting the whole thing and moving it in a
few years.

On Jan 23, 12:27*pm, Andy Dingley wrote:

I don't like the poured concrete slab idea. It's a bit over-complex
for what I'm planning, the structure on top is very light (a
fibreglass dome) and so doesn't really need much, and I'm also
concerned about possibly lifting the whole thing and moving it in a
few years.

How are you going to lift a two foot high dwarf wall? Do whatever you
want. You might want to fit some rebar into the wall to try to stop
it cracking but it sounds like you're not too worried.

On 23 Jan, 12:54, adder1969 wrote:

How are you going to lift a two foot high dwarf wall?

Break it apart and throw it away. Still easier than a concrete slab.
If I do move it, it's because I'll be looking to preserve the
fibreglass dome, not necessarily the brickwork. Although for that
matter, I probably _could_ slice brickwork apart and re-assemble it.
Certainly the paving slabs would be liftable and re-usable.

The paving slabs under the tractor shed (approx shed #4 of 7 in
total!) still have their camouflage paint visible on them, from when
they began life as part of Burtonwood airfield during WW2. I know I've
lifted and moved them twice myself in the last 30 years, and they
weren't new when we got them.