Hi All,

I am laying down a concrete base for my 16' x 10' timber shed /
workshop.

I have dug down 5 inches below ground level and am planning to lay:

4 inches of compacted hardcore
A layer of sand
Damp proof membrane
Then 4 inches of concrete (so the concrete should finish about 3
inches above ground level.)

I have a few questions which I would be grateful if anyone can
answer:-

1) Should I lay the form board / shuttering down before I lay the
hardcore? (This means boards need to be about 8 inches high). Or
should I lay the hardcore first, then 4 inch high boards (nailed to
stakes driven into the ground). I am worried that if I put the boards
down first, they may split when compacting the hard core with a
whacker plate.
2) Is a 19mm thick board ok to use (for the shuttering)
3) What do I do with the damp proof membrane after the concrete has
set - should I just cut the edge of it flush with the concrete?

Any help would be appreciated!
Thanks,
Rob

I have a few questions which I would be grateful if anyone can
answer:-

1) Should I lay the form board / shuttering down before I lay the
hardcore?
I wouldn't, I would compact the hardcore then put the formers on top. Set
the top of the formers to finished concrete floor level with a gap
underneath so the concrete flows under the formers to seal the top of the
hardcore.

(This means boards need to be about 8 inches high). Or
should I lay the hardcore first, then 4 inch high boards (nailed to
stakes driven into the ground). I am worried that if I put the boards
down first, they may split when compacting the hard core with a
whacker plate.
2) Is a 19mm thick board ok to use (for the shuttering)

So long as you use enough support stakes to keep them straight 19mm is
ample.

3) What do I do with the damp proof membrane after the concrete has
set - should I just cut the edge of it flush with the concrete?

I would bring it up the sides of the concrete if you can to stop damp from
the soil working in at the sides.

I have almost finished building a shed/workshop of my own
http://www.twango.com/channel/Muddymike.Workshop

Mike

Someone told me that the base should be slightly smaller than the shed so
that rain water runs down the walls and then down the sides of the slab. If
the slab is bigger then the water can sit on small bit of the slab around
the edge and rot the bottom of the shed. I've no idea if this is a real
problem ot not but it seems to make sense. The problem with making it
smaller is the accuracy required.

"Rob" wrote in message
ups.com...
Hi All,

I am laying down a concrete base for my 16' x 10' timber shed /
workshop.
snip

You should get all the info you need from the excellent web site below.
http://www.pavingexpert.com/

Chris S

"CWatters" wrote in message
...
Someone told me that the base should be slightly smaller than the shed so
that rain water runs down the walls and then down the sides of the slab.
If
the slab is bigger then the water can sit on small bit of the slab around
the edge and rot the bottom of the shed. I've no idea if this is a real
problem ot not but it seems to make sense. The problem with making it
smaller is the accuracy required.

It is a real problem, but more to bounce than to sitting in puddles

Water hits concrete base, bounces up and then rots the
floor from below.

Remedy is a rubber skirt (strips cut from excess pond liner)

and then also a gutter on the side of the roof (feeds a water butt)


Not a problem for the bounce up to the side of the shed
because that's usually treated.

On Tue, 28 Aug 2007 08:19:58 +0100, "Peter" wrote:


"CWatters" wrote in message
...
Someone told me that the base should be slightly smaller than the shed so
that rain water runs down the walls and then down the sides of the slab.
If
the slab is bigger then the water can sit on small bit of the slab around
the edge and rot the bottom of the shed. I've no idea if this is a real
problem ot not but it seems to make sense. The problem with making it
smaller is the accuracy required.

It is a real problem, but more to bounce than to sitting in puddles

Water hits concrete base, bounces up and then rots the
floor from below.

Remedy is a rubber skirt (strips cut from excess pond liner)

and then also a gutter on the side of the roof (feeds a water butt)


Not a problem for the bounce up to the side of the shed
because that's usually treated.


Put it on blocks.

It is a real problem, but more to bounce than to sitting in puddles
Water hits concrete base, bounces up and then rots the
floor from below.
Remedy is a rubber skirt (strips cut from excess pond liner)
and then also a gutter on the side of the roof (feeds a water butt)
Not a problem for the bounce up to the side of the shed
because that's usually treated.
Put it on blocks.

Unfortunately that would aggravate the problem because it is sitting
on wooden bearers at the moment, so creating the gap at
the base of the shed wall through which the bouncing water passes
so hitting the underside of the floor.

In article , "Peter" writes:
| It is a real problem, but more to bounce than to sitting in puddles
| Water hits concrete base, bounces up and then rots the
| floor from below.
| Remedy is a rubber skirt (strips cut from excess pond liner)
| and then also a gutter on the side of the roof (feeds a water butt)
| Not a problem for the bounce up to the side of the shed
| because that's usually treated.
| Put it on blocks.
|
| Unfortunately that would aggravate the problem because it is sitting
| on wooden bearers at the moment, so creating the gap at
| the base of the shed wall through which the bouncing water passes
| so hitting the underside of the floor.

No, it wouldn't. You are mistaken as to what the problem is.

Getting wet does not harm timber - staying damp does. If there is
no airflow, it will get damp in the autumn and stay that way until
spring. In wet years or locations, it will stay damp all year.
The reason to put sheds on bearers is to allow an airflow and not
to protect them from rain.

Gutters are a reasonable solution; a rubber skirt is precisely the
wrong thing to do.


Regards,
Nick Maclaren.

"Nick Maclaren" wrote in message
...
Gutters are a reasonable solution; a rubber skirt is precisely the
wrong thing to do.

The rubber skirt solved the problem for me, stopping the undersplash
on the side where the concrete was wider than the shed. On the other
side, where the shed overhung the flower bed, there wasn't
a problem.