Preparing ground for summer house


J

Jason Judge

Okay, my next job: put up a summer house in the garden.

We have the house itself, one of the 7ft corner units manufactured by Solisand sold by just about everyone at wilding varying prices and brand names.

I have a patch of lawn in a corner, and need a solid surface there to placeit on. I have nine square paving slabs and eight strips of paving edging (15cm x 90cm paving slabs) that can be arranged into the right shape and size.

I would like to surround the summer house with a strip of gravel soak-away,because water has been a bit of a problem lately, so I guess the foundations need to be "self-supporting", since they won't have lawn soil to push upagainst it.

So - how would you recommend I go about this? I suspect I need something concrete-based around the circumference, to keep it all in shape, but just sand or gravel in the middle (under the paving slabs)? How deep would the soak-away need to be, so make any difference (and I know that is a "depends" answer, and may depend on whether a layer of gravel under the whole thing serves as a big, wide soakaway, perhaps)? What kind of depth would I need to go down to? I wouldn't have thought I need to go down too deep, as this is now a big heavy thing.

And if I'm using the wrong terminology, it's because I'm not a builder - just a home-owner.

More of the grass around the summer house may (or probably will) be paved over in time, so this is one reason I need to be careful about water. The garden is enclosed by a wall, and rain water does not leave the garden onto public land or other people's property.

Thanks.

-- Jason
 
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T

The Natural Philosopher

Jason said:
Okay, my next job: put up a summer house in the garden.

We have the house itself, one of the 7ft corner units manufactured by Solis and sold by just about everyone at wilding varying prices and brand names.

I have a patch of lawn in a corner, and need a solid surface there to place it on. I have nine square paving slabs and eight strips of paving edging (15cm x 90cm paving slabs) that can be arranged into the right shape and size.

I would like to surround the summer house with a strip of gravel soak-away, because water has been a bit of a problem lately, so I guess the foundations need to be "self-supporting", since they won't have lawn soil to push up against it.

So - how would you recommend I go about this? I suspect I need something concrete-based around the circumference, to keep it all in shape, but just sand or gravel in the middle (under the paving slabs)? How deep would the soak-away need to be, so make any difference (and I know that is a "depends" answer, and may depend on whether a layer of gravel under the whole thing serves as a big, wide soakaway, perhaps)? What kind of depth would I need to go down to? I wouldn't have thought I need to go down too deep, as this is now a big heavy thing.

And if I'm using the wrong terminology, it's because I'm not a builder - just a home-owner.

More of the grass around the summer house may (or probably will) be paved over in time, so this is one reason I need to be careful about water. The garden is enclosed by a wall, and rain water does not leave the garden onto public land or other people's property.

Thanks.

-- Jason
for a lightweight shed, simply level, lay a ring of slabs around the
shed exterior and stick a brick on each and shove that under the main
floor joists.


--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.
 
P

Phil L

Jason said:
Okay, my next job: put up a summer house in the garden.

We have the house itself, one of the 7ft corner units manufactured by
Solis and sold by just about everyone at wilding varying prices and
brand names.

I have a patch of lawn in a corner, and need a solid surface there to
place it on. I have nine square paving slabs and eight strips of
paving edging (15cm x 90cm paving slabs) that can be arranged into
the right shape and size.

I would like to surround the summer house with a strip of gravel
soak-away, because water has been a bit of a problem lately, so I
guess the foundations need to be "self-supporting", since they won't
have lawn soil to push up against it.

So - how would you recommend I go about this? I suspect I need
something concrete-based around the circumference, to keep it all in
shape, but just sand or gravel in the middle (under the paving
slabs)? How deep would the soak-away need to be, so make any
difference (and I know that is a "depends" answer, and may depend on
whether a layer of gravel under the whole thing serves as a big, wide
soakaway, perhaps)? What kind of depth would I need to go down to? I
wouldn't have thought I need to go down too deep, as this is now a
big heavy thing.

It sounds like you've already designed something in your head, but it's not
gone down in print too well.

What do you mean 'self supporting foundations'
Are you intending having the summer house raised up higher than the rest of
the garden?
And if I'm using the wrong terminology, it's because I'm not a
builder - just a home-owner.

More of the grass around the summer house may (or probably will) be
paved over in time, so this is one reason I need to be careful about
water. The garden is enclosed by a wall, and rain water does not
leave the garden onto public land or other people's property.
Remove the grass - just the grass - no soil, to a depth of about 2 inches.
rake over sharp sand and level, add to this a bag of dry cement and rake
this into the sand.
Lay paving on this.
erect summer house.
once flags have set in place (after a few days or so) dig a spade's depth
and width trench around perimeter and infill with gravel
 
J

Jason Judge

It sounds like you've already designed something in your head, but it's not

gone down in print too well.
No, the intention is not to raise it above ground level. I would like to surround it with a small trench filled with gravel - partly as somewhere for rain water to go, and sink away. In my head, gravel would not support any sideways pressure, so I am assuming if the foundations (or whatever is there) is not prevented from squeezing sideways like a sandwich full of chutney,then it may sink. Maybe with the weight spread out, this is not a problem?
What do you mean 'self supporting foundations'

Are you intending having the summer house raised up higher than the rest of

the garden?











Remove the grass - just the grass - no soil, to a depth of about 2 inches..

rake over sharp sand and level, add to this a bag of dry cement and rake

this into the sand.

Lay paving on this.

erect summer house.

once flags have set in place (after a few days or so) dig a spade's depth

and width trench around perimeter and infill with gravel
Cool. That sounds straight-forward :)

Is that depth of two inches from the top of the flags or the bottom of the flags? I'm guessing it would be the depth of just the sand/cement mix, otherwise the sand layer would only be half an inch thick once the depth of theflags are taken into account, which does not seem like much to me.
 
P

Phil L

Jason said:
On Sunday, 19 August 2012 15:36:05 UTC+1, Phil L wrote:

No, the intention is not to raise it above ground level. I would like
to surround it with a small trench filled with gravel - partly as
somewhere for rain water to go, and sink away. In my head, gravel
would not support any sideways pressure, so I am assuming if the
foundations (or whatever is there) is not prevented from squeezing
sideways like a sandwich full of chutney, then it may sink. Maybe
with the weight spread out, this is not a problem?
It shouldn't be a problem, there's not that much weight in a dozen flags and
a summer house, but ISWYM, the end flag may 'creep' slightly if it's got
somewhere to go and this does happen....you could use edgings, although the
150mm ones you've got probably aren't deep enough, I'd be tempted to use
300mm ones (half flags) concreted in 200mm deep and then pave up to these.
Make your soakaway wider, about 18 in, but shallower, say about 6 inches, so
as not to undermine the concrete or edgings
Cool. That sounds straight-forward :)

Is that depth of two inches from the top of the flags or the bottom
of the flags? I'm guessing it would be the depth of just the
sand/cement mix, otherwise the sand layer would only be half an inch
thick once the depth of the flags are taken into account, which does
not seem like much to me.
You want the finished surface to be slightly higer than the lawn, so take
off 2 in of grass and soil, add 2 inches of sand/cement and 2 in of slabs
and it shouldn't fill up with water
 
J

Jeremy Nicoll - news posts

Jason Judge said:
In my head, gravel would not support any sideways pressure, so I am
assuming if the foundations (or whatever is there) is not prevented from
squeezing sideways like a sandwich full of chutney, then it may sink.
Maybe with the weight spread out, this is not a problem?
Gravel resists sideways pressure reasonably well. I have a gravel drive and
when I bring the car in, the gravel doesn't all get squeezed out to the
side! Nor does it appear to move much when I walk on it. My shed stands
directly on the gravel.

On the other hand, the gravelled area here covers what used to be a sloping
down ramp from the street and a garage (now demolished)'s floor and the
remains of its walls. The garage area was filled with hardcore before a
weed control fabric and then gravel was laid on top. The overall area does
have concrete edging on it, but it was put there not so much to stop gravel
squeezing out (though I suppose it must do) but to make a neat edge where
otherwise there'd be several inches depth of hardcore and gravel visible.
 
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J

Jason Judge

...
Remove the grass - just the grass - no soil, to a depth of about 2 inches..

rake over sharp sand and level, add to this a bag of dry cement and rake

this into the sand.

Lay paving on this.

erect summer house.

once flags have set in place (after a few days or so) dig a spade's depth

and width trench around perimeter and infill with gravel
Looking around the internet at descriptions like this, they tend to recommend a mix of 1:8 (cement to sharp sand). Is that what I am aiming for?

With sand/cement 2" deep and a total area of 6ft x 6ft comes to 0.05m x 2m x 2m = 0.2 cubic metres

At 600kg per cubic metre of raw material (source: Screwfix site), 0.2 cubicmetres is about 120kg of material (600x0.2), which is five bags in total (at 25kg per bag).

Digging a little deeper than two inches, five bags of sand to one bag of cement would do it, with a little cement left over to tidy up the edges.

If I wanted to do the edges down to 20cm deep and 10cm wide, with firmer concrete, to keep everything together, then I would need to add that on (~8m length x 0.2 x 0.2 = 0.16 cubic metres - another 3 or 4 bags - a surprising amount). Perhaps I can half that using old house bricks around the edge.

Sound about right? Or have I dropped a decimal point somewhere. 5 to 6 bagsof material for a 2m square area down to 2" with a dry mix, and half as much again for a deeper border, with some old house bricks in there, easily pulled out of skips in the area if I don't already have enough laying around..

-- Jason
 
D

Dave Liquorice

for a lightweight shed, simply level, lay a ring of slabs around the
shed exterior and stick a brick on each and shove that under the main
floor joists.
Yeah, I don't know why people insist on solid concrete rafts or paved
areas under sheds (summer houses). Nothing will grow under there, too
dark and dry. The OP mentions he doesn't want to raise the summer house
off the ground, I feel that is a mistake. Being timber it needs good
ventilation to stop it rotting (treated or not), wether it is mounted
above bare ground or a useless paved area.

Not sure about the french drain either. Does the roof have a gutter and
down spouts or is this to provide a landing place and drain for rain
running straight off the roof? For the latter you probably need something
at least a foot wide maybe 18" and about 6" deep. Filled with 20mm or so
"gravel". Pea gravel will be washed out by the momentum of the falling
water.
 
J

Jason Judge

Yeah, I don't know why people insist on solid concrete rafts or paved

areas under sheds (summer houses). Nothing will grow under there, too

dark and dry. The OP mentions he doesn't want to raise the summer house

off the ground, I feel that is a mistake. Being timber it needs good

ventilation to stop it rotting (treated or not), wether it is mounted

above bare ground or a useless paved area.



Not sure about the french drain either. Does the roof have a gutter and

down spouts or is this to provide a landing place and drain for rain

running straight off the roof? For the latter you probably need something

at least a foot wide maybe 18" and about 6" deep. Filled with 20mm or so

"gravel". Pea gravel will be washed out by the momentum of the falling
Okay, so steer clear of fine gravel. There is no gutter at the moment, but no reason why I can't add one. The summer house is fitting into a corner ofthe garden, with walls on two sides. The corner has an angle of about 108°, so there is a wedge-shaped gap behind the rear two walls (remember, it's a corner unit). Once reason for the French drain (new name to me;-) is to fill that gap, since I don't want anything to be growing back there.

There will be similar wedge-shaped gaps at the front too.

The paving slabs I am using with the hope that they will not be wicking water up from the ground. A neighbour was chucking them out, so it has saved him a trip to the tip, and me a trip to the DIY store. The ground here, nearthe coast, is never dry. Ever.

The floor joists are quite thin - about 1.5" high and spaced about a foot apart. They would need supporting over the whole floor area. I could put something more substantial in and raise the thing a little, if more ventilation would help.

-- Jason
 
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J

Jeremy Nicoll - news posts

Jason Judge said:
The paving slabs I am using with the hope that they will not be wicking
water up from the ground.
Indeed, but water may well pool on top of them.

One advantage of having a shed standing on gravel is that water drains away
very easily.
 

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