Am in the planning stage of a new 14'x14' shed, and have a few questions.
What depth of hardcore to use under the 4" slab?
How can I get rid of the tree stump in the way? Bear in mind I'm notoriously cheap.
What timber size would be good for the roof frame?
Thinking of doing the roof with OSB followed by corrugated steel.
On 28/08/14 12:22, email@example.com wrote:
Oh. wet fingers depth. Hoew thick is the slab? Ok 4".. thats decent
enough Do you care if it cracks a bit? are you on clay? are there any
Get in a mini digger anyway. Dig a trench round the tree to expose any
lateral roots, cut em with an axe, and the hoick the whole thing out
cutting any bits that seem to prevent you.
Bear in mind I'm notoriously cheap.
Matey a mini digger is about 130 quid for a day. If you use that to mash
up the site and level it. you will at least have a more or less
predictable scenario under the slab. Then use rebar when laying te
concrete slab. With your hardcore and sand under to get decent drainage
and have the possibility of some soil movement that can be absorbed by
a loose fill later.
In genearl remove any large lumps, and enoiufg depth for waht you want,
stick dp0wn 4-6" of hardcore and sand, then revbaber propped up an inch
or so, then cast te slab,
You probably can actually build any walls right on to that without a
DPc, or foundations, or if its all timber, just make sosme small brick
spacers to space the wood work off te damp concrete
2 x 4 should be well OK.
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. – Erwin Knoll
On 28/08/14 12:22, firstname.lastname@example.org wrote:
On compacted undisturbed soil, you can get away with little more than
sand with about 1 part in 8-10 of cement overlaid with slabs on smaller
A 4" slab would work direct on soil (though it might move a bit over the
years), but if you want industrial, 6" Type 1 MOT plate whacked down to
about 4" under the concrete would be very very stable.
For less physical effort, have you considered just pouring 2 strip
foundations about 6" wide and maybe 1' deep ontop of a trench of well
rammed hardcore then running 4x2" decking joists between them at about
You'll raise the structure but OTOH you'll have good ventilation under
On 28/08/2014 12:22, email@example.com wrote:
Spade, axe and scaffold pole and lots of time depending on how big the
stump was. The resulting hole will cause you problems with settlment.
My former pear tree location down to grass is still susbsinding slightly
years after removal of the main >1" roots as the smaller stuff gradually
rots away and shrinks. Annual top dressing fixes it on a lawn.
Unless there is some reason for having a concrete floor, such mounting heav
y machinery, I would go for the raised wooden floor and get the benefit of
ventilation. In that case all you need to do is support the floor on piers
be it brick, stacked flags, concrete filled pipes or you can use fancy conc
rete and metal adjustable piers, see example here,
Raising the floor enables you to eliminate rising damp problems and also to
insulate underneath the floor.
On Thursday, August 28, 2014 8:02:20 PM UTC+1, The Natural Philosopher wrote:
Too true. I made that mistake with the first shed I built and using a ramp is only a p.i.t.a. Though I loathe working with concrete I built another shed alongside it with a concrete floor. Their both full now.
OSB lets you use that very thin plastic coated steel sheet which is
pretty cheap. This sort of thing.
Those sheets look like wall sections and I reckon you're going to need
a lot of screws and washers to hold it down. Every screw hole is a
potential leak. The sections also need to be held down and sealed at
both ends or the water will blow in under the corrugations. My Screwfix
nightmare shed used this stuff and it took ages to build, millions of
screws and umpteen tubes of sealant to make it waterproof. TMH had an
identical bad experience IIRC.
It is a while since I bought this stuff but my recollection is more like
£1.00/m for 0.5mm painted finish. More for plastic coated obviously.
Check the price with a local outlet.
One problem with any metal roofing is underside condensation. Worst case
is cattle housing in frosty conditions where it *rains* inside when the
Sun comes out:-) You may want to consider some waterproof layer
protecting your OSB. Roof pitch is an issue with 12.5deg. the minimum
for agricultural buildings.
Pitched roof is nice as you can store lots of junk on the tie beams.
Downside is two lots of gutter/rain drip to deal with.
There are issues with how close you can construct a timber building to a
boundary as discussed previously.
Fixing screws have neoprene sealant washers and are fitted in the
Expanded foam strips are available to seal the ridge.
Stitcher screws every 0.5m up the laps. You can get rolls of butyl strip
(sticky one side) to seal the laps.
One point... metal roofing is noisy. Every time a cloud covers the Sun
the stuff shrinks.
You might find something useful on the Steadmans site
I should explain more. Interior climate is important, it must remain dry an
d avoid extreme temp swings. Hence the choice of an underboarded roof and a
slab that will moderate temp swings.
The shed will contain floor loads of 5-10 tonnes. The plan was to do a 2 st
age build. First a quick cheap timber structure will go up, then just insid
e that will more slowly go up a breeze block structure. When the wood rots
the breeze wall will be rendered. However it seems it would be cheaper to j
ust do block - which is better largely comes down to timing, there are issu
es I wont bore you with about that.
So a suspended timber floor is impractical, it'll be concrete slab - unless
scalpings would be workable. We don't have anything set up to heat or comp
ress them though.
The Natural Philosopher wrote:
There's a biggish tree right next to the proposed shed. The soil's clay & w
ell settled. I guess masonry means no cracks, otherwise I wouldnt worry.
Yes... that works, but. The question of who'll do the work is unsettled. I
wont be able to, and I'm not comfortable putting an axe in the hands of one
of the prime candidates. Drill, no problem, saw ok, chainsaw no.
With the tree right next to it, I can see the value of rebar. With masonry
walls I guess I'll need to dig down round the edge for the wall. Frost dept
h is about 45cm, so presumably need to go deeper. Unless I'm missing someth
Re damp the plan so far is no built-in dpc, just bitumen the floor and inte
rior of the 1st course of blocks.
What's the snow load for 4" & 6": with roof overhangs its 4.5m x 4.5m x 0.1
m x 200-300 kg/m3 for settled snow = 405-607kg for 4", 607-910kg for 6".
Half of 900kg on 4.5m of 2x4 gives 1" sag with clear spruce according to sa
gulator. A central support could be added to improve that, so 2x4 sounds qu
n > its own. Its likely going to be the strongest component anyway
Corrie on polystyrene might be better. I assume poly isn't robust enough to
just lay between frame & corrie & screw through, leaving the timber frame
on the interior side of insulation. So how to avoid condensation & rot?
Tim Lamb wrote:
I clearly need to read up on how it should be fitted. I didn't find any inf
o of use on that site.
We definitely can't live with indoor rain, though if the roof could be pers
uaded to act as a dehumidifier that would be very welcome - but only if it
doesnt take the bulk of the indoor air to dew point, which I presume it wou
Noise is a nonissue.
So in short a lot of questions remain, at least one of which only we here c
an answer, namely whether to build block from day 1 or begin with timber. I
wish it were more straightforward.
OK, that describes my passive solar house very well.
I did the house much better by using galvanised
pressed metal beams, inverted J profile. Full width
rigid foam paper faced panels drop into that and are
held in with metal wedges. Much cheaper than OSB
and much better thermally too.
The inverted J beams have timber rafters bolted to the
top flange with the depth of the timber rafters providing
the very minimal slope to the metal decking roof that
goes on the top of the timber rafters.
Those inverted J beams will span 14' trivially.
No point in that timber structure at all. Makes a lot more
sense to use the block walls for the roof beams to go on.
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