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Water tank on roof - question about weight
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ppmoore
Nov 7, 2011, 6:01:00 AM11/7/11
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Hello,
I'm in the process of installing a rain water tank on my flat roof to
store water to water the garden with during the summer. I've bought a
200 litre plastic tank (weighing 200 kilogram when full), and was
wondering if flat roofs in general can take this weight. I was
thinking of setting the tank on two 1 metre concrete beams, side by
side, to spread out the weight, but these together with a concrete
block I was also thinking of putting in the tank to stop it blowing
away when empty, is also extra weight.
Can anyone advise?
Many thanks,
Paul
I'm in the process of installing a rain water tank on my flat roof to
store water to water the garden with during the summer. I've bought a
200 litre plastic tank (weighing 200 kilogram when full), and was
wondering if flat roofs in general can take this weight. I was
thinking of setting the tank on two 1 metre concrete beams, side by
side, to spread out the weight, but these together with a concrete
block I was also thinking of putting in the tank to stop it blowing
away when empty, is also extra weight.
Can anyone advise?
Many thanks,
Paul
Brian Gaff
Nov 7, 2011, 7:07:32 AM11/7/11
to
I'd say no. Though it really depends on the roof.
Brian
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"ppmoore" <polo...@gmail.com> wrote in message
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Brian
--
Brian Gaff - bri...@blueyonder.co.uk
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"ppmoore" <polo...@gmail.com> wrote in message
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Dave Liquorice
Nov 7, 2011, 7:01:56 AM11/7/11
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On Mon, 7 Nov 2011 03:01:00 -0800 (PST), ppmoore wrote:
> I've bought a 200 litre plastic tank (weighing 200 kilogram when full),
Plus the weight of the tank. B-)
> I've bought a 200 litre plastic tank (weighing 200 kilogram when full),
> and was wondering if flat roofs in general can take this weight.
floor. ie 7x2 joists at 18" centers. We got some calculations done
and the strucural enginer suggested a platform from 4 3x2's (3
dimension vertical) with an 18mm ply top to spread the load across at
least 4 floor joists. This is also at one end, not the middle of the
span of joists.
> I was thinking of setting the tank on two 1 metre concrete beams, side
> by side, to spread out the weight,
supported on a smooth flat surface. What is the flat roof covered
with? If it's just felt (built up, torch on WHY) then I wouldn't be
surprised to find the loading from spreader beams pushing their way
through over time and any small stones trapped...
--
Cheers
Dave.
Andrew Gabriel
Nov 7, 2011, 8:16:04 AM11/7/11
to
In article <b87896a9-6a6d-445a...@eh5g2000vbb.googlegroups.com>,
You'll need to get a structural surveyor to assess this in conjunction
with determining the roof structure. Note the roof also needs to support
a depth of snow.
I had a structural surveyor check before I removed an upstairs wall
which was not far from the storage tanks in the loft. Fortunately in
my case, the water tank weight was spread across 6 of the A frame
ceiling joists with a well sprung timber frame, so he said none of
the upstairs walls were supporting it. Indeed, when I pulled off the
coving, I found the wall didn't actually go right up to the ceiling,
and had been built after the ceiling was plasterboarded ;-)
But this is the sort of thing than needs checking first.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
with determining the roof structure. Note the roof also needs to support
a depth of snow.
I had a structural surveyor check before I removed an upstairs wall
which was not far from the storage tanks in the loft. Fortunately in
my case, the water tank weight was spread across 6 of the A frame
ceiling joists with a well sprung timber frame, so he said none of
the upstairs walls were supporting it. Indeed, when I pulled off the
coving, I found the wall didn't actually go right up to the ceiling,
and had been built after the ceiling was plasterboarded ;-)
But this is the sort of thing than needs checking first.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Newshound
Nov 7, 2011, 5:45:42 PM11/7/11
to
more 3x3 tanalised fence posts, say 2 metres long. Set perpendicular to
the joists, if you can determine which way they run. Rather than a
concrete block inside you could bolt the tank on to the posts with coach
bolts, penny washers, and silicone or mastic to seal.
ppmoore
Nov 10, 2011, 1:01:17 AM11/10/11
to
Many thanks everyone for the replies.
On a more general level, is there a general formula or rule of thumb
that describes the maximum weight that can be applied per square
metre, for various thicknesses of joist. I suppose it also depends on
the joist spacing.
Paul
On a more general level, is there a general formula or rule of thumb
that describes the maximum weight that can be applied per square
metre, for various thicknesses of joist. I suppose it also depends on
the joist spacing.
Paul
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