Maximum joist length?
David in Normandy
outbuilding. The room dimensions are 7 metres by 5 metres constructed
with a single thickness of breeze blocks. He is planning having 7 metre
long joists and fixing down traditional tongue and groove floorboards on
top.
Is this feasible? 7 metres sounds like a very long span unsupported,
assuming that you can even get 7 metre long joists? I would have thought
that at least one cross beam would be needed for such a span.
I'm happy to lay floorboards and do the associated DIY but I'm no
structural engineer!
Suggestions?
--
David in Normandy. Davidin...@yahoo.fr
To e-mail you must include the password FROG on the
subject line, or it will be automatically deleted
by a filter and not reach my inbox.
dennis@home
"David in Normandy" <Davidin...@nospam.nospam> wrote in message
news:4e037b42$0$14696$ba4a...@reader.news.orange.fr...
> Someone has asked me to help put in an upper floor in a farm outbuilding.
> The room dimensions are 7 metres by 5 metres constructed with a single
> thickness of breeze blocks. He is planning having 7 metre long joists and
> fixing down traditional tongue and groove floorboards on top.
>
> Is this feasible? 7 metres sounds like a very long span unsupported,
> assuming that you can even get 7 metre long joists? I would have thought
> that at least one cross beam would be needed for such a span.
>
> I'm happy to lay floorboards and do the associated DIY but I'm no
> structural engineer!
>
> Suggestions?
Engineered joists will do it (just).
http://www.jji-joists.co.uk/index.php/technical_info/interactive_span_table
for example.
The Medway Handyman
> Someone has asked me to help put in an upper floor in a farm
> outbuilding. The room dimensions are 7 metres by 5 metres constructed
> with a single thickness of breeze blocks. He is planning having 7 metre
> long joists and fixing down traditional tongue and groove floorboards on
> top.
>
> Is this feasible? 7 metres sounds like a very long span unsupported,
> assuming that you can even get 7 metre long joists? I would have thought
> that at least one cross beam would be needed for such a span.
>
> I'm happy to lay floorboards and do the associated DIY but I'm no
> structural engineer!
>
> Suggestions?
>
Table A of the Building Regs suggests a 9 x 3 will only span about 5.5m,
so probably no.
--
Dave - The Medway Handyman www.medwayhandyman.co.uk
d...@gglz.com
wrote:
> Someone has asked me to help put in an upper floor in a farm
> outbuilding. The room dimensions are 7 metres by 5 metres constructed
> with a single thickness of breeze blocks. He is planning having 7 metre
> long joists and fixing down traditional tongue and groove floorboards on
> top.
>
> Is this feasible? 7 metres sounds like a very long span unsupported,
> assuming that you can even get 7 metre long joists? I would have thought
> that at least one cross beam would be needed for such a span.
>
> I'm happy to lay floorboards and do the associated DIY but I'm no
> structural engineer!
>
> Suggestions?
>
> --
> To e-mail you must include the password FROG on the
> subject line, or it will be automatically deleted
> by a filter and not reach my inbox.
Is there some earth-shattering reason for not laying the joists in the
5m direction?
Dave Liquorice
> Someone has asked me to help put in an upper floor in a farm
> outbuilding. The room dimensions are 7 metres by 5 metres constructed
> with a single thickness of breeze blocks. He is planning having 7 metre
> long joists and fixing down traditional tongue and groove floorboards on
> top.
Our 2nd floor (22mm chip on top, plasterboard underneath) is
supported by 7 x 2 joists at normal spacing and it is, erm, "bouncy".
These joists are
only 4.5m long...
Gut feeling is that 7m is going to need some seriously chunky bits of
timber, 8 x 4, 8 x 6? they won't come cheap in 7m lengths.
Why doesn't he use the 5m dimension for the joists?
--
Cheers
Dave.
John Williamson
Eet ees ze French way, m'sieur. ;-)
Seriously, the costs to buy the larger number of 5 metre joists will be
a lot lower than for the 7 metre ones, the cheapest way may end up being
a steel joist in the centre of the long dimension, supported by two
450mm square piers in the wall, and 3.5 metre joists, which will be
about half the size of five metre ones, which, in turn, would be about
half the size of seven metre ones, if he can get them. Unless he's got a
load of seven metre long steel joists laying round in the farmyard
somewhere.
--
Tciao for Now!
John.
d...@gglz.com
wrote:
> On Thu, 23 Jun 2011 19:43:13 +0200, David in Normandy wrote:
> > Someone has asked me to help put in an upper floor in a farm
> > outbuilding. The room dimensions are 7 metres by 5 metres constructed
> > with a single thickness of breeze blocks. He is planning having 7 metre
> > long joists and fixing down traditional tongue and groove floorboards on
> > top.
>
> Our 2nd floor (22mm chip on top, plasterboard underneath) is
> supported by 7 x 2 joists at normal spacing and it is, erm, "bouncy".
> These joists are
> only 4.5m long...
8 x 2 (250*50mm) would be to code for 4m span, 400mm spacing - I
think, for domestic floor loads.
> Gut feeling is that 7m is going to need some seriously chunky bits of
> timber, 8 x 4, 8 x 6? they won't come cheap in 7m lengths.
Depth is what counts. Strength is proportional to square of the depth,
Stiffness is cube of the depth.
fred
Normandy <Davidin...@nospam.nospam> writes
>Someone has asked me to help put in an upper floor in a farm
>outbuilding. The room dimensions are 7 metres by 5 metres constructed
>with a single thickness of breeze blocks. He is planning having 7 metre
>long joists and fixing down traditional tongue and groove floorboards on
>top.
>
>Is this feasible? 7 metres sounds like a very long span unsupported,
>assuming that you can even get 7 metre long joists? I would have thought
>that at least one cross beam would be needed for such a span.
>
>I'm happy to lay floorboards and do the associated DIY but I'm no
>structural engineer!
>
>Suggestions?
>
7m which I suspect could get a bit expensive and bouncy.
This came up on a quick search (engineered joist span):
http://www.trussform.co.uk/
Useful data here on spans and rigidity:
http://www.trussform.co.uk/download/TJI_Technical_Guide.pdf
Note plenty of options at about 5m diminishing towards 7m.
Not local to you of course but I'm sure there will be outfits in France
too.
--
fred
FIVE TV's superbright logo - not the DOG's, it's bollocks
John Rumm
> outbuilding. The room dimensions are 7 metres by 5 metres constructed
> with a single thickness of breeze blocks. He is planning having 7 metre
> long joists and fixing down traditional tongue and groove floorboards on
> top.
>
> Is this feasible? 7 metres sounds like a very long span unsupported,
> assuming that you can even get 7 metre long joists? I would have thought
> that at least one cross beam would be needed for such a span.
>
> I'm happy to lay floorboards and do the associated DIY but I'm no
> structural engineer!
>
> Suggestions?
If using joints, then run them the 5m direction...
even then its making life difficult. A 7m steel down the centre and 3.5m
joists either side sounds much better.
--
Cheers,
John.
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carlhit...@gmail.com
Length 27' x death 8' x height 8' with a slope for the roof upto 10'
I am considering using 2" x 4" for all the Framing with 16" between each uprights.
Again for the rafters I was thinking of using the same wood 2" x 4" at 9' lengths to allow for some overhang.
Does anyone have any concerns or suggestions
newshound
end, say a 6x2, you might get away with uprights at say 48 inches
(although I would be inclined to use 4x4 uprights).
What roof material? Is this in an exposed or windy area? What about snow
load?
You'll need some diagonal bracing for the outer "wall", I think; A
suitable roofing material would provide diagonal bracing for the roof plane.
Andrew
tiled with artificial slate or marley concrete tiles or something
lightweight like epdm ? . You might have to go up to 6x2 for the
rafters.
The manufacturers of whatever hard roofing you choose should have
tables on their website showing the amount of overlap neeed for
your 12? degree pitch. There are limited tile choices for a
pitch that low, eg
https://www.jjroofingsupplies.co.uk/pitched-roofing/roof-tiles/?minimumpitch_ln=567
