Floorboards and joist spacing?
David in Normandy
are approx 2 feet (60 cm) apart and the new floorboards are
2 cm thick. Are the joists too wide apart? Would the
floorboards flex too much with that spacing?
In principle I could fasten some extra joists between the
existing ones to take the weight. Is this worth doing? Any
other suggestions please?
The area will become a bedroom and bathroom (with shower
only, no heavy bath).
--
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.
Martin Bonner
wrote:
> I'm replacing the rotten floorboards upstairs. The joists
> are approx 2 feet (60 cm) apart and the new floorboards are
> 2 cm thick. Are the joists too wide apart? Would the
> floorboards flex too much with that spacing?
>
> In principle I could fasten some extra joists between the
> existing ones to take the weight. Is this worth doing? Any
> other suggestions please?
>
all /sorts/ of interesting numbers. (If I were you, I would assume
that the bed legs will be a point load exactly in the middle of a
single floorboard.)
Somebody should be along shortly with the Building Regs answer (even
if they don't apply to you).
Roger Mills
David in Normandy <Davidin...@yahoo.fr> wrote:
> I'm replacing the rotten floorboards upstairs. The joists
> are approx 2 feet (60 cm) apart and the new floorboards are
> 2 cm thick. Are the joists too wide apart? Would the
> floorboards flex too much with that spacing?
>
> In principle I could fasten some extra joists between the
> existing ones to take the weight. Is this worth doing? Any
> other suggestions please?
>
> The area will become a bedroom and bathroom (with shower
> only, no heavy bath).
How thick were the original floorboards? Were they the tongue and groove
type? Are the new ones? What section are the joists, and what is the span?
Are you planning to support heavier loads than were supported by the old
floor?
I think you need to answer these question before anyone can comment
sensibly.
--
Cheers,
Roger
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David in Normandy
> In an earlier contribution to this discussion,
> David in Normandy <Davidin...@yahoo.fr> wrote:
>
> > I'm replacing the rotten floorboards upstairs. The joists
> > are approx 2 feet (60 cm) apart and the new floorboards are
> > 2 cm thick. Are the joists too wide apart? Would the
> > floorboards flex too much with that spacing?
> >
> > In principle I could fasten some extra joists between the
> > existing ones to take the weight. Is this worth doing? Any
> > other suggestions please?
> >
> > The area will become a bedroom and bathroom (with shower
> > only, no heavy bath).
>
> How thick were the original floorboards? Were they the tongue and groove
> type? Are the new ones? What section are the joists, and what is the span?
> Are you planning to support heavier loads than were supported by the old
> floor?
>
> I think you need to answer these question before anyone can comment
> sensibly.
>
The original floorboards were tongue and groove as are the
new ones. The joists that will support them are only 3
inches cross section but supported immediately below by
strong joists going the opposite direction at 12 inch
spacing. The span of the upper set of joists is quite small
at only around 10 feet, but as I say they are very well
supported. The old floorboards did not support anything as
far as I'm aware, it was treated as an uninhabited space.
The new floorboards will be directly inside a bathroom so
will have to support a shower cubicle, toilet, wash basin
and small cupboard only.
As it stands the new (2 cm thick) tongue and groove
floorboards would be supported on the upper joists at
intervals of approx 2 feet.
The Natural Philosopher
I think you will be fine mate.
Roger Mills
I think in that case that I would generally go with the 24" spacing, but put
intermediate supports in just the areas where the highest loads will be.
24" spacing is a *bit* wide for joists, but using 20mm T&G boards, any point
loads will be spread across several boards - and 20mm is thicker that your
average modern floorboard (in UK)anyway.
ma...@atics.co.uk
> I'm replacing the rotten floorboards upstairs. The joists
> are approx 2 feet (60 cm) apart and the new floorboards are
> 2 cm thick. Are the joists too wide apart? Would the
> floorboards flex too much with that spacing?
>
> In principle I could fasten some extra joists between the
> existing ones to take the weight. Is this worth doing? Any
> other suggestions please?
>
> The area will become a bedroom and bathroom (with shower
> only, no heavy bath).
> --
> To e-mail you must include the password FROG on the
> subject line, or it will be automatically deleted.
Dear David
You are over the limit at 24" but with T and G well laid I agree with
the others that you will be unlikely to have a problem. It all depends
on how stiff you want the final surface. Personally, if it were mine
and all I had to do was to put some 3" timbers in between over the
main beams to get down to 12" centres then I would do that.
As the area is to be a bathroom and shower I would not use any form of
chip board T&G - "water proof" or not! I would use appropriate ply
especially under the shower and bearing in mind the tendencies of
showers to leak if the substrate can move, make the floor stiff and
the wall surfaces finish (also ply) INSIDE the shower tray
Chris
Chris
Mark
<watt....@googlemail.com> wrote:
>In an earlier contribution to this discussion,
>David in Normandy <Davidin...@yahoo.fr> wrote:
>
>>>
>>
>> The original floorboards were tongue and groove as are the
>> new ones. The joists that will support them are only 3
>> inches cross section but supported immediately below by
>> strong joists going the opposite direction at 12 inch
>> spacing. The span of the upper set of joists is quite small
>> at only around 10 feet, but as I say they are very well
>> supported. The old floorboards did not support anything as
>> far as I'm aware, it was treated as an uninhabited space.
>> The new floorboards will be directly inside a bathroom so
>> will have to support a shower cubicle, toilet, wash basin
>> and small cupboard only.
>>
>> As it stands the new (2 cm thick) tongue and groove
>> floorboards would be supported on the upper joists at
>> intervals of approx 2 feet.
>
>I think in that case that I would generally go with the 24" spacing, but put
>intermediate supports in just the areas where the highest loads will be.
>
>24" spacing is a *bit* wide for joists, but using 20mm T&G boards, any point
>loads will be spread across several boards - and 20mm is thicker that your
>average modern floorboard (in UK)anyway.
Building regulations recommend 22mm with 18mm as a minimum IIRC.
M.
Roger
from David in Normandy <Davidin...@yahoo.fr> contains these words:
> The original floorboards were tongue and groove as are the
> new ones. The joists that will support them are only 3
> inches cross section but supported immediately below by
> strong joists going the opposite direction at 12 inch
> spacing. The span of the upper set of joists is quite small
> at only around 10 feet, but as I say they are very well
> supported. The old floorboards did not support anything as
> far as I'm aware, it was treated as an uninhabited space.
> The new floorboards will be directly inside a bathroom so
> will have to support a shower cubicle, toilet, wash basin
> and small cupboard only.
> As it stands the new (2 cm thick) tongue and groove
> floorboards would be supported on the upper joists at
> intervals of approx 2 feet.
FWIW my 1965 Builders and Architects diary (kept for all the useful
information it contains) gives 3/4" t & g at 16" centres, 7/8" at 18"
and 1" at 21" so your floor boards are more than a little light by those
standards. But your floor is only going to be lightly loaded so I don't
think you should have any problems. Just think what sort of heavy loads
a domestic floor has to carry in some circumstances.
If your bathroom had been going to contain a bath I would have suggested
an additional plank under each foot just to span from one joist to the
next if any of the feet were going to inconsiderately plant themselves
anywhere close to midway between joists.
--
Roger Chapman
David in Normandy
Thanks. Your figures confirm my gut feeling that some of
the spacing was too wide to be really solid.
I bit the bullet today and put some extra joists in between
the widest spaced joists. The original joists must have
been put in before tape measures or rulers were invented as
none of them were consistently spaced, varying from around
19" to 28" apart.
I also put some noggins between the joists where the toilet
is intended to go - at least it should be possible to screw
it down tightly through the floorboards and into the
noggins below. I don't want a wobbly loo.
meow...@care2.com
> I'm replacing the rotten floorboards upstairs. The joists
> are approx 2 feet (60 cm) apart and the new floorboards are
> 2 cm thick. Are the joists too wide apart? Would the
> floorboards flex too much with that spacing?
>
> In principle I could fasten some extra joists between the
> existing ones to take the weight. Is this worth doing? Any
> other suggestions please?
>
> The area will become a bedroom and bathroom (with shower
> only, no heavy bath).
You've not given enough info here or later. One would need all 3
dimensions of each layer of the structure to know the result.
However inadequate strength is most unlikely, bounce is the issue
that can crop up. FWIW 2x4 joists at 16" spanning over 10ft with
half inch floor boards are plenty strong enough for anything but
baths, even though theyre far below what BR now insists on. BR
sizes are primarily dictated by noise transmission, not strength,
bounce or plaster cracking.
NT