Hi,

Just had interesting discussion with BCO (see my Part P mail today) and
I am erecting a stud wall in a bedroom in line with joists but about 3
inches into the 14 inch void. The stud is attached to another wall at
one end and it will be about 12 foot long (sorry for old units but its a
50's house).
The BCO is not happy with me putting 4x2 studding between the joists
which are 7x2 inches. He advised my to get a structural engineer to
check what extra support was required and implied noggins every 400mm.
He also said I might be able to get "Super Beam" software on Trial to
calculate loadings.

I had already decided to put in some noggins but would appreciate any
advice as to what size and spacings would generally be suitable.

I'd guess the BCO is looking for structural calculations for the
existing floor, to prove it's good for the normal imposed load as well
as the new static load of the wall.

Peter Hemmings wrote:
Hi,

Just had interesting discussion with BCO (see my Part P mail today)
and I am erecting a stud wall in a bedroom in line with joists but
about 3 inches into the 14 inch void. The stud is attached to
another wall at one end and it will be about 12 foot long (sorry for
old units but its a 50's house).
The BCO is not happy with me putting 4x2 studding between the joists
which are 7x2 inches. He advised my to get a structural engineer to
check what extra support was required and implied noggins every 400mm.
He also said I might be able to get "Super Beam" software on Trial to
calculate loadings.

I had already decided to put in some noggins but would appreciate any
advice as to what size and spacings would generally be suitable.

The BCO is taking the p!$$.

What weight does he think is in a 12ft stud wall?
6 X 8/4 p-boards @ 4kg ea
2 bags plaster @ 25kg ea
10 x 8ft 3/2 timbers @ 2kg ea
2 X 12ft top and bottom timbers @ 3kg ea

Grand total = 100kg - and this is over 12ft X 4inch, making it 4 sq feet of
area...plus, some of this weight will also be alleviated by your fixings
into the wall!! - I know the above is only a rough estimate but it's
unlikely to be far off.
It's far less than having a cooker standing on the same amount of floor area
and there must be hundreds of thousands of these all over the country,
strangely, I've never heard of one falling through the floor.

Use noggins if you want to but it's unlikely he'll re-check

The message
from Peter Hemmings contains these words:

Just had interesting discussion with BCO (see my Part P mail today) and
I am erecting a stud wall in a bedroom in line with joists but about 3
inches into the 14 inch void. The stud is attached to another wall at
one end and it will be about 12 foot long (sorry for old units but its a
50's house).
The BCO is not happy with me putting 4x2 studding between the joists
which are 7x2 inches. He advised my to get a structural engineer to
check what extra support was required and implied noggins every 400mm.
He also said I might be able to get "Super Beam" software on Trial to
calculate loadings.

I had already decided to put in some noggins but would appreciate any
advice as to what size and spacings would generally be suitable.

Sorry, can't help but count yourself lucky. My BCO insisted on double
width joists under stud walling in a loft conversion. Existing joists
were 8" x 2". One of several runs went in as 8" x 4" instead of two
clamped 8" x 2"s. In retrospect I wish I had done everything I could in
8" x 4" but my brother-in-law initially balked at manhandling the
weight.

--
Roger Chapman

Phil L wrote:

The BCO is taking the p!$$.

Not so sure that he in this case, although it does depend a bit on the
length of the wall, the size of the existing joists.

What weight does he think is in a 12ft stud wall?
6 X 8/4 p-boards @ 4kg ea

Those sound much easier to lift than the ones I am used to. ;-)

A standard 2400x1200x12.5mm PB is about 23kg IIRC so we have 138kg of
plasterboard (assuming the OPs walls are about 8' tall)

2 bags plaster @ 25kg ea

yup 50kg of that

10 x 8ft 3/2 timbers @ 2kg ea

More like 5.4kg each I make that (at an approx density of 600kg/m^3 for
structural pine softwood), so 54kg of those

2 X 12ft top and bottom timbers @ 3kg ea

8.1kg / each, so 16kg for them

Grand total = 100kg - and this is over 12ft X 4inch, making it 4 sq feet of

Pushing 260kg by my calcs!

So 2600N over 3.6m span is an extra uniform spread dead load of over 0.7
kN/m. If you also have to allow for the normal dead load on the joist
imposed by the floor and anything placed on the floor against the wall
(typically 0.8 kN/m) then there is as much again to add. So if the stud
wall were directly over the joist, it would in effect be doubling the
design load on it.

area...plus, some of this weight will also be alleviated by your fixings
into the wall!! - I know the above is only a rough estimate but it's
unlikely to be far off.

True, you were within one order of magnitude ;-)

It's far less than having a cooker standing on the same amount of floor area
and there must be hundreds of thousands of these all over the country,
strangely, I've never heard of one falling through the floor.

The reality is that it is unlikely anything will break, but you will
fail to meet the structural bending and deflection limits specified by
the building regs. Needless to say a BCO is unlikely to sign this off.

The OP stated an original joist size of 175x50 ish, which is only just
in spec[1] for the floor at a 3.6m span.

[1] Superbeam calculats the mid span deflection at just under 10mm, with
a maximum allowed of just under 11mm at that span. This assumes C16
timber in a load sharing arragement.

Use noggins if you want to but it's unlikely he'll re-check

In this situation even with the wall load shared between two joists you
are going to be out of spec, since you are quite close to the limit as
it is, without the wall.

The normal solution here would be to stick another joist beside it and
bolt them together with timber connectors and plate washers.


--
Cheers,

John.

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\================================================= ================/

Roger wrote:

Sorry, can't help but count yourself lucky. My BCO insisted on double
width joists under stud walling in a loft conversion. Existing joists

Yup, that is what the architect speced on my one as well... ended up
needing to use flitch plates on some of them as well when there were
other stringers that added extra point loads.

were 8" x 2". One of several runs went in as 8" x 4" instead of two
clamped 8" x 2"s. In retrospect I wish I had done everything I could in
8" x 4" but my brother-in-law initially balked at manhandling the
weight.

Oddly enough you can assume a slightly greater design strength for two
side by side beams, than you can for a single beam of the same total
cross section.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
Phil L wrote:

The BCO is taking the p!$$.


Not so sure that he in this case, although it does depend a bit on the
length of the wall, the size of the existing joists.

What weight does he think is in a 12ft stud wall?
6 X 8/4 p-boards @ 4kg ea


Those sound much easier to lift than the ones I am used to. ;-)

A standard 2400x1200x12.5mm PB is about 23kg IIRC so we have 138kg of
plasterboard (assuming the OPs walls are about 8' tall)

2 bags plaster @ 25kg ea


yup 50kg of that

10 x 8ft 3/2 timbers @ 2kg ea


More like 5.4kg each I make that (at an approx density of 600kg/m^3 for
structural pine softwood), so 54kg of those

2 X 12ft top and bottom timbers @ 3kg ea


8.1kg / each, so 16kg for them

Grand total = 100kg - and this is over 12ft X 4inch, making it 4 sq
feet of


Pushing 260kg by my calcs!

So 2600N over 3.6m span is an extra uniform spread dead load of over 0.7
kN/m. If you also have to allow for the normal dead load on the joist
imposed by the floor and anything placed on the floor against the wall
(typically 0.8 kN/m) then there is as much again to add. So if the stud
wall were directly over the joist, it would in effect be doubling the
design load on it.

area...plus, some of this weight will also be alleviated by your
fixings into the wall!! - I know the above is only a rough estimate
but it's unlikely to be far off.


True, you were within one order of magnitude ;-)

It's far less than having a cooker standing on the same amount of
floor area and there must be hundreds of thousands of these all over
the country, strangely, I've never heard of one falling through the
floor.


The reality is that it is unlikely anything will break, but you will
fail to meet the structural bending and deflection limits specified by
the building regs. Needless to say a BCO is unlikely to sign this off.

The OP stated an original joist size of 175x50 ish, which is only just
in spec[1] for the floor at a 3.6m span.

[1] Superbeam calculats the mid span deflection at just under 10mm, with
a maximum allowed of just under 11mm at that span. This assumes C16
timber in a load sharing arragement.

Use noggins if you want to but it's unlikely he'll re-check


In this situation even with the wall load shared between two joists you
are going to be out of spec, since you are quite close to the limit as
it is, without the wall.

The normal solution here would be to stick another joist beside it and
bolt them together with timber connectors and plate washers.



My present situation is that the BCO implied he would accept noggins
every 400mm but it looks that the "norm" should be another joist!
I have just measured the total width of the room and it is 3.9 metres
wide (stud will be 2.9m).
My big problem is fitting a new joist. I have several ring main cables
running through the joist, and 2 heating pipes on the top of it!

If I did bolt another joist on to it would I have to support it on
hangers at each end?
The second joist would still not quite be under the stud wall so would I
also need noggins between the joists?

Is there anywhere which gives weight of a square metre of various stud
constructions as different peoples estimates seem very different!?

I think I will ask the BCO (in writing) if he can confirm he would
accept 400mm noggins or if I must get the calculations done.
He did imply he would accept noggins!!

Thanks

Peter Hemmings wrote:

My present situation is that the BCO implied he would accept noggins
every 400mm but it looks that the "norm" should be another joist!
I have just measured the total width of the room and it is 3.9 metres
wide (stud will be 2.9m).

With the 2.9m wall at one end of the 3.9m joist I take it?

My big problem is fitting a new joist. I have several ring main cables
running through the joist, and 2 heating pipes on the top of it!

The cables could be either be cut and reconnected after the joist is in,
or you may find a socket close enough to disconnect them at temporarily.

You may find The joist can be positioned while laying on its side and
then rotated into position - which may help solve the pipe problem.

If I did bolt another joist on to it would I have to support it on
hangers at each end?

Probably - they don't like to see joists sat in cut out sections of wall
these days. How is the current one supported?

The second joist would still not quite be under the stud wall so would I
also need noggins between the joists?

Ideally, unless is it at leat partially over the joist.

Is there anywhere which gives weight of a square metre of various stud
constructions as different peoples estimates seem very different!?

Well weights for plasterboard can be got from the manufacturers sites:

http://www.british-gypsum.bpb.com/pr...wallboard.aspx
http://tinyurl.com/quzve

Bags of plaster are easy to calculate, so that just leaves the wood,
which you could estimate from density as I did, or stick a bit on the
scales and see! ;-)

I think I will ask the BCO (in writing) if he can confirm he would
accept 400mm noggins or if I must get the calculations done.
He did imply he would accept noggins!!

I think I would also be inclined to think through how the loading will
be imposed in reality. If the wall will form (for example) the side of a
shower room, and there is unlikely to be furniture placed against it on
either side, then the assumptions made for its designed floor load will
tend to be overly pessimistic. Hence using much of the design capacity
to carry a wall instead of floor loading is unlikely to result in any
problems. If however you were going to stick a run of heavy wardrobes
against the wall, then I would probably go with a new joist and
noggings, or two new joists directly under the wall.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
Peter Hemmings wrote:

My present situation is that the BCO implied he would accept noggins
every 400mm but it looks that the "norm" should be another joist!
I have just measured the total width of the room and it is 3.9 metres
wide (stud will be 2.9m).


With the 2.9m wall at one end of the 3.9m joist I take it?

Yep

My big problem is fitting a new joist. I have several ring main
cables running through the joist, and 2 heating pipes on the top of it!


The cables could be either be cut and reconnected after the joist is in,
or you may find a socket close enough to disconnect them at temporarily.


Yep but I like to try and not put in any junction boxes!


You may find The joist can be positioned while laying on its side and
then rotated into position - which may help solve the pipe problem.

If I did bolt another joist on to it would I have to support it on
hangers at each end?


Probably - they don't like to see joists sat in cut out sections of wall
these days. How is the current one supported?

50's semi, real solid walls with joists into wall!


The second joist would still not quite be under the stud wall so would
I also need noggins between the joists?


Ideally, unless is it at leat partially over the joist.


OK

Is there anywhere which gives weight of a square metre of various stud
constructions as different peoples estimates seem very different!?


Well weights for plasterboard can be got from the manufacturers sites:

http://www.british-gypsum.bpb.com/pr...wallboard.aspx

http://tinyurl.com/quzve


OK

Bags of plaster are easy to calculate, so that just leaves the wood,
which you could estimate from density as I did, or stick a bit on the
scales and see! ;-)

I think I will ask the BCO (in writing) if he can confirm he would
accept 400mm noggins or if I must get the calculations done.
He did imply he would accept noggins!!


I think I would also be inclined to think through how the loading will
be imposed in reality. If the wall will form (for example) the side of a
shower room, and there is unlikely to be furniture placed against it on
either side, then the assumptions made for its designed floor load will
tend to be overly pessimistic. Hence using much of the design capacity
to carry a wall instead of floor loading is unlikely to result in any
problems. If however you were going to stick a run of heavy wardrobes
against the wall, then I would probably go with a new joist and
noggings, or two new joists directly under the wall.


When you say design floor load, is this all calculated (set) in the
"super Beam" S/W, surely the loadings would be different for each type
of room?
I was going to download a trial version and see what it produced but #I
thought I would get some facts and advice first!

I my youth (a very very long time ago) I did study mechanics and
moments on beams! I thought that the as there were several joists
crossed by T&G boards the loading would be spread across the floor, I
assume the S/W will take this into consideration!?

Well, I will only have an ordinary bed against it and nothing at all on
the stud (sink and radiator will be on the existing brick wall).

Thanks for the information

Peter Hemmings wrote:

I think I would also be inclined to think through how the loading will
be imposed in reality. If the wall will form (for example) the side of
a shower room, and there is unlikely to be furniture placed against it
on either side, then the assumptions made for its designed floor load
will tend to be overly pessimistic. Hence using much of the design
capacity to carry a wall instead of floor loading is unlikely to
result in any problems. If however you were going to stick a run of
heavy wardrobes against the wall, then I would probably go with a new
joist and noggings, or two new joists directly under the wall.


When you say design floor load, is this all calculated (set) in the
"super Beam" S/W, surely the loadings would be different for each type
of room?

The actual loadings are not set in SB, you need to specify those... You
can also specify if a load is a uniform one acting over all or part of a
beam, or a point load, or even a varing load. There are a number of
"standard" floor loadings that are typically used. For a domestic
property; 0.8kN/m uniformly spread on a joist is a common loading to use.

I was going to download a trial version and see what it produced but #I
thought I would get some facts and advice first!

I my youth (a very very long time ago) I did study mechanics and
moments on beams! I thought that the as there were several joists
crossed by T&G boards the loading would be spread across the floor, I
assume the S/W will take this into consideration!?

Yes you can specify the number of joists acting together, including so
called "load sharing".

Well, I will only have an ordinary bed against it and nothing at all on
the stud (sink and radiator will be on the existing brick wall).

Hence why the BCO is letting you "get away" with noggings between two
joists! (if you have a play with SB you will see that your existing
joists are pretty close to the design limit just carrying the floor).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Peter Hemmings wrote:

Hi,

Just had interesting discussion with BCO (see my Part P mail today) and
I am erecting a stud wall in a bedroom in line with joists but about 3
inches into the 14 inch void. The stud is attached to another wall at
one end and it will be about 12 foot long (sorry for old units but its a
50's house).
The BCO is not happy with me putting 4x2 studding between the joists
which are 7x2 inches. He advised my to get a structural engineer to
check what extra support was required and implied noggins every 400mm.
He also said I might be able to get "Super Beam" software on Trial to
calculate loadings.

I had already decided to put in some noggins but would appreciate any
advice as to what size and spacings would generally be suitable.

The posts so far appear to imply that the stud wall will be an even
loading on the floor structure below it, but it wont. A stud wall is a
relatively rigid wooden structure fixed top, bottom and both ends, and
as such a fair bit of the the weight will be borne by the end fixings,
since the stud structure will reisst bending (sag). And some of the
weight will be carried by the top fixings too. And finally, the wood at
the bottom supoprting the remaining forces is not just the flooring
joist, but flooring joist + floor + wall sole plate.

This is why in practice stud walls sitting on floorboards on 6"
flooring joists work fine.


NT

John Rumm wrote:
Peter Hemmings wrote:

I think I would also be inclined to think through how the loading
will be imposed in reality. If the wall will form (for example) the
side of a shower room, and there is unlikely to be furniture placed
against it on either side, then the assumptions made for its designed
floor load will tend to be overly pessimistic. Hence using much of
the design capacity to carry a wall instead of floor loading is
unlikely to result in any problems. If however you were going to
stick a run of heavy wardrobes against the wall, then I would
probably go with a new joist and noggings, or two new joists directly
under the wall.


When you say design floor load, is this all calculated (set) in the
"super Beam" S/W, surely the loadings would be different for each type
of room?


The actual loadings are not set in SB, you need to specify those... You
can also specify if a load is a uniform one acting over all or part of a
beam, or a point load, or even a varing load. There are a number of
"standard" floor loadings that are typically used. For a domestic
property; 0.8kN/m uniformly spread on a joist is a common loading to use.

I was going to download a trial version and see what it produced but
#I thought I would get some facts and advice first!

I my youth (a very very long time ago) I did study mechanics and
moments on beams! I thought that the as there were several joists
crossed by T&G boards the loading would be spread across the floor, I
assume the S/W will take this into consideration!?


Yes you can specify the number of joists acting together, including so
called "load sharing".

Well, I will only have an ordinary bed against it and nothing at all
on the stud (sink and radiator will be on the existing brick wall).


Hence why the BCO is letting you "get away" with noggings between two
joists! (if you have a play with SB you will see that your existing
joists are pretty close to the design limit just carrying the floor).



I have asked the BCO to confirm in writing that noggins would be
acceptable and went to a local "Engineer" to try for some more free advice.
I found that he also advises the local BO and knows the BCO - my big
foot in it I think!
He states that the joists would be insufficient for the existing span
(just over 4m) and I would probably need another joist bolted on plus
noggins!

And, for this to be calculated and give recommendations he would need
to visit and his cost would be £200 approx! I can seen my budget
rapidly rising ATM.

Because of "Er in Doors" refusing to have the floor cut up and having to
re-do the plumbing and electrics this project may well be floundering!

I did manage to talk through possible solutions with the Engineer before
he showed me the door! He thought the preferred method would be extra
bolt on joist with noggins (but needed to check existing wood quality
and shear stresses!).

He ruled out extra plates each side of the joist because of the extra
loading, but said a split steel under the stud should also be OK.
I understand one of the "standard" steel sizes is within 1mm of my 7"x2"
joists.

If I have to pick an option I will probably pick the steel as the floor
span already flexes slightly when bouncing up and down on the bed (as
can be seen in the wardrobe mirror)!!!!
(please excuse any wrong terminology).

Just in case I do pursue this:
how would I run 22mm copper pipe through a steel?
how do I secure a floor board to a steel ie I want a removable board for
access inside the en-suite which finishes at the stud which would be
over the steel, I assume a piece of wood is fitted at the side of the
"H" section?

Any other comments?

Thanks

Peter Hemmings wrote:

Hence why the BCO is letting you "get away" with noggings between two
joists! (if you have a play with SB you will see that your existing
joists are pretty close to the design limit just carrying the floor).


I have asked the BCO to confirm in writing that noggins would be
acceptable and went to a local "Engineer" to try for some more free advice.
I found that he also advises the local BO and knows the BCO - my big
foot in it I think!
He states that the joists would be insufficient for the existing span
(just over 4m) and I would probably need another joist bolted on plus
noggins!

When I stuck your existing figures into SB then it looked to be right on
the limit - but that was using the 3.6m span you mentioned in an earlier
post. If it is 3.9m then it is already a bit too bendy for a current
design.

And, for this to be calculated and give recommendations he would need
to visit and his cost would be £200 approx! I can seen my budget
rapidly rising ATM.

Seeing as he will probably look, then go model it in SB and print the
results out for you, it would be cheaper to buy the full version of SB
and DIY!

Because of "Er in Doors" refusing to have the floor cut up and having to
re-do the plumbing and electrics this project may well be floundering!

Doubt she will be doing the plumbing though ;-)

I did manage to talk through possible solutions with the Engineer before
he showed me the door! He thought the preferred method would be extra
bolt on joist with noggins (but needed to check existing wood quality
and shear stresses!).

In reality that ought to be more than good enough. Especially as you
know the real floor load will be significantly less than a typical
design load.

However the slight difficulty is that your current joists don't quite
meet regulations for their span. Since the wall is imposing a similar
load to the floor[2] (for the purposes of the calcaulations) that is
also just out of spec with the extra joist. You could however argue that
the extra timber in the sole and top plates of the wall will more than
compensate.

[2] What NT's post says about the extra stiffness from the sole and top
plates of the wall is true, but a 3x2 "side on" over that span does not
add much. You will have little if any fixing to the ceiling either I
would have thought, and only one end is fixed to a wall.

Another solution is to build the wall just a little lighter - say using
9mm PB intead of 12.5mm. Perhaps even just taping and filling rather
than skimming would be enough reduction.

He ruled out extra plates each side of the joist because of the extra
loading, but said a split steel under the stud should also be OK.
I understand one of the "standard" steel sizes is within 1mm of my 7"x2"
joists.

If I have to pick an option I will probably pick the steel as the floor
span already flexes slightly when bouncing up and down on the bed (as
can be seen in the wardrobe mirror)!!!!

Ooo Err! ;-)

Another solution for eliminating the bounce is to add herringbone
bracing across the centre span of the joists - that makes quite a
difference to the stiffness of a floor. You can either do it with
traditional wodden braces, or you can get steel straps ready made for
the job you just nail into place.

Just in case I do pursue this:
how would I run 22mm copper pipe through a steel?

With difficulty!

If you need to use steel, the first option to consider would be a flitch
beam - i.e. another wood joist beside the current one with a steel plate
sandwiched between them. This way you could use a flitch plate that is
only 75% of the height of the joist, leaving enough space to get a pipe
past (although in the non preferred notching method!). In fact a quick
play with SD suggests that a 6mm thick half height flitch plate might be
good enough.

Another option would be some form of composite wood beam of the type
with top and bottom rails and a ply web in the centre - these are easy
to take services through. Not sure they come out much stronger though.
Some of the makers web sites will do the calcs for you.

You would also perhaps cope if you specified an extra joist - but make
it a 7x3" and specify C24 timber.

how do I secure a floor board to a steel ie I want a removable board for
access inside the en-suite which finishes at the stud which would be
over the steel, I assume a piece of wood is fitted at the side of the
"H" section?

Spose - not had to use steel like this before. You would probably need
to bolt or nail[1] a wood plate to the side of the steel to pick up the
floor.


[1] apparently common practice with a suitable explosive cartridge nailer!

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

I you subtract the load supported at each end of the wall by the
current wall, is there enough leeway to put a beam/large purlin above
the wall, and have a hanging wall? Only reasonable if it is easy to put
a beam in the loft.



John Rumm wrote:
Peter Hemmings wrote:

Hence why the BCO is letting you "get away" with noggings between two
joists! (if you have a play with SB you will see that your existing
joists are pretty close to the design limit just carrying the floor).


I have asked the BCO to confirm in writing that noggins would be
acceptable and went to a local "Engineer" to try for some more free advice.
I found that he also advises the local BO and knows the BCO - my big
foot in it I think!
He states that the joists would be insufficient for the existing span
(just over 4m) and I would probably need another joist bolted on plus
noggins!

When I stuck your existing figures into SB then it looked to be right on
the limit - but that was using the 3.6m span you mentioned in an earlier
post. If it is 3.9m then it is already a bit too bendy for a current
design.

And, for this to be calculated and give recommendations he would need
to visit and his cost would be £200 approx! I can seen my budget
rapidly rising ATM.

Seeing as he will probably look, then go model it in SB and print the
results out for you, it would be cheaper to buy the full version of SB
and DIY!

Because of "Er in Doors" refusing to have the floor cut up and having to
re-do the plumbing and electrics this project may well be floundering!

Doubt she will be doing the plumbing though ;-)

I did manage to talk through possible solutions with the Engineer before
he showed me the door! He thought the preferred method would be extra
bolt on joist with noggins (but needed to check existing wood quality
and shear stresses!).

In reality that ought to be more than good enough. Especially as you
know the real floor load will be significantly less than a typical
design load.

However the slight difficulty is that your current joists don't quite
meet regulations for their span. Since the wall is imposing a similar
load to the floor[2] (for the purposes of the calcaulations) that is
also just out of spec with the extra joist. You could however argue that
the extra timber in the sole and top plates of the wall will more than
compensate.

[2] What NT's post says about the extra stiffness from the sole and top
plates of the wall is true, but a 3x2 "side on" over that span does not
add much. You will have little if any fixing to the ceiling either I
would have thought, and only one end is fixed to a wall.

Another solution is to build the wall just a little lighter - say using
9mm PB intead of 12.5mm. Perhaps even just taping and filling rather
than skimming would be enough reduction.

He ruled out extra plates each side of the joist because of the extra
loading, but said a split steel under the stud should also be OK.
I understand one of the "standard" steel sizes is within 1mm of my 7"x2"
joists.

If I have to pick an option I will probably pick the steel as the floor
span already flexes slightly when bouncing up and down on the bed (as
can be seen in the wardrobe mirror)!!!!

Ooo Err! ;-)

Another solution for eliminating the bounce is to add herringbone
bracing across the centre span of the joists - that makes quite a
difference to the stiffness of a floor. You can either do it with
traditional wodden braces, or you can get steel straps ready made for
the job you just nail into place.

Just in case I do pursue this:
how would I run 22mm copper pipe through a steel?

With difficulty!

If you need to use steel, the first option to consider would be a flitch
beam - i.e. another wood joist beside the current one with a steel plate
sandwiched between them. This way you could use a flitch plate that is
only 75% of the height of the joist, leaving enough space to get a pipe
past (although in the non preferred notching method!). In fact a quick
play with SD suggests that a 6mm thick half height flitch plate might be
good enough.

Another option would be some form of composite wood beam of the type
with top and bottom rails and a ply web in the centre - these are easy
to take services through. Not sure they come out much stronger though.
Some of the makers web sites will do the calcs for you.

You would also perhaps cope if you specified an extra joist - but make
it a 7x3" and specify C24 timber.

how do I secure a floor board to a steel ie I want a removable board for
access inside the en-suite which finishes at the stud which would be
over the steel, I assume a piece of wood is fitted at the side of the
"H" section?

Spose - not had to use steel like this before. You would probably need
to bolt or nail[1] a wood plate to the side of the steel to pick up the
floor.


[1] apparently common practice with a suitable explosive cartridge nailer!

--
Cheers,

John.

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nafuk wrote:
I you subtract the load supported at each end of the wall by the
current wall, is there enough leeway to put a beam/large purlin above
the wall, and have a hanging wall? Only reasonable if it is easy to put
a beam in the loft.


If you put a diagonal strut or 2 in the partition you can turn it into
a load bearing truss - even supporting the floors above and below if
necessary. Your BCO might need calcs though as he is obviously a ****.
I put a heavy stud partition in my chapel conversiion, between the
joists jsut on the floorboards. 12ft by 11ft high, with heavy fire
door in the middle. No probs. Slight hairline crack at ceiling junction
but no worse than normal shrinkage.

cheers
Jacob

John Rumm wrote:

[2] What NT's post says about the extra stiffness from the sole and top
plates of the wall is true, but a 3x2 "side on" over that span does not
add much.


Sure, but the stud wall contributes twice that, as you've got sole
_and_ header plate connected to each other by lots of uprights. On
borderline floor loads this might be enough to tip the scales.

Next possible move is to make your floor joist, floor and soleplate one
item structurally by gluing and screwing every 6", so youve effectively
got significantly deeper woodwork there.

Then if the top is close enough to a ceiling joist to get a purchase up
there, youve got more woodwork you can get into the equation.

You will have little if any fixing to the ceiling either I
would have thought, and only one end is fixed to a wall.

If it lines up with a joist, all is well. If not but its close one can
sometimes use small thick metal L brackets receessed a few mm into the
ceiling plaster to reach a joist. Noggins are also an option, but make
more mess above.

I also like Jacob's / Norman's idea of supporting the stud wall off the
walls by using triangular woodwork.

Using all these tricks should get you a fair way, and paperwork is
easier than joist replacement.


NT

wrote:
John Rumm wrote:

[2] What NT's post says about the extra stiffness from the sole and top
plates of the wall is true, but a 3x2 "side on" over that span does not
add much.


Sure, but the stud wall contributes twice that, as you've got sole
_and_ header plate connected to each other by lots of uprights. On
borderline floor loads this might be enough to tip the scales.

And you could use bigger wood of course.


NT

normanwisdom wrote:
nafuk wrote:

I you subtract the load supported at each end of the wall by the
current wall, is there enough leeway to put a beam/large purlin above
the wall, and have a hanging wall? Only reasonable if it is easy to put
a beam in the loft.



If you put a diagonal strut or 2 in the partition you can turn it into
a load bearing truss - even supporting the floors above and below if
necessary. Your BCO might need calcs though as he is obviously a ****.
I put a heavy stud partition in my chapel conversiion, between the
joists jsut on the floorboards. 12ft by 11ft high, with heavy fire
door in the middle. No probs. Slight hairline crack at ceiling junction
but no worse than normal shrinkage.

Good idea, although would that not require the wall to be supported at
both ends though? By the sounds of this wall it does not span the room.

--
Cheers,

John.

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| John Rumm - john(at)internode(dot)co(dot)uk |
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