Hi all,

I've got another joist question that I'd appreciate a few comments on,
totally separate to my various 'loft' posts.

Basically, in case you hadn't already read in another post, the back of our
upstairs flat currently has it's exit to the rear yard downstairs, i.e. the
stairs are inside the flat and eat up a fair portion of, what will become,
our new kitchen. The plan is to move the door from downstairs to upstairs
and bolt a new metal fire escape on the back of the house. I can then fit a
new floor where the stairs used to be and all will be dandy.

Well, after a weekend of knocking various holes in walls to see how the
joists run, this would appear to be the situation:-
http://www.pciq.co.uk/pics/joists1.gif

Now, obviously I need to somehow put a floor where the current staircase is,
however I have a number of dilemmas:-

1. I can't disturb the existing floor joists since they support our
downstairs neighbour's ceiling and I don't really want to be stung for a
replastering bill.

2. Joist A would appear to be supporting half (?) of the weight of the
current floor and ceiling via Joist B, so I don't want to put any extra
weight on Joist A OR B, which rules out simply shoving some new joists in
and hanging between the wall and Joist B.

3. Likewise, I can't really run a couple of longer new joists perpendicular
to the existing joists, suspended between the back wall and Joist A, since
again I would imagine Joist A would be supporting too much weight.

4. I can't up-rate Joist A with steel on the back, since there's a concrete
floor behind it.


SO, the only thing I can think of is to do this:-
http://www.pciq.co.uk/pics/joists2.gif

Basically, I'll install a temporary joist from the back wall to the concrete
floor and fasten the existing joists to this using twisted restraint strap.
This should provide enough support to stop the ceiling from collapsing while
I remove Joist B. I'll then just bolt new joists to the existing joists and
remove the temporary joist once everything is secure.

Can anyone think of any problems with this or does anyone have any better
ideas?

All of the joists in question are 65 x 175mm and the span from left to right
is 2370mm. I tried downloading SuperBeam but it makes no sense. :-)

As a side note, if a joist hanger isn't quite at the right height, which of
course it will be, what's the best way of 'packing' between the joist hanger
and the joist to bring the joist up to the perfect height? Slate?

Anyway, cheers again in advance!

Andy
new SDS drill has just arrived... REALLY feel the need to damage
something...

The plan is to move the door from downstairs to upstairs
and bolt a new metal fire escape on the back of the house.

What terms are you on with downstairs? They might be willing to let you (a)
prop up the joists and (b) pay you some dosh, if you sell them the
downstairs portion of the staircase.

Christian.

In article , Pecanfan wrote:
Basically, I'll install a temporary joist from the back wall to the
concrete floor and fasten the existing joists to this using twisted
restraint strap. This should provide enough support to stop the
ceiling from collapsing while I remove Joist B. I'll then just
bolt new joists to the existing joists and remove the temporary
joist once everything is secure.
Can anyone think of any problems with this or does anyone have any
better ideas?

All of the joists in question are 65 x 175mm and the span from left
to right is 2370mm.

That all sounds quite sensible, although it would save time if your
neighbour downstairs would allow some temporary propping while you
removed trimmer joist B. Where you bolt the old and new joists
together I would want to see large square washers under the bolt heads
and nuts with double sided toothed washers in the join. The bolt
size/spacing does need to be checked for adequacy.

I tried downloading SuperBeam but it makes no sense. :-)

Will you forgive me not adding this to the quotes on our website g

--
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Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

What terms are you on with downstairs?

Well, not great. We've just moved in and they're moving out so aren't keen
on me doing ANY building work while their house is on the market. On top of
this, we're swapping the bathroom and kitchen over and they're not at all
happy about having a bathroom above their spare bedroom (which is actually
their main bedroom) - although it'll be fully soundproofed, damp-proofed and
all plumbing will be running above the floor - and the alternative is a
KITCHEN!! God damn it... Deep breaths...

prop up the joists and (b) pay you some dosh, if you sell them the
downstairs portion of the staircase.

By the time we've got planning and b.regs through for the new staircase we
*might* have some new neighbours who might be a bit more accommodating -
having said that, we're considering using the underfloor void as some sort
of beer storage area. :-) Having said that, some extra cash towards the
refurb wouldn't go a miss!

Andy

By the time we've got planning and b.regs through for the new staircase we
*might* have some new neighbours who might be a bit more accommodating -
having said that, we're considering using the underfloor void as some sort
of beer storage area. :-) Having said that, some extra cash towards the
refurb wouldn't go a miss!

Personally, I'd consider waiting, if the flat sale is likely to be imminent.
However, I suppose the sale part could occur after your side of the
conversion.

Christian.

By the time we've got planning and b.regs through for the new staircase
we
*might* have some new neighbours who might be a bit more accommodating -
having said that, we're considering using the underfloor void as some
sort
of beer storage area. :-) Having said that, some extra cash towards the
refurb wouldn't go a miss!

Have you got the freeholder's consent?


I've checked with our solicitor and we shouldn't need the freeholder's (i.e.
the owners of the downstairs flat) consent.

Andy

In article , Pecanfan wrote:
By the time we've got planning and b.regs through for the new staircase we
*might* have some new neighbours who might be a bit more accommodating -
having said that, we're considering using the underfloor void as some sort
of beer storage area. :-) Having said that, some extra cash towards the
refurb wouldn't go a miss!

Have you got the freeholder's consent?

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

In an earlier contribution to this discussion,
Pecanfan wrote:

Hi all,

I've got another joist question that I'd appreciate a few comments on,
totally separate to my various 'loft' posts.

Basically, in case you hadn't already read in another post, the back
of our upstairs flat currently has it's exit to the rear yard
downstairs, i.e. the stairs are inside the flat and eat up a fair
portion of, what will become, our new kitchen. The plan is to move
the door from downstairs to upstairs and bolt a new metal fire escape
on the back of the house. I can then fit a new floor where the
stairs used to be and all will be dandy.

Well, after a weekend of knocking various holes in walls to see how
the joists run, this would appear to be the situation:-
http://www.pciq.co.uk/pics/joists1.gif

Now, obviously I need to somehow put a floor where the current
staircase is, however I have a number of dilemmas:-

1. I can't disturb the existing floor joists since they support our
downstairs neighbour's ceiling and I don't really want to be stung
for a replastering bill.

2. Joist A would appear to be supporting half (?) of the weight of
the current floor and ceiling via Joist B, so I don't want to put any
extra weight on Joist A OR B, which rules out simply shoving some new
joists in and hanging between the wall and Joist B.

3. Likewise, I can't really run a couple of longer new joists
perpendicular to the existing joists, suspended between the back wall
and Joist A, since again I would imagine Joist A would be supporting
too much weight.

4. I can't up-rate Joist A with steel on the back, since there's a
concrete floor behind it.


SO, the only thing I can think of is to do this:-
http://www.pciq.co.uk/pics/joists2.gif

Basically, I'll install a temporary joist from the back wall to the
concrete floor and fasten the existing joists to this using twisted
restraint strap. This should provide enough support to stop the
ceiling from collapsing while I remove Joist B. I'll then just bolt
new joists to the existing joists and remove the temporary joist once
everything is secure.

Can anyone think of any problems with this or does anyone have any
better ideas?

All of the joists in question are 65 x 175mm and the span from left
to right is 2370mm. I tried downloading SuperBeam but it makes no
sense. :-)

As a side note, if a joist hanger isn't quite at the right height,
which of course it will be, what's the best way of 'packing' between
the joist hanger and the joist to bring the joist up to the perfect
height? Slate?

Anyway, cheers again in advance!

Andy
new SDS drill has just arrived... REALLY feel the need to damage
something...

I think I would be looking to double up Joist B, rather than removing it -
and then put some new joists from B2 across the stair void. What is the
thickness and level of the concrete floor behind Joist A? Could you bolt A
to the concrete, and thus make it able to support one end of B2?

As others have suggested, you may have some negotiation scope with the
downstairs owners (new if not current) concerning what happens to the space
currently occupied by the stairs.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

I think I would be looking to double up Joist B, rather than removing it -
and then put some new joists from B2 across the stair void. What is the
thickness and level of the concrete floor behind Joist A? Could you bolt A
to the concrete, and thus make it able to support one end of B2?


The concrete floor section is at the same level as the floorboards covering
the joists. I have no idea how thick it is though. I also have no idea how
it's held up so I'm slightly nervous about relying on it for support. It's
a 1900's terraced flat and I didn't even know they had concrete back then!

Andy

In an earlier contribution to this discussion,
Pecanfan wrote:

I think I would be looking to double up Joist B, rather than
removing it - and then put some new joists from B2 across the stair
void. What is the thickness and level of the concrete floor behind
Joist A? Could you bolt A to the concrete, and thus make it able to
support one end of B2?


The concrete floor section is at the same level as the floorboards
covering the joists. I have no idea how thick it is though. I also
have no idea how it's held up so I'm slightly nervous about relying
on it for support. It's a 1900's terraced flat and I didn't even
know they had concrete back then!

Andy

Have you asked yout tame structural engineer for advice?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Pecanfan wrote:

SO, the only thing I can think of is to do this:-
http://www.pciq.co.uk/pics/joists2.gif

Rather than trying to extend the existing joists beside the stairs, I
would be tempted to strengthen A (and B if required) to allow you to do
the more "natural" additon of new joists over the stairwell.

You may find that you could insert a temporary joist parallel to A but
say 6" away from it, and then fix B to it. Then cut B a couple of inches
short of A and insert a new joist beside A and bolt it to the existing
A. Now rehang B back onto the strengthened A. If B is not up to carrying
the extra load over the stairs then you could also double this at that
stage. Finally hand the new joists over the stairwell from B to the wall.

--
Cheers,

John.

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

The concrete floor section is at the same level as the floorboards
covering the joists. I have no idea how thick it is though. I also
have no idea how it's held up so I'm slightly nervous about relying
on it for support. It's a 1900's terraced flat and I didn't even
know they had concrete back then!

Andy

Have you asked yout tame structural engineer for advice?

Not on this one (yet) - but if he comes out again to measure up for the loft
I might pick his brains a bit more...

Andy

SO, the only thing I can think of is to do this:-
http://www.pciq.co.uk/pics/joists2.gif

Rather than trying to extend the existing joists beside the stairs, I
would be tempted to strengthen A (and B if required) to allow you to do
the more "natural" additon of new joists over the stairwell.

You may find that you could insert a temporary joist parallel to A but
say 6" away from it, and then fix B to it. Then cut B a couple of inches
short of A and insert a new joist beside A and bolt it to the existing
A. Now rehang B back onto the strengthened A. If B is not up to carrying
the extra load over the stairs then you could also double this at that
stage. Finally hand the new joists over the stairwell from B to the wall.


Mmm... but, how can I insert a temporary joist parallel to A but 6" away
from it without cutting B first (and our neighbour's ceiling falling down)?
Or have I totally missed the point? :-)

Oh hold on, do you mean a temporary joist above the floor and strap it onto
B to hold it up temporarily while I cut the end of it?

Wouldn't you still be relying on a strengthened Joist A to support 1/2 of
the entire floor weight?

Andy

Pecanfan wrote:

Mmm... but, how can I insert a temporary joist parallel to A but 6" away
from it without cutting B first (and our neighbour's ceiling falling down)?
Or have I totally missed the point? :-)

Oh hold on, do you mean a temporary joist above the floor and strap it onto
B to hold it up temporarily while I cut the end of it?

Yup - that is what I was thinking...

Wouldn't you still be relying on a strengthened Joist A to support 1/2 of
the entire floor weight?

That is not far from the situation you currently have (looking at your
original diagram) since the floor joists hang off B which in turn hangs
of A - so A is taking half the full floor load, plus possibly half the
stair load (the wall at the other end of B taking the other half of the
floor load).

If you double the strength of A, then one ought to expect it would be
able to take the additional weight of the other half of the floor. In
reality it will not be as extream as "other half", since if your drawing
is roughly to scale, thent the stair area is less than the existing
floor area, and also you would be loosing the load of the stairs.

--
Cheers,

John.

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

Just as an aside, and after reading all of the posts in this thread...

I hope that you have adequate Public Liability Insurance!

If you start tinkering with the removal of these joists (even though you
take adequate precautions etc.) and the ceiling caves in on the downstairs
flat (hopefully while the people are out...) there'll be HELL to pay! If
they're in at the time, you might have to pay the next-of-kin!!!

Also, as someone else pointed out - but I don't think you realised his
point, are you the Freeholder of your flat? You can be the owner but not own
the Freehold - in which case you are a Leaseholder. If you are a Leaseholder
you will need to obtain the permission of the Lessor to make the alterations
(which you prolly won't get), and if you do there could be a clause to "make
good" before you sell - which means putting it back the way it was
originally! That may prove difficult if you've already sold the staircase
space.

--

Reply address is spamtrapped. Remove theobvious for valid e-mail address

Just as an aside, and after reading all of the posts in this thread...
I hope that you have adequate Public Liability Insurance!
If you start tinkering with the removal of these joists (even though you
take adequate precautions etc.) and the ceiling caves in on the downstairs
flat (hopefully while the people are out...) there'll be HELL to pay! If
they're in at the time, you might have to pay the next-of-kin!!!

Surely you could say that for just about any DIY job? There's always an
element of risk - you could plumb a bath in and flood downstairs, build a
new fence and it falls on your neighbour's dog etc etc. ...and I'm pretty
sure public liability insurance wouldn't be applicable in a case such as
this. If I were employing builders to do the work *they'd* need to have
public liability insurance.

It will also be physically impossible for the ceiling to cave in.

Also, as someone else pointed out - but I don't think you realised his
point, are you the Freeholder of your flat? You can be the owner but not
own
the Freehold - in which case you are a Leaseholder. If you are a
Leaseholder
you will need to obtain the permission of the Lessor to make the
alterations
(which you prolly won't get), and if you do there could be a clause to
"make
good" before you sell - which means putting it back the way it was
originally! That may prove difficult if you've already sold the staircase
space.

As I said, "I've checked with our solicitor and we shouldn't need the
freeholder's (i.e. the owners of the downstairs flat) consent.". It's a
standard terraced flat agreement whereby the upper flat owns the freehold to
the lower flat and the leasehold to the upper flat; the lower flat owns the
freehold to the upper flat and the leasehold to the lower flat. This
agreement is in place to simplify maintenance between the two flats etc.
It's not designed to wrap simple building work in red tape.

Andy

In article , Pecanfan wrote:
As I said, "I've checked with our solicitor and we shouldn't need
the freeholder's (i.e. the owners of the downstairs flat)
consent.". It's a standard terraced flat agreement whereby the
upper flat owns the freehold to the lower flat and the leasehold
to the upper flat; the lower flat owns the freehold to the upper
flat and the leasehold to the lower flat. This agreement is in
place to simplify maintenance between the two flats etc. It's not
designed to wrap simple building work in red tape.

Well yes, but I would argue that this is not 'simple' in the sense
that it does significantly alter your flat and if done wrongly would
impact on the flat below. When you sell you will be asked whether
you have made alterations and asked whether you obtained any
necessary statutory consents and the freeholder's approval.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

"Paul King" wrote in message . ..
Just as an aside, and after reading all of the posts in this thread...

I hope that you have adequate Public Liability Insurance!

If you start tinkering with the removal of these joists (even though you
take adequate precautions etc.) and the ceiling caves in on the downstairs
flat (hopefully while the people are out...) there'll be HELL to pay! If
they're in at the time, you might have to pay the next-of-kin!!!

Also, as someone else pointed out - but I don't think you realised his
point, are you the Freeholder of your flat? You can be the owner but not own
the Freehold - in which case you are a Leaseholder. If you are a Leaseholder
you will need to obtain the permission of the Lessor to make the alterations
(which you prolly won't get), and if you do there could be a clause to "make
good" before you sell - which means putting it back the way it was
originally! That may prove difficult if you've already sold the staircase
space.



I see a series of issues here.

Firstly the floor structure will presumably be covered by the party
wall act, so if your neighbour doesnt want any work doing that will
add a couple of grand of legal costs, plus dictate how you do the
work, which can again add costs.

Secondly I dont like your propsed beam extensions at all. The wood
thats there is sized for the half run, significantly bigger would be
wanted for double the run. Also how you propose to tie the 2 might
weaken the structure.

3rd I think it would really help to understand what the problem is:
its not so much collapse, but sag. Wood can sag by a foot or more over
a 20' run without breaking. Joists are sized to limit sag. Sag causes
cracking of plaster ceilings, which are not very flexible.

Rather than try to extend the beams, which would certainly result in
the ceiling breaking up, my first thought would be to remove joist B
entirely (using temp support of course) and put new joists running
full width alongside the old ones, without removing the old ones, and
attach old and new securely together. BUT do not do this unless you
consult a struc eng who says its ok in your particular case to do it,
as it might not be.

There is one more issue: I dont know what size the joists are now, nor
what build regs says about you doing this, but you might possibly find
that to conform to BRs you'd need to put bigger wood in that is there
presently. If you should get caught in this trap, theres always
steelwork, flitch beams, hardwood, etc.


Regards, NT

Thanks for the reply - please see comments below:-

I see a series of issues here.

Firstly the floor structure will presumably be covered by the party
wall act, so if your neighbour doesnt want any work doing that will
add a couple of grand of legal costs, plus dictate how you do the
work, which can again add costs.

Without getting into the technicalities of the Party Wall Act, I'm kind of
hoping the neighbour doesn't object since the impact will be negligible. I
will be serving notice under the act but, by my understanding anyway, the
Act is more biased towards the owner doing the building work as opposed to
the objector - i.e. even if they do object there's not a lot they can do
about it without getting an injunction... I could be TOTALLY wrong here
though so please, anyone, don't take this as gospel! :-)


Secondly I dont like your propsed beam extensions at all. The wood
thats there is sized for the half run, significantly bigger would be
wanted for double the run. Also how you propose to tie the 2 might
weaken the structure.

As mentioned in the OP, the current joists are 65 x 175mm (2.5" x 7") - the
same size as all the joists in the house, some of which span 3 or 4 times
the width proposed. I'll probably eat my words, but I really don't see it
as being much of a problem. Especially since there's currently a bath,
toilet and sink resting on said joists and, following the building work,
there will be nothing resting on said joists.


Rather than try to extend the beams, which would certainly result in
the ceiling breaking up...

Erm... 'it would certainly result in the ceiling breaking up'... are you
sure about this? Since posting this I've had building control and a
structural engineer look over my plans and they can't see any problems with
them!


...my first thought would be to remove joist B
entirely (using temp support of course) and put new joists running
full width alongside the old ones, without removing the old ones, and
attach old and new securely together. BUT do not do this unless you
consult a struc eng who says its ok in your particular case to do it,
as it might not be.

Good idea, although I do think this is overkill for the particular scenario.
In reality the worst that could happen is that the downstairs ceiling cracks
a bit - and this *is* pretty unlikely. I can't see there being sufficient
deflection to cause catastrophic failure of the ceiling.


There is one more issue: I dont know what size the joists are now, nor
what build regs says about you doing this, but you might possibly find
that to conform to BRs you'd need to put bigger wood in that is there
presently. If you should get caught in this trap, theres always
steelwork, flitch beams, hardwood, etc.

I'm no structural engineer, but I'm pretty certain 7" joists are sufficient
to span a 2.3m gap. :-)

Cheers for all the info though - much appreciated.

Andy

In article , N.
Thornton wrote:
Secondly I dont like your propsed beam extensions at all. The wood
thats there is sized for the half run,

Well no, because the original post said "All of the joists in question
are 65 x 175mm and the span from left to right is 2370mm." The joists
are presumably that size because that's what was needed over the main
rooms and they've used the same size throughout.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

Tony Bryer wrote:

In article , N.
Thornton wrote:

Secondly I dont like your propsed beam extensions at all. The wood
thats there is sized for the half run,


Well no, because the original post said "All of the joists in question
are 65 x 175mm and the span from left to right is 2370mm." The joists
are presumably that size because that's what was needed over the main
rooms and they've used the same size throughout.

Indeed, a software application we know well ;-) shows a max deflection
of under 2mm at that length (assuming a 0.8kn/m uniform load with load
sharing, and C16 timber) - so well in spec. I an not sure if the 2.3 m
specified is the total length including the stairs, or just the existing
floor. If it is just the existing floor, and adding in the stairs added
another meter or so to the span, then it looks like the deflection is
still in spec.

--
Cheers,

John.

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

"Pecanfan" wrote in message ...
Thanks for the reply - please see comments below:-

I see a series of issues here.

Firstly the floor structure will presumably be covered by the party
wall act, so if your neighbour doesnt want any work doing that will
add a couple of grand of legal costs, plus dictate how you do the
work, which can again add costs.

Without getting into the technicalities of the Party Wall Act, I'm kind of
hoping the neighbour doesn't object since the impact will be negligible. I
will be serving notice under the act but, by my understanding anyway, the
Act is more biased towards the owner doing the building work as opposed to
the objector - i.e. even if they do object there's not a lot they can do
about it without getting an injunction... I could be TOTALLY wrong here
though so please, anyone, don't take this as gospel! :-)

you sound optimistic. They cant generally stop you doing the work,
but they can make it cost a couple of grand more on legal costs, and
make you do it in a way that may be less convenient.


Rather than try to extend the beams, which would certainly result in
the ceiling breaking up...

Erm... 'it would certainly result in the ceiling breaking up'... are you
sure about this? Since posting this I've had building control and a
structural engineer look over my plans and they can't see any problems with
them!

Well, theyre the experts, Im not. I just cant imagine how you could do
all this work without ever causing small movements to the joist stubs,
which would crack the ceiling up. But I'm no struc eng.


The rest of your points I take on board, basically I overlooked the 7"
size somewhere. G luck.


Regards, NT

Secondly I dont like your propsed beam extensions at all. The wood
thats there is sized for the half run,


Well no, because the original post said "All of the joists in question
are 65 x 175mm and the span from left to right is 2370mm." The joists
are presumably that size because that's what was needed over the main
rooms and they've used the same size throughout.

Indeed, a software application we know well ;-) shows a max deflection
of under 2mm at that length (assuming a 0.8kn/m uniform load with load
sharing, and C16 timber) - so well in spec. I an not sure if the 2.3 m
specified is the total length including the stairs, or just the existing
floor. If it is just the existing floor, and adding in the stairs added
another meter or so to the span, then it looks like the deflection is
still in spec.

2.3m is the total length including the stairwell so should be OK - cheers
for doing the calcs! :-)

Andy

Pecanfan wrote:

2.3m is the total length including the stairwell so should be OK - cheers
for doing the calcs! :-)

If you have the demo of superbeam there, then you could model all of the
joists. You may find that you can simply add the new joists without
needing major rework on the existing ones.

.... in fact ... ok just did it. (usual caveats apply)

It looks like you could leave Joist B as is, since it is not that
heavily loaded (I am assuming its length is about 2m based on your
diagram). Over the stairwell you could add some 175x50 joists (approx 1m
long?) hung between the wall and B, and B will still be in spec.

This leaves A, which is now carrying extra load at the point where B
joins it. That is now right on the limit with regard bending (if you
also assume it is carrying a bit of floor load - which in reality it may
or may not be carrying, due to its proximity to the concrete beside it).
If one were to stick another 175x65 joist (or narrower if you want)
beside it and bolt it to it, then you would be well in spec on that.


--
Cheers,

John.

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2.3m is the total length including the stairwell so should be OK -
cheers
for doing the calcs! :-)

If you have the demo of superbeam there, then you could model all of the
joists. You may find that you can simply add the new joists without
needing major rework on the existing ones.

... in fact ... ok just did it. (usual caveats apply)

It looks like you could leave Joist B as is, since it is not that
heavily loaded (I am assuming its length is about 2m based on your
diagram). Over the stairwell you could add some 175x50 joists (approx 1m
long?) hung between the wall and B, and B will still be in spec.

This leaves A, which is now carrying extra load at the point where B
joins it. That is now right on the limit with regard bending (if you
also assume it is carrying a bit of floor load - which in reality it may
or may not be carrying, due to its proximity to the concrete beside it).
If one were to stick another 175x65 joist (or narrower if you want)
beside it and bolt it to it, then you would be well in spec on that.

Woohoo! Cheers John. :-)

As I say, I loaded SuperBeam up. Looked through various screens. Got
frightened. Closed it again. (Sorry Tony! :-) )
Hold on...
Yup, tried it again and the same thing happened! :-(

I'll see how the ground lies once I've managed to rip the partition wall
down between the stairwell and existing bathroom... and also lifted the
boards where the bath is etc. It *might* be possible to bolt A to the
concrete (along with another joist or even some steel), not sure until I do
a bit more demolition though. BTW, yes - joist B is 2140mm and the
stairwell is 910mm wide.

Ta!

Andy

As I say, I loaded SuperBeam up. Looked through various screens. Got
frightened. Closed it again. (Sorry Tony! :-) )
Hold on...
Yup, tried it again and the same thing happened! :-(

Same for me. However, the 3rd time, I just about worked it out, at least for
single horizontal beams. You add the beam, edit it and enter the various
loadings. Point loads for other beams coming off it, or a uniform load along
the entire length for flooring. You need to allow 2kN/m2 for the floor.

I'm not entirely sure I'm getting the vertical columns 100%, yet.

Christian.

Pecanfan wrote:


As I say, I loaded SuperBeam up. Looked through various screens. Got
frightened. Closed it again. (Sorry Tony! :-) )
Hold on...
Yup, tried it again and the same thing happened! :-(

You will probably find it makes more sense once you have seen a
completed project in it! (I was in the fortunate position of having the
full set of calcs produced by an architect, hence it was simple enough
to go back to the program and fiddle around a bit until I could
reproduce the same figures and understand what the various bits were
doing).

To model a beam, start by creating one (CTRL + B), and give it a name.
Then specify the loadings. First you enter a type for the load i.e. U
for uniform. Then enter the load (in kN) say 0.8 for a typical floor
with joists on 400mm centres (this is a linear load rather than sq
area). For each load you specify you may not need all the parameters -
it will vary on circumstance. Click Apply. (you can get a fair amount of
info out of the help pages).

Now specify the Timber specs. Enter your beam size (175x63), C16 timber,
and for a floor you can specify "load sharing". Click apply. That's the
beam modelled. So for one of your existing cross member beams that
connect to joist B, you would specify the length, load type "U", load
(W1) 0.8. Timber as described above. Now play with the icons at the top
and you should be able to display the forces on the beam and the bending
and shear loads along its length.

To model a beam like B, I find the "B/F Reaction" button is handy. This
lets you specify a point load on one beam by reference to another beam
rather than having to copy the loads manualy (a bit like referring to
another cell in a spreadsheet). Note the beam you refer to needs to be
higher up the list in the project manager. So you can add the reaction
caused by one end of you cross joists to B (in your case both ends will
be exerting the same down force so it does not matter which). You can
use the same beam to add a load to B repeatedly, just by changing the
distance along the beam where it intersects (e.g. 0.2, 0.6, 1, 1.4m etc
for 400mm centres).

Finally do A in the same way.

If a beam fails, then you need to go play with its parameters to see
what you need to do to prevent that.

(if you need more detailed instructions than that, then drop me an email
since any more here is probably going to get pretty dull for our readers ;-)

I'll see how the ground lies once I've managed to rip the partition wall
down between the stairwell and existing bathroom... and also lifted the
boards where the bath is etc. It *might* be possible to bolt A to the
concrete (along with another joist or even some steel), not sure until I do

Not sure you will need to bolt it to the concrete... in fact if it is
not attached then I would be inclined not so so that you don't have to
start modelling the loading on that as well! When I was fiddling with
the figures I found just bolting another beam beside it was enough.

--
Cheers,

John.

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