Hi,

Can anyone help me with the following problem. I'm currently
renovating a 3 storey terraced house, and have moved onto the top floor
(see diagram below). The top floor is in the roof, but isn't an attic
conversion as there is an original dormer window to the front. The
problem I have is I want to create more space by knocking down a wall
(see * in the diagram below - it's only a lathe and plaster wall, non
load bearing) and taking the room into the eaves. This should be easy,
but where they used 6x2 joists (see 1) in the room, they used 3x2
joists (see 2) in the eaves. On top and across of the smaller joists
runs a 6x2 joist, which I guess is to stop them sagging with the weight
of the ceiling below. This joist is supported by the outer wall and
the last 6x2 joist. I guess this joist will have to come out
eventually as it's 3 inches higher than the floor in the room (3 inch
joist below + 6 inch joist = 9 inches vs 6 inch joist in the room)

How can I re-inforce these smaller joists so they can take the weight
of people moving around (although they are in the eaves, there is
enough head room for a bed, desk, etc). I'd also like to be able to
keep the whole floor at the same level.

I really appreciate any help.

Cheers


_________________________
| |
|22222222221222222222222|
| |
|2222222222122222222222_|
| |
|222222222212222222222|
| |
|222222222212222222222|__
| |
|22222222221222222222222|
|________ |
|**1************|
|111111111111111|
| |
|111111111111111|
STAIRS | |
|111111111111111|
| |
|11111 etc, etc |
| |
--DOOR--| |
| _|
| |
| |
| |
| |__
| |
|________ ___|
| |
| |
| |
| |
| |
|___________|
DORMER WINDOW

Sorry diagram should look like this:

_________________________
| |
|22222222221222222222222|
| |
|2222222222122222222222_|
| |
|222222222212222222222|
| |
|222222222212222222222|__
| |
|22222222221222222222222|
|________ |
|**1************|
|111111111111111|
| |
|111111111111111|
STAIRS | |
|111111111111111|
| |
|11111 etc, etc |
| |
--DOOR--| |
| _|
| |
| |
| |
| |__
| |
|________ ___|
| |
| |
| |
| |
| |
|__________|
DORMER WINDOW



Callum wrote:
Hi,

Can anyone help me with the following problem. I'm currently
renovating a 3 storey terraced house, and have moved onto the top floor
(see diagram below). The top floor is in the roof, but isn't an attic
conversion as there is an original dormer window to the front. The
problem I have is I want to create more space by knocking down a wall
(see * in the diagram below - it's only a lathe and plaster wall, non
load bearing) and taking the room into the eaves. This should be easy,
but where they used 6x2 joists (see 1) in the room, they used 3x2
joists (see 2) in the eaves. On top and across of the smaller joists
runs a 6x2 joist, which I guess is to stop them sagging with the weight
of the ceiling below. This joist is supported by the outer wall and
the last 6x2 joist. I guess this joist will have to come out
eventually as it's 3 inches higher than the floor in the room (3 inch
joist below + 6 inch joist = 9 inches vs 6 inch joist in the room)

How can I re-inforce these smaller joists so they can take the weight
of people moving around (although they are in the eaves, there is
enough head room for a bed, desk, etc). I'd also like to be able to
keep the whole floor at the same level.

I really appreciate any help.

Cheers


_________________________
| |
|22222222221222222222222|
| |
|2222222222122222222222_|
| |
|222222222212222222222|
| |
|222222222212222222222|__
| |
|22222222221222222222222|
|________ |
|**1************|
|111111111111111|
| |
|111111111111111|
STAIRS | |
|111111111111111|
| |
|11111 etc, etc |
| |
--DOOR--| |
| _|
| |
| |
| |
| |__
| |
|________ ___|
| |
| |
| |
| |
| |
|___________|
DORMER WINDOW

or not....anyone get the gist from the rubbish diagram? Try clicking
view original, it seems to be properly formatted there.

In an earlier contribution to this discussion,
Callum wrote:

Hi,

Can anyone help me with the following problem. I'm currently
renovating a 3 storey terraced house, and have moved onto the top
floor (see diagram below). The top floor is in the roof, but isn't
an attic conversion as there is an original dormer window to the
front. The problem I have is I want to create more space by knocking
down a wall (see * in the diagram below - it's only a lathe and
plaster wall, non load bearing) and taking the room into the eaves.
This should be easy, but where they used 6x2 joists (see 1) in the
room, they used 3x2 joists (see 2) in the eaves. On top and across
of the smaller joists runs a 6x2 joist, which I guess is to stop them
sagging with the weight of the ceiling below. This joist is
supported by the outer wall and the last 6x2 joist. I guess this
joist will have to come out eventually as it's 3 inches higher than
the floor in the room (3 inch joist below + 6 inch joist = 9 inches
vs 6 inch joist in the room)

How can I re-inforce these smaller joists so they can take the weight
of people moving around (although they are in the eaves, there is
enough head room for a bed, desk, etc). I'd also like to be able to
keep the whole floor at the same level.

I really appreciate any help.

Cheers

I think I've got a fair idea from the diagram - although ascii art isn't a
very good way to represent it.

What's the max unsupported span of the 6 x 2 joists?

Am I right in thinking that the joists are at right angles to the roof
rafters in plan view - rather than the more usual parallel arrangement?

What is actually holding the roof up - are there purlins, supported in the
end walls? If not, are you *sure* that this stud wall is not structural, and
is not helping to support the roof?

Assuming that the stud wall *isn't*structural, and that the span is ok for 6
x 2's, could you fix a new 6 x 2 to the side of each 3 x 2 - and support the
ends off the end walls with hangers? You'd have to remove the 6 x 2 running
the other way - but that shouldn't be a problem.

As always, the advice has to be to consult a structural engineer - but it
doesn't hurt to have your own ideas first, as a basis for discussion.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In article . com,
"Callum" says...
Hi,

Can anyone help me with the following problem. I'm currently
renovating a 3 storey terraced house, and have moved onto the top floor
(see diagram below). The top floor is in the roof, but isn't an attic
conversion as there is an original dormer window to the front. The
problem I have is I want to create more space by knocking down a wall
(see * in the diagram below - it's only a lathe and plaster wall, non
load bearing)

Just because it's a stud wall doesn't mean that it's not holding the
roof up.

and taking the room into the eaves. This should be easy,
but where they used 6x2 joists (see 1) in the room, they used 3x2
joists (see 2) in the eaves. On top and across of the smaller joists
runs a 6x2 joist, which I guess is to stop them sagging with the weight
of the ceiling below. This joist is supported by the outer wall and
the last 6x2 joist. I guess this joist will have to come out
eventually as it's 3 inches higher than the floor in the room (3 inch
joist below + 6 inch joist = 9 inches vs 6 inch joist in the room)

How can I re-inforce these smaller joists so they can take the weight
of people moving around (although they are in the eaves, there is
enough head room for a bed, desk, etc). I'd also like to be able to
keep the whole floor at the same level.

I think the simplest solution is to fit more 6x2 joists alongside the
single one at the rear, then build up the floor at the front by three
inches. But you probably don't want to lose the headroom.
The best solution is to replace the 3" joists with 6" joists, but
that would require new ceilings downstairs.
An alternative is to build up the 3" joists to 6" by gluing and
screwing additional 3x2 along each one and fixing the ends by bolting
metal plates down the sides. Would this meet with building regs
approval? Probably best to ask a structural engineer.

Callum wrote:

Can anyone help me with the following problem. I'm currently
renovating a 3 storey terraced house, and have moved onto the top floor
(see diagram below). The top floor is in the roof, but isn't an attic
conversion as there is an original dormer window to the front. The
problem I have is I want to create more space by knocking down a wall
(see * in the diagram below - it's only a lathe and plaster wall, non
load bearing) and taking the room into the eaves. This should be easy,

You may well be right, but don't assume that just because it is a stud
wall it is not load bearing.

but where they used 6x2 joists (see 1) in the room, they used 3x2
joists (see 2) in the eaves. On top and across of the smaller joists
runs a 6x2 joist, which I guess is to stop them sagging with the weight
of the ceiling below. This joist is supported by the outer wall and
the last 6x2 joist. I guess this joist will have to come out
eventually as it's 3 inches higher than the floor in the room (3 inch
joist below + 6 inch joist = 9 inches vs 6 inch joist in the room)

Oh, I think I have played this game before... ;-)

How can I re-inforce these smaller joists so they can take the weight
of people moving around (although they are in the eaves, there is
enough head room for a bed, desk, etc). I'd also like to be able to
keep the whole floor at the same level.

The way it is normally done is to ignore the smaller joists and insert
ones of the required size interspaced between them so that the new ones
run parallel to the old ones.

That does mean that you will need to cut the old tie beam however. The
way to do this is one section at a time. before you cut a section you
strap what will be the cut ends to something solid so that it can not
move. After you have at least two of the new beams in place, you can
then place a noggin between them, which you fix to the old joist to
replace the function of the tie beam for that joist.

Here is one I did ealier:

http://www.internode.co.uk/loft/floor.htm

First and second photos on this page show what it sounds like you are
describing. The tie beam was only a 4x2 in my case, but the same
principle applies. The last photo shows the floor with the tie beam gone
and its function replaced by noggins.

Two things spring to mind. Firstly doing this will probably need
building regulations approval (and hence submission of a building notice
etc). The BCO may want to see calculations to show the new floor will
meet the required deflection limits etc.

Secondly, it is usual to insert new beams with a spacer under their ends
so that they keep clear of the existing ceiling. This saves and chance
of damaging the ceiling when they deflect. In your case however you may
not want to do this since it would take the floor level up a bit from
the rest of the joists. You may be able to get away slightly less deep
(but perhaps wider) joists - although you are not starting with much.


--
Cheers,

John.

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

In message , John
Rumm writes
snips.

Two things spring to mind. Firstly doing this will probably need
building regulations approval (and hence submission of a building
notice etc). The BCO may want to see calculations to show the new floor
will meet the required deflection limits etc.

Secondly, it is usual to insert new beams with a spacer under their
ends so that they keep clear of the existing ceiling. This saves and
chance of damaging the ceiling when they deflect. In your case however
you may not want to do this since it would take the floor level up a
bit from the rest of the joists. You may be able to get away slightly
less deep (but perhaps wider) joists - although you are not starting
with much.

Having lived in a bungalow converted to have dormer bedrooms I can
confirm that secondary joists not fixed to the originals causes problems
with the existing ceiling. In our case this was limited to the plaster
skin popping off the nail heads but still a nuisance.

regards



--
Tim Lamb

In article . com,
Callum wrote:
Can anyone help me with the following problem. I'm currently
renovating a 3 storey terraced house, and have moved onto the top floor
(see diagram below). The top floor is in the roof, but isn't an attic
conversion as there is an original dormer window to the front. The
problem I have is I want to create more space by knocking down a wall
(see * in the diagram below - it's only a lathe and plaster wall, non
load bearing) and taking the room into the eaves. This should be easy,
but where they used 6x2 joists (see 1) in the room, they used 3x2
joists (see 2) in the eaves. On top and across of the smaller joists
runs a 6x2 joist, which I guess is to stop them sagging with the weight
of the ceiling below. This joist is supported by the outer wall and
the last 6x2 joist. I guess this joist will have to come out
eventually as it's 3 inches higher than the floor in the room (3 inch
joist below + 6 inch joist = 9 inches vs 6 inch joist in the room)

How can I re-inforce these smaller joists so they can take the weight
of people moving around (although they are in the eaves, there is
enough head room for a bed, desk, etc). I'd also like to be able to
keep the whole floor at the same level.

This is more or less exactly what I did to my existing attic room - the
only difference being the dormer was at the back.

Ended up putting in a steel at one end, and new joists front to back
sitting over the existing.

Think your best plan is to get a structural engineer in now, rather than
later. The studding wall you describe as non load bearing almost certainly
is, as it forms a triangle between floor joists and rafters.

--
*If love is blind, why is lingerie so popular? *

Dave Plowman London SW
To e-mail, change noise into sound.

Thanks guys for all your useful messages. I'm pretty sure the wall is
non load bearing as the 'studs' are attached to a 6x2 beam running
across the rafters (at about head height) which is bedded into the
walls each side of the house.

I think probably the best course of action will be to install the 6x2s
in between the 3x2s and attach them to the walls with hangers. Would I
require an inspection from the builder officer for this, even though it
matches with the rest of the room (and the house come to think of it).


Though to be on the safe side I'll probably be looking in the yellow
pages for a structural engineer tomorrow!

Thanks again.

Callum wrote:

I think probably the best course of action will be to install the 6x2s
in between the 3x2s and attach them to the walls with hangers. Would I
require an inspection from the builder officer for this, even though it
matches with the rest of the room (and the house come to think of it).

The trickey bit is that it will need to comply with current building
regs. The old floor may not meet them. There would be no need to bring
the old floor up to spec, howevfer the new one would have to meet the
spec. Hence if calculations show that you actually need deeper beams to
keep the deflection under the required limits you may have a matching
problem!

Though to be on the safe side I'll probably be looking in the yellow
pages for a structural engineer tomorrow!

You could have a play with the demo version of superbeam:

http://www.sda.co.uk/sbw.htm

and see what sort of answers you get first - that may give you a good
indication of how difficult it is likely to be.

(You can just model one beam to start with - enter the dimensions, and a
uniform load of say 0.8kN/m, turn on "load sharing", and see what
happens. If you are having difficulty getting in spec then you can
experiment with wider beams, better timber (i.e. C24 instead fo C16), or
even flitch beams (i.e. with steel plates in them).


--
Cheers,

John.

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

In an earlier contribution to this discussion,
Callum wrote:

Thanks guys for all your useful messages. I'm pretty sure the wall is
non load bearing as the 'studs' are attached to a 6x2 beam running
across the rafters (at about head height) which is bedded into the
walls each side of the house.

How far apart are the end walls? 6x2 doesn't sound to me to be a very large
section for a purlin. Mine are 9x3 and are supported by load-bearing walls
half way along. Do you have any load-bearing walls *under* your joists? It
wouldn't surprise me if one of the studs doubled as a strut to support the
middle of the purlin.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Thanks John I'll take a look at the link.

Set square...the party walls are about 3m apart. There is a plaster
and lathe wall directly below the joist supporting the studs. It's a
very small house (2 up, 2 down with 3 floors!) so not sure wether the
roof would require much support. Although the rafters look particulary
flimsy!

Callum wrote:

Set square...the party walls are about 3m apart. There is a plaster

OK, I just did a quick test beam in superbeam for you: 3m span, C16
timber of 50x150mm configured as a load sharing system. Assuming a
uniform floor load of 0.8kN/m (i.e. the floor and no other dead load
structural elements like walls etc)

Surprisingly that does actually meet the required spec. It shows a max
deflection of about 7mm (the limit would be 9mm for a 3m beam according
to building regs). The problem here would be potential damage to the
ceilings. So I tried another test with 50x140mm timber. This just
scrapes through with a 8.7mm deflection! However that would allow you to
space the beams 1 cm higher than the ceiling level and hopefully they
would keep clear of it.

Personally I think I would either switch to C24 timber of 50x140mm (7mm
deflection) or alternatively stay with C16 but go for 75x140mm beams
(under 6mm deflection) to allow more margin for error.

(Note you may have difficulty buying 140mm high beams since this is not
a standard depth - however 150 could be thicknessed down if required)

and lathe wall directly below the joist supporting the studs. It's a

This may make life easier if it is currently load bearing since by the
look of your diagram is splits the span in half.

very small house (2 up, 2 down with 3 floors!) so not sure wether the
roof would require much support. Although the rafters look particulary
flimsy!

As long as you don't go hacking out purlins or any other stays that
support the rafters your ought to be no worse off. You will need to
insulate and clad the underside of the rafters, which will add a little
weight though.

What depth are the rafters?
Is there under tile felt (i.e. sarking)?
Are there any soffit / ridge vents?


--
Cheers,

John.

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

In an earlier contribution to this discussion,
John Rumm wrote:


OK, I just did a quick test beam in superbeam for you: 3m span, C16
timber of 50x150mm configured as a load sharing system. Assuming a
uniform floor load of 0.8kN/m (i.e. the floor and no other dead load
structural elements like walls etc)

I would be more interested to see a superbeam calc for the purlin - having
to hold the roof up all on its own, once the stud wall under it has been
removed. [I may be wrong, but I suspect that the purlin is currently
supported all along its length by load-bearing walls which go all the way
down to ground level].
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In article ,
Set Square wrote:
I would be more interested to see a superbeam calc for the purlin -
having to hold the roof up all on its own, once the stud wall under it
has been removed. [I may be wrong, but I suspect that the purlin is
currently supported all along its length by load-bearing walls which go
all the way down to ground level].

Wouldn't that be a bit unusual in the normal two rooms per floor house?

--
*Money isn't everything, but it sure keeps the kids in touch.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

I would be more interested to see a superbeam calc for the purlin -
having to hold the roof up all on its own, once the stud wall under it
has been removed. [I may be wrong, but I suspect that the purlin is
currently supported all along its length by load-bearing walls which go
all the way down to ground level].


Wouldn't that be a bit unusual in the normal two rooms per floor house?

It is quite common to have a stay somewhere in the middle of the purlin
to brace it, however that function may be being satisfied by the wall
transferring the load to the floor of the loft (or more accurately a
beam spanning the width of the house under the floor).

It would be interesting to know what kind beam is under the wall marked
with "***1*****" on the diagram.

I had a similar problem when I did my loft, there were purlins on three
sides mid way along the span of the rafters. Two of these were going
since the pitched roof was also going (gable wall on one side, and
dormer on the rear). The front one however needed to be replaced with a
dwarf wall to support all the front rafters.

If you look:

http://www.internode.co.uk/loft/images/beams1.jpg

The original purlin can just be seen here (with the fluorescent light on
it). The stay runs obliquely down from roughly the middle of the purlin
to a the supporting wall in the middle of the house.

In cross section you had:

/\
/ \
/ \
/ \
/ \
/P\ /p\
/ \ / \
/ \ / \
/ \ / \
## ## ##

Where "p" indicates the purlin running into the axis of the page.

The replacement was (with d indicating the dwarf wall):

/\________________
/ # #
/ # #
/ # #
/ # #
/ # # #
/ # # #
/ # # #\
/ #_____________#_________#__\
## # ## ##
d


See the first piccie after the "Finishing the Front" section:

http://www.internode.co.uk/loft/superstructure.htm



--
Cheers,

John.

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

I had a chat with a builder who's doing the same thing to a house a
couple doors down. It's slightly different as they dont have the
dormer window, it's flat fronted so theres slightly more headroom on
the top floor.

Basically they were told by the council that the minimum size beam that
could be used in their case was 8x2. These were run parallel with the
3x2s and doubled up round the chimney (to support the beams directly in
front).

You were right in thinking the 6x2 purlin was supported by the studs so
they had to strap on another 4x2 beam to strengthen it. The actual
span of the purlin was in fact 3.6m (from party wall to party wall).

Unfortunately all this means I'll have a two level floor but without
taking out the ceiling below I'll have to accept this.

I forgot to ask the builder about bolting beams together, is there a
standard way of doing this (i.e. what size bolts, the spacing of these,
etc)?

In article . com,
Callum wrote:
You were right in thinking the 6x2 purlin was supported by the studs so
they had to strap on another 4x2 beam to strengthen it. The actual
span of the purlin was in fact 3.6m (from party wall to party wall).

What they did with mine was to put in two new purlins (approx 1/3 way
along) and remove the old to give a 'flat' ceiling down to the new stud
wall.

--
*I don't suffer from insanity, I enjoy every minute of it *

Dave Plowman London SW
To e-mail, change noise into sound.

Callum wrote:

I had a chat with a builder who's doing the same thing to a house a
couple doors down. It's slightly different as they dont have the
dormer window, it's flat fronted so theres slightly more headroom on
the top floor.

Basically they were told by the council that the minimum size beam that
could be used in their case was 8x2. These were run parallel with the
3x2s and doubled up round the chimney (to support the beams directly in
front).

If you can show calculations to the council to demonstrate that your
choice of beam is sound then you should be able to use whatever "works".
Using 8x2 however would not be a major hassle in the scheme of things
since you could simply lift the existing floor and add a 2x2 on top of
the beams to rais the height to match the new bit.

You were right in thinking the 6x2 purlin was supported by the studs so
they had to strap on another 4x2 beam to strengthen it. The actual
span of the purlin was in fact 3.6m (from party wall to party wall).

The would suggest that either the roof construction is lighter that I
assumed, or it has some extra support you have not mentioned, or, they
have gone for a solution that is not really up to spec!

According to the calcs I did, even a 12x2 is not big enough, and that
was assuming a 3m span not 3.6. Hence why I suggested a flitch beam to
get the required strength.

Unfortunately all this means I'll have a two level floor but without
taking out the ceiling below I'll have to accept this.

Unless you prove the smaller beam is ok in the back, or pad the beams in
the front.

I forgot to ask the builder about bolting beams together, is there a
standard way of doing this (i.e. what size bolts, the spacing of these,
etc)?

If you are bolting, then 12mm bolts every 600mm on alternate edges, 50mm
in from the edge. Square plate washers under the nut and bolt head. If
it is a timber to timber joint (i.e. no flitch plate) then a dog tooth
timber connector goes on the bolt between the two bits of wood.

Sometimes when you just have a double side by side joist you can simply
nail them together.

If you go for any other bolt size then the costs go up rapidly because
the dog connectors and plate washers that are commonly available are
only in 12mm usually. So you would end up having stuff made or at least
adapted.


--
Cheers,

John.

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

Thanks for all your help John. Is there any way I can re-inforce the
beam with steel instead of having to replace with a flitch beam? Would
this beam be supported by the walls or just strapped to the existing
one?

Callum wrote:

Thanks for all your help John. Is there any way I can re-inforce the
beam with steel instead of having to replace with a flitch beam? Would

You could add a steel beam either under it to support it, or completely
detached from it a little further up or down the rafters. If you sized
that to take the full load then you could ignore the wood beam to all
intents and purposes.

I suggested a flitch as that is the simplest way to go based on where
you are starting from. The beam you have becomes half the flitch - all
you would need to do it add another wood beam the same as the existing
and a steel plate to the side of it and bolt them together. This may
prove to be the least disruptive.

this beam be supported by the walls or just strapped to the existing
one?

Any new beam ought to be supported on the wall ends unless you can show
by calculation that the exiting wood end is strong enough in shear
andbending at the interface with the wall.



--
Cheers,

John.

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