Hi

I have a few questions about converting my loft, I have read a few
threads on this site and found out alot of very usefull information but
alase no answers to the questions I have.

I live in a terrace house with a 9m by 4.5m loft space which is all
open with no obtrusive w shape or v shapes to be seen. It has two part
walls it does have 2 jiosts 8" by 2" on the floor and 4 (two each side)
one quite low to the roof and the othere about 1.5 meters up from floor
hight these rest on the party walls can some on please advice the best
way to creat a workable floor space I will be useing the area as
storage and possible office I am awair that to convert this I would
need a 30 min fire barrier with stairs and loft insulation but I will
be unable to fit the stairs as have no room due to other work done on
the house before we bought it I have fitted a nice set of wooden loft
ladders that retract and this will surfice for my needs and I will be
fitting an excape velux after the flooring is done.

my neighbour has alrady converted his loft and terned it into a very
nice space he has fitted stairs and done a proper job on the face value
of it but I asked him for advice and he know nothing of the structual
forces at work and had just guessed the best wood to use he has also
not gone through building regs which I am not to chuffed about but dont
want to start world war three with them as still got to live there.

My question is this what is the best configurational layout i.e jiost
on hangers or pun through the party walls ? if so could some one let me
know what the calculations are for the size of the wood or what wood I
would be best to use.

by the way I also have 4"x2" lengths of wood running from the frount
to the back of the house 9m split in to and resting on the centre wall
of the property.

any help would be greatly recieved.

"squelchy" wrote in message
oups.com...
Hi

I have a few questions about converting my loft, I have read a few
threads on this site and found out alot of very usefull information but
alase no answers to the questions I have.

I live in a terrace house with a 9m by 4.5m loft space which is all
open with no obtrusive w shape or v shapes to be seen. It has two part
walls it does have 2 jiosts 8" by 2" on the floor ...

Without sight of your space it's difficult to identify these ... but if they
don't seem to be supporting something then they _might_ be 'ties' rather
than 'joists'. Such ties are secured to the ceiling joists (for the room
below) and stiffen the ceiling (below).

.......... and 4 (two each side)
one quite low to the roof and the othere about 1.5 meters up from floor
hight these rest on the party walls ...

I've interpreted your statement to imply that your terraced property has a
party wall at either end. These walls will tranmit forces down to the
foundations ... and to mother Earth. The bits of timber, two each side, are
'purlins'. Supported by the party walls they provide support for the
'rafters' that go from the 'ridge beam' to the wall plates.

can some on please advice the best
way to creat a workable floor space I will be useing the area as
storage and possible office I am awair that to convert this I would
need a 30 min fire barrier with stairs and loft insulation but I will
be unable to fit the stairs as have no room due to other work done on
the house before we bought it I have fitted a nice set of wooden loft
ladders that retract and this will surfice for my needs and I will be
fitting an excape velux after the flooring is done.

IANAL ! nor a BCO!
The preferred jargon nowadays seems to be 'room in the roof' rather than
'loft conversion'. If you haven't got a 'proper stairway' {meeting Building
Regs} than ipso-facto you _can't_ have a room in the roof.
You seem to be be describing an 'attic' space. Such a space may be boarded
and used for storage but not as a habitable room.


my neighbour has alrady converted his loft and terned it into a very
nice space he has fitted stairs and done a proper job on the face value
of it but I asked him for advice and he know nothing of the structual
forces at work and had just guessed the best wood to use he has also
not gone through building regs which I am not to chuffed about but dont
want to start world war three with them as still got to live there.

Ignore everything your neighbour has done. No Building Control means that
it's illegal.
From your post it doesn't seem to be 'a proper job' within in the meaning of
the Act!
No 'Sign -off' means that he'd have difficulty making any insurance claim.

My question is this what is the best configurational layout i.e jiost
on hangers or pun through the party walls ? if so could some one let me
know what the calculations are for the size of the wood or what wood I
would be best to use.

The conventional method is to provide a new load bearing floor that is
supported off both party walls. A 'web' of either steel or timbers is then
surfaced. In principle the 'web' is not in contact with the existing attic
floor/bedroom ceiling. A structural engineer's calcs will be needed


by the way I also have 4"x2" lengths of wood running from the frount
to the back of the house 9m split in to and resting on the centre wall
of the property.

AIUI, the central wall is termed the spline wall, the 4"x2" 's provide
something to fix the ceiling joists to. [The spline wall will be utised in
the design of the 'web' to transmit the load of the new load-bearing floor.

any help would be greatly recieved.


Ask around for a 'Architectural Technician' to advise you. [IMHO, you don't
require a fully fledged Architect. Your Councils Building Regulation
department will help you ... if you ask them nicely.

--

Brian

"squelchy" wrote:
Hi

I have a few questions about converting my loft, I have read a few
threads on this site and found out alot of very usefull information but
alase no answers to the questions I have.

I live in a terrace house with a 9m by 4.5m loft space which is all
open with no obtrusive w shape or v shapes to be seen. It has two part
walls it does have 2 jiosts 8" by 2" on the floor and 4 (two each side)
one quite low to the roof and the othere about 1.5 meters up from floor
hight these rest on the party walls can some on please advice the best
way to creat a workable floor space I will be useing the area as
storage and possible office I am awair that to convert this I would
need a 30 min fire barrier with stairs and loft insulation but I will
be unable to fit the stairs as have no room due to other work done on
the house before we bought it I have fitted a nice set of wooden loft
ladders that retract and this will surfice for my needs and I will be
fitting an excape velux after the flooring is done.

my neighbour has alrady converted his loft and terned it into a very
nice space he has fitted stairs and done a proper job on the face value
of it but I asked him for advice and he know nothing of the structual
forces at work and had just guessed the best wood to use he has also
not gone through building regs which I am not to chuffed about but dont
want to start world war three with them as still got to live there.

My question is this what is the best configurational layout i.e jiost
on hangers or pun through the party walls ? if so could some one let me
know what the calculations are for the size of the wood or what wood I
would be best to use.

by the way I also have 4"x2" lengths of wood running from the frount
to the back of the house 9m split in to and resting on the centre wall
of the property.

any help would be greatly recieved.

http://www.localsurveyorsdirect.co.uk/web/architectural_building_design_surevyors_report.htm l

My question is this what is the best configurational layout i.e jiost
on hangers or pun through the party walls ? if so could some one let me
know what the calculations are for the size of the wood or what wood I
would be best to use.

Sounds pretty much like mine.

The "joists" 1.5 metres up are called purlins. Are there any struts to these
(i.e. in the middle) that require moving?

If not, and the space is suitably uncluttered, all you need are deeper floor
joists, placed alongside the existing ceiling joists, resting on the front,
middle and back as before.

When you do this, think about where the stairs would come in if you decided
to convert properly and ensure you trim out a suitable hole. Also, you may
be allowed to use shallower joists if you glue plywood down over the joists,
rather than just using chipboard.

It will all need to be designed by a structural engineer.

Christian.

Thank you both for your advice,

there is nothing obstructing the perlins in the middle they have been
renforced with additional lenghs of equal size at some piont bolted to
the existing ones and feed into the party walls they have also layed 4"
by 2" lenths of wood the intire length of the roof jioned in the middle
with bolts on top of the joists to stop the roof from splaying I have
been told I can replace these with metal strapping as this is done on
most houses instead of using wood as it is less obtrusive. I have
obtained some metal banding from b & Q and was going to use this as at
the moment there is no tension on any of the spans i.e there is 7 in
total they are attached to the roof batons i think that the name for
them.

so if I get this right I can put in new jiost raised above the old ones
and two addtional ons in the middle and attach a web of timber to creat
a floating floor.

If I was to go over comply with building regulations on this part of my
build what size would the beams need to be out of timber and should I
imbed then in the party walls or put them on jiost hangers ?

squelchy wrote:

I live in a terrace house with a 9m by 4.5m loft space which is all
open with no obtrusive w shape or v shapes to be seen. It has two part

Where are these part walls?

walls it does have 2 jiosts 8" by 2" on the floor and 4 (two each side)
one quite low to the roof and the othere about 1.5 meters up from floor
hight these rest on the party walls can some on please advice the best
way to creat a workable floor space I will be useing the area as

As the others said, "purlins" by the sounds of it. These can be taken
away if required but their function (stopping the rafters sagging in the
middle from he weight of the tiles) needs to be taken up by something
else like a dwarf wall.

storage and possible office I am awair that to convert this I would
need a 30 min fire barrier with stairs and loft insulation but I will
be unable to fit the stairs as have no room due to other work done on
the house before we bought it I have fitted a nice set of wooden loft
ladders that retract and this will surfice for my needs and I will be
fitting an excape velux after the flooring is done.

The rules governing stairs are somewhat relaxed for lofts, so you may
find that a "space saver" stair would be acceptable (i.e. one with
alternate treads cut away and a much steeper pitch than normal)

my neighbour has alrady converted his loft and terned it into a very
nice space he has fitted stairs and done a proper job on the face value
of it but I asked him for advice and he know nothing of the structual
forces at work and had just guessed the best wood to use he has also
not gone through building regs which I am not to chuffed about but dont
want to start world war three with them as still got to live there.

If he did it a while ago there would be nothing much anyone could do
about it anyway... (it would also give some reassurance that he got
something right since it is still there!)

My question is this what is the best configurational layout i.e jiost
on hangers or pun through the party walls ? if so could some one let me
know what the calculations are for the size of the wood or what wood I
would be best to use.

For joist sizing you can get some idea from the standard tables in the
building regs documents, or you can calculate the required sizes to meet
the loading, bending, and shear limits imposed both by building regs and
the nature of the timber. If you read through the into on my page here I
cover the information sources and the software that you can use to do this:

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

by the way I also have 4"x2" lengths of wood running from the frount
to the back of the house 9m split in to and resting on the centre wall
of the property.

If you have a central supporting wall then it is quite common to use the
same layout for the new floor. You place a extra 3/4" or 1" spacing
plate on the wall plates between the existing joists on all the walls,
and then sit the new beams on these. That ensures that the new floor
does not make contact with the existing ceiling.

For an example, see how I did my floor structure here :

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

--
Cheers,

John.

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

thank you for your advice

Where are these part walls?

I live in a terrace house with a plan as below

-----------------------------------
----------------------------------- party wall 9m meter lengths
= / - / =
= / - / =
= / - / =
= / - / =
------....------------------....---- party wall 9m meter lengths
------....------------------....----

/ is jiosts 8" by 2" 4.5m legths so the width is 4.5m in total from
party wall to party wall

= roof with tiles on

- is wall through middle of house which goes to foundation single
brick

...... where my and my neighbours jiost go through the party wall i.e
his conversion and the one for his house and mine.

with limited ability to show drawings, below is where the tiled roof
section is tyed together with 4" by 2" wood 4.5m lengths bolted
together to form 9m lenth then bolted to the roof trusses

----------------------------------- party wall 9m lengths
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
------....------------------....--- party wall 9m lengths
------....------------------....---


would I be able to put four jiost into the party walls and tie these
together with wood on jiost hangers to creat a grid like below and
remove the above roof ties and replace with metal banding ?

-----------------------------------
----------------------------------- party wall 9m lengths
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
------....------------------....---- party wall 9m lengths
------....------------------....----

would you recomend putting the joists through the wall or putting them
on heavey duty jiost hangers either by carving out the morter with a
grinders and remortering in the jiost hangers or bolting them to the
party walls with heavy duty wall bolts ?

the webbing would be made up of jiost hangers nailed to the main jiosts
and then boarding over the top with chip board.

I do not rearly want to start romoving tiles from the roof as not
looking to go the hole hog and fully convert just want a good solid
floor so no chance of damaging the plastering below.

what size wood would be best and creat a solid floor i.e webbing and
jiosts ?

I appreciate that I should get a structual engineer to look over
everything but rearly do not want the expence. I cannot get building
regs inviolved as they will not touch it as I only want to use my new
wooden fold away ladders that I fitted just a week ago hense after
looking on here realised that not a good idea to just board over the
4"x2"s that are holding up the cealing below I have already notices
some cracks from me walking through the loft that where not there
before lucky I have a plastering friend that is sorting out allot of
work for me at the moment anyway.

squelchy wrote:

Where are these part walls?


I live in a terrace house with a plan as below

-----------------------------------
----------------------------------- party wall 9m meter lengths
= / - / =
= / - / =
= / - / =
= / - / =
------....------------------....---- party wall 9m meter lengths
------....------------------....----

Ah, sorry I may have been getting the wrong end of the stick - I take it
when you said in your original post "it has two part walls", that was a
just a typo and you meant it has two "party" walls. It sounded as if you
has two bits of wall in the loft!

with limited ability to show drawings, below is where the tiled roof
section is tyed together with 4" by 2" wood 4.5m lengths bolted
together to form 9m lenth then bolted to the roof trusses

----------------------------------- party wall 9m lengths
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
------....------------------....--- party wall 9m lengths
------....------------------....---

You may find switching to a mono spaced font helps when dooing this type
of ASCII drawing - otherwise it is hard to make sense of unless we are
using the same font and software as you!

would I be able to put four jiost into the party walls and tie these
together with wood on jiost hangers to creat a grid like below and
remove the above roof ties and replace with metal banding ?

-----------------------------------
----------------------------------- party wall 9m lengths
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
------....------------------....---- party wall 9m lengths
------....------------------....----

There are two difficulties here. One is a practical one - have you got
the headroom to do this since you will be raising the whole floor by
about 10" minimum?

The second is an engineering one - if you used four cross beams as you
suggest then you would in effect have to support three sets of 3m beams
running front to back. This means that the front and back beams will be
carrying upto 12 of these joist ends (assuming 400mm spacing), and the
middle two will be carrying twice that. If you work on a loading of
0.8kN/m for your floor, that is 2.4kN per joist or 1.2kN downforce on
each end of the joist. This will give 14.4kN uniformly distributed
across the 4.5m span on your cross beams, and for the middle two this
would rise to 28.8kN. This is way over what would be an acceptable load
on a timber or even a flitch beam. So you would have to use heavy steel
beams here.

The more practical alternative is to insert 8x3" beams in between and
parallel to the existing ceiling joists and remove the tie beams
altogether. You could then insert a row of noggings between the new
floor beams which you fix to the ceiling joists.

would you recomend putting the joists through the wall or putting them
on heavey duty jiost hangers either by carving out the morter with a
grinders and remortering in the jiost hangers or bolting them to the
party walls with heavy duty wall bolts ?

Hangers are the favoured way these days. It saves creating a break in
the fire protection between the buildings and is less likely that the
ends will rot should the masonry get damp. You can get steel shoes
designed to go flat on a wall, which you fix with rawl bolts.

I do not rearly want to start romoving tiles from the roof as not

Not sure why you think you would need to?

looking to go the hole hog and fully convert just want a good solid
floor so no chance of damaging the plastering below.

This is why you normally space the underside of the new floor joists off
the existing ceiling level by a small amount. That way it is isolated
(it also keeps noise transmission down)

what size wood would be best and creat a solid floor i.e webbing and
jiosts ?

Assuming you want a floor that would pass building regs for a habitable
room:

You could use 4.5m beams that ran front to back on 400mm spacings,
resting on the middle wall and the front and back walls. For this you
eould need 8x3" C16 timber. (in fact you would probably make then a
little bit longer so that they overlap at the middle wall, and nail em
together with some builders band at the crosover.

Where the beams meet the front and rear walls you would need to cut the
ends at an angle to prevent the top of the beam hitting the tiles.

I appreciate that I should get a structual engineer to look over
everything but rearly do not want the expence. I cannot get building

Much depends on what you are planning to do with the space. Making a
storeage area is easy enough, however if you try to create a habitable
space it is also easy to build a deathtrap if you don't pay attention to
the details. This is one of the areas where it is very worthwhile
following the building regs. It will also make selling the place in the
future possible.

regs inviolved as they will not touch it as I only want to use my new
wooden fold away ladders that I fitted just a week ago hense after

It might be worth investigating if you could fit in a space saver stair.



--
Cheers,

John.

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

Hi John firstly thank you for your advice can you please answer these
questions for me -

Can you please let me know how these calculations are done so I can
calulate the correct loads with different materials and wood thickness
as I like knowing these things for future referance?

The second is an engineering one - if you used four cross beams as you
suggest then you would in effect have to support three sets of 3m beams
running front to back. This means that the front and back beams will be
carrying upto 12 of these joist ends (assuming 400mm spacing), and the
middle two will be carrying twice that. If you work on a loading of
0.8kN/m for your floor, that is 2.4kN per joist or 1.2kN downforce on
each end of the joist. This will give 14.4kN uniformly distributed
across the 4.5m span on your cross beams, and for the middle two this
would rise to 28.8kN. This is way over what would be an acceptable load
on a timber or even a flitch beam. So you would have to use heavy steel
beams here.


The more practical alternative is to insert 8x3" beams in between and
parallel to the existing ceiling joists and remove the tie beams
altogether. You could then insert a row of noggings between the new
floor beams which you fix to the ceiling joists.

sounds like a good plan as this would give me a higher cealing it is
quite large already though with a middle hight of around 3m so quite
allot to work with.

how would I go about this i.e how to support the cealing before the tie
beams are removed I guess you need to remove these before you put in
the 4.5m sections from the outer house walls to the center wall ? would
I attach the cealing jiosts to the perlins with metal ties and cut the
tie beams into sections to remove them ?

I am guessing this would pass the preasure to the middle wall and the
frount and back walls of our house the floor tie beam looks quite
large, is it not doing that much that it can be easyley removed as you
sirjest? (sorry my spellings not very good)

I have been informed that I could also hang 8"x3" jiost on the party
walls at 400mm centres using jiost hangers with the morter of the
current brick walls grinded out and then placing the hangers in the
wall and cementing them in is this a practical way of doing it ? and
would it give me the same amount of structual stregth i.e is it better
to hang jiost on the frount and back of the house or the two party
walls ?

if I do hang the jiost over the fround and back walls how would I
attach them to the walls just lay them on or what part should they be
succed to ?

thank you for your help with this in advance.




John Rumm wrote:
squelchy wrote:

Where are these part walls?


I live in a terrace house with a plan as below

-----------------------------------
----------------------------------- party wall 9m meter lengths
= / - / =
= / - / =
= / - / =
= / - / =
------....------------------....---- party wall 9m meter lengths
------....------------------....----

Ah, sorry I may have been getting the wrong end of the stick - I take it
when you said in your original post "it has two part walls", that was a
just a typo and you meant it has two "party" walls. It sounded as if you
has two bits of wall in the loft!

with limited ability to show drawings, below is where the tiled roof
section is tyed together with 4" by 2" wood 4.5m lengths bolted
together to form 9m lenth then bolted to the roof trusses

----------------------------------- party wall 9m lengths
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
='''''''''''''''''''''' -''''''''''''''''''''''''''''''''''''''=
------....------------------....--- party wall 9m lengths
------....------------------....---

You may find switching to a mono spaced font helps when dooing this type
of ASCII drawing - otherwise it is hard to make sense of unless we are
using the same font and software as you!

would I be able to put four jiost into the party walls and tie these
together with wood on jiost hangers to creat a grid like below and
remove the above roof ties and replace with metal banding ?

-----------------------------------
----------------------------------- party wall 9m lengths
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
= / / / - / / / =
------....------------------....---- party wall 9m lengths
------....------------------....----

There are two difficulties here. One is a practical one - have you got
the headroom to do this since you will be raising the whole floor by
about 10" minimum?

The second is an engineering one - if you used four cross beams as you
suggest then you would in effect have to support three sets of 3m beams
running front to back. This means that the front and back beams will be
carrying upto 12 of these joist ends (assuming 400mm spacing), and the
middle two will be carrying twice that. If you work on a loading of
0.8kN/m for your floor, that is 2.4kN per joist or 1.2kN downforce on
each end of the joist. This will give 14.4kN uniformly distributed
across the 4.5m span on your cross beams, and for the middle two this
would rise to 28.8kN. This is way over what would be an acceptable load
on a timber or even a flitch beam. So you would have to use heavy steel
beams here.

The more practical alternative is to insert 8x3" beams in between and
parallel to the existing ceiling joists and remove the tie beams
altogether. You could then insert a row of noggings between the new
floor beams which you fix to the ceiling joists.

would you recomend putting the joists through the wall or putting them
on heavey duty jiost hangers either by carving out the morter with a
grinders and remortering in the jiost hangers or bolting them to the
party walls with heavy duty wall bolts ?

Hangers are the favoured way these days. It saves creating a break in
the fire protection between the buildings and is less likely that the
ends will rot should the masonry get damp. You can get steel shoes
designed to go flat on a wall, which you fix with rawl bolts.

I do not rearly want to start romoving tiles from the roof as not

Not sure why you think you would need to?

looking to go the hole hog and fully convert just want a good solid
floor so no chance of damaging the plastering below.

This is why you normally space the underside of the new floor joists off
the existing ceiling level by a small amount. That way it is isolated
(it also keeps noise transmission down)

what size wood would be best and creat a solid floor i.e webbing and
jiosts ?

Assuming you want a floor that would pass building regs for a habitable
room:

You could use 4.5m beams that ran front to back on 400mm spacings,
resting on the middle wall and the front and back walls. For this you
eould need 8x3" C16 timber. (in fact you would probably make then a
little bit longer so that they overlap at the middle wall, and nail em
together with some builders band at the crosover.

Where the beams meet the front and rear walls you would need to cut the
ends at an angle to prevent the top of the beam hitting the tiles.

I appreciate that I should get a structual engineer to look over
everything but rearly do not want the expence. I cannot get building

Much depends on what you are planning to do with the space. Making a
storeage area is easy enough, however if you try to create a habitable
space it is also easy to build a deathtrap if you don't pay attention to
the details. This is one of the areas where it is very worthwhile
following the building regs. It will also make selling the place in the
future possible.

regs inviolved as they will not touch it as I only want to use my new
wooden fold away ladders that I fitted just a week ago hense after

It might be worth investigating if you could fit in a space saver stair.



--
Cheers,

John.

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

Hi John firstly thank you for your advice can you please answer these
questions for me -

Can you please let me know how these calculations are done so I can
calulate the correct loads with different materials and wood thickness
as I like knowing these things for future referance?

The how (as in mathematically) is quite complex - not because the sums
are that difficult in themselves, but because there are lots of
different ones you need for dealing with point loads or uniform loads,
bending, and shear forces etc. If you want that level of detail then I
suggest some of the books I have linked to he

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

The practical answer (and the way that most architects etc are going to
produce the calculations) is using a software package designed for the
task.

You can download a demo version of Superbeam (the one my architect used)
he

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

Note however that software is not a total solution. If you don't know
what data to feed into it, you will simply end up with a potentially
dangerous design faster! With plenty of research and a book like:

http://www.amazon.co.uk/exec/obidos/...ternodeltdcomp

You can probably get a good deal of the source data you would need to
produce unsable data for the program.

The more practical alternative is to insert 8x3" beams in between and

parallel to the existing ceiling joists and remove the tie beams
altogether. You could then insert a row of noggings between the new
floor beams which you fix to the ceiling joists.


sounds like a good plan as this would give me a higher cealing it is
quite large already though with a middle hight of around 3m so quite
allot to work with.

how would I go about this i.e how to support the cealing before the tie
beams are removed I guess you need to remove these before you put in
the 4.5m sections from the outer house walls to the center wall ? would
I attach the cealing jiosts to the perlins with metal ties and cut the
tie beams into sections to remove them ?

First let me state again I have not seen your loft - so there may be
some fundamental deign point I am missing. Also while I am an engineer,
I am not a structural one. In other words don't go hacking lumps out of
your roof until you have verified what I am saying!

If you have a close look at the first two photo's on this page you can
see me doing exactly this:

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

The tie beams were in my case only 4x2" like the other loft joists. They
ran across the loft and were skew nailed to each of the joists. Hence
their main function was to prevent latteral movement of the joists, and
provide a little coupling and load sharing to the adjacent joists. Note
however they strength of this coupling was limited by the relatively low
forces that would have been required to pull the nails out[1].

To allow the joist to be inserted, we prepared *three* lengths of 4x1"
to use as temporary straps. You can nail these to the purlin[2], and the
to the tie itself. We used one either side of the section to be removed.
After these were in place a section of the tie was cut out. To insert
the next joist you nail up the third one up to the side of the next cut,
and then when that is in place, take out the middle one (that way you
never "let go" of the tie beam and alow a bit of the ceiling to sag).


[1] You would need to look carfully at you larger cross beam and see how
it is fixed to the joists to understand if it is simply doing the same
as my ones were, or if it also performs some other function.

[2] Leave the heads sticking out so you can pullem out and reuse the
next time!

I am guessing this would pass the preasure to the middle wall and the
frount and back walls of our house the floor tie beam looks quite
large, is it not doing that much that it can be easyley removed as you
sirjest? (sorry my spellings not very good)

If it is doing as I susspect, then it can be removed in the way
desribed. Once you have at least two new big joists in place you can
stick a 2x2" noggin across between them and nail them to the old ceiling
joist and the sides of the new floor joists. That will then duplicate
the function of the tie beam.

I have been informed that I could also hang 8"x3" jiost on the party
walls at 400mm centres using jiost hangers with the morter of the
current brick walls grinded out and then placing the hangers in the
wall and cementing them in is this a practical way of doing it ? and
would it give me the same amount of structual stregth i.e is it better
to hang jiost on the frount and back of the house or the two party
walls ?

You could, but it is harder work, takes longer, is more expensive, and
you loose 4" extra headroom.

if I do hang the jiost over the fround and back walls how would I
attach them to the walls just lay them on or what part should they be
succed to ?

The tops of the load bearing walls will probably already have a "wall
plate" on them (i.e. timber beam running along the inner course of
brickwork). This will normally be fixed to top of the wall, and each of
the rafters will be fixed to it by cutting a "birdsmouth joint" in the
rafter, and nailing it to the wall plate. To add your floor, you first
nail a packing piece to the wall plate between all the existing joists
(this gives clearance between the underside of the new floor and the
ceiling below). The new joists themselves are then skew nailed to the
packer. There is not much structural purpose to this fixing - the beams
are designed to carry the load simply resting on the wall plate, they
are not held in tension - but it does serve to stop them sliding about!

--
Cheers,

John.

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