I have a house that was built in 1984. The roof trusses are constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.

In an earlier contribution to this discussion,
Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are
constructed from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have
no idea what the rating of the wood is. Each truss is spaced about
600mm (centre to centre) apart. The ceiling joist part of the truss
spans 7.2 metres. Some of the wood has been spliced together using
what looks like perforated metal sheets banged into each side of the
wooden beams. The roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively
used for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.

Are the ceiling joists unsupported for the whole 7.2 metres - or are there
intermediate stud walls which give additional support?
--
Cheers,
Roger
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Roger Mills wrote:
In an earlier contribution to this discussion,
Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are
constructed from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have
no idea what the rating of the wood is. Each truss is spaced about
600mm (centre to centre) apart. The ceiling joist part of the truss
spans 7.2 metres. Some of the wood has been spliced together using
what looks like perforated metal sheets banged into each side of the
wooden beams. The roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively
used for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.

Are the ceiling joists unsupported for the whole 7.2 metres - or are there
intermediate stud walls which give additional support?
There are intermediate stud walls, which hopefully give support. There
is also a cold water tank (up there) that supplies my hot water cylinder
in the airing cupboard in the bathroom. It is supported by two wooden
beams laid across 4 of the ceiling joists. Doesn't seem to have caused a
problem.

It is probably going to be ok for what I want, I just like to have all
of the relevant information.

On 10 Apr, 12:52, Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.


If those really span 7.2m I dont think I'd put anything on them.


NT

On Apr 10, 4:53 pm, wrote:
On 10 Apr, 12:52, Rob Horton wrote:





I have a house that was built in 1984. The roof trusses are constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.

If those really span 7.2m I dont think I'd put anything on them.



...but they're not spanning 7.2 unsupported - it's all triangulated

wrote:
On 10 Apr, 12:52, Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.


If those really span 7.2m I dont think I'd put anything on them.


They are W "Warren" braced. Ultimate breaking strain probably around 2-5
tons on any given beam. Unacceptable deflection? probably a fair bit
less. Probably half a ton on any beam. Adding a chipboard floor to
spread the load will probably result in a floor not much worse than any
normal room.
NT

The Natural Philosopher wrote:

wrote:

On 10 Apr, 12:52, Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.



If those really span 7.2m I dont think I'd put anything on them.


They are W "Warren" braced. Ultimate breaking strain probably around 2-5
tons on any given beam. Unacceptable deflection? probably a fair bit
less. Probably half a ton on any beam. Adding a chipboard floor to
spread the load will probably result in a floor not much worse than any
normal room.

I would be tempted to use normal floor boards spaced out by the width of
a board. They are much lighter than chipboard.

Dave

On Apr 10, 1:39 pm, Rob Horton wrote:
Roger Mills wrote:
In an earlier contribution to this discussion,
Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are
constructed from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have
no idea what the rating of the wood is. Each truss is spaced about
600mm (centre to centre) apart. The ceiling joist part of the truss
spans 7.2 metres. Some of the wood has been spliced together using
what looks like perforated metal sheets banged into each side of the
wooden beams. The roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively
used for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Are the ceiling joists unsupported for the whole 7.2 metres - or are there
intermediate stud walls which give additional support?

There are intermediate stud walls, which hopefully give support. There
is also a cold water tank (up there) that supplies my hot water cylinder
in the airing cupboard in the bathroom. It is supported by two wooden
beams laid across 4 of the ceiling joists. Doesn't seem to have caused a
problem.

It is probably going to be ok for what I want, I just like to have all
of the relevant information.

I think you will find that the supports for the tank span a small room
such as a bathroom. This room's walls will be taking the strain.

And to be even more brutal, the laws concerning cross bracing were
changed at about that time so your present roof might not be up to
modern standards. Do you know what kind of cross bracing you have and
what modern standards are for that type of roof?

Perhaps someone on here will point out to us what these standards are
these days.

On 10 Apr, 20:16, "Weatherlawyer" wrote:
On Apr 10, 1:39 pm, Rob Horton wrote:
Roger Mills wrote:
In an earlier contribution to this discussion,
Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are
constructed from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have
no idea what the rating of the wood is. Each truss is spaced about
600mm (centre to centre) apart. The ceiling joist part of the truss
spans 7.2 metres. Some of the wood has been spliced together using
what looks like perforated metal sheets banged into each side of the
wooden beams. The roof trusses are of a W type, fink, construction.

There are intermediate stud walls, which hopefully give support. There

And to be even more brutal, the laws concerning cross bracing were
changed at about that time so your present roof might not be up to
modern standards. Do you know what kind of cross bracing you have and
what modern standards are for that type of roof?

Perhaps someone on here will point out to us what these standards are
these days.

10s of millions of houses arent upto the latest BR. Over 10 mill have
no cross bracing at all. As issues go its a minor one.


NT

"The Natural Philosopher" wrote in message
...
wrote:
On 10 Apr, 12:52, Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.


If those really span 7.2m I dont think I'd put anything on them.


They are W "Warren" braced. Ultimate breaking strain probably around 2-5
tons on any given beam. Unacceptable deflection? probably a fair bit
less. Probably half a ton on any beam. Adding a chipboard floor to
spread the load will probably result in a floor not much worse than any
normal room.
NT


I can't find any reference to the figures above in the truss searches I've
done to date - do you have a reference perhaps?

I've been watching this thread with interest, as next week we move into a
70s bungalow with a very similar roof structure. Our trusses are spanning
7.7 metres, and made up from the same 95x35 timber. The only real difference
is that our trusses are on a slightly narrower 500mm spacing. There are
internal block walls under most of the trusses, but interestingly at one end
of the building there is a 3 metre section with no support - and no apparent
ceiling bowing. There is an existing water tank, sitting on 100x50 timbers
nailed(!) to the vertical members, parallel to three of the truss bases, at
about a foot up - presumably to gain a little extra head. This is only
partly over an internal wall, and does not seem to have distorted the
structure - although I need to check this more carefully once we are in.

Our new neighbours (who have been there some twenty years) have boarded out
their loft, and store a fair bit of "stuff", and say they have had no
problems to date.

I would like to add extra insulation to the 100mm or so that is there now,
and was thinking of adding parallel joists above the present bases of the
trusses, to give space for another 150mm of glass fibre. These joists would
be something like 100 or 125x35m, sitting on blocks on the wall plates, and
bolted to the truss vertical(ish) members. The centre of each joist would
have to have a bolted joint, as 7.5 metre timber is (obviously) difficult to
get, and impossible to get into the roof space anyway. I could then board
out the centre 3.5m or so for access and storage.

My rough calculations seem to show that the cost of the timber & glass fibre
would be a bit less than the equivalent insulation value of Kingspan or
similar, and the timber/glass combination would make subsequent access to
services easier in the future. I would also assume that effectively doubling
the truss bases, albeit at a slightly higher level, should make the
ceiling/loft floor more rigid.

Has anyone done anything like this to date, or have any thoughts?

Charles F

"Charles Fearnley" wrote in
message ...

"The Natural Philosopher" wrote in message
...
wrote:
On 10 Apr, 12:52, Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are
constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively
used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.


If those really span 7.2m I dont think I'd put anything on them.


They are W "Warren" braced. Ultimate breaking strain probably around 2-5
tons on any given beam. Unacceptable deflection? probably a fair bit
less. Probably half a ton on any beam. Adding a chipboard floor to
spread the load will probably result in a floor not much worse than any
normal room.
NT


I can't find any reference to the figures above in the truss searches I've
done to date - do you have a reference perhaps?

I've been watching this thread with interest, as next week we move into a
70s bungalow with a very similar roof structure. Our trusses are spanning
7.7 metres, and made up from the same 95x35 timber. The only real
difference
is that our trusses are on a slightly narrower 500mm spacing. There are
internal block walls under most of the trusses, but interestingly at one
end
of the building there is a 3 metre section with no support - and no
apparent
ceiling bowing. There is an existing water tank, sitting on 100x50
timbers
nailed(!) to the vertical members, parallel to three of the truss bases,
at
about a foot up - presumably to gain a little extra head. This is only
partly over an internal wall, and does not seem to have distorted the
structure - although I need to check this more carefully once we are in.

Our new neighbours (who have been there some twenty years) have boarded
out
their loft, and store a fair bit of "stuff", and say they have had no
problems to date.

I would like to add extra insulation to the 100mm or so that is there now,
and was thinking of adding parallel joists above the present bases of the
trusses, to give space for another 150mm of glass fibre. These joists
would
be something like 100 or 125x35m, sitting on blocks on the wall plates,
and
bolted to the truss vertical(ish) members. The centre of each joist would
have to have a bolted joint, as 7.5 metre timber is (obviously) difficult
to
get, and impossible to get into the roof space anyway. I could then board
out the centre 3.5m or so for access and storage.

My rough calculations seem to show that the cost of the timber & glass
fibre
would be a bit less than the equivalent insulation value of Kingspan or
similar, and the timber/glass combination would make subsequent access to
services easier in the future. I would also assume that effectively
doubling
the truss bases, albeit at a slightly higher level, should make the
ceiling/loft floor more rigid.

Has anyone done anything like this to date, or have any thoughts?
I have a similar style loft with 95mm x 35mm timbers. I screwed lengths of
95x35 onto the timbers first before boarding so the existing 100m insulation
was not comprimised. Also spend time and effort getting 8'x2' sheets of
flooring board in the loft rather than the expensive B&Q "loft floor packs"
as its much cheaper and considerably quicker.

Also a good excuse to get yourself some new power tools to play with as
flooring is much quicker with one drill with say 4mm drill for screw holes,
another for countersink and an electric screw driver to screw down.

Oh also last chance to get down the stud walls to get access to mains (or to
lighting ring) to put some handy mains sockets in the loft for aerial amps
etc.

Charles Fearnley wrote:
"The Natural Philosopher" wrote in message
...
wrote:
On 10 Apr, 12:52, Rob Horton wrote:

I have a house that was built in 1984. The roof trusses are constructed
from wood that is 34mm (1 3/8") by 95mm (3 3/4"). I have no idea what
the rating of the wood is. Each truss is spaced about 600mm (centre to
centre) apart. The ceiling joist part of the truss spans 7.2 metres.
Some of the wood has been spliced together using what looks like
perforated metal sheets banged into each side of the wooden beams. The
roof trusses are of a W type, fink, construction.

I want to partly board the roof area using Knauf spaceboard (chipboard
with polyfoam insulation underneath) so that It can be effectively used
for storage.

Where can I find information about the load carrying capacity for my
roof space? Something like kg/m2?

Thanks.

If those really span 7.2m I dont think I'd put anything on them.


They are W "Warren" braced. Ultimate breaking strain probably around 2-5
tons on any given beam. Unacceptable deflection? probably a fair bit
less. Probably half a ton on any beam. Adding a chipboard floor to
spread the load will probably result in a floor not much worse than any
normal room.
NT


I can't find any reference to the figures above in the truss searches I've
done to date - do you have a reference perhaps?

Nope. Just that I have lifted a tin on similar unsupported beam sizes
over a similar span.


I've been watching this thread with interest, as next week we move into a
70s bungalow with a very similar roof structure. Our trusses are spanning
7.7 metres, and made up from the same 95x35 timber. The only real difference
is that our trusses are on a slightly narrower 500mm spacing. There are
internal block walls under most of the trusses, but interestingly at one end
of the building there is a 3 metre section with no support - and no apparent
ceiling bowing. There is an existing water tank, sitting on 100x50 timbers
nailed(!) to the vertical members, parallel to three of the truss bases, at
about a foot up - presumably to gain a little extra head. This is only
partly over an internal wall, and does not seem to have distorted the
structure - although I need to check this more carefully once we are in.

Our new neighbours (who have been there some twenty years) have boarded out
their loft, and store a fair bit of "stuff", and say they have had no
problems to date.

I would like to add extra insulation to the 100mm or so that is there now,
and was thinking of adding parallel joists above the present bases of the
trusses, to give space for another 150mm of glass fibre. These joists would
be something like 100 or 125x35m, sitting on blocks on the wall plates, and
bolted to the truss vertical(ish) members. The centre of each joist would
have to have a bolted joint, as 7.5 metre timber is (obviously) difficult to
get, and impossible to get into the roof space anyway. I could then board
out the centre 3.5m or so for access and storage.

My rough calculations seem to show that the cost of the timber & glass fibre
would be a bit less than the equivalent insulation value of Kingspan or
similar, and the timber/glass combination would make subsequent access to
services easier in the future. I would also assume that effectively doubling
the truss bases, albeit at a slightly higher level, should make the
ceiling/loft floor more rigid.

Has anyone done anything like this to date, or have any thoughts?


Well the one way yo brace a loft floor that really works is to bolt
verticals - BOLT - between the rafters and the joists...its not as rigid
as warren bracing, but its a lot better than nowt.

Wood is a lot stronger then people think, its juts very elastic, and
most regulations are in the light of unacceptable deflections rather
than collapse.

The key is in bracing it into truss structures.


Charles F