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Default Roof timbers

In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support the
roofing timbers whilst building the house. The house has what I believe is
called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle from
the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold things
upright whilst assembling the roof?


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"John" wrote in message
...
In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support
the roofing timbers whilst building the house. The house has what I
believe is called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle
from the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold
things upright whilst assembling the roof?


Maybe this link will work and clarify what I am trying to explain:

http://tinyurl.com/2w5x8kl


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On 30/05/10 16:24, John wrote:
wrote in message
...
In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support
the roofing timbers whilst building the house. The house has what I
believe is called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle
from the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold
things upright whilst assembling the roof?


Maybe this link will work and clarify what I am trying to explain:

http://tinyurl.com/2w5x8kl



I'll go out on a limb here - I can't see those 2 weedy nails holding
that diagonal in are capable of resisting major shearing forces. So I
*think* that you are right and it was a building aid rather than an
integral part of the structure.

Why is there such a large gap between those middle rafters? Without
seeing the rest of the roof, what is there about the construction that
would resist the roof folding flat, if that diagonal were important?

If you are concerned, you could screw that timber across the bottoms of
the rafters right next to the braces and put in several short diagonal
braces between the braces so they are not so obstructive which should
add general stiffness to the assembly.

Some more photos of the rest of the roof could be useful.

--
Tim Watts

Hung parliament? Rather have a hanged parliament.
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"Tim Watts" wrote in message
...
On 30/05/10 16:24, John wrote:
wrote in message
...
In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support
the roofing timbers whilst building the house. The house has what I
believe is called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle
from the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold
things upright whilst assembling the roof?


Maybe this link will work and clarify what I am trying to explain:

http://tinyurl.com/2w5x8kl



I'll go out on a limb here - I can't see those 2 weedy nails holding that
diagonal in are capable of resisting major shearing forces. So I *think*
that you are right and it was a building aid rather than an integral part
of the structure.

Why is there such a large gap between those middle rafters? Without seeing
the rest of the roof, what is there about the construction that would
resist the roof folding flat, if that diagonal were important?

If you are concerned, you could screw that timber across the bottoms of
the rafters right next to the braces and put in several short diagonal
braces between the braces so they are not so obstructive which should add
general stiffness to the assembly.

Some more photos of the rest of the roof could be useful.

--
Tim Watts

Hung parliament? Rather have a hanged parliament.


Tim - I have added some more photos - some looking up at the short ridge.
The large gap aligns with the loft hatch and ceiling support timbers.
There are 5 timbers supporting the ridge.


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Additional photos added.

http://tinyurl.com/2w5x8kl




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On May 30, 4:24*pm, "John" wrote:
"John" wrote in message

...

In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support
the roofing timbers whilst building the house. The house has what I
believe is called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle
from the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold
things upright whilst assembling the roof?


Maybe this link will work and clarify what I am trying to explain:

http://tinyurl.com/2w5x8kl


The 3" x 3/4" or 75mm x 19mm timbers are there for a pacific reason.
They are not temporary supports; they are all part of the stress of
side movement on truss roof construction. It was found that in the
early days of truss roof use, that when the weight of the roof tiles
was loaded the trusses would sway. The diagonal braces, as they are
called. Were introduced to stop sway. If you’ve ever work on a truss
roof without bracing, as you moved about it was a bit unstable. They
are not put into position until all the trusses have been erected.
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Why do you want to move it?

--
Cheers,

John.


To make room for a panel on which to mount a combi boiler. I am planning on
erecting a vertical timber to align with an existing vertical - then
spanning the gap with a plywood panel clad in plasterboard. The space is
above an existing boiler and on the same line as an existing flue.


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On 30/05/10 21:05, John Rumm wrote:
On 30/05/2010 17:54, John wrote:
Additional photos added.

http://tinyurl.com/2w5x8kl


Other than confirming its a trussed design - W trusses by the looks of
it - it does not tell us much more. The diagonal timber could be "moved"
in the sense that a duplicate one could be fixed to the underside of the
rafters (on both opposing roof slopes to be sure!) rather than the inner
part of the W, and then the original one removed.


I'll go with that too.

The diagonal doesn't look very structural - not with that random bit of
metal band on the base of it.

But, as John says, you cannot go wrong with some diagonals under the and
across the rafters and the net effect will be the same - they'll be out
teh way then.

I would use screws rather than nails to avoid banging the crap out of
the roof (5mm ScrewTite or Reissers would make it simple without much
risk of spliiting the rafters)

Why do you want to move it?



--
Tim Watts

Hung parliament? Rather have a hanged parliament.
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On 30/05/10 19:34, Kipper at sea wrote:
On May 30, 4:24 pm, wrote:
wrote in message

...

In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support
the roofing timbers whilst building the house. The house has what I
believe is called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle
from the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold
things upright whilst assembling the roof?


Maybe this link will work and clarify what I am trying to explain:

http://tinyurl.com/2w5x8kl


The 3" x 3/4" or 75mm x 19mm timbers are there for a pacific reason.
They are not temporary supports; they are all part of the stress of
side movement on truss roof construction. It was found that in the
early days of truss roof use, that when the weight of the roof tiles
was loaded the trusses would sway. The diagonal braces, as they are
called. Were introduced to stop sway. If you’ve ever work on a truss
roof without bracing, as you moved about it was a bit unstable. They
are not put into position until all the trusses have been erected.


Interesting...

Any reason they didn't strap the rafters with diagonals?

In fact. I have seen under-rafter strapping on my old rented house
(modern truss roof) - so I'm *guessing* it was down to how the builders
felt on the day?

--
Tim Watts

Hung parliament? Rather have a hanged parliament.
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[Default] On Sun, 30 May 2010 16:14:08 +0100, a certain chimpanzee,
"John" , randomly hit the keyboard and
wrote:

In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support the
roofing timbers whilst building the house. The house has what I believe is
called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle from
the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold things
upright whilst assembling the roof?

From the photos, I would have a few observations:
1. The centres of the trusses looks very random. Either the centres of
the trusses either side are much less than 600mm, or the central pair
are way over.
2. Just looked it up, and provided that the hips are properly
constructed, and the distance between then is 1.8mm or less[*], you
don't need diagonal bracing (under the rafters from wallplate to
ridge) ...
3. Which you don't appear to have.

The bits of timber in question could be chevron bracing, but this is
only required to trusses exceeding 8m in length[*].

You could move the chevron brace to run in an opposite direction, but
I would be reluctant to remove it entirely without knowing for sure
whether it's needed or not.

The other question is, "do you really want your boiler in the loft?"
[*] Assuming normal wind loads (i.e., you're not on top of a hillside
or an exposed fen or something).
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have I strayed"?


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"Hugo Nebula" abuse@localhost wrote in message
news
[Default] On Sun, 30 May 2010 16:14:08 +0100, a certain chimpanzee,
"John" , randomly hit the keyboard and
wrote:

In preparation for putting a boiler in my loft I am wondering if a
particular timber is just what the builders used temporarily to support
the
roofing timbers whilst building the house. The house has what I believe is
called a double hipped roof.
The timber in question is about 3/4" x 3" - it runs at a shallow angle
from
the bottom of a roof member - upward to tie in with 3 others.
Anyone able to advise? Do builders use temporary bits of wood to hold
things
upright whilst assembling the roof?

From the photos, I would have a few observations:
1. The centres of the trusses looks very random. Either the centres of
the trusses either side are much less than 600mm, or the central pair
are way over.
2. Just looked it up, and provided that the hips are properly
constructed, and the distance between then is 1.8mm or less[*], you
don't need diagonal bracing (under the rafters from wallplate to
ridge) ...
3. Which you don't appear to have.

The bits of timber in question could be chevron bracing, but this is
only required to trusses exceeding 8m in length[*].

You could move the chevron brace to run in an opposite direction, but
I would be reluctant to remove it entirely without knowing for sure
whether it's needed or not.

The other question is, "do you really want your boiler in the loft?"

[*] Assuming normal wind loads (i.e., you're not on top of a hillside
or an exposed fen or something).
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have I strayed"?


Many thanks.

The reason for planning to put the boiler in the loft is that I have very
little built in cupboard space. The existing floor standing boiler occupies
a substantial part of what could be a useful cupboard on the landing. To
replace it with a wall mounted boiler would still require a significant
amount of space being taken up - and the construction is only plasterboard
(no timber supports) - whilst I could overcome any weaknesses, it seems that
it may as well go in the loft - after all, it hardly needs to be accessed
frequently.

I have looked at the timbers again and have decided that if I bring my
proposed back board supports forward by 2" then I won't get a clash with the
brace which was my concern.

The large spacing incidentally is 650mm (centre to centre)


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In article ,
Tim Watts writes:
On 30/05/10 19:34, Kipper at sea wrote:

The 3" x 3/4" or 75mm x 19mm timbers are there for a pacific reason.
They are not temporary supports; they are all part of the stress of
side movement on truss roof construction. It was found that in the
early days of truss roof use, that when the weight of the roof tiles
was loaded the trusses would sway. The diagonal braces, as they are
called. Were introduced to stop sway. If you’ve ever work on a truss
roof without bracing, as you moved about it was a bit unstable. They
are not put into position until all the trusses have been erected.


Interesting...

Any reason they didn't strap the rafters with diagonals?

In fact. I have seen under-rafter strapping on my old rented house
(modern truss roof) - so I'm *guessing* it was down to how the builders
felt on the day?


They work best on the timbers which are nearest to being vertical.
The rafters usually are the least vertical in a trussed roof.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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