From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that nothing is still permitted (unless you are using some
composite joists made with stringers and web).

--
Cheers,

John.

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

John Rumm wrote:
John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that nothing is still permitted (unless you are using some

Very true! :-)

composite joists made with stringers and web).


--
Chris Green

On Mar 9, 8:22 am, John Rumm wrote:
John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that nothing is still permitted

I can see why it would be prohibited in the central half of the joist
length. but why is it prohibited at the ends of the joist? Surely
that's the palce where it would have least effect on the strength.

BTW, how DO people install central heating pipes now? Do they have to
use flexible ones and drill through the joist centre?

Robert

On Fri, 09 Mar 2007 08:22:17 +0000, John Rumm
wrote:

John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that
nothing
is still permitted (unless you are using some
composite joists made with stringers and web).

I take it you mean "notching" and not "nothing" ..lol

On 9 Mar 2007 02:24:48 -0800, "Robert Laws"
wrote:

On Mar 9, 8:22 am, John Rumm wrote:
John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that nothing is still permitted

I can see why it would be prohibited in the central half of the joist
length. but why is it prohibited at the ends of the joist? Surely
that's the palce where it would have least effect on the strength.

BTW, how DO people install central heating pipes now? Do they have to
use flexible ones and drill through the joist centre?

Robert

I would imagine that notches anywhere would affect the allowable
deflection of the joist, to some extent. After all, the joist depths
are calculated from tables to meet the requirements of the span. But
you are right - how to get around the problem of CH pipes? I suppose
that the only practical solution is to notch at the ends, with
shearing force being the only real factor there as opposed to
deflection.
In my house, there are quite a few cases of joists notched in the
centre and electrical cables run on top. I've re-routed most of the
electrical cables but haven't bothered to strengthen the notched
places with plywood (and probably never will since the joists are not
deflecting too much!).

Maris

Robert Laws wrote:

Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that nothing is still permitted

I can see why it would be prohibited in the central half of the joist
length. but why is it prohibited at the ends of the joist? Surely
that's the palce where it would have least effect on the strength.

It is the place that is least affected by any bending forces on the
joist, but *most* affected by any shear forces, since it is immediately
adjacent to the point of support (via hanger, wall etc). Notches here
could enable the joist to split at the end.

BTW, how DO people install central heating pipes now? Do they have to
use flexible ones and drill through the joist centre?

In an ideal world, you can still use notches - just be a bit choosy
where you notch. In the real world most plumbers seem to hack lumps out
any place they fell like it!


--
Cheers,

John.

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

Stuart B wrote:
On Fri, 09 Mar 2007 08:22:17 +0000, John Rumm
wrote:

John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?
Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that
nothing
is still permitted (unless you are using some
composite joists made with stringers and web).

I take it you mean "notching" and not "nothing" ..lol

Yup, sorry!

--
Cheers,

John.

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

On Thu, 08 Mar 2007 23:40:30 +0000, John Stumbles wrote:

From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

OK I own up. I wrote this section.

Well this is part A of the BR and has been for some while.
I have at least one gas fitting book that covers this matter.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 09 Mar 2007 02:24:48 -0800, Robert Laws wrote:

On Mar 9, 8:22 am, John Rumm wrote:
John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that nothing is still permitted

I can see why it would be prohibited in the central half of the joist
length. but why is it prohibited at the ends of the joist? Surely
that's the palce where it would have least effect on the strength.

But the shear stresses are highest at the ends.



BTW, how DO people install central heating pipes now? Do they have to
use flexible ones and drill through the joist centre?

Robert


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 09 Mar 2007 11:16:41 +0000, John Rumm wrote:

Stuart B wrote:
On Fri, 09 Mar 2007 08:22:17 +0000, John Rumm
wrote:

John Stumbles wrote:
From the wiki:
(http://wiki.diyfaq.org.uk/index.php?...Heating_Design)

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?
Not that I am aware of, there are restrictions as to where (between 0.1
and 0.25 x span) and how deep (no more than 0.125 x joist depth), but
other than that
nothing
is still permitted (unless you are using some
composite joists made with stringers and web).

I take it you mean "notching" and not "nothing" ..lol

Yup, sorry!

OK I think I over stated the case here. Although much of the text is
probably still OK.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

Ed Sirett wrote:

"In the past installers may have notched the tops (or bottom
sides) of joists to install pipe work. This practice is now forbidden by
the building regs and also leaves the pipes vulnerable to damage."

Have I missed a(nother) change of regs?

OK I own up. I wrote this section.

Well this is part A of the BR and has been for some while.
I have at least one gas fitting book that covers this matter.

Do you have a section number in the BR document? I could not find
anything in the latest (2004) edition (which is odd because I am sure I
have seen reference to it somewhere).

--
Cheers,

John.

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

On Sat, 10 Mar 2007 02:47:04 +0000, a particular chimpanzee, John Rumm
randomly hit the keyboard and
produced:

Ed Sirett wrote:

Well this is part A of the BR and has been for some while.
I have at least one gas fitting book that covers this matter.

Do you have a section number in the BR document? I could not find
anything in the latest (2004) edition (which is odd because I am sure I
have seen reference to it somewhere).

The old span tables (including the notching diagrams) were removed
from the 2004 Approved Document A, and section 2b just refers to the
TRADA document or BS 5268-2 and BS 8103-3, both of which are available
for a fee[1]. The guidance hasn't changed from the 'old' 1992 AD A
which can still be downloaded from the Planning Portal website.

Notching outside these parameters is not 'prohibited'; these are
'rules-of-thumb', and if you wish not to take advantage of them, you
will need to demonstrate by calculation that the member is still
adequate for the loads upon it.

[1] The TRADA tables were removed, as I understand it, at the request
of TRADA because either the Government didn't want to pay the fees to
TRADA for reproducing them, or TRADA thought they could earn more by
publishing them themselves.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"