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Default Hole in Joist

I need to bore a hole in a joist to take a shower waste. Reading the regs
tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house - load on
it will never be high.

Pragmatically - would you go ahead and bore the hole?
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Default Hole in Joist


DerbyBorn wrote:

the regs tells me that in a 20cm Joist the max hole can be 32mm I
need to pass a pipe of 42mm diameter!


Reinforce the joist by bolting metal plates to both sides?

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Default Hole in Joist

On 26/06/2019 18:23, Andy Burns wrote:

DerbyBorn wrote:

the regs tells me that in a 20cm Joist the max hole can be 32mm I
need to pass a pipe of 42mm diameter!


Reinforce the joist by bolting metal plates to both sides?


Or bolt it to the wall.

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Default Hole in Joist



the regs tells me that in a 20cm Joist the max hole can be 32mm I
need to pass a pipe of 42mm diameter!


Reinforce the joist by bolting metal plates to both sides?


Or bolt it to the wall.


Access would be very destructive.
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Default Hole in Joist

On 26/06/2019 18:33, DerbyBorn wrote:

the regs tells me that in a 20cm Joist the max hole can be 32mm I
need to pass a pipe of 42mm diameter!

Reinforce the joist by bolting metal plates to both sides?


Or bolt it to the wall.


Access would be very destructive.


So not as simple as just lifting the boards either side of the hole then:-(



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Default Hole in Joist

On 26/06/2019 18:17, DerbyBorn wrote:
I need to bore a hole in a joist to take a shower waste. Reading the regs
tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house - load on
it will never be high.

Pragmatically - would you go ahead and bore the hole?


Yes.

(noting a hole in the centre is better mid span, and a notch better near
the ends)


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Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
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Default Hole in Joist

John Rumm wrote in
o.uk:

On 26/06/2019 18:17, DerbyBorn wrote:
I need to bore a hole in a joist to take a shower waste. Reading the
regs tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house -
load on it will never be high.

Pragmatically - would you go ahead and bore the hole?


Yes.

(noting a hole in the centre is better mid span, and a notch better
near the ends)



I now reckon I am okay up to 50mm on a 200mm deep joist:

https://www.labc.co.uk/news/how-get-...-solid-timber-
joists
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Default Hole in Joist


"DerbyBorn" wrote in message
2.222...
I need to bore a hole in a joist to take a shower waste. Reading the regs
tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house - load on
it will never be high.

Pragmatically - would you go ahead and bore the hole?


go on take a chance ...all the other joists and flooringwill stop anything
bad happening.......


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Default Hole in Joist

On 26/06/2019 18:17, DerbyBorn wrote:
I need to bore a hole in a joist to take a shower waste. Reading the regs
tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house - load on
it will never be high.

Pragmatically - would you go ahead and bore the hole?

yes. I might add another joist alongside


--
€œIt is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
who pay no price for being wrong.€

Thomas Sowell
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Default Hole in Joist

On 26/06/2019 18:17, DerbyBorn wrote:
I need to bore a hole in a joist to take a shower waste. Reading the regs
tells me that in a 20cm Joist the max hole can be 32mm


That is probably a *suggestion* that means in the case of thick plunbers
they will never cause the joist to collapse.



I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house - load on
it will never be high.


Exactly. And yet the regs don't take that into account.

Rules are for the guidance of wise men and the obedience of fools




--
€œIt is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
who pay no price for being wrong.€

Thomas Sowell


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Default Hole in Joist

On 26/06/2019 19:05, Chris Hogg wrote:
On Wed, 26 Jun 2019 18:23:37 +0100, Andy Burns
wrote:


DerbyBorn wrote:

the regs tells me that in a 20cm Joist the max hole can be 32mm I
need to pass a pipe of 42mm diameter!


Reinforce the joist by bolting metal plates to both sides?


The any beam of that sort is in tension along its lower edge,
compression along its upper edge, as it takes load. A metal plate
along the lower edge should be sufficient, e.g. a long mending plate
or flat strap, something like this https://tinyurl.com/y3wloogy
But IANA structural engineer!

TBH slap[ping somne falss fibre n each side woul probably do a huge amouint.

I actually did this for a model plane wingh - calculated the increase in
strength of a wing with a carbon fibre strip glued along the top and
bottom of the main spar.

MASSIVE increase in strength with just a tiny amount of carbon fibre.

Wood is cheap. Its also a crap structural material.

https://www.scottsofthrapston.co.uk/...-floor-joists/

Is where things are going as wood gets more expensive


--
If you tell a lie big enough and keep repeating it, people will
eventually come to believe it. The lie can be maintained only for such
time as the State can shield the people from the political, economic
and/or military consequences of the lie. It thus becomes vitally
important for the State to use all of its powers to repress dissent, for
the truth is the mortal enemy of the lie, and thus by extension, the
truth is the greatest enemy of the State.

Joseph Goebbels



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Default Hole in Joist

On 26/06/2019 19:47, DerbyBorn wrote:
John Rumm wrote in
o.uk:

On 26/06/2019 18:17, DerbyBorn wrote:
I need to bore a hole in a joist to take a shower waste. Reading the
regs tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house -
load on it will never be high.

Pragmatically - would you go ahead and bore the hole?


Yes.

(noting a hole in the centre is better mid span, and a notch better
near the ends)



I now reckon I am okay up to 50mm on a 200mm deep joist:

https://www.labc.co.uk/news/how-get-...-solid-timber-
joists

I was going to say what John said. But that link looks pretty good to me!
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Default Hole in Joist

I was just going to say something similar, even a second piece of timber
suitable attached across the weakened point might be enough. It very much
depends on the place and design of the building I guess.
Brian

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"Andy Burns" wrote in message
...

DerbyBorn wrote:

the regs tells me that in a 20cm Joist the max hole can be 32mm I
need to pass a pipe of 42mm diameter!


Reinforce the joist by bolting metal plates to both sides?



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Default Hole in Joist

On Wednesday, 26 June 2019 18:17:47 UTC+1, DerbyBorn wrote:
I need to bore a hole in a joist to take a shower waste. Reading the regs
tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house - load on
it will never be high.

Pragmatically - would you go ahead and bore the hole?


The regs on joist sizes have nothing to do with safety. They're more about meeting noise transmission targets. If OTOH it's an old house with bouncy floors I'd add noggings each side of a large hole. But 2" out of 8" isn't large.


NT
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Default Hole in Joist

On Wednesday, 26 June 2019 18:17:47 UTC+1, DerbyBorn wrote:
I need to bore a hole in a joist to take a shower waste. Reading the regs
tells me that in a 20cm Joist the max hole can be 32mm

I need to pass a pipe of 42mm diameter!

The joist is right next to a wall at the outer edge of the house - load on
it will never be high.

Pragmatically - would you go ahead and bore the hole?


Glue and screw an extra bit of wood on to the joist spanning the hole. PVA would do the jpb

Drill the hole through both joist and wood.
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