Notching joists in bathroom refit

[dagger]

I need to run 32mm waste from one side of the room to the other to get to existing waste and there is no way we can reroute etc etc

som my question is;

is there a better place to notch (ie nearer the supporting wall or is in the middle better)

also is a hole through the middle better than notching at top

thanks gents

 

[gas4you]

There are set regs about notching positions and sizes etc.

Drilling through the middle of the joist will leave a stronger result.

If I remember you should only drill between 20 and 40% of the joist span.

 

[Breesey]

Technically you can't just do it anywhere in the joist.

What is your joist's depth and length?


Generally you can only notch to 1/8 the depth of the joist in a zone between 7% and 1/4(25%) the length from one end. Holes, on the depth centre line should be 1/4 depth in diameter max, in a zone between 1/4 (25%) and 2/5 (40%) the length of the joist, from the end of the joist.

 

[ChrisR]

Often a better solution is to bring a skirting out 32mm and put it behind, or go out of the "other " wall and round the corner.

 

[dagger]

cheers gents

Ive measured the joist and its 8 inches high. so I can safely notch out up to 2 inches (50mm ish) out of the top then ?

In reality I only need about 34mm so I will make it as small as poss.

do you think I need to then add some stiffening brace support type battens on these notched joists under the notches or will it be okay as is ???

cheers again

 

[Breesey]

NO! NO! NO!

You can drill a 2" hole through the centre line of the notch, close to the end as I said in my other post.

OR

You can put a notch 1" deep in the top. Again in the zone close to either end as I said in previous post.

If you follow the recommendations your joists will be fine. Trying to reinforce is pointless. If you've over cut it it's b******d

Do NOT notch 2".

 

[dagger]

okay sorry got a bit confuzzed

so I'd better go 2" through the middle of the joist then as 1" isnt enough

cheers

 

[Breesey]

That's it.