Can joists be drilled to take bathroom plastic waste pipes?

[HomerSimpson]

I'm sure this has been asked and answered before but I couldn't find it on search.

My joists run the wrong way for our new proposed bathroom layout. Is it permissable to drill the joists with a hole saw to take 32mm or even 40mm plastic waste pipes? or do I have to build a boxed-in skirting board around the perimeter of the room to link up with main 110mm downpipe?

 

[ollski]

I'm sure this has been asked and answered before but I couldn't find it on search.

My joists run the wrong way for our new proposed bathroom layout. Is it permissable to drill the joists with a hole saw to take 32mm or even 40mm plastic waste pipes? or do I have to build a boxed-in skirting board around the perimeter of the room to link up with main 110mm downpipe?

Only if you have whopping great big joists , can't remember the joist notcing and drilling figures off the top of my head, but sure you will need to surface mount waste pipes and box them in.

 

[ChrisR]

Search for recent answer to this

 

[ollski]

sorry I misinformed you, if you are drilling holes through the joist then te measurements are:

acceptable between 25 - 40 % of the span of the joist measured in from the supporting wall and a maximum diameter of 25% of the depth of the joist on the centre line.

 

[brumylad]

box em in with fitted bathroom furniture (Like fitted kitchen furniture) if u can.

 

[Paul Barker]

No point drilling them because you won't get the pipe in the hole, you have to slot them, no more than 1/8th of the depth of the joist, the distance from supporting wall mentioned. If you do run below floor use solvent weld pipe. Can you run with the joists to an alternate wall and then go round the outside of the building?

If not, then as people are saying, box them in above floor.

 

[HomerSimpson]

Thanks Paul...you've just saved me from lots of hassle!
I should have realised that I wouldn't have been able to thread a rigid pipe through the holes anyway. Thank you...I'm glad I asked now.

 

[doitall]

Assuming the joists are the standard 400mm centres and 250 x 50mm in size, then provided you can drill a straight hole 10mm larger than the pipe, it's quite easy to thread plastic pipe through the hole.

The real issue is any tight spots wher the pipe passes throught he joist will creak for ever and a day.

 

[JPC]

i remember summit about not drilling holes more than 1/8 of the height of the joist (the same as a notch) so that wont work unless ur joists are around 400 mm high. ! plus the issue of threading them.

pauls right....try going on the o/s of the house one way or another

 

[ollski]

i remember summit about not drilling holes more than 1/8 of the height of the joist (the same as a notch) so that wont work unless ur joists are around 400 mm high. ! plus the issue of threading them.

pauls right....try going on the o/s of the house one way or another

Holes are 1/4, notches are 1/8

 

[JPC]

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[ChrisR]

1/4 , max of 50 mm. Holes are easy to make as long as you have a drill capable. Just measure carefully!

 

[gwernybwch]

Hi all,

Thought that I would add to this thread rather than start a new one. Similar to the OP, I'm renovating my upstairs bathroom and the joists run perpendicular to where I need the shower waste pipe to flow.
The joists (7") have previously been drilled and fitted with a 32mm waste pipe (previously fitted with a bath only).

I'm hoping to get both a mains fed shower and a bath in the bathroom.

Although the shower I'm going to fit will be a plith / on risers style, I don't think that there is the option of having the waste pipe boxed in running around the corners of the bathroom.
The reason for this is that I am going to fit a roll-top type bath, therefore don't want boxing running around the bottom edge of the bath.

(Q1) As part of the bathroom already has the joists drilled for 32mm waste pipe, will 32mm be sufficient for a mains fed shower?
(Q2) If I need to replace the waste pipe - either some of the 32mm or all it for 40mm, how would you actually thread the pipe into the joists?
Very short lengths of waste pipe and then several solvent weld joints? Core drill the outside wall, then slide the complete length in?

Thanks in advance for any replies.

 

[stevehit]

I had this problem when I did may bathroom, over a year ago. I core drilled the wall, and slide a single pipe (no joins) from the outside, with no problems. (Someone on the inside to guide the end as you shove it through can avoid considerable frustration.) I also reinforced the joists where I'd cut the holes with 800 mm long x joist height lengths of 18mmm ply, screwed and glued to both sides of each joist. Maybe overkill, but the floor is solid and I've not experienced any movement or grout lines cracking, etc.
Finally, I'd say that you need at least 40mm dia waste for your shower. Don't forget to allow for a suitable fall for the waste pipe when you make your holes.