Cutting Into Floor Joist, For Shower Tray Drain Pipe.

ParSec · 16-12-2024 12:35AM #1

I'm thinking of taking the bath out of our first floor bathroom and replacing it with a shower in the same footprint. The existing drain runs above the floor boards under the bath and out through the external wall. The issue I have, is with running the new 44mm diameter drain pipe for the shower, below floor board level, as the floor joists are not running in the correct direction, allowing me to take the drain out through the same external wall.

The two options regarding the placement of the shower tray are (a) flat on the floor boards (ideal) or (b) have the tray raised to a minimum height, to avoid too high of a step. Option (a) would mean taking the drain through the centre of one joist measuring 115x36mm, which is located tight to the external wall. Option (b) could range from taking a notch off the top of the joist, to running the drain over the floor board.

Due to the joist location, it has minimal loading. What is standard practice in this situation, with regard to either drilling through the joist or notching from the top of the joist or are they a non runner? How deep could the notch be, if it's ok to do this? Could a reinforcing plate with 44mm hole in it or strapping be used on the joist, to provide some extra strengthening?

Thank you in advance for your replies.

ParSec.

DublinDilbert · 16-12-2024 01:02PM

Yes i wouldn't normally notch a joist too deeply for the reasons you've outlined. On another forum I read a response from a guy who fits dental chairs/equipment, which are often in the middle of a treatment room upstairs and he gets steel plates made up for either side of the joist which he joins with bolts before notching the joist(s), as the chair is often in the middle of the room.

If the joist is tight to the wall, i would probably try slip something between the joist and the wall (damp proofing, plastic etc), then I would drive in 3 large (10mm) express nails either side of where you will notch to give the joist lots of support from that wall. These don't have to be driven fully home as they are just for support, but try keep them lowish in the joist. I would then take a hole saw to the joist.

whizbang · 26-12-2024 12:04AM

+++. its absolutely worth having the shower tray on the floor level. Pay attention to the type of drain used tho..

Calahonda52 · 29-12-2024 07:40PM

How did you dry ;;[do you propose to drill the wall] behind the joist that is // to it

Cutting Into Floor Joist, For Shower Tray Drain Pipe.

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