Cutting hole for toilet waste between joists

swumhole · Dec 13, 2011

Hi all,

Newbie question, sorry if been asked before but I've searched and come up with nothing!

I'm looking at buying a house but it has a seriously small bathroom (4'9" wide and 9'10" long with a chimney breast along one wall), so there is no bath in, just a shower. I think I could install a small bath along the short wall but I would have to move the toilet, but there would be no space for the waste pipe above the floorboards as the pipe needs to go out the wall the bath will be against. There is only one external wall.
As the joists are running in the right direction I thought I may be able to run the waste pipe under the floor and through the wall but would this weaken the integrity of the joists either side of the four inch hole?

Any advice would really be appreciated (the Mrs doesnt want a macerator but apparently cant live without a bath!!).

Huge thanks!
Ken.

Best · Dec 13, 2011

Shouldn't do any harm to joists if hole is cut & built up again or best way to be core drilled.

stevetheplumber · Dec 14, 2011

you can get a four inch pipe through under the bath at the opposite end to the taps if that helps

Puddle · Dec 14, 2011

As steve says,soil pipe should fit under end of bath,if you use the end with the bigger slop,You should be able to get a 5'' bath in there,if you get one with no tap holes,you can use overflow filler or on in side wall,to allow you to bury bath ends into wall more to get rid of excess length maybe

but as best says, if you think would be neater you can run out between joists,not a problem

Bernie2 · Dec 14, 2011

Hmm!

Go careful check your joist centres for loading, as a bath full of water and its occupant can weigh a lot. If the joist spacing is too high you might find yourself having a bath in the room below. Check on the free Building Regulations site in the Construction section for joist size, space and loading. The room may just have a shower in for a reason. Perhaps the room was not a bathroom before and putting a bath in may overload the floor. In point sometimes you have to tell the local building control officer what you intend to do.

Best · Dec 14, 2011

If I read your question right, then what you said is, that it suits you to go below the floor, between the joists, & the joists are running right way, so all you want to know is if hole between joists will weaken anything? If I had read it right, then answer is no.

tamz · Dec 14, 2011

Think about a P shaped bath if you are getting a 5ft one. Gives a bit extra room.

swumhole · Dec 16, 2011

Best said:
If I read your question right, then what you said is, that it suits you to go below the floor, between the joists, & the joists are running right way, so all you want to know is if hole between joists will weaken anything? If I had read it right, then answer is no.

On the nose! Thanks for the reply and thanks to all others too, as I wasn't aware the slope at opposite end to the taps would be large enough for the bog waste.

Thanks again

Ken

Best · Dec 16, 2011

Nice if you can have the soil pipe below the floor, but can be a bit of effort. If the joists are not very deep, use the tight male & female 90 degree bend. The male side of it can be fitted through floor if necessary.