Shower waste hits joist

[mcgregory]

Hello,

Just bought a shower tray only to find the waste is slap bang over a joist.

I really don't want to build a step up.

Can I .. hear me out first .. cut the joist and use trimmers. Lots of them?

Thanks

 

[markproperjob]

i do this all the time, cut sections out of joists to run pipework. just dont go too deep into joist! halfway max.
anyway, you really dont want to install a shower tray slap bang on the floor, as-
1/ all waste piping must be accessible
2/ if the waste trap starts to leak and you have no access, its ceiling below chopping time!
3/ low height trays are great for smashing your toes into!!
the industry standars is to support the tray on 3''x2 cls timbers, allowing waste trap access, and then fit a upvc trimming strip around it and seal it up.

 

[Alpha man]

You should only notch any type of wooden joist a 1/3rd of the through.

 

[mcgregory]

Thanks for the prompt replies. I would need to remove the section of the joist completely, it is spot on, couldn't have lined it up better if I tried

I'm considering - in no order:

* cutting the joist, but laying 2 new joists each side.
* We may be able to get a Merlyte Tray Panel 145mm high - sounds like raising the tray is the sensible option anyway?
* trying to swap it with Bathroom Village (I'm sure the waste on the tray in the showroom was in a diff location).

Many thanks again. I was hoping to get trimmers etc. in place before my plumber turns up next week.

 

[kirkgas]

i do this all the time, cut sections out of joists to run pipework. just dont go too deep into joist! halfway max.
anyway, you really dont want to install a shower tray slap bang on the floor, as-
1/ all waste piping must be accessible
2/ if the waste trap starts to leak and you have no access, its ceiling below chopping time!
3/ low height trays are great for smashing your toes into!!
the industry standars is to support the tray on 3''x2 cls timbers, allowing waste trap access, and then fit a upvc trimming strip around it and seal it up.

sorry but you need a quick look in the building regs (the info is also in the gas training notes) you cannot cut a waste pipe half way down a joist, this will cause serious structural damage

 

[oldplumber]

modern house joints are built to min spec ie there is no leeway in cutting out too much, or they will fail. Proper victorian joists can take a little more damage and keep working ok, or so most previous plumbers and electricians seem to believe when I look around my old house!!

 

[tr7dan]

Maximum depth of notch in a floor joist is 1/8th of the depth of the joist - so in a 200mm joist (8") a 25mm (1") notch is allowed, in a 150mm (6") joist it's just 18.75mm (3/4").

Also, if you wanna be pedantic the notch should be no more than 1/4 of the way along the span from the supporting structure and no closer than 0.07 from the support.... and if you wanna be really, really pedantic the notches shouldn't be cut square but should be 'U' shaped in the corners (though you would definitely get a gold star in your exercise book if you do that one)

As for cutting halfway through the joist, or even 1/3rd of the way....Yee Haa !! John Wayne, eat your heart out !!

Why don't you use a Easiplumb tray (tray on legs)? - you can get a heavy resin tray with feet that screw directly into bosses embedded in the resin so they are really solid. Some of them are quite low profile and fitted with a high flow waste trap they don't stand much higher off the floor than a standard tray. If it's going against a stud wall use Aquapanel tile backing board and use an adhesive/sealer (eg. Soudalls Fix-All) between the board and tray then it's going nowhere.

Dan

 

[WHPES]

Never Never cut a joist!!!!!

Totally ignore what the second poster wrote - this is very very wrong!

Change your tray or buy a riser kit

 

[Avatar]

i agreee - 20mm pipes only through joists, waste pipes are too much!

 

[mcgregory]

Seriously, big thanks for all the responses. It was a bit of a panic last night when we measured up. Off to order a riser kit now. Then I can get the noggins in under the shower and bath this weekend, all set for the plumber and electrician next week to drill them out again

BTW it's an 1898 Vic terrace with 2x7 joists, well in on the first floor anyway. The kitchen seems to be 2x3, doh

Now if only I could find the soil pipe downstairs, 5 ft dwarf walls under the house and no sign of it ...