Hole for shower waste (help/advice)

[abrob1]

Hi all,

Currently installing a new resin shower tray around 22kg.

I’ve gone for a low profile one and have had to cut a hold for the waste to be flush with the chipboard flooring.

Question is, is that hole too big and could cause integrity loss? I have no access from underneath and I need to get my hand and tool in to cut back the original waste further as it protruded the floor.

Hardiebacker 6mm or 12mm (I’ve bought both) will be installed over the floor before layinh shoeer tray.

The joists are roughly where the white lines are.

I’m also thinking of using a flexible waste pipe as the new trap location is very close to the existing waste pipe so solvent welding might be very tricky in a tight space.

Any advice appreciated. Thanks

 

[abrob1]

 

[foxhole]

Hire a plumber.

 

[abrob1]

Hire a plumber.

Well no, fortunately the point of this forum is for DIY advice. If I wanted to hire a plumber I wouldn’t have posted this lol

PS, if you don’t have anything helpful to add then please just politely scroll past. Thanks

 

[jj4091]

Does it flex when you stand on it. If not it should be ok. Epecially once the tray is installed.

 

[robinbanks]

is that hole too big and could cause integrity loss?

Be reet. If you’re bothered, cut some 2x3 noggins to the width, load with glue, pass through the hole and screw in place through the chipboard, near to the noggin ends. Pre drilling the chipboard so the screw is loose in it with help the joint pull tight. Self reaming screws like Screwfix turbo series will help avoid splitting the nogs

Glue the hardiebacker down to the chipboard with expanding urethane glue and increase your screw density around the area

Any advice appreciated

The trade talk forums isn’t really for questions like this, more for tradesmen to talk to each other about stuff

Flooring or plumbing is where I woulda put it

 

[denso13]

Question is, is that hole too big and could cause integrity loss?

No, and you don't need hardibacker below the shower tray unless it bothers you.

I wouldn't use a flexi below a tray if at all possible unless you have no other choice.

 

[abrob1]

Does it flex when you stand on it. If not it should be ok. Epecially once the tray is installed.

No not at all and yes once tray on the weight is a bit more distributed.

 

[abrob1]

Be reet. If you’re bothered, cut some 2x3 noggins to the width, load with glue, pass through the hole and screw in place through the chipboard, near to the noggin ends. Pre drilling the chipboard so the screw is loose in it with help the joint pull tight. Self reaming screws like Screwfix turbo series will help avoid splitting the nogs

View attachment 412133
Glue the hardiebacker down to the chipboard with expanding urethane glue and increase your screw density around the area


The trade talk forums isn’t really for questions like this, more for tradesmen to talk to each other about stuff

Flooring or plumbing is where I woulda put it

Thanks, this really does help. Sorry I don’t use these forums much so my bad.