Help with shower waste to SVP connection

[laur89]

Hello! I'm at a bit of a loss and would really apreciate some help.
We have a shower waste which needs to be connected to the SVP. The shower waste is already low and needs falls.
However there are 6 joists and a steel post in the way.

Does anyone have any tips/ideas on how to connect the waste?

I've attached some images to illustrate. The yellow mark up is what we'd like to do but joists and steel are in the way.

Thanks in advance!

 

[freddiemercurystwin]

Can you post the images in the thread, we shouldn't have to download something from a first time poster.

 

[laur89]

Apologies, I wasn't sure how to do that. Thanks

 

[freddiemercurystwin]

There are limits as to the size and position of any holes you make in the joists: https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists You might have to go above or below the joists. Whoever did the Regs drawings should have specified half a dozen posi joists instead. Shame because the quality of the build looks good but whoever was building it has not thought ahead either. That said there are various products that claim to get round the problem, you should check your Building Control Officer will accept them before you get your saw out eg https://www.strongtie.co.uk/en-UK/products/solid-joist-notch-reinforcement-kit-snrk

A hole in the steel can be made but will need to be designed/calculated by your SE and might require some onsite welding etc and obviously accessing the steel now will be a right PITA with the timber joists either side.

It seems like a rather predictable and avoidable problem.

 

[laur89]

Thank you freddiemercurystwin really appreciate your answer.

 

[freddiemercurystwin]

@laur89 I just realised I originally posted the LABC link twice, the second link should have been this one: https://www.strongtie.co.uk/en-UK/products/solid-joist-notch-reinforcement-kit-snrk

 

[Madrab]

Overall length of the run?

As far as a design standard is concerned then so many people try to get away with the absolute min when it comes to showers that are to be inset or flat to the floor, unfortunately they tend to pay for it later when the waste runs becomes restricted or blocked and end up with overflowing shower trays that won't drain properly and then chemicals get used. Unfortunately I see it all the time these days when it comes to sorting out clients low level showers that the 'bathroom' installer has fitted with next to no fall or has butchered the joists.

This is the time to get the design right and set up carefully, min fall is 19mm/m but for a low level shower you are more looking @ a min of 25mm/m for good flow and the closer to 45mm/m to aid in self cleansing. That then has to be incorporated into the overall waste run to the stack. Sometime that means either raising the tray on a plinth or dropping the run down below the level of the joists.

Shouldn't really be more than 3m max on a 40mm waste pipe to satisfy the regs, any more than that and it can run into trouble over the longer term. Don't forget to add 0.3m effective length for every bend.

TBH though, depending on what is wanted, all this should really have been incorporated into the design of the floor structures to avoid where it is now.