Bathroom floor loading- waste pipe running through each joist...

[tony1851]

If you are planning to add more load to a floor which is already overloaded and over-spanned, you would probably find it easier/cheaper to add a steel beam below at right-angles, somewhere near mid-span, and packed tight to the joists.
It probably won't make any noticeable difference to the deflection but would give peace of mind. You would have the downstand of the beam to live with, though maybe you could add a false ceiling to hide it?
A 152 x152 steel beam would do the job.

 

[jacko555]

. You would have the downstand of the beam to live with, though maybe you could add a false ceiling to hide it?
A 152 x152 steel beam would do the job.

Luckily wifey wants a lower, false ceiling with downlights in the kitchen. As the existing ceiling is cracked, this is already budgeted for.

The SE specified a 203x102x23UB on 250x100x150mm padstones, with 100mm of steel on each padstone. So 3.2m long. Positioned at right angles to the joists, at 2.5m into a 4.5m span.

[Edit]
The steel was a "left field" idea a builder he consulted suggested. However, the maths work so the SE included it as a valid option

 

[tony1851]

If I may say, that beam is unnecessarily deep for the load and span involved; a 152 deep beam would be perfectly satisfactory and would save you 50mm of headroom.
But who am I?.........

 

[dontbelieveawordofit]

Oh dear, that's a shame to see.

You may have fallen foul of a bathroom installer who was a jack of all trades and a master of none, see it more often these days.

Any experience plumber would always reject cutting in a waste pipe perpendicular through joists, the pipe is just too large to run through the joists without compromising its strength, that would then drive a change in the design with the waste/basin being relocated.

All that hassle and cost for such an easily avoided design faux pas.

Seriously unfortunate for you but it's a great example for a DIY site where anyone else may be considering doing the same to their bathroom.

very general starement. in my opinion plumbers are the most complacent of the trades and more than willing to bodge it ,cover up and take the money. and a 40mm waste isn’t always too big for a joist. depends on the joist.

 

[dontbelieveawordofit]

never have to go far to see a plumbing bodge. and this bloke is gas safe.

 

[Madrab]

very general starement. in my opinion plumbers are the most complacent of the trades and more than willing to bodge it ,cover up and take the money. and a 40mm waste isn’t always too big for a joist. depends on the joist.

Of course its a very general statement, as it's a very general problem in my trade, that I come across all the time. The trouble is that anyone can call themselves a 'plumber' and then give my profession a bad name. Alas it's the same in any of the trades these days.

I correct more kitchen and bathroom screwups that have been fitted by 'professional' bathroom & kitchen fitters these days that any other repair. The industry has made it too easy to DIY the work making it possible for anyone to be a 'plumber'

Are you a trade professional?

I can assure you that most properly qualified plumbers that carry indemnity insurance, guarantee their work etc would not cut a 32/40mm waste pipe into the centre of any joist, even if that joist was large enough to take it. There is always a safer/easier way of doing it than that but that's all down to training and experience.

You will invariably find that the closest to a plumber that the workers that would do that kind of unprofessional work would be is having slept with one. Those are the 'plumbers' I'm talking about.

There will always be bad professionals in any line of work. Oh and BTW it's not plumbing work fitting and positioning a boiler and it's flue, a person doesn't need to be a trained plumber to be Gas Safe registered.

 

[dontbelieveawordofit]

i’m a plasteter . qualified.
and a plumber, gas safe fitted the boiler/flue.....
so in an installation where the customer wants a 25mm tray flush to the floor and you need to route a 40 mm pipe through or across 2 cut outs in 2 180x50mm joists you’d refuse the work or insist they site the tray on a base?