shower tray - how low will trap sit??

[beezo]

Hi guys,

Ive been asked to fit a shower cubicle for some pensioners as they are having trouble getting in and out of the bath.

when Ive looked where the existing waste is for the bath, it runs pararelle to the joists in the soil stack which is inside the house. The waste pipe is however almost level with the top of the joists with a slight fall but enough.

Thing is, this new shower base is willbe going it the opposite end of the bathroom. This means i will have to notch the joists out to accomodate a new waste pipe from the shower to existing waste pipe.

problem is, they want to order to order an ultra low profile shower base and im worried that by the time you add a shower waste and trap. The outlet from the trap is going to be a few inches below the top of the joists.

if this is the case, i dont think it can be done as there is no way the joists can be cut out that much and also, it will mean the new waste will be running uphill towards the existing waste, again a no no

does anyone have any idea how low the outlet from a waste trap will sit from say the bottom of the shower tray. Is there low profile traps that can be bought?? or is there a better way of doing it??

i would assume the ultra low profile base is wanted so the pensioner do not have to 'stepup' too much and that its not much of a trip hazard.

any advice much appreciated

 

[Richard C]

You should not be notching/drilling joists at all outside permitted zones. See regulations for notching of joists;
http://www.eastdevon.gov.uk/bc-guidancenote7-notchingofjoists.pdf
If you notch outside these areas, you must reinforce the joists to maintain their strength.

This trap or somethign similar may do the trick;
http://www.ivesbathrooms.co.uk/products/CHROME-SHOWER-WASTE-TRAP-FOR-LOW-PROFILE-TRAYS

There is also a maximum length of un-vented waste run you can fit; 3m for 40mm dia 4m for 50mm dia. Distances greater than this will constantly siphon the trap leading to smells. Absolute minimum fall you should aim for is 18mm/m but 24mm/m is the accepted norm.

Are you doing this as a favour or a paid job? If so you really should be doing it correctly & in accordance with B Regs, even if it means a new connection to the soil stack, extra work but not that difficult if it’s plastic. I doubt your pensioners will be too happy to end up with a non compliant installation or a compromised floor structure.

 

[Charnwood]

Whale Gulper or Phlexicare shower waste pump?

Whale

Phlexicare

 

[xr4x4]

i know its not ideal, but dont fit a low level shower tray?

with most trays your looking the top of the waste pipe coming level with the bottom of the floorboards. (with a shallow trap)

 

[muggles]

Thing is, this new shower base is willbe going it the opposite end of the bathroom. This means i will have to notch the joists out to accomodate a new waste pipe from the shower to existing waste pipe.

You can't do that!!! Notching joists for waste pipe contravenes the building regs as you're taking too much out, you can only remove 15% of the depth MAXIMUM with a notch. Minimum fall is 19mm per metre, if the bathroom is 1.5m wide (guessing as you haven't said) then you'd need to take out about 70mm of the last joist, meaning your joists would need to be 470mm deep, which they aren't.

problem is, they want to order to order an ultra low profile shower base and im worried that by the time you add a shower waste and trap. The outlet from the trap is going to be a few inches below the top of the joists.

Outlet should come to just below the floorboards if you're using a proper shower trap

is there a better way of doing it??

Negotiate an alternative location for the tray, maybe where the bath was as you're presumably taking that out, there must be somewhere it can go where you can get the waste in, even if you need to drill a new connection into the stack.

 

[Richard C]

Minimum fall is 19mm per metre

Sorry if it seems a bit petty & I don’t want to fall out over 1mm but I think you’ll find it’s 18mm per metre as I posted.

Personally, I go for the old 1:40 which is equivalent to 25mm per metre.

 

[sooey]

It's only twelve and a half percent the depth of the joist as well.

 

[muggles]

It's only twelve and a half percent the depth of the joist as well.

There's two versions of the rules, although I've never seen 12.5% quoted anywhere, it's 15% depth between 10% and 20% of the span, or 10% depth between 7% and 25% of the span, IE a wider notching area permits a lesser depth. Your 12.5% is, I think, now outdated

 

[sooey]

It's usually quoted as 0.125 X depth, which equals an eighth or twelve and a half percent. I've never seen the figures you posted, so like you say, I'm out of date.