Revision question help

[Scottwood75]

I'm retaking one of my exams and there is a question in there that confuses me. in the drawing for the house, it has the soil stack coming up into the bathroom, in the corner of the room. Infront is a shower tray, and further along the wall is a WC. The question is, "an architect has specified that all waste pipes from the WC are to discharge into the primary ventilated stack and conveyed above the flooring in a closed boxing. What problems may arise where the joists are running width ways"

I made a crappy pic on paint to give a better idea. All I can think of is that the joists cant be notched as the soil stack is too large, but apart from that the pipes are running above the floor? very confused

By the way the circle is the soil stack and the rectangle is meant to be the boxing, dont know why I forgot to label them.

 

[REDSAW]

think the answer may be the shower cannot be fixed to the wall due to boxing and the shower drainage piped into the soil line will suffer back-syphonage from toilet

 

[Scottwood75]

I put that about the boxing and that the correct gradient for the toilet waste may not be achievable. Didn't think about the shower waste, or that fact that the actual shower may not be able to be fitted to the wall. I put about the boxing stopping the tray from being fitted correctly. Thats very helpful thanks

The main thing though, Is its saying why will the direction of the joists affect it, any ideas?

Could one thing be that the shower trap might not be able to be fitted if the joists are running across under the floor?

 

[Smcart5]

Do you need to notch the joists to fit any pipes in?, if the joists need notching its more difficult if you have to cut through the grain of the wood rather than with it, that's the best way to describe it, hopefully you know what i mean...

 

[WHPES]

You cannot remove more than a certain percentage of the floor joists or it will weaken the structure of the floor. Can't remember off hand but its in the building regs. The shower may need a riser kit and above-floor waste pipe (which you will have to box in). Also position of trap if there is a joist underneath the outlet - you may have to put just a standard shower waste fitting without trap and have a running trap a bit further along where there are no joists below.

 

[Scottwood75]

You cannot remove more than a certain percentage of the floor joists or it will weaken the structure of the floor. Can't remember off hand but its in the building regs. The shower may need a riser kit and above-floor waste pipe (which you will have to box in). Also position of trap if there is a joist underneath the outlet - you may have to put just a standard shower waste fitting without trap and have a running trap a bit further along where there are no joists below.

its no more then 1/8th of the floor joist. Thats really great thanks mate, gives me some good stuff to look into

Do you need to notch the joists to fit any pipes in?, if the joists need notching its more difficult if you have to cut through the grain of the wood rather than with it, that's the best way to describe it, hopefully you know what i mean...

Yeah I think I know mate, like its easier to cut going with the grain instead of against it?

 

[Bernie2]

Hmm!

A shower waste connected into the vertical stack would have to be lower than the WC branch connection, which would put the shower connection probably below the joist and in the room below.

If you download a copy of the guide to the Building Regs document H. Section 1 diagram 2 gives you a picture explaining branch positions.

 

[Scottwood75]

Hmm!

A shower waste connected into the vertical stack would have to be lower than the WC branch connection, which would put the shower connection probably below the joist and in the room below.

If you download a copy of the guide to the Building Regs document H. Section 1 diagram 2 gives you a picture explaining branch positions.

I found something in my Training manual that says the offset would need to be 200mm between a Wc branch and a discharge brange. So that would mean the shower discharge branch would need to be 200mm lower and therefore under the floor, which would mean notching 40mm pipe into a joist. if the average joist is 9 and a quarter inches and thats roughly 235mm then 1/8th of that is 29.375 and 40mm would not be allowed to be notched into it. I think I have it!

 

[WHPES]

You would have to go lower than 200mm and box in the visible part in the room below.

 

[justlead1]

Having raised the shower tray. You would need to form a parallel junction to accommodate shower waste.

 

[Scottwood75]

Having raised the shower tray. You would need to form a parallel junction to accommodate shower waste.

The question didnt ask about raising the shower tray or overcoming the problem just what problems could occur with the joists running in that direction. Need to find a way of putting this stuff into the form of an answer