Soil and Vent pipes and Basement Flats

[Rayment84]

Just installing a bathroom in a basement flat. Kitchen, bath, basin and toilet waste are all to go down single underground drainage pipe which then connects to the underground drainage from rest of property above, then runs to sewer under garden. Would the basement flat be ok if we installed a 110mm air admittance valve in the bathoom, angled and run up wall to a height thats 1m above highest overflow on that system? Would run to outside but bathroom situated in centre of property so running ventilation to an external stack is not viable.

There is a chance that the main underground drainage to the sewer from the property is going to be dug up and re laid, would it be better off to have 2 separate runs of foul drainage to the sewer, one for flat and one for house above, as this can be reconfigured at the same time? Or is it worth suggesting an anti-flooding valve be installed on to the single line to the basement? Was in the merchants and one guy suggested to use an anti-rodent barrier on the basement drainage, but would this be wise to try to prevent any flooding?

Any thoughts or opinions would be a great help. Thanks in advance

 

[joni os]

The anti flood valve needs to be on separate run otherwise if it blocks you will get your neighbours waste even if it don't flood. AAV taken above highest spill level OK.

 

[stevetheplumber]

if its a bath basin and wc you might just need a stubstack

 

[Rayment84]

The anti flood valve needs to be on separate run otherwise if it blocks you will get your neighbours waste even if it don't flood. AAV taken above highest spill level OK.

So AAV above highest spill over level in basement would be OK? Or highest spillover on upstairs?

 

[joni os]

Highest spill over in room containing AAV. or any appliance attached to the sub stack,

 

[chris watkins]

You need to abide by Part H of the Building Regs & the work on the drainage most likely will be notifiable.

That said, does the drain line from basement flat connect to the stack taking the floors above or does it connect to the horizontal drain run out to the sewer? As if it is a horizontal connection there is the minimum distances to consider from the invert to that branch, even if it below ground. How many stores above is there ?

As steve said you may just need a stub, what is the fixation with AAAV (Durgo,s) most of the time they are expensive, cause problems & are unnecessary on single story stacks.

 

[Unregistered]

You need to abide by Part H of the Building Regs & the work on the drainage most likely will be notifiable.

That said, does the drain line from basement flat connect to the stack taking the floors above or does it connect to the horizontal drain run out to the sewer? As if it is a horizontal connection there is the minimum distances to consider from the invert to that branch, even if it below ground. How many stores above is there ?

As steve said you may just need a stub, what is the fixation with AAAV (Durgo,s) most of the time they are expensive, cause problems & are unnecessary on single story stacks.

Thanks guys. Once work is completed it will technically be the beginning of the run to the sewer as the stack solely for the bathroom on first floor will connect further down the pipework at 3.5m from the underground drainage connection in basement bathroom. The house above only has the one bathroom on the first floor, no other WCs etc, and kitchen will connect into same underground drainage but further again down the run to the sewer

 

[chris watkins]

So no worries then about compression at the base of the stack.

Strictly speaking the head (end) of the run should be the point at which the drain is ventilated to atmosphere but you might get away with it being further down the run & a stub on the end, given that it is only a house conversion but you really should speak to Building Control first as they have the final say.

 

[Unregistered]

So no worries then about compression at the base of the stack.

Strictly speaking the head (end) of the run should be the point at which the drain is ventilated to atmosphere but you might get away with it being further down the run & a stub on the end, given that it is only a house conversion but you really should speak to Building Control first as they have the final say.

Awesome, thanks Chris, much appreciated