Drains in integral garage.

[Kelvin25]

We are having a garage conversion. However our front bathroom pipes drain into garage where there is a gulley, drain stack.
We intend to reroute the waste pipes instead to the outside rather than box them.
To do this we need to take them outside via wall under ceiling to join outside drains(waterway). However we have a problem with existing drain. Do we just block it with cement or dig and place it outside to run underground to join existing drains for rainfall.
The costs vary considerably between jobs.
Would building control have any problem with the blocking off ? What are the alternatives?

 

[John D v2.0]

Having a gully in your garage is odd.

I'm having trouble understanding exactly your idea, but the important thing is not to leave any pipe connected to the drainage system unless it is in use.
Also unless you have a combined system (rain and sewage) you can't connect the bathroom to a rainwater gulley. Otherwise it may end up untreated in a river.

So in your case you need to disconnect the old gulley where it joins the main drain and cap it there. Then you need to connect the new stack from your bathroom to the nearest foul drain. You might need an AAV or a vent on the stack.

 

[^woody^]

Any redundant section of drain should be removed up to the branch.

 

[Kelvin25]

It's difficult to explain but basically upstairs bathroom pipes at front of the house come down into the front integral garage ceiling down the wall and into the ground at the garage wall. The stack collects all 3 into one pipe which enters the floor. Next to this pipe is a small gully grid which provides access to drain.
Having pipes inside a converted room is unsightly and worse if they leak or smell. That's the main reason to route them outside. They will still come down from ceilings about 10cm but a lowered ceiling should conceal them on their way outside.
Once disconnected the drain will not receive any sewage so needs be capped. One builder is saying it needs to breathe. Another says we can just block it. Both are thinking of diverting drain to outside rainwater drain. They say that rainwater and sewage blink up to main one so having bathroom joining to rainwater is not an issue.
Surely they building inspector can't allow this as drainage is part of regs.

 

[Kelvin25]

It's difficult to explain but basically upstairs bathroom pipes at front of the house come down into the front integral garage ceiling down the wall and into the ground at the garage wall. The stack collects all 3 into one pipe which enters the floor. Next to this pipe is a small gully grid which provides access to drain.
Having pipes inside a converted room is unsightly and worse if they leak or smell. That's the main reason to route them outside. They will still come down from ceilings about 10cm but a lowered ceiling should conceal them on their way outside.
Once disconnected the drain will not receive any sewage so needs be capped. One builder is saying it needs to breathe. Another says we can just block it. Both are thinking of diverting drain to outside rainwater drain. They say that rainwater and sewage blink up to main one so having bathroom joining to rainwater is not an issue.
Surely they building inspector can't allow this as drainage is part of regs.

I'm having quotes but builder are quoting on jobs which are not equivalent as the drain job is adding more labour and different ways of doing the job.

 

[John D v2.0]

Once disconnected the drain will not receive any sewage so needs be capped. One builder is saying it needs to breathe. Another says we can just block it. Both are thinking of diverting drain to outside rainwater drain. They say that rainwater and sewage blink up to main one so having bathroom joining to rainwater is not an issue.
Surely they building inspector can't allow this as drainage is part of regs.

The breathing is probably just ventilation, it's recommended that every house has a vent for the stack above the eaves usually, but if you're not the last house and have an aav you can get away without one. I'm assuming you already have so the diversion lower shown won't affect it.
Drainage is indeed covered by building regs, do make sure it's all checked and signed off before you pay.
Sounds like you have a combined system, but check this with the building inspector if you're not sure.

 

[Ian H]

Best thing would be if they moved it outside and connected back up to the original pipework where it is already outside.

It will more than likely be in the same direction and save any possible issues with your surface/foul connections.

 

[Kelvin25]

Best thing would be if they moved it outside and connected back up to the original pipework where it is already outside.

It will more than likely be in the same direction and save any possible issues with your surface/foul connections.

That's what one builder suggested. It seems he knew what he was talking about or wanted to do it properly.
Had quotes from 5.5k to 10k for job.

 

[Ian H]

How much just for the drain work?

Inside sounds easy and outside by the sounds of it would be to locate the pipe coming out from the garage, dig down and fit a new rest bend in place of the straight pipe. The upstream section would then be obsolete and you could fill it with concrete. You might need a manhole where it joins the next drain unless an access in the new stack would do.

Do you not fancy DIY'ing it?

 

[Kelvin25]

Just had a conversation with local BC officer who is visiting site. He said that it would be sufficient to block the gulley at the opening and cement over it . There is no need cap it at branch or take it outside. If confirmed when he visits this reduces the labour costs involved. He said he sees no reason to route it outside. He also agreed we can take waste pipes outside. Need to confirm if they can connect to rainwater drain .

 

[Kelvin25]

How much just for the drain work?

Inside sounds easy and outside by the sounds of it would be to locate the pipe coming out from the garage, dig down and fit a new rest bend in place of the straight pipe. The upstream section would then be obsolete and you could fill it with concrete. You might need a manhole where it joins the next drain unless an access in the new stack would do.

Do you not fancy DIY'ing it?

No the price for job is for garage conversion including drain work .

 

[Ian H]

Cool, just make sure the concrete doesn't run too far into the drain.