Rat proof sewer vent

[Jono11]

Hi all

I spent some time tracking down an odd noise and found a rat chewing trough my cast iron sewer vent cap. It has managed to chew away all the grills and has only been stopped by the clothes dryer which was pushed back against the vent ( the vent is at ground level in the garage). The rat does not look like it is going to stop until it escapes.
I need to replace the vent but can only find PVC ones, are they good enough to stop rats and is it normal to have rats doing this or is it a sign of a problem in the drain.

Thanks for any help
Jono

 

[Nige F]

PVC won't stop a rat - you have an old air Inlet to a manhole there . You need to find the manhole - post some pics - and the air inlet is not needed.

 

[Jono11]

Thanks, it is right above a manhole, I can get some pics later but from memory there are a couple of pipes from bath etc merging into one open channel at the bottom of the manhole.
There is no other vent pipe though, its an old 1920's bungalow if that makes any difference.
It looks just like this one

 

[Nige F]

As I thought - a inlet to an old fashioned system - the manhole most likely has an interceptor ( buchan ) trap . Lots of posts about them on diynot. The inlet can be sealed off - knock it off and cement up the pipe. Have the manhole cover up so you don't get broken bits falling in as you sort out the old inlet. Somewhere there should be a tall vent pipe going up + above the roof. The idea was air in your low level inlet - then out of the tall vent . The main sewer was supposed to be kept separate by your interceptor trap . All old and pointless now. As long as you have the tall open vent you are fine.

 

[Jono11]

Unfortunately there is no tall vent pipe, the garage also gets a bit whiffy at times, well most of the time.
Do I need to leave it then.

 

[Nige F]

You need to get a vent pipe installed, and block the inlet. You are getting sewer gas in the garage and rats are trying also. A line drawing of your house showing where your WC is and any manholes would give us a good idea where a vent could go. It's not unknown for the vent to be on the next door house/bungalow if it's close to yours.

 

[Hugh Jaleak]

I'd echo everything Nige has said, and I suspect this vent is the cause of your whiffy garage. These vents were designed with a Mica flap inside that was supposed to act as a one way valve, to allow fresh air into the system, but keep smells out. They invariably fail, (usually open) and this is the result. Pic of the manhole may help, the associated pipe to these vents is usually one or 2 bricks down from the top of the chamber.

By the sound of things, if there isn't a vent stack, I'd suspect someone has removed it in the past. Never known a low level went without a stack in a property of that age.

 

[Jono11]

Hi all
here is a pic of inside the manhole and a pic of the location of the manhole with the vent and ex-rainwater drain with the washing machine outlet. These are all inside the garage
To the left of the manhole the pipe goes to a rainwater grate, the kitchen sink also drains into this via a pvc pipe.
Behind the wall in the pic is the bathroom
To the right is the driveway with another manhole which only has 1 in and 1 out and then the road

 

[Nige F]

I can see now - someone built your garage onto the side of the house,and not wanting to penetrate the new roof with the existing tall vent pipe, they tore it down and put that inlet "valve" in it's place

 

[Hugh Jaleak]

Think Nige has hit the nail on the head. It appears the drain continues upstream of the manhole in the picture, does any of the pipework upstream re emerge from the garage do you know? (You mention another gulley etc, any of this outside the garage footprint?)

I'm looking at options for reinstating the vent, with minimal hassle, and then the existing can be blocked off inside the chamber, and at floor level in the garage. Ratty will have to find another exit and your garage will smell somewhat sweeter.

 

[Jono11]

Hi All
Sorry for the delay in replying, the wife wanted new carpets, the carpet fitter said you should replaster first, the plasterer said you need to move that light switch away from the door as it is broken and in the way, the electrician said the door frame needs replacing. I am trying to convince her laminate flooring would be better as I can lay it.
The other drain grate is by the kitchen, it is a open drain the roof gutter drains into, the kitchen sink also drains into it via a pipe attached to the wall ending above the grate.
From the photo it is the pipe heading to the left with gunk in it.

Any ideas on if I can have a DIY vent outside the garage.
Thanks
Jono

 

[Hugh Jaleak]

You certainly can have a DIY vent outside the garage, it's just where to connect it! Ideally needs to be as near to the head (top) of the run as possible, but if easier, extend the existing vent upwards through the garage roof. If not, then look at teeing into the drain outside the garage, near the kitchen gulley if practical, and run to a vent stack from there.

 

[Jono11]

It's probably going to have to go through the roof then. The roof is corrugated bitumen, can I just mark out the circle, drill holes round then cut.
Thanks for all the help
Jono

 

[dilalio]

It's probably going to have to go through the roof then. The roof is corrugated bitumen, can I just mark out the circle, drill holes round then cut.
Thanks for all the help
Jono

Yes. And you'll need something like this...
https://www.warmairheaters.com/product/dektite-ezi-seal/