Drainage

As we are adding a kitchen, utility room, and WC in the rear extension and we are moving the bathroom in the existing house the drains are going to need some changes.

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This is the drawing showing the current drains and the changes that were planned.

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The original plan was to use 450mm plastic inspection chambers to install the two new accesses that will be required at the drain junctions. Unfortunately the building inspector said no to that as we were going to be down more than the 1.2m that they allowed those to be used for.

The consequence of that is that we were going to have to use concrete chambers with a 1200mm diameter. The picture is of them shortly after being delivered.

To my mind this is a completely unnecessary 'overkill' on this as I doubt anyone will ever go down them anyway.

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During the building inspector's visit he told us that we should speak to Southern Water about our new connections to the sewer pipe as we would need them to give authorisation.

Southern Water informed us that if we filled in the form on the website and sent them £710 (as we were making two connections) they would post us a letter of authorisation. They wouldn't actually have to come and look at anything as the building inspector was doing that.

This seemed like an awful lot of money to put my name on a form letter and post it to me so we set about re-designing the drainage arrangement and sent it off to building control for them to approve. The new plan is on the left.

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Whilst reducing the oversite for the foundations we came across the neighbour's drain pipe.

We had all forgotten that this had been laid very shallow and as a consequence it was grazed by the digger bucket.

Unfortunately the graze was enough to crack the top of it so a repair was going to be required. A new section of pipe was added and this will then disappear (just) below ground once the correct levels are made up later.

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And in the picture on the left you can see the reason the pipe was so close to the surface.

It would appear that when the drain was replaced, rather than dig right down to the existing level of drain the people doing the job laid a much shallower pipe and created a backdrop in the manhole to take it down to the existing level in there.

The pipe to the neighbours in at the top and the one on the right is the existing toilet one that we will be connecting on to.

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Having settled on our plan for the drains the first job was to make a hole in the house wall to put a connection in for a toilet in the existing bathroom.

As the bathroom will be widened when it is turned into the en-suite for the third bedroom this connection is not actually going into the current bathroom.

A hole was made in the floor of the bedroom and access knocked through into the bathroom.

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Here's how the hole looks on the outside.

It is a little larger than required as we were one brick out when we calculated its location.

The existing drain for the bathroom, on the left, will be removed once the new ones are in place.

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A 90 degree bend was put in the hole in the floor and this will then have the toilet, basin, and bath plumbed into the top of it.

The picture shows the pipe exiting the hole and travelling across the top of the foundation to the manhole. There is a 'Y' piece yet to be added to connect into the new bathroom at the point where you can see the black joining ring.

Within the extension this will all be below the floor and once the ground levels are made up will disappear below ground outside.

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Here is the pipe dropping down into a hole alongside the manhole in order to pick up the existing connection into the main sewer.

The plastic bag is covering the open end of the 'T', this pipe will be extended once the manhole brickwork has been brought up to ground level and it will then form a capped access within the manhole chamber.

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At the other end of the extension is the new drain for the kitchen, utility room, and toilet.

The inspection chamber has been placed and the pipe connected into the sewer using the same access point as the existing toilet drain which is being removed.

You can see the white pipe which serves as the temporay drain for the current kitchen in the bottom of the picture.

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And this is a view of that temporary kitchen drain.

This will be made a bit more sensible later so that we can get the bricks for the walls laid.

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Here's the 'Y' piece having been fitted and the drain placed for the new bathroom in the existing house.

The access has been knocked through and the pipe placed into the hole with a cap on the end. Once I am ready to connect the bathroom I can add to this run later.

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The drain connection for the new kitchen, utility room, and WC had not been connected as it was serving as the access point for the temporary drain for the existing kitchen.

With the doors being fitted that had to be moved, so the new drain connection was added. The pipe was fed through the wall and a bend placed on the end. This was then concreted into place.

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The other side of the wall there is only a short run into the inspection chamber so this was also concreted in.

The concrete should now stop the rain running into the floor space through the hole that was there and it can dry out ready to lay the floor joists.