Conservatory Foundation Problem - sewage pipe!

[crackerjak]

Good evening all,

Hoping somebody can shed some light on this issue for me. I have purchased and collected a 2nd hand conservatory on ebay. We began digging the foundations today at a size of 600x600mm. Unfortunately we found a shared sewage pipe runs straight through the foundation. Details and a diagram are below (not to scale but gives a good idea).

I cannot move the pipe, so is there a way of building around this sewage pipe?



The conservatory is 3m depth x 3.25m wide.
Footings 600x600mm.
Pipe enters right hand footing level with the 3.25m footing (see diagram).
It then continues at an angle into the width footing, by the time it reaches the other side it is approx 200mm inside the footing at a depth of approx 650mm.


Any help on this will be greatly appreciated.

Thanks

Jak

Untitled

• crackerjak
• 30 May 2015
• 1

 

[nickjb]

If it is shared then you'll need to speak to the water company. You'll need to get a build over agreement. They might need to survey and will certainly take some money off you for the privilege. Or just hope you don't damage the sewer or that they ever need to do any remedial work to the sewer.

The actual build over should be fairly easy. You need to dig lower than the sewer then bridge over it.

 

[noseall]

A one metre dig footing along with 300mm of concrete means that you will still be below the pipe, even when the concrete is poured.

Then lintel over it.

We would renew this section of sewer (in plastic) in any case meaning we could temporarily remove the new section whilst digging the footing.

 

[crackerjak]

Okay so if i dig to 1m, get concrete poured to 300mm, how do i lintel over it? Do i need to dig an even wider trench so that i can access both sides of the pipe and then use numerous lintels across the 3.25m trench?

Not sure how itll work with such a long piece of pipe in the footing.

Thanks

Jak

 

[noseall]

Looking at your drawing suggests that the pipe only clashes with the brickwork at two points.

Or am I reading it wrong?

 

[crackerjak]

Noseall - its a rough drawing, the block work begins 175mm in from the edge of the 600x600mm foundations. The pipe is 600mm below brick work in the foundations. A birds eye view will show the pipe runs beneath both projecting walls and the width wall.

Thanks

Jak

 

[theprinceofdarkness]

In your sketch the black line shows your foundation slab which goes lower then the sewer. Then you block up to the pipe and put a pair of lintels in where the pipe pierces your underground wall skins. leave at least 1" of clearance all around the pipe which you fill with pugging or now a days polystyrene.
Frank

 

[crackerjak]

Hi Frank,

At the moment the pipe is below my 600mm foundation - do you recommend digging out beneath it? And the side which is still under earth?

The pipe wont be piercing brick work as this is to be a trench fill, so will only pass through the concrete foundation.

To clarify i need to protect the pipe across its length within the concrete foundation.


Thanks

Jak

 

[noseall]

You need to protect the pipe from the building and not fully envelop it.

As I said earlier, finish your footing below the pipe.

You may need to dig the foundation wider at the point where the pipe encroaches onto the masonry. This is so that you can provide brick-work beyond the building line then lintel back.

 

[Flyboytim]

About 8 years ago, I wished to convert a 1930's Garage (too narrow for modern vehicles) into a study at the front and a utility room at the back. However, Severn and Trent had a surface water sewer running through the front garden close and parallel to the front of the building line and would not permit footings to be dug within one metre of the sewer. I was told I would have to organize, at my own expense, using one of their accredited contractors, the video survey of the sewer to check its integrity and actual position, as the S&T plans were vague as to the actual pipe run, and there was no certainty that any application for overbuilding would be granted, and the fees were non-returnable. And there would be an inevitable delay.

I had to go for a no additional load solution, so I ended up fitting Versapanel external cladding on a timber frame, and since I had already purchased matching bricks, my wife spent a day wet cutting 20 mm brick slips from the faces of the bricks for application to the cladding panel. Of course, she got thoroughly covered in red brick slurry!

Fitting the cladding was easy and took just a few hours.

No one could tell that the wall was not solid, and looked great.

I hope you can find a solution to your problem.

 

[jeds]

Okay so if i dig to 1m, get concrete poured to 300mm, how do i lintel over it? Do i need to dig an even wider trench so that i can access both sides of the pipe and then use numerous lintels across the 3.25m trench?

Not sure how itll work with such a long piece of pipe in the footing.

Thanks

Jak

I like how you completely ignored the bit about getting permission to build over a public sewer.

 

[crackerjak]

Jeds - not at all. I need to know all the info first anyway so i can provide it to them! I cant provide a blank sheet of paper as a method statement.

Cheers

Jak

 

[theprinceofdarkness]

A technique I once used was to put in a padstone out side the building. So the padstone was bridged to the side foundation with a lintel. From this lintel there was a second lintel that ran across a sewer and sat on foundation strip for the back wall. Its a long time ago, but at the time the lintels are not that big, say 300 X 150 X 1.4m with three bits of 8mm steel in each. Building the shuttering was fiddly, and you have to let the bottom one cure before you can build the one sitting on it. You could terminate your side foundations to what your water board consider a "safe distance. then put a pad stone in line and the magic "safe" distance away on the outside of the building. Then have a couple of pairs of pad stones (the safe distance etc) along the back wall. Then finally cast the BIG lintel across all four of them that will carry your rear wall. Watch out for your levels each lintel will consume some!
Frank