Manholes in Garden for Extension build

jimmycrackcorm

I've been thinking for a while about building an extension out the back of my house. There are two manholes in the back garden (house at the entrance to our estate). They would be close to the side of the build so although they would not affect directly it I'm curious what effect they would have on the extension foundations given that there are pipes somewhere in the garden.

sinnerboy

They would not prevent an extension in most cases But under no circumstances should you attempt this with "builder alone". For hopefully obvious reasons you must appoint an engineer in this case.

martinn123

jimmycrackcorm wrote: »

I've been thinking for a while about building an extension out the back of my house. There are two manholes in the back garden (house at the entrance to our estate). They would be close to the side of the build so although they would not affect directly it I'm curious what effect they would have on the extension foundations given that there are pipes somewhere in the garden.

Just for clarity, are they ''manholes'' or A.J's ( about 9'' square plastic cover, to provide access should you need to rod a blockage )

If they are manholes, certainly consult an engineer, you will not be allowed to move them, as they are probably part of the sewerage system for your estate, and under the control of L A.

If however they are A.J's and your comment '' there are pipes somewhere in the garden'' its quite common.
Most Contractors will tell you there are pipes out the back of the majority of houses, especially in an estate, and constructing an extention will involve dealing with pipes, A.J's etc in a majority of cases.

So in this event, use of terms like

sinnerboy wrote:

But under no circumstances should you attempt this with "builder alone".

and

you must appoint an engineer in this case.

is possibly a little severe, on Contractors who are compitent in this area.

However if in doubt, get Professional opinion.

jimmycrackcorm

martinn123 wrote: »

If they are manholes, certainly consult an engineer, you will not be allowed to move them, as they are probably part of the sewerage system for your estate, and under the control of L A.

They are the proper metal manholes. They wouldn't have to be moved as they would be to the side of the build. My query is, as they are to do with the estate sewerage or whatever then I'm guessing the pipes leading to them might make a problem for the extension foundations.

An architect friend suggested a builder would put in some sort of foundation bridge over them but I don't know what that is...

martinn123

In certain circumstances, depending on the diamater of the pipes, depth, etc, it may be possible to bridge the pipes for foundations.

Basically a concrete head, similar to what is over your windows can be constructed to prevent any weight bearing down on the pipes.

However as stated above take professional advice, as if its done wrong you will be in the shyte.