House foundations & New Paving.

[lizzy]

We are currently looking at having a new driveway installed. Not sure at this point what type, ideally patterned concrete. My question relates more to the house.

Our foundations are the concrete raft type. The problem is the foundations extend beyond the walls of the house by approx. 1yd. The damp proof course on the house is only 2 bricks above the raft. I'm trying to find out whether it would be possible to cut-away some the raft so the new driveway can go closer to the side of the house. Our neighbours all have left the raft showing or gone over the top of it and reduced the height of the damp proof course to a stupidly short height, neither are a good solution in my mind. It would be a real pain to do, but I'm thinking if it would be possible just to take away the top few inches of the exposed concrete than it shouldn't hurt?

Would we need to involve a structural engineer to gain an answer?

Thanks in advance.

 

[rickj]

you dont say how old the house is. depending how old the raft is it might have steel reinforement in it so hacking the concrete away is not recommended. are you sure its a raft and not a ring beam which is part of a piled foundation? either way the concrete is structural and you should go for another option. you could pave over the concrete and raise the height of the dpc on the outer leaf of brickwork (assuming its a cavity wall) this quite acceptable but would involve a chemical injection dpc rather than hacking out the brickwork and laying a traditionable dpc. if its a cavity wall the height of the dpc on the outer brickwork should not have any effect on that of the inner brickwork. many houses have different heights of dpcs on the inner and outer walls of the cavity for various reasons.

 

[masona]

Can you post a picture ? There are way round the dpc problem but I need to see a picture or drawing.

 

[lizzy]

Thanks fella's. The house is about 25years old (maybe a little older). I've had a couple of contractors look at quoting. Neither had seen anything like it before. One suggested cutting into the raft the other said go over the top. I must admit from what I have read on here and on other sites, it is probably best to leave the raft well alone. Although I still may seek the advice of a surveyor to be sure.

Rick - I hadn't thought about the DPC solution, that could be the way around it - thanks.

Masona - I would love to be able to post a pic, but unfortunetly I don't have any available.