New Basement below an Existing House

[oxbridge]

I have to provide a method statement and outline design as part of a planning application showing how we intend to retrofit a basement under an existing building and demonstrate how we will maintain support to the existing structure and not distress it.

To make matters more complicated the house is part of a terrace and it is also a listed building. If you're not familiar with the term listed building, it means it's of signiicant historic interest.

The attached section shows typically what we're trying to create. The project is in it's infancy and therefore we do not have a contractor on board yet to benefit from their insight. Any thoughts?

 

[csd72]

oxbridge,

apsix was correct in his explanation.

Another issue that I forgot to mention is that you cannot effectively tank (waterproof) the underpinning. You would need an internal wall anyway. Even if you could then the waterproofing for your house will be in the neighbors property - a party wall act nightmare waiting to happen.

It is generally accepted that basements like this will not achieve the full footprint.

I really recomend you read the references that I listed.

 

[kslee1000]

If the case is as csd72 implied - there are buildings in close vicinity to the house in concern, then I don't think there exist easy and cheap solution for a full size basement. Use micro piles, do it from inside of the house.

 

[Debaser]

For everyones info, I've attached a couple of photos of typical London terraces, to enable people to visualise the sort of thing that Oxbridge may be encountering, vis available working space, etc.

http://files.engineering.com/getfil...a76ba1d8ed&file=typical-victorian-terrace.jpg

http://files.engineering.com/getfil...c31d2afb254&file=typical-georgian-terrace.bmp

Oxbridge, would it be possible to show the sort of location you will be working in and show the constraints?

 

[BAretired]

Debaser cleared up a lot for me. I thought it was just the house that was a listed building. Now, I assume that the entire terrace is a listed building. That make thinks quite a bit more difficult as there is no access outside the walls.



BA

 

[BSE05]

I have alot of concern about excavating and undermining the party wall of the adjacent row houses. I have worked on similar properties in Boston, but never attempted this.

Even if you underpin the wall with concrete sections, minipiles, helical piles, can you guarantee that the soil on the opposite side of the party wall will not fall into your excavation? Your neighbors could come rolling in!

Soil stabilization is the real problem. What is your soil type? Have you inquired on the geotech forum? They may have some ideas. Remember what is your risk versus your reward--some projects may not be worth it.

 

[Prepakt1]

This job can be done and can be waterproofed. Its difficult but possible.You would probably need to build two walls.Put a membrane on the inside of the first then pour another to keep the membrane in place. I would also probably advise some ring drains at the bottom of the walls with valves leading to a drain sump in case the membrane ever fails.
The soils under the nieghbours would have top be stabilised with grout before excavating which is itself not an easy process.
The cost however would be very high and your construction insurance is questionable. If you have not got general coverage for this type work like a major company might have. Insurance companies are going to turn you down.

Intrusion Prepakt /marineconcrete.com

 

[csd72]

Sorry everyone I didnt think to translate, a terrace house in the UK is the same as a row house in the US.

Prepakt1,

Exactly what I was trying to imply.

 

[Debaser]

"Sorry everyone I didnt think to translate, a terrace house in the UK is the same as a row house in the US."

The one downside of this site. 787,000 engineers separated by a common language.