Cost of building a new basement

[crustycracker]

I am hoping to start building a new side extension later this year (weather pending) of size 8m x 4m. All PP is approved. However after browsing thru various website recently I became aware of 'the basement'. I turned away at first but reading about it more and more I then considered whether or not to construct a new basement before I build the new extension, so the basement walls would effectively become the foundations for the extension above. It may be painstakingly obvious that statement but I thought I had better make it clear.
I am waiting to see if I need further PP, even though my footprint wont increase, however building regs will apply (naturally) and there are other things like getting soil checked (boreholes), water table checked, more drawings and structural calculations. I think from a loose enquiry that the calcs will be about £750. From the WWW I think the cost per sq.mt. will be in region of £350-£400. All I want to achieve is a cast concrete box that is waterproof and I can build my extension on. The carcassing of it will wait until I can afford it perhaps next year.
I don't have drainage issues or neighbour issues, house is on a slight slope in the country and no neighbours. Ground is rather rocky. The previous extension only went down about 18" and the building inspector was well happy. We had 6" foundations.
Are there any of you out there that have recently undertaken such a project? If so I would would appreciate some info, like what materials you used, construction design, blockwork walls, poured walls, rough cost, etc.
I know that the finished product will add to the cost of the property in the long term. I am hoping that I can achieve my goal within a £10K budget.

Thanks CC

 

[DeludedAussie]

I am hoping to start building a new side extension later this year (weather pending) of size 8m x 4m. All PP is approved. However after browsing thru various website recently I became aware of 'the basement'. I turned away at first but reading about it more and more I then considered whether or not to construct a new basement before I build the new extension, so the basement walls would effectively become the foundations for the extension above. It may be painstakingly obvious that statement but I thought I had better make it clear.
I am waiting to see if I need further PP, even though my footprint wont increase, however building regs will apply (naturally) and there are other things like getting soil checked (boreholes), water table checked, more drawings and structural calculations. I think from a loose enquiry that the calcs will be about £750. From the WWW I think the cost per sq.mt. will be in region of £350-£400. All I want to achieve is a cast concrete box that is waterproof and I can build my extension on. The carcassing of it will wait until I can afford it perhaps next year.
I don't have drainage issues or neighbour issues, house is on a slight slope in the country and no neighbours. Ground is rather rocky. The previous extension only went down about 18" and the building inspector was well happy. We had 6" foundations.
Are there any of you out there that have recently undertaken such a project? If so I would would appreciate some info, like what materials you used, construction design, blockwork walls, poured walls, rough cost, etc.
I know that the finished product will add to the cost of the property in the long term. I am hoping that I can achieve my goal within a £10K budget.

Thanks CC

I d also be interested in this

 

[crustycracker]

I am hoping to start building a new side extension later this year (weather pending) of size 8m x 4m. All PP is approved. However after browsing thru various website recently I became aware of 'the basement'. I turned away at first but reading about it more and more I then considered whether or not to construct a new basement before I build the new extension, so the basement walls would effectively become the foundations for the extension above. It may be painstakingly obvious that statement but I thought I had better make it clear.
I am waiting to see if I need further PP, even though my footprint wont increase, however building regs will apply (naturally) and there are other things like getting soil checked (boreholes), water table checked, more drawings and structural calculations. I think from a loose enquiry that the calcs will be about £750. From the WWW I think the cost per sq.mt. will be in region of £350-£400. All I want to achieve is a cast concrete box that is waterproof and I can build my extension on. The carcassing of it will wait until I can afford it perhaps next year.
I don't have drainage issues or neighbour issues, house is on a slight slope in the country and no neighbours. Ground is rather rocky. The previous extension only went down about 18" and the building inspector was well happy. We had 6" foundations.
Are there any of you out there that have recently undertaken such a project? If so I would would appreciate some info, like what materials you used, construction design, blockwork walls, poured walls, rough cost, etc.
I know that the finished product will add to the cost of the property in the long term. I am hoping that I can achieve my goal within a £10K budget.

Thanks CC

I d also be interested in this

Latest ------ I have since heard from the planning department who say that the subject is a grey area and I will have to supply details, which you would anyway if making a planning application, and that I must submit a Certificate of Lawfullness. Not really an awful lot of help. What the hell is that? They have given me a link to go into and check which I will do later.
Aslo I have been advised by the structuaral engineer that a set of drawings will have to be made which I am fully aware of anyway, so that he can carry out the calculations. That's all for now.

CC

 

[steveywonda]

Hi,

I'd also be very interested in this. How are you getting on?

I am just in the planning stage for an 8x4.5m side extension to our semi detatched 1950s house. We are on a slope so plan to build the first and ground floors level with the existing house and incorporate a 'basement' garage underneath. The drive currently slopes up so we effectively will have a level drive into the garage with the other floors above. The front and left side of the 'basement' will be visible, the back and right side (the side adjoining the existing property) will be underground.

I'd be very interested in what materials etc. people have used and any issues they've had.

Thanks in advance
Steve

 

[skotl]

I d also be interested in this

Excellent could do with a laugh!