underpinning

[sean1405]

can anyone give me some advise

i have just got planning for adding a second floor to my kitchen bco says that kitchen will need underpinning 2mtrs below original 450 deep .
is this standard?
no trees

 

[Shytalkz]

Is his comment based on an inspection of the existing foundations, or does he just consider that it is required merely because more loading is to be applied?

If the increase is a nominal amount - say 10 to 15% - then, providing the foundations bear into reasonable soils and there is no evidence of any movement having occurred to the original structure, in principle there would not be any requirement to underpin. But you would probably need to get a SE to say so, before such an approach is accepted by the BCO.

However, if the percentage increase is significant, then you will be required to ensure that the foundations comply with current standards, in respect of depth and applied bearing pressures.

450mm depth of underpin is the minimum practical depth that allows access to get in and clean down the underside of the existing foundation.

 

[sean1405]

there is some cracks in old block work but se said its due to render on light weight blocks . both bco and se have looked at trial holes and se says at the end of the day its upto the bco ???

 

[^woody^]

.... se says at the end of the day its upto the bco ???

WTF ..... sack him and get a proper guy with some knowledge and a backbone.

The person doing the foundation design tells the BCO what is required, not the other way around

 

[Shytalkz]

Well hasn't that SE earnt his fee? Not.

As Woodster says (again - you been having lessons, Woodster???!)

 

[sean1405]

Thanks woody
thats what i wanted to hear he keeps changing things first foundations will be fine then all of this sick of keep digging holes , just want the job to start .
thanks

 

[mikric]

Anyone interested in this post have a look at this product, had some details of this come into our office the other day , does it work ? what do you chaps think http://www.uretek.co.uk/

 

[Shytalkz]

Yes, have used it once, when I had no option, but only as temporary works. Worked brilliantly, it has to be said.

Norwich City Council seem to use it all the time on their stock. My concern, as with conventional grouting, is that you don't know where it's going/gone, or how successful it's been at dealing with all the voiding.

It's been about for around 10 years or so - long term capabilities? Who knows.

 

[mikric]

Yes theory sounds great, but do SEs recognise it as a good enough alternative for traditional methods ? Think there is a case at work as whether it is notifiable works or not ??

 

[Shytalkz]

It's not something that I would hang my PII hat on, for sure, Mik.