Extension footings depth

[^woody^]

It makes no sense to me?

Perhaps you need to notify the architectural design industry that everyone except your family friend is doing it wrong? Or ask the family friend for 30 years worth of refunds for his half-a-job poxy specifying?

Or you could make friends with a new designer who will take account of the site, will have knowledge of the potential ground conditions (or know when to specify testing if appropriate), and will know about BS8500 and if it applies or not, of if a specialist design is required, and will design a typical foundation that can be aproved and priced.

 

[Notch7]

So what value is being added by an architect specifying the foundation design prior to the dig?

It allows the builder to quote more realistically. I did a job last year, which was close up to a leylandii hedge in clay soil, the clients builder quoted for a 1 metre dig, I warned him a few times he should price for 2m+ and warn the client. BCO was 2.5m and the trenches were collapsing so had to be shuttered. Client fell out with builder and ended up getting somebody else in.

Knowing in advance that trench depth might be over a metre can help the builder -he can hire a bigger machine rather having to do a swap over.

The fun starts with a job which has restricted access and needs deep trenches or piles

Its true you cant tell whats in the ground- Ive seen top soil 800mm deep, not a problem but then the job needs block and beam, which has a lead time.

Digging a test hole doesnt prove much.....it wont find a capped off well or an area of back fill.

 

[Leofric]

How many different permutations of building / site and ground conditions can you get - lots If it isn't straightforward and if the architect has any sense they will pass it on to the structural engineer to sort out the foundations.

 

[an203888]

Perhaps you need to notify the architectural design industry that everyone except your family friend is doing it wrong? Or ask the family friend for 30 years worth of refunds for his half-a-job poxy specifying?

Or you could make friends with a new designer who will take account of the site, will have knowledge of the potential ground conditions (or know when to specify testing if appropriate), and will know about BS8500 and if it applies or not, of if a specialist design is required, and will design a typical foundation that can be aproved and priced.

OK, should I genuinely look to complain and get refund on the work my designer has done? I'm otherwise very happy with what he has done for the price.
I beleive he does have knowledge of the potential cround conditions, hence why he has specified beam and block rather than a slab. I didn't know that he should be specifying exact foundation designs. Have you got an example you could share for me?

 

[an203888]

How many different permutations of building / site and ground conditions can you get - lots If it isn't straightforward and if the architect has any sense they will pass it on to the structural engineer to sort out the foundations.

I think it is straightforward... just doing due diligence.

 

[johnny2007]

I wouldn't rush at condemning the architect.
Usually in the plans, where they show the fundations they write something along the lines of: xyz mm concrete filled fundations subject to Building Control approval.
So the rule of thumb is always to contact BC before excavating and ask what they want.
Most times they will say to dig down a certain depth and then they will come out to inspect.
At that point they would either approve the footing depth or say what's required.
Builders know this and quote accordingly to a set m3 of concrete.
Any extra is extra and it's usually stated in the quote.

 

[an203888]

I wouldn't rush at condemning the architect.
Usually in the plans, where they show the fundations they write something along the lines of: xyz mm concrete filled fundations subject to Building Control approval.
So the rule of thumb is always to contact BC before excavating and ask what they want.
Most times they will say to dig down a certain depth and then they will come out to inspect.
At that point they would either approve the footing depth or say what's required.
Builders know this and quote accordingly to a set m3 of concrete.
Any extra is extra and it's usually stated in the quote.

This is what is said... and that's all. BC also give guidance on their website which all makes sense. What doesn't make sense is that I essentially have a retaining wall about 1.2 meters away which drops down about 600mm... my existing house footings go down 860mm on what appears to be (test hole) solid ground so they go another 260mm deeper than ground which isn't that far away. I would have thought that it would need to go down deeper than 260mm.

Screenshot_20191208_185202_com.google.android.apps.docs~2

• an203888
• 8 Dec 2019

 

[Leofric]

I think it is straightforward.

So what is the problem

 

[John D v2.0]

Our structural engineer wandered about the garden looking at trees and then said 1m deep but he wanted to look in the trench before concreting. The more information up front the better, but no one is going to put their neck on the line for any thing unseen, but you do expect them to put a bit of effort in.
Depends if you spent 200 pounds on someone to do building regs drawings or you spent 2k on a structural engineer and the same again on an architect with letters after their name. And even then they don't come with x-ray specs.

 

[pilsbury]

Perhaps you need to notify the architectural design industry that everyone except your family friend is doing it wrong? Or ask the family friend for 30 years worth of refunds for his half-a-job poxy specifying?

Cold blooded!

 

[an203888]

Cold blooded!

I thought so!!

 

[an203888]

Just for an update on this. I have spoked to building control who dont seem to see it as an issue. They spoke about making sure that at the bottom of the foundations the loading is taken uo at a 25% angle and as long as that doesnt cross over into the retaining wall then it should be fine. They also said they would be happy to come have a look just book it in - which is exactly what I will do. They were very helpful.