Foundation plans

[Taff]

Can someone have a quick look at the pic for the founds please just to make sure they are ok. I ain’t got a clue ? I’ve dug a hole to have a look under the soil and it’s solid clay at an estimate of 300 mm down 

 

ta

 

 

[ProDave]

The clue is "Foundations as per S Engineers spec"

 

You are expected to have a structural engineer look at the soil type, which will probably involve digging some test holes, and he will specify what is needed for your ground conditions.

[MortarThePoint]

+1 for ProDave's response

 

There are lots of factors to consider including nearby trees, future planting requirements, volume change potential of bearing strata and so on. Clay can be complicated by the fact that it can swell (heave) or contract (subside) depending on water levels and how thirsty nearby trees are (or were if cut down).

 

I'm not trying to scare you, but I personally left that side of things to the pros with their experience and insurance.

Edited February 27, 2020 by MortarThePoint

[dnb]

There's clay and clay. I have clay soil and your design wouldn't work on my land at all. I had a couple of soil samples taken (by hand) and analysed by a friend. It cost a few pounds but confirmed what nearby house owners had told me - that I had highly shrinkable clay with signicant heave potential. And a lot of trees of course. I didn't bother with expensive bore holes (after all, the piling people would do this for me eventually ? ), instead I had the SE specify everything for the sensible worst case outcome based on what next door had done 2 years previously. Next stop piles and a lot of claymaster. (It was more cost effective than my other option of 2.6m deep strip)  In the end, the pile design changed slightly because of a higher percentage chalk in the clay at 3 to 5 metre depth at one end of the site, but the cost of the change was less than the survey would have cost and I lost no time.

 

Your clay might be much more forgiving of course - the clay back where I grew up only needed a metre or so depth of strip foundation. Talk to people who have built recently in the immediate area if possible so you can ask informed questions of the SE. Both my SE and BCO turned out to be quite knowledgable about the geology of the area around my house because it's a well studied ANOB and the SE did the pile design for my next but one neighbour. Building control and warranty people will all want to see a design that works else they will just say no.

[Taff]

Oh wow different types of clay ?!  We’re just big kids really always playing with clay! It’s a good thing that I’m the one just messing about on site and not getting involved, the house would end up lopsided. I’m told we have engineers assessing over the next couple of weeks. Monday morning is the start of the dig we had to wait for archeological to come and sit with their flask and await skeletons to be unearthed! Just need to keep crossing fingers 

[Taff]

12 hours ago, MortarThePoint said:

+1 for ProDave's response

 

There are lots of factors to consider including nearby trees, future planting requirements, volume change potential of bearing strata and so on. Clay can be complicated by the fact that it can swell (heave) or contract (subside) depending on water levels and how thirsty nearby trees are (or were if cut down).

 

I'm not trying to scare you, but I personally left that side of things to the pros with their experience and insurance.

Thankfully there are only 3 small trees around 15 meters from the corner of the house. Absolutely agree I wouldn’t know where to start 

[Taff]

15 hours ago, ProDave said:

The clue is "Foundations as per S Engineers spec"

 

You are expected to have a structural engineer look at the soil type, which will probably involve digging some test holes, and he will specify what is needed for your ground conditions.

? I’ve been told to keep away ?

[joe90]

I am on clay, didn’t use an SE, got the building inspector (local council) to look in a test hole and he just specified 700mm deep, I wanted 700mm wide for my wall make up. Simples, no expenditure .?

[Taff]

Ok so contractor are now having to re look at founds now that they have dug a great big hole. I’m told couple of options. We were originally planning for a slab however, we may have to use pile! I’m immediately thinking a million pounds on to our budget, which we ain’t got. Has anyone had experience, if it were pile, are we talking she’d loads of cash more? 

[Mr Punter]

If you are using local authority building control, get the building inspector to visit and they are likely to have experience of foundation types where you are.  If piles are needed they may also suggest piling contractors.

[Jeremy Harris]

+1 to the above.  Building inspectors have two useful qualities (usually), local knowledge and often (but not always) a pragmatic approach to issues arising during construction.    The LABC one that looked after most of our build was great, really helpful and genuinely very interested in what we were trying to do.

[joe90]

2 minutes ago, Jeremy Harris said:

+1 to the above.  Building inspectors have two useful qualities (usually), local knowledge and often (but not always) a pragmatic approach to issues arising during construction.    The LABC one that looked after most of our build was great, really helpful and genuinely very interested in what we were trying to do.

yup, see my post above.

[Taff]

Build control is a firm from Yorkshire, we are in Northumberland!! Don’t know how that works, however we are using a local engineer to test soils etc and plan the foundations, we are just awaiting the options, I’m just terrified that if it were pile then this could possibly blow our budget get ?

[Mr Punter]

Discuss with your engineer.  It could be fine with a strip footing.  (S)he should be able to give ball park costs for the options.

[MintSprint]

Approved Document A to the Building Regulations may be useful, if you're trying to do it without soil testing or the input of an Engineer. Pages 36 and 37...

 

In the absence of testing to determine the MPI, depth will need to be to the satisfaction of the Building Control inspector, and they will certainly want to be below the level of any evident intrusion by tree roots.

Edited March 19, 2020 by MintSprint

[Taff]

Think the engineer and everyone else is going up tomorrow so will also pop up to get the gossip. I’ll make sure we are 1 metre apart ??