Building new houses on clay

oldskoo1

Are there any rules defined to prevent builders constructing new propety on clay without treating the earth?

Talking to my neighbour he told me the soil is a nightmare and full of clay. Looking on a map online it seems there might be clay in the area.

We've sold our 15 year old house and moved into a newer house, 8 years old nearby.

Would clay soil be a problem on this type of newish house or are builders required to treat or dig out clay soil before construction? With subsidence in mind.

Thanks

G_M

Most of London is built on clay.....

Some of it (London I mean, not the clay) has been around for a few centuries.

(Actually, thinking about it, the clay's been around for centuries too!)

art_for_arts_sake

G_M wrote: »

Most of London is built on clay.....

Some of it (London I mean, not the clay) has been around for a few centuries.

(Actually, thinking about it, the clay's been around for centuries too!)

Yes, but in those days, houses were allowed to "move" by using lime mortar, and many of the houses that survived the Blitz did so because of the way they were built. Modern houses are effectively built on a concrete foundation with Portland cement mortar which doesn't allow for any movement. Plus the ties used to connect the two skins of brick and block together aren't as strong as the bricklaying bonds used centuries ago. We've managed to unlearn everything our ancestors found out for themselves, including ventilation, as the many posts on here mentioning problems with damp prove.

teneighty

I think your neighbour is being rather melodramatic.

Clay is a perfectly good sub-soil for foundations provided you go deep enough, for most residential properties that is a minimum of one metre. If there are large mature trees in close proximity sometimes considerably deeper.

The problem with clay is that it expands and contracts slightly depending on it's moisture content. However, it has been found that at a depth of one metre it remains stable as it is unaffected by rain, frost etc. Large mature tree roots can obviously go much deeper than one metre so can dry out the clay to much greater depths or cause the clay to swell and expand if the tree is subsequently removed.

The draught of 1976 caused a lot of subsidence problems for newer houses so after that most houses built on clay sub-soils had the minimum one metre foundation depth enforced by local authority building control. An eight year old property should be fine but if you are worried check with your local authority to see if they did the building control inspections and they should have the records of the foundation depths.

Shallower foundations on clay may not be a problem, it just means that the property may have some slight seasonal movement. Provided the entire building moves together that can usually be accomodated, especially in older buildings which were constructed to withstand minor movement and hairline cracking in plaster etc. is tolerated as "character". The main problems come when only part of the building moves due to localised shrinkage or expansion in the clay due to tree roots or leaking drain etc.

oldskoo1

Thanks this is great information

Our house is a 8 year old 3 storey at the top of a slight hill. There are no mature trees nearby. Only some mid sized screening trees at the bottom of the garden.

Reassuring that clay isn't an issue providing foundation is deep enough. I would have thought with the house being quite new they would have put correct foundation in.

G_M

oldskoo1 wrote: »

Thanks this is great information

Our house is a 8 year old 3 storey at the top of a slight hill. There are no mature trees nearby. Only some mid sized screening trees at the bottom of the garden.

Reassuring that clay isn't an issue providing foundation is deep enough. I would have thought with the house being quite new they would have put correct foundation in.

That's why these days there are strict Building Regulations.