Depth of foundations for a conservatory?

[happyhippydad]

Hello,

I have just dug the foundations out for my new conservatory. The builder said to dig them 500mm deep. I have researched on line and I get a huge variance in depth stated, ranging from 600mm - 1500mm.

This is an experienced builder who does good work and has a good reputation so if he says 500mm is sufficient then I expect it is but i just wanted to ask peoples views on here?

Many thanks.

 

[stuart45]

The depth of foundations is dependant on your ground conditions.

 

[^woody^]

This is an experienced builder who does good work and has a good reputation

What's his work like from 5/10/15 years ago on these 500mm foundations?

A time to stop digging could be when you are at the same level as the house foundations.

Did the good builder mention building over or near to drains and how this affects foundations and even permissions?

 

[Notch7]

Hello,

I have just dug the foundations out for my new conservatory. The builder said to dig them 500mm deep. I have researched on line and I get a huge variance in depth stated, ranging from 600mm - 1500mm.

This is an experienced builder who does good work and has a good reputation so if he says 500mm is sufficient then I expect it is but i just wanted to ask peoples views on here?

Many thanks.

The best guide for digging foundations is to match what a building inspector would expect.

So, depth is governed by soil type, whether virgin soil or made up ground, existing house foundation depth, nearby foul drainage, trees in the zone of influence.

In simple terms if your ground has high load bearing capacity and is of non shrinkable material, 500mm might be ok, depending on where top soil finishes and ground bearing sub soil starts.

note that foundations needs a good flat bottomed trench with no sloping and the loose crumb at the bottom removed. The sides of the trench should indicate the type of soil you have dug through.

if you have trees nearby and you are in shrinkable clay, then depth will be quite significant.

So hence the reason why your research showed up a big variation!