Nothing wrong in that and I inspect them whether it be new housing, extensions etc, can't even guess how many strip foundations I've seen but it its well into the 10's of thousand.
You haven't answered the question.
Would you build your detached house on 200mm concrete?
And are you sure you only used a 200mm shallow strip on your extension?
Or was it more like 300mm/400mm?
Fortunately there's you here giving good advice for strong fundations (God help the fools listening to you).
And fortunately it's not only me laughing at you, your reputation preceeds you, hence why many here call you nosef@ckall
What's it going to take for you to realise you are wrong?
You've had the NHBC guidance quoted at you, some of the most helpful/experienced/knowledgeable forum members saying you're wrong, one of whom is a BCO.
200mm, in the right conditions is enough concrete.
If you say so.
Weirdly I was never called back for a collapsed porch, cracked walls, etc.
Must have been pure luck...
To build on 200mm concrete you need solid ground, not available anywhere in the london area as far as i know.
Maybe in the rocky montains of Scotland, but surely not around here.
That porch that collapsed had failed fundations and the "master" was suggesting building on even weaker ones.
Read the thread.
150mm thick foundations are acceptable in the majority of cases, although in reality 225mm are generally used to allow for/save the time levelling the bottom of the trench.
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