Digging the foundations - My House Extension

A one storey extension
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Digging the foundations
Sunday, 8th April (Easter Day): I really had not considered starting to dig the foundations today but I had nothing else to do that I could think of and weather forecast was for hot weather for the next few days.

So out came the shovel!

I uncovered the drainage pipe from my neighbour (don't ask!). This will need to be protected with a bridge before pouring the concrete.
The first bit was dug quite quickly.

I was most pleased to realise that I had not uncovered the gas pipe!

I dug down to the subsoil which is solid sand at my house. Half of the trench was sub soil, while the other half had been previously dug.
This part of the trench will be all at the same depth but the next section will lower so there will be a step in the foundations.

The foundations are to be 600mm wide and 250mm (8") deep.
I'll dig the last section of the trench tomorrow and then peg out to fix the exact depth.

I seem to have achieved a lot in just over a month - I only started building the windows at the beginning of March!
Monday, 9th April (Bank Holiday Monday): First task of the day was to dig the foundation trenches on the south side of the extension.

I soon uncovered the the main house drain - the nearest pipe in the photo on the left. I also discovered the old salt glazed pipe that was replaced by the new drain 20 years ago. I would like to leave this in place as I do not want to disturb it even though it is not used.
A bit more digging uncovered the expected mains gas pipe cutting across the trench.
Digging out the last foundation trench shows the gas pipe following the line of the trench as predicted.
The rest of the day was spent pegging out the trenches to get the levels right. This was achieved using wooden pegs, a long length of wood and a level. Due to the drop, I decided to include two steps in the trench at the points shown by the white shuttering.

I enclosed the gas and the drainage pipes with shuttering. I will fill the foundation trenches with concrete in two stages. The first stage will be up to the top of the shuttering. The pipe tunnels will be filled with gravel and covered with pre-cast concrete slabs. The top layer will then be poured to bring the thickness up to 9".
The same applies to the other pipes crossing the trench at the other end of the extension.

I hope building control are happy with what I am proposing! I will call them tomorrow and try to arrange to get them to come and undertake their first inspection.

The weather is forecast to be very hot for the next few days so I want to get on and pour the foundations before it rains.
Copyright: Chris Gare 2007 - 2018
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