Going Deeper Underground!
This is the stage we are at, as of July 2012 before digging foundations and after demolishing our conservatory. Our plan is to saw cut along the yellow line shown in both photos below painted on the floor as this will be the width of our foundation. I started with a 9" angle gringer with a load of discs I managed to pick up off a friend who just happened to have loads floating about, it took a while but it went ok and the finish isn't bad either.
I needed to ask the building inspector at our first meeting (The 'commencement' meeting) that my proposed plan for the foundations is ok, although I am fairly confident it'll be fine having spoken with others and doing some research.
I needed to ask the building inspector at our first meeting (The 'commencement' meeting) that my proposed plan for the foundations is ok, although I am fairly confident it'll be fine having spoken with others and doing some research.
The Foundation Plan
After the first meeting with the Building Control inspector, we had a bit of a chat and pretty much agreed what the general foundation detail should be which is shown on the right.
There was the added complication of a sewer in the site so this had to be bridged over using a lintel. More detail including a sketch on this here. Later I also noticed that the depth of the concrete for the new footing needed to be at least 450mm deep not the 300mm deep which I originally thought would be ok! This is to protect the footing from frost. If you are building on Clay then you may have to increase the depth of concrete to a minimum of 750mm as clay is prone to expanding and contracting with frost. |
The picture to the left is what I showed to the building inspector at our first meeting to ensure he was happy. The material I am digging in is Chalk, in the building regulations there is a table which tells you the probable width of the foundations (here on page 37) I opted for a 600mm Wide trench as this seemed to cover most senarios. With regards to the depth, most situations the most you shouldn't need to dig any more than 1metre. However, best checked with the Building Control guys as this is completely dependant on the depth of the harder ground and where it is. The advice I got from the building inspector which worked ok was that you want to be about 4 inches into the hard ground (in my case, chalk) this will dictate the depth of your footing. I did a trial hole and found that 600mm under the existing ground level should be ok for the underside of the footing. |