Nearly finished frame - 1foot deep by 1 foot wide
How wide should I have the ends and middle- planning on buying a standard block to match the exsisting wall which are about 90X190X390mm approx
Sounds like your existing wall is built in metric blocks, I hav'nt seen them since my days in the workshop in Bolton Street.
Normal size blocks are usually 100mm X 215mm X 440mm plus 10mm added on to the eheight and length for mortar joint.
If they are metric blocks you will need more than the 136 blocks I qouted you.
You will need around 180 if your going to put 2 piers between the two end ones like Billk suggested, or 171 if you only put one pier in the middle between the piers that you will need at either end.
Personally a wall that long I would put a pier at either end and one in the middle, but hey the more piers the better for a sound job.
Where ever you are putting the piers, widen your foundation by 9 inches at the points and side of the wall that you are going to build your piers. and allow an extra 4 to 6 inches past the end of the piers also.
Oh by the way these are exact amount of blocks needed for the wall, so it would would be a good idea to order a few extra for breakages etc,
usually 10% is the norm.
KOH