In article ,
Space_Cowby wrote:
Don't care what the web site tells you. 20 years of experience
tells me a stiff mortar will make no difference at all. By good
bricks you must a class a engineering brick which will resist
dampness but it just travels thru the mortar joint.

No: build a manhole with semi-engineering bricks and 1:3 mortar and
the brickwork will be 100% (OK 99.5%) watertight.

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Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm