|Floor joists where
chiseled off at an angle
for a metal lath and cement floor.
|The joists were chopped down
forming a point.
An illustration showing how splitting the joists at
an angle allowing mortar to form full keys.
|Without cutting off the joists
at an angle, the flat
areas form weak spots in the floor, leading to cracking and failure.
It really gives me a pain to see someone put
in a mud floor using flat lath and stiff mortar on plywood.
The metal lath offers no reinforcement this way.
You may as well just pour mortar on the plywood with no lath.
You may have seen our chipping method before.
Chipping was used many years ago to plaster over old walls.
In old buildings, I have found this plaster easy to knock off. Chipping alone isn't enough to bond mortar permanently to an old wall.
A chemical bond is used along with chipping to ensure a permanent bond.
The point is that holes are made allowing some mechanical key for the plaster.