Civil Engineering Reference
In-Depth Information
Repair of cracks
●
Where cracks could be caused by
size changes in the substrate, site
practices should ensure that
movement joints are carried
through the thickness of the render
with no hard material bridging a
joint at any point. Otherwise, at
changes of substrate material, site
work should ensure that the bond
between render and substrate is
interrupted so that the render is
fully isolated from the substrate at
those locations (Figure 9.24). Non-
corrodible reinforcement should be
securely fixed to the substrate on
both sides of the isolated area.
Fixings clear of joint
Inspection
The problems to look for are:
◊
detachment - incorrect mixes or poor
surface preparation
cracking
◊
◊
peeling of finishes
◊
friable surfaces
◊
incorrect mixes
incorrect lath fixing
◊
EML on isolating layer
(eg of plastics sheet)
Render coats
◊
poor surface preparation - scratch
coats inadequate
Figure 9.24
The bond between render and substrate
should be interrupted at changes of
material
◊
lack of proper curing
impact damage on thin renders over
thermal insulation
◊
◊
sulfate attack
◊
inadequacy of existing sill projections
when adding insulating renders
