18
Cracking wall finishes
The HeatShift system reduces the wall temperatures
and minimizes the possibility of cracking wall
fi
nishes.
If a clean
fi
nish with no tile, etc. is desired, joints in the
cement board and the transition to gypsum board
will require special attention if future cracking is to be
controlled. Be aware that temperatures on the non-
combustible wall surface above the appliance can
exceed 175°F.
Below are some tips on how to best avoid any cracking:
• Allow materials to dry thoroughly before
fi
nishing
the wall. Cement board has the ability to absorb up
to 30 percent of its weight in water and may shrink as
much as 1/8” over a 48” length when drying from a
saturated condition. Running the
fi
replace before
fi
nal
fi
nishing will help drive out moisture.
• Always pre-drill screw holes through cement board
and use screws with self-milling head.
• Always use tape over joints.
• Behind joints, double up studs or use studs “on the
fl
at” to add extra support to the joint. Adhesive on
the backside of wall board behind any joints can help
control di
ff
erential movement.
• Use multiple, thinner coats of joint compound and al-
low to dry thoroughly between coats.
• Ensure framing materials are dry.
• After
fi
nishing the wall, introduce heat gradually to
slowly dry any excess moisture rather than drying too
fast.
• Avoid notching cement board or tiles around corners
of window opening and instead provide a joint that
intersects the corner.
Planning
Wall Finish
Cracks
Provide joints
either here or
here
