BOSS Products


Conspec Family Business BadgeConspec Warranty BadgeNon combustible silicate cement mortar


$10.95 $6.79

BOSS – 139 Hi-Temp Fire Mortar Caulk

BOSS – 139 Hi-Temp Mortar is a non combustible silicate cement that can withstand extremely high temperatures. Formulated for repairing chimneys, fireplaces and sealing wood-burning stoves and appliances, this product has strong adhesion and sets to become rock hard when fired. BOSS 139 Hi-Temp Mortar cannot be used in areas where there is constant movement, or where wet conditions exist or may occur. BOSS 139 Hi-Temp Mortar has been tested and exceeds ASTM E-136. Can be used in wood frame construction where an ASTM E-136 non combustible sealant is specified and where allowed by the building code. This includes sealing around pipes, ducts, vents and chimneys at ceiling and floor level before drywall is applied.

• A non-combustible silicate cement for temperature ranges from 0°F – 800°F
• Formulated for repairing chimneys, fireplaces, and sealing wood-burning stoves and appliances.
• Excellent adhesion and sets to become rock hard when cured.
• Conforms to ASTM E-136
• This sealant can be used on wood frame construction where a non-combustible sealant is required.
• No asbestos fillers
• VOC Compliant

Weight 16 oz
Dimensions 2 x 2 x 9 in
Product Type


Product Color


Product Size


You may also like…