FIRE PROOFING FAQ

Is spray-on fireproofing, joint compound or mortar an adequate fire stop in construction joints? 
NO! All material used in firestopping joints such as top or head of wall, perimeter/curtain-wall gap, control joints, etc. will have to pass a cyclical test (500-cycles - UL 2079) and then pass the fire and hose stream test in a fully extended situation. This means that cementitious fireproofing, tape/joint compound or firestopping mortar (typically pink, red, or brown) that is commonly used by drywall contractors at the head of sheetrock walls is definitely out. The problem with these type of materials is that with any movement of the assembly, cracks occur which can allow fire, smoke and toxic fumes through. A material that has expansion and compression characteristics is required.

Are Straw Bale buildings fire proof?
As straw bales are firmly compacted, they do not hold enough oxygen to facilitate combustion. Straw bales exposed to fire will smoulder and char, but will not burn. Typically walls are always plastered which further protects the walls. Extensive fire tests which have been conducted on straw bale structures have proven that a straw bale in-fill wall assembly is a far greater fire-resistant assembly than a wood frame wall assembly using the same finishes.

What is Monokote® MK-6®?
Monokote® MK-6® is a gypsum based cementitious spray-applied fire resistive material for structural steel framed buildings.

Can Monokote® MK-6® be applied by trowel?
Monokote® MK-6® is designed to be spray-applied. All of our testing is done with spray-applied material. Patching and small areas can be troweled. Care must be taken to assure an acceptable installation.

What is Monokote® Accelerator?

Is the use of Accelerator necessary?
While not absolutely necessary, Monokote® MK-6®/HY® is designed to be used with Monokote® Accelerator - it is part of the patented High Yield (HY) System. If the accelerator is not used, set time will be longer and the product yield (board feet per bag) will be significantly lower. The fire resistive properties are not affected.

Who is responsible for determining hourly ratings and the correct UL design and ultimately the correct thickness of fireproofing?
Model building codes and numerous state laws mandate that only the "Design Professional" (a registered architect or professional engineer) can make these determinations. W. R. Grace & Co.-Conn. can only recommend the appropriate design and thicknesses. All of our recommendations must be reviewed and approved by the design professional for the particular project through the contractor's normal submittal process and this information must subsequently be reviewed and approved by the building code official having jurisdiction for the specific project.

Can I apply Monokote® over primed steel?
Yes, although we recommend that the best surface is lightly rusted, unprimed steel. The use of primers is governed by Underwriters Laboratories Inc. and must be tested in accordance with ASTM E 736. All spray-applied fire resistive materials require a clean surface that is free of rolling compounds, mill scale and other substances that will impair the proper adhesion of the fireproofing material.

What steel primers are allowed for use with Monokote® MK-6®?
Grace maintains compatibility listings on over 200 commercially available steel primers, more than any other fireproofing manufacturer. Check with your Grace Fireproofing Products Sales Representative for assistance on the compatibility of steel primers.

Can Monokote® be exposed to weather?
Monokote® MK-6® is a gypsum based product and is not intended for long term exposure to weather. However, it's high gypsum binder content does permit the normal amount of exposure that is part of the typical construction process. Our high-density, portland cement based product, Monokote® Z-146 , is approved for exterior applications where exposure to wind, rain, and freeze/thaw cycles are anticipated.

Can Monokote® MK-6® products be painted?
Yes, under certain circumstances, Monokote® can be painted. However, the use of paints and sealers is governed by Underwriters Laboratories Inc. The surface flammability and smoke development characteristics of the paint or sealer must be tested in accordance with ASTM E 84. Generally, the paint must demonstrate a flame spread index of less than 200 and smoke developed of less than 450. The paint must be compatible with gypsum based construction materials. The Monokote® MK-6® must be completely dry and the paint application should not saturate the surface.

Do Monokote® products require a sealer in their application?
Absolutely not. The Monokote® family of products does not require, nor do we recommend, surface sealers or water tamping. The hard surface of gypsum-based and cement-based cementitious fireproofing materials delivers excellent in-place performance, including demonstrated resistance to air erosion and abrasion. Monokote® is appropriate for virtually all fireproofing applications including air-handling plenums. Certain types of facilities, clean rooms and hospitals for example, may desire a surface sealer as added protection.