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Fireproofing - FAQs
Fireproofing is a complex business.
The following list of frequently asked questions has been developed to
address some of the many issues surrounding fireproofing. For additional
help or inquiries, contact your Grace Fireproofing Products Sales Representative.
Click on the question to view response.
Monokote® MK-6® is a gypsum based cementitious
spray-applied fire resistive material for structural steel framed buildings.
The term cementitious as defined by ASTM or Underwriters
Laboratories Inc. applies to all fireproofing that is wet mixed and
then pumped as a slurry. Cementitious does not refer to portland
cement content.
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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.
It does not work this way! Thicknesses
for hourly ratings are derived from individual UL fire resistance designs.
(We have over 120 designs to choose from). These are classified as:
- Floor Assemblies
- Floor or Roof Beam-only Assemblies
- Roof Assemblies
- Columns
- Walls
Within these broad categories thicknesses are
dependent on:
- Steel shape and size
- Type of concrete (Normal Weight or Light
Weight)
- Thickness of concrete
- Type of insulation
As you can see, there are no easy answers to
this question. Consult your Grace Fireproofing products sales representative
for assistance on selecting the appropriate design.
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Yes, all Monokote® Fireproofing products manufactured
by W.R. Grace & Co. - Conn. are asbestos free.
Monokote® Accelerator is aluminum sulfate (alum).
Monokote® Accelerator reacts with the retarder in the gypsum. (Gypsum
is normally retarded to allow for pumping and mixing.) This allows Monokote®
MK-6® to set in 10-20 minutes. The use of Monokote® Accelerator
with MK-6® results in a lower installed cost.
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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.
Drying rate is variable and is dependent upon
many factors including -
- Thickness
- Temperature
- Relative Humidity
- Ventilation
The material "sets" within hours but can take
many days to fully dry. As with any spray-applied fire-resistive material
it is important to follow the manufacturer's recommended ventilation
requirements.
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No. Monokote® MK-6® is designed for new
construction conditions. Post abatement respray is done over post-removal
"lockdown agents" and Retro-Guard® is the product recommended for these conditions. Only Retro-Guard® has been fire tested at UL with 12 different UL classified lockdowns. Retro-Guard® is specially formulated for
enclosed areas and has a distinctive blue color.
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.
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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.
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.
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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.
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.
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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.
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