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FLOORING DECISIONS?
Balancing quality, safety, and durability Ned Leverage |
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It is never easy to build a laboratory facility, new or renovated. By necessity there are many entities and specific expertise that need input and these areas of influence do not necessarily intersect with easy transition. This is particularly true of flooring. There are those, who for some reason, still see flooring as a commodity purchase. As long as those individuals continue to operate, flooring decisions promise to be tough work. If you need to be convinced flooring should not be treated as a commodity, read further. Before the end user has the opportunity to give their input, others have already begun to shape the project. Considerations such as the affordability of the project, the impact of the construction on other programs, financial, architectural, and general programmatic aspects of the project are key elements of planning. These considerations are necessary in order to determine the feasibility of the project. If the project is not feasible it does not proceed.
With specific
respect to the interior finishes, there are several influences that
affect opinions regarding finish selection. First, there is the Guide
for the Care and Use of Laboratory Animals or what is generally known
as the “Guide.” While the Guide does not tell us specifically what materials
to use or how to construct the space, it does serve as a starting point
where we begin to establish industry recommendations toward the spirit
of what is considered good quality housing for the reasons of cleanability,
disinfection, and maintenance of long term environmental quality. In
short, good husbandry yields quality data. To paraphrase the Guide with
respect to facility finishes in general, it says that building materials
should facilitate efficient and hygienic operations. It says that finishes
should be durable, moisture proof, fire resistant, and that seamless
applications are most desirable. It continues to say that they should
be highly resistant to the effects of cleaning agents, scrubbing, high-pressure
sprays, and impact. Finally, it says that the facility in general should
be well-planned, well designed, well constructed, and properly maintained
so as to facilitate efficient, economical, and safe operation. (The
Guide continues to further delineate specific recommendations for floors,
walls, and ceilings separately.) However,
the Guide is not the only influence at work. In the real world there
are construction considerations that come into play. Cost of construction
is a real concern. Considering the overall cost of vivarium space, counting
dollars does not necessarily equate to being cheap: it is simply prudent.
Cost should never interfere with selecting finishes that are of the
highest quality or assure safety and durability, but neither should
money be wasted on useless virtues. Further, cost is not always defined
as the cost of the installed product. Costs can also be related to the
time lost during installation. The speed of construction is often a
major concern in the selection of construction finishes. Research deadlines
for new drug approvals or to coordinate with specific teaching cycles
often need to be met. The need to allow research to begin on time can
be critical in overall planning. Interior finishes can either enhance
or delay construction time. In short, time also equals money. Material
and labor availability are another influence that can affect the type
of materials that are used in the construction. These considerations
are often geographic and/or event driven. The rebuilding of the Southeastern
United States after the 2004 hurricane season will surely increase the
cost of construction products and affect labor availability. There are
likely to be price increases and/or a shortage of products available
to the trades. If these shortages or price increases are severe enough,
they will force comparisons with alternate materials to allow other
construction to continue. Local
building codes always have some affect on the type of materials that
can be used and the type of construction that will be accepted. All
of these influences affect price and consequently the design of the
facility. Furthermore, as a facility manager or director, most of these
influences are beyond your control. Finally,
the third sphere of influence involves the daily operational concerns
of the facility. Facility operations are dependent on the smooth uninterrupted
flow of research and affordable per diem charges. High premiums are
placed on low facility maintenance and operating costs. In order to
achieve this goal, it is essential to install products that are tough,
that require little or no recoating, and do not deteriorate under normal
use. End users want surfaces that are easy to clean and that withstand
chemical attack. It is becoming even more important that finishes are
quick and easy to repair and that the repair is safe both for the employees
and animals exposed to the repair process. The costs of facility maintenance,
however, come from a different pocket than dollars for construction.
The emphasis is different. Is
there any surprise that pleasing everyone while building a new facility
is so difficult when there are so many influences affecting the outcome?
In addition to the paraphrased general statements from the Guide relevant
to the animal facility referenced earlier, the Guide gives specific
insight for floors. It recommends that floors be moisture resistant
and non-adsorbent. It suggests that they be impact resistant and relatively
smooth but acknowledges that texture may be required. The Guide states
that floors should be resistant to biological materials and hot water
(thermal effects) and that they should withstand the effects of cleaning
agents and disinfectants. They should be capable of supporting the weight
of racks, equipment, and stored materials. It addresses the fact that
flooring should be sloped to the drains and that flooring should be
monolithic while acknowledging that minimal joints may be required.
Other outside terms and requirements such as cost, speed of construction,
fast track construction, lightweight concrete, and structural movement
enter as architectural and construction concerns. More recently, end
users have become concerned about materials that repair easily and safely.
Materials that have no VOC and no HAP make that possible. Architects
and owners are increasingly interested in clean technology as well with
consideration about LEED compliance. Considering the Guide’s suggestions along with the end user’s requirements and the construction preferences and limitations can be a confusing undertaking. Hopefully, we can, at this point, begin to shed some light on the important factors that influence the flooring decision for your facility. Durability An important place to start in designing a flooring system is with the issue of durability. Durability encompasses many of the factors mentioned above and, in general, equates to the useable life cycle of the floor. Durability is most affected by moisture in general. There are two issues with moisture; one is vapor transition through the concrete and the other is the degradation of flooring caused by exposure to topical moisture during use. Topical
Moisture Topical moisture,
probably the primary thought when the Guide references moisture resistant
and non-absorbent, is not generally addressed as a floor durability
issue. Other issues have clouded its importance. To fully appreciate
the effects of topical moisture, we have to first understand the history
of flooring. The evolution of major flooring systems began with latex
mortar systems. These early systems worked well over time because, at
that time, the abuse level to floors from daily use was limited primarily
to impact. Although surface chipping did occur, it was accepted as a
natural consequence of flooring systems. Chemical abuse was limited
to alkaline detergents that mimicked common household detergents which
were mostly used to clean small, galvanized caging and rack units. The
detergents were fairly innocuous and had little impact on flooring.
Additionally, latex systems are generally comfortable with water. As the animal holding protocols changed to include stainless steel cages, the cleaning regimes began to include acid cleaners. Since the latex flooring lacked chemical resistance to acids, latex floors began to fail. Epoxy mortars were the natural step in evolution. Epoxy mortars utilize installation techniques that had been acquired from latex mortars so there were skilled mechanics readily available for the new flooring materials. It was further understood at the time that epoxies had better chemical resistance; the shift to epoxy was understandable. As time progressed, we began to understand that although epoxies used in that generation of technology were more chemically resistant in general than latex, they were still not up to the task of withstanding an ever expanding and more aggressive line of acid cleaners and more aggressive disinfectants. The industry also began to understand that mortar flooring systems were inherently porous and, as such, absorbed liquids and nutrients into the body of the floor through chipped areas in the floor surface. Because of near perfect temperature, the absorption of liquids and nutrients created an aggressive environment for anaerobic microbes to flourish. Anaerobic metabolism includes the breakdown of epoxy substrates and the production of chemical byproducts that also destroy epoxy molecules. Since moisture enters through chips in the floor and carries materials which begin the destruction of the floor, it would appear that the use of mortar flooring systems would not be in the spirit of the Guide. The requirement for non-absorptive flooring is violated by porous systems. In
the 1980’s the industry realized that porous floors could not only be
absorbent but, because air expands and contracts as it changes temperatures,
could also be a contributor to the laboratory environment. Based on
this new understanding, the animal holding industry began to prefer
the use of resin rich systems, commonly known as broadcast systems.
The broadcast systems are virtually non-porous, therefore the damage
from impact is isolated to a localized area. Since the damaged area
in broadcast floors is much smaller, the floor is easier to repair.
The lack of porosity meets the spirit of the Guide since broadcast systems
are non-absorbent and consequently do not degrade as do mortars. However,
while broadcast flooring satisfied the moisture resistance and non-absorptive
issues, another moisture problem was created.
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The types of moisture vapor damage are different for mortar and broadcast systems. Mortar systems tend to absorb vapor from the substrate and allow it to dissipate gradually through the system. As moisture absorbs through the floor system, the high alkalinity of the absorbed vapor begins to have an integral effect on the epoxy. Eventually the floor will also begin to loose compressive and tensile strength and will begin to crumble under routine weight loads. Broadcast floors tend to block vapor rates that are greater than 3 pounds per 24 hours per 1000 sq ft. The collection of moisture affects the bond to the concrete, resulting in blister formation and eventual larger delaminated areas. If moisture vapor transmission is present either from within or under the substrate, no other aspects of flooring matter. The life of the flooring system will be significantly shortened. We know from research on concrete that the rate of vapor transmission for a given set of moisture, temperature, humidity, and osmotic conditions depends on the porosity of the concrete substrate. We know from other research that higher density concrete results in slower vapor transmission rates. Broadcast flooring was once thought to be impervious and, as such, unable to allow for any vapor transmission. However based on the knowledge of the ability of broadcast flooring to maintain bond strength to the substrate at vapor transmission rates less than 3 pounds per 24 hours per 1000 sq ft, we began to understand that at least some limited porosity that can be tolerated by broadcast systems. That understanding became the starting point for the newer technology research into the remediation of the vapor problem. Remediation techniques are now available to eliminate moisture vapor transmission problems in flooring and have been used successfully for the past five to ten years. The initial cost of flooring is increased by the use of remediation but it is less expensive to treat the problem in the beginning than to be faced later with the potential of floor removal and resurfacing with a new floor. Chemical
Resistance We have also learned through chemical resistance testing that reagent grade chemicals are not as abusive as commercial chemical formulations. For example, commercially available 37% phosphoric acid cleaner will be more aggressive to specific flooring than a 37% phosphoric acid reagent solution is to the same flooring sample. Even so, resin formulators (including us) still publish chemical resistance charts based on challenges made using reagent grade chemicals. This practice is still common because (as with animal research) the initial comparative work was begun using reagent grade chemicals. We now recommend using formulator published chemical resistance lists only as an initial guideline or aid to selecting the proper chemical family to use as a seal coat. We further recommend testing the chemicals you currently use against samples of the flooring proposed for your facility. Only in this way can you be assured that the flooring will withstand the chemical challenge. (For more specific information regarding chemical resistance visit our website and read the paper “Chemical Resistance in Resinous Flooring.” The paper outlines the test procedure and discusses the issue in more depth than we can afford in this article.) The
important information to remember at this point is that once again,
flooring cost is generally increased where chemical resistance is important.
Resinous flooring is not a commodity purchase and can not be treated
as such. Generic epoxy seal coats will not perform well in today’s vivarium.
Even if a seal coat is reference by the formulator as being chemical
resistant, test it before committing. Expansion joints are designed to allow movement to occur either as expansion and contraction or settlement. The use of expansion joints is intended to eliminate uncontrolled cracking in the concrete. Generally, expansion joints are wide joints and the adjacent slabs are separated by soft materials. These joints are designed to move. Finally, control joints are joints that are literally cut into the wet slab and are placed in areas of the slab where movement is expected so that if the slab needs to move it will crack at the control joint as opposed to exhibiting random cracking. One is designed to move, one is designed to crack if necessary, and one is not expected to move at all. The need to properly detail each type of joint so that they do not fail is as critical to the durability of a flooring system as are moisture remediation and chemical resistance. Improperly treated joints will either crack (open) from contraction of the slab or buckle and/or delaminate from the compression of the joint caused by expansion of the concrete. Lateral rotation or uneven settlement of adjacent slabs will also cause cracking and/or delamination of the flooring as well. Regardless how the damage occurs, each will require down time and access to the clean facility or barrier to repair. The questions most frequently asked about joint construction are how to best deal with the different joints and which ones are likely to move. The
Guide recommends that flooring in the vivarium be monolithic while acknowledging
that minimal joints would be acceptable. This recommendation ignores
the potential for damage to the floor and the problems associated with
repair. We recommend the operationally conservative approach; treat
all joints as moving joints and, as such, reference all joints through
the floor, caulking the joint with an elastomeric caulk to ensure it
is sealed. The caulk is a maintenance issue and needs to be evaluated
periodically to assure it remains sealed. This however is a minor inconvenience
when compared to the noise and dust associated with floor repair that
could otherwise occur.
Animal research is driving concerns for more durable floors. In addition to the operational needs discussed so far, the industry drivers include the need for floors:
The flooring industry is offering alternatives to current flooring products. The newest products are a result of improved and innovative chemistry that contain no VOC and no HAP. This means there are no volatiles to off gas into the environment and no hazardous immersions to breathe. Not only is this an advantage for the research environment during occupied renovations but it is also safer for the contractor’s crew and anyone else associated with the process during new construction. Materials can now be UV cured which enhances tighter cross linking at cure and yields better chemical resistance, higher physical properties, and a more controlled immediate cure. Flooring products such as this will lead the way to providing the new industry needs as outlined above. The reference to a four letter word says it all I believe. As the industry has evolved it has forced its component parts to keep up with the changes and its new demands as well. We are challenged to produce a product that will service the industry with longevity in both function as well as aesthetics while at the same time having the ability to adapt to new unforeseen abuses. The facility still has the need to be compliant with the recommendations of the Guide. As such the flooring should do all the good things we discussed above. The flooring industry can accomplish all that is needed by following good design principles. We have the ability to work with the major issue of functional durability while at the same time dealing with design requirements (within reason), structural requirements, timing issues, and still keep costs commensurate with the level of the product. |
| Reprinted with
permission. animalLABNEWS™: November / December• 2004 Vol.3• NO. 7 |
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