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For a vivarium to work properly—meaning, safe for personnel and animals, supportive of the research, durable, efficient, sustainable and built within the means of the specific operation—you have to know what materials to select, and where in the facility they are best utilized. To those embarking on a considerably expensive renovation or new construction project, materials and finishes can seem like a relatively minor consideration, but in fact, their impact on everything from facility operation to the quality of the research performed is both real and significant.

I speak on the topic frequently, having designed and overseen the construction of millions of square feet of corporate, institutional and government vivarium space—and I’ve learned something on virtually every job, both confirmation of what works and discoveries of things that might not work, for a wide variety of reasons. When I hear from people during and after my presentations, and during client meetings prior to the beginning of design work, the primary concerns they express are how a vivarium can be made as robust and maintenance-free as possible. These concerns are extremely valid (fixing a problem within a vivarium can disrupt research), but have to compete on all building projects with other issues of cost, operational efficiency, and sustainability.

Inevitably, certain trade-offs will need to be made, which is why your familiarity with vivarium materials and finishes, and your designer’s experience with specifying and installing them, will go a great distance toward ensuring your vivarium spaces are among the successful ones.

Large animal holding room with MMA flooring and FRP wall panels.

SCRATCHING THE SURFACE

“Maintainable” is the only shared criterion for the selection of all materials and finishes mentioned in this article. “Durable” describes most of them. Other criteria vary only slightly—for example, “waterproof” for flooring, “water resistant” for walls—while many more only apply to certain materials because of their location or the expectation of abuse. Examples: It is important that flooring and walls are chemically and biologically resistant, and as maintenance free as possible. I’ll note the specialized criteria as I discuss each vivarium component, beginning with the most vital.

Rodent holding room with epoxy flooring and high-performance epoxy wall coating.

FLOORING

The range of surface types that are appropriate in different areas of vivaria is wide, encompassing everything from concrete to vinyl to rubber, but the vast majority specified are in the category of resins: broadcast epoxy, troweled epoxy, urethane and methylmethacrylate (MMA).

Epoxy is the original resinous floor product, which 60 years later represents the majority of vivarium flooring we’ve installed. An oil-based product, it is made in nearly 100 formulations by different manufacturers, which makes writing a specification for a particular epoxy with distinct characteristics very important. As suggested by their names, the two primary types of epoxy floors, broadcast and troweled, differ in the way they are applied and in their durability. For all resin floors, the concrete substrate needs to be dry and there is a limit to the amount of moisture allowed in the concrete by each manufacturer. A high-quality vapor retarder and appropriate subbase will allow the slab to dry over time before the flooring is installed. If there is too much moisture remaining, mitigation can be performed by applying chemicals before the resin floor is installed, reducing vapor transmission. All resin floors involve preparing the concrete floor by shot blasting to eliminate curing chemicals and increase the area of adhesion. A primer is then installed.

For broadcast flooring, a layer of liquid epoxy is poured onto the concrete subbase, leveling it. The installer then scatters or “broadcasts” an aggregate of quartz sand onto the epoxy while it’s wet. When it dries, loose aggregate can be vacuumed up and typically another round of liquid epoxy and aggregate is applied, followed by a clear topcoat of either epoxy or urethane. In theory, you could add a third coat of epoxy and aggregate, although this is typically avoided for cost reasons. Troweled epoxy is a more effective option for a thicker floor—while both feature high compressive strength, troweled epoxy’s is much higher—but so is its cost, due to the need for a trained professional to install it. Because troweled epoxy comes premixed with aggregate, it requires skill to keep the color of the mix consistent and to spread and level it by hand. Both flooring types utilize a troweled coved base to seal the joint between the floor and wall.

More expensive still is MMA, but the industry has nevertheless seen growing interest in this resin-based alternative. The primary reason is its quick drying time; whereas epoxy floors can’t be walked on for a day or two while they cure, MMA floors dry in an hour. One byproduct is that these floors are also more complicated to install—the liquid has to be worked in very small batches—but in other respects they are similar to epoxy. MMA has even stronger adhesion properties, and the filler or “aggregate” used in MMA is acrylic flakes or sometimes quartz, which can lead to a floor that is more or less rough, depending on the application, or something closer in texture to an orange peel. All of these floors produce odors that have to be ventilated during construction.

Holding suite corridor with epoxy flooring, high-performance epoxy wall coating, and aluminum wall guards.

Resinous floors that are used much more sparingly include two urethane-based options—thin-film urethane, which is the least expensive flooring option aside from plain sealed concrete, and “urethane concrete,” a mixture of urethane embedded in concrete, which is among the most chemical- and heat-resistant of all the resin floors.

A unique (and rare to the vivarium industry) resinous product is vinyl ester, which originated in the chemical tank industry. Vinyl ester features high bonding ability and is extremely chemical resistant. Less expensive than troweled epoxy, it would, if it were more readily available, be a good option for all vivarium areas except those set aside for hooved animals.

All resinous floors meet coefficient of friction standards, making them highly suitable for many vivarium areas. Once dry, they have almost twice the strength of concrete. Installed cove bases are integral to the floor and extend from 4-in. to 8-in. up walls, making these floors like a bathtub. They’re inherently moisture barriers in and of themselves, both keeping moisture from the concrete from infiltrating up into the floor system, and keeping moisture above from damaging the floor system or the building structure underneath. Despite all that, we recommend the installation of a waterproof membrane beneath all flooring surfaces including resin floors when installed in wet areas on raised floors above occupied space, mitigating any risk of an expensive and inconvenient repair job down the road.

The one popular non-resinous floor that has applicability in vivaria is industrial-grade sheet vinyl/rubber; in fact, it is growing in popularity, mostly due to its being softer and quieter than resin flooring. Its benefits and drawbacks make for a complicated package: It is slip-resistant, impervious to hot water (which can melt epoxy floors) and will generally withstand a rigorous environment to a greater degree. At the same time, rolling metal casters underneath heavy equipment can cause bubbling of the surface (due to friction-caused heat melting the adhesive), and it has a tendency to scuff, requiring a certain amount of special cleaning, training and scrubbing equipment (even with special treatment, they can look increasingly dirty over time). Like thin-film urethane, it is applicable mostly to small-animal facilities, and surgery/procedure rooms.

The overwhelming prevalence of resinous floors in vivaria means that, in addition to specifying a flooring type, you’ll have to select the surface finish, and this will vary depending on the amount of foot traffic (hooved or not), the weight and portability of the equipment used in each area, the types and amounts of chemicals that will be used in each area, and the presence of hot and cold water in each area. The particular circumstances will affect the floor slope, the texture, the presence of floor trenches for drainage, and numerous other considerations. Our primary piece of advice with regard to this is to have mockups made and get all the particulars agreed to with the floor manufacturer or specifier before the floor is sent to bid as changes to texture during construction can add significant cost.

Specifying floors is mainly a matter of understanding each floor’s specifications, the type of substrate it will be adhered to, how the space is going to be used, and how the floor will be maintained. Even the simplest and least costly alternatives require careful thought, and even additional resources. An example is large barnyard animal spaces, which frequently feature durable, easy to maintain, and inexpensive sealed concrete floors. Dealing with these animals’ urine and fecal matter, however, typically results in the purchase of raised plastic mats to rest on the concrete, as well as to the specification of imprinted texture in the concrete for slip-resistance—which alters maintenance procedures. There really is no such thing as a simply selected floor.

Rodent procedure room with epoxy flooring, high-performance epoxy coating, stainless steel casework, and phenolic resin casework.

WALLS

Although they suffer a bit less abuse than do floors, vivarium walls are similar in terms of both the potential issues they face and the criteria for their selection. The primary materials used to construct walls are concrete block, which was for years the go-to material, and metal stud construction faced with either gypsum board (selected 50 percent of the time) or fiberglass-reinforced plastic (FRP; 10 percent) or a combination of both. While CMU (concrete masonry unit) construction remains valued for its strength and durability, its drop from 90 percent to 40 percent of the walls specified is due to its lack of flexibility and the advent of high volumes of rodent caging, dry spaces that lend themselves to a different approach. It is also particularly expensive to install in higher-grade seismic zones. Metal stud construction using abuse-resistant gypsum board can in fact be used in the creation of walls that are suitable for larger animals, as well, at a much lower price. FRP is considered the in-between choice—more durable than gypsum board, more flexible than CMU—but its price point is the highest of all three. One can combine abuse-resistant gypsum board with thinner FRP to gain durability and keep the cost in line with CMU.

More robust gypsum board panels are available that were originally intended for high-traffic areas in schools and exterior applications, but have found a home in some vivaria. Essentially fiberglass-reinforced gypsum board, they are heavy-duty, abuse-resistant and mold and moisture resistant.

By an overwhelming margin, the surface of choice for vivarium walls is high-performance epoxy coating, which is typically referred to as “epoxy paint” even though it has little in common with the epoxy paint you’d find at your local hardware store. These more-expensive coatings are marked by extremely high solids content, which means they require the skills of trained technicians to apply properly. Other epoxy-based coatings include troweled epoxy, which is even thicker and more difficult to apply, and fiberglass-reinforced epoxy paint, which is most often specified for rooms where walls will be sprayed with steam or high-temperature water.

Whereas most flooring vulnerabilities involve exposure to elements and forces such as water, chemical compounds and weight, walls must be impervious to many of these while also countering the threats posed by animals and people. Four-legged behaviors include rubbing on wall seams (swine), picking at imperfections (primates) and scratching at panels (dogs), all of which can cause significant damage, while the biggest danger to walls is heavy carts and cages pushed by vivarium staff. There are wall solutions available elsewhere (a seamless, heat-welded, sanitary vinyl product has made inroads in Europe) and other, floor-to-wall-applicable products such as fiberglass-reinforced plastic that have their adherents in the States that can help withstand cart-inflicted damage—and then, of course, there are numerous methods for protecting door jambs, corners, and wall panels. Corridor walls typically feature two separate aluminum (or stainless steel) guardrails, high and low, as well as stainless steel diamond plate in alcoves, and carts and other equipment transporters can be outfitted with rubber bumpers.

Finally, walls need to be designed and constructed (and sometimes, outfitted) to limit air and sound transmission (many methods of controlling sound owe more to knowledge of animal behavior), mitigate the effects of substrate cracking resulting from the inevitable expansion and contraction of concrete, inhibit the movement of vermin—or even to enliven spaces with colors or outdoor scenes. All specialty products or applications are worth asking your architect about.

Rodent holding room with sheet vinyl flooring and high-performance epoxy wall coatings.

CEILINGS

Because ceilings are the least likely surfaces to take abuse (the occasional flung feces can be wiped down), most of the trade-offs in ceiling materials specification involve weighing durability against accessibility to space above the ceiling where mechanical, electrical, and plumbing equipment reside. Heavier-grade materials, such as cement plaster and precast concrete, which are also the most costly ceiling systems, make accessibility to interstitial space difficult. But the most common ceiling materials are moisture-resistant gypsum board and FRP panels. By far, gypsum board ceilings with access to mechanical, electrical, and plumbing equipment above the ceilings via an interstitial space is the preferred method. Keep in mind that access panels should always be kept out of holding rooms, and should only be used in rooms where access won’t interfere with day-to-day functionality.

Where access is needed and an interstitial space is not affordable or practical, FRP tiles are our preferred product. While there’s a wide variety of quality available, we only recommend using the higher quality FRP systems, because lower-quality systems are not smooth and have a tendency to sag. These ceilings are sealed using clips above the grid that holds them in place or gaskets between the tile and grid. Some systems come with accessible clips.

Whichever materials find their way onto vivarium ceilings, they’ll have to accommodate various components that are routinely suspended in different rooms, such as equipment supports, surgery lights and autopsy equipment.

MATERIAL FACT

Materials and finish selection for vivaria starts with the species going into the room, how the animals will be housed, and how the space will be maintained. But even a list that small will require careful decision-making. For example, providing animals with appropriate bedding, which is better for their well-being, raises a host of maintenance issues. Dry containment will be necessary to keep shavings out of the wastewater stream, and the grit of the flooring finish will have to be rough enough to provide slip-resistance and smooth enough both to allow for cleanability and to protect the skin of animals from harm. And a facility that has swine in one room and sheep in the next, say, will have to keep all that in mind plus those animals’ distinct hooves.

For the humans who work there, the choice of materials and finishes should make their work so routine that they forget all about them. Anytime they have to stop what they’re doing and take care of something that has been damaged or is not working—and that, just for starters, will typically require moving animals out of the space for the duration of the repair—takes away from their focus on research. Ideally, the emphasis on proper materials selection during design will lead to a vivarium so robust and long-lasting that workers won’t need to worry about infrastructure for years.

Mark Corey is a principal with Flad Architects in Madison, Wisc. mcorey@flad.com

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