Are finished concrete floors right for your school? An architect's view

Marblelife of Delaware Valley colored and polished this concrete hallway in a Philadelphia school after the worn floor covering was removed.

As part of my research into the story “Are finished concrete floors right for your school?” which I’m writing for American School & Hospital Facility Magazine, I interviewed Mark Muller, Treanor Architects, Lawrence, Kan., whose firm has designed for many schools, including the Lawrence public school system, University of Kansas, University of Missouri and Kansas State University.

Mark’s short answer to that question is – it depends.

Whether or not a school should use concrete floors depends on the floor’s purpose, the size of the project budget, the size of the maintenance budget, the desired aesthetic, and environmental concerns.

Whether or not Mark recommends concrete floors – and he has in many cases – depends on all the preceding factors and a few more.

“You have to consider the level of expertise of your contractor base,” he says, “and the degree of difficulty of the installation.”

That includes the amount of time you’ve got to complete the project. While all projects are “schedule-sensitive,” Mark says, students returning after summer break, for example, means that the work may be accelerated to the point of nonconformance with the spec.

Construction activities create wear and tear on a slab that is exposed for the duration of construction. For example, oil spilled on an exposed slab that’s meant to eventually be a finished concrete floor will set a project back while the surface is cleaned. The same type of damage to a slab that’s meant to be covered by tile or carpet isn’t as much of a disaster, Mark said.

Construction creates wear and tear on exposed slabs set to become finished floors. A concrete floor protection plan will help keep the project on pace.

And while the possible “X-factors” such as spills don’t present insurmountable obstacles, design professionals do have to consider their likelihood and potential in making their recommendations, and in writing the specifications.

The first piece of advice Mark offers school officials tasked with deciding on flooring options is to consult a design professional trained to weigh and evaluate these factors.

Utility spaces
That said, there are some places in schools where finished concrete floors are always appropriate. They include janitorial and electrical spaces, and anywhere there could be wheeled traffic and other heavy use.

Those floors, at a minimum, require some sort of dustproofing, such as a film-forming sealer or a hardener-densifier.

Student, staff and faculty spaces
Flooring options increase in student, faculty and staff spaces. Finished concrete flooring is still a good choice in vocational “shop” classrooms, corridors, and other areas where a hard floor surface is acceptable.

You have to be careful about choosing concrete floors for labs where students might be handling acids or reagents, or art rooms where dyes and paints might be spilled, Mark said.

Concrete floors with a limited aesthetic — a few colors without extensive and expensive saw-cut designs – may be a good choice for cafeterias. But you have to weigh the cost of the grinding and other surface prep against that of simply putting down resilient flooring materials.

On the other hand, since finished concrete floors don’t need waxing, buffing or stripping, they can save on the maintenance budget, Mark said.

“Be sure to educate the maintenance staff on that point,” he added. “Some maintenance technicians are of the opinion that if it’s horizontal and doesn’t have carpet, it should be waxed and buffed no matter what.”

Eliminating waxing, buffing and stripping can save schools quite a bit of money over the course of a year, a decade or a bond-issue, he said.

Wherever concrete flooring is being considered, Mark said, the acoustics of those spaces should be taken into account. In many cases an acoustical panel ceiling will mitigate some of the “liveliness” of sound that a hard surface flooring material will promote, as will some wall and window treatments, but often the solution is to soften the acoustics with carpeting.

The flooring in this auditorium is a combination -- sealed, trowel finished concrete for durability and low-maintenance, and carpet for its sound-softening properties.

Larger rooms may benefit from concrete floors. However, Mark said, since the hard surface can help in projecting sounds, there are escalated risks for acoustical backfire. Check with an acoustician.

Rehab
To get the simplified cleaning and maintenance benefits of concrete flooring, school officials will sometimes remove worn-out carpet or tile, exposing and finishing the concrete floor underneath.
It’s not a bad idea, since the concrete floors will last the life of the building. But you may want to reconsider, Mark said, if the worn flooring to be replaced is vinyl asbestos tile.

Vinyl asbestos tiles, and particularly the mastic used for adhesion, can introduce harmful fibers into the air if removed by abrasive or mechanical means. Asbestos abatement procedures must be followed, which can get expensive, so simply covering the old tiles with another floor covering is an acceptable solution, and may be the best bet for cash-strapped schools, Mark said.

Environmental concerns
Asbestos tiles aside, finished concrete floors do offer environmental advantages. New concrete is usually produced locally, so you avoid the energy consumption for lengthy transport of heavy rolls of carpet and boxes of tile.

Old concrete, already there, doesn’t even require the limited transport cost of a concrete transport truck.

Since concrete floors don’t need to be replaced, they don’t take up space in landfills like other flooring types that have to be removed at the end of their service lives, or because of accidents – floods or spills for example. While many flooring manufacturers offer recycling options for their products, concrete will remain serviceable for the life of the building.

All these factors, from budget to contractor skill to environmental concerns must be weighed, Mark says. In the end, finished concrete floors are a reasonable choice, if not the only choice, for many school spaces – and definitely worthy of consideration.
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