When Do Concrete
and Tilt-up Construction Make More Sense Than Steel Buildings?
several factors that may make other methods of construction, most notably tilt-up
construction, a better choice than steel buildings.
The most obvious factor
is the building's size. For projects less than 50,000 square feet, steel is generally
the least expensive alternative. For a building of this size, the fixed or "open
the door" costs of a tilt-up construction project (like the rental of a large
crane, for example) make it more expensive than steel, even though concrete is
usually a less expensive raw material. As projects become larger than 50,000 square
feet, however, the lower price of concrete starts to offset tilt-up construction's
fixed costs and this method becomes cost-competitive with a metal building. The
larger the building, the more advantageous tilt-up construction becomes.
cost of the steel building kit will usually be lower than a price quoted for a
concrete building, even a tilt-up construction building. If customizing or modifications
to the kit are necessary to meet the owner's needs, these design costs must be
included when comparing the prices. Also, the kit price may not include costs
that are normally incorporated into a quote for a tilt-up or traditionally constructed
building. Some of those costs include concrete foundation, permits, erection and
assembly costs, taxes, electrical wiring, plumbing, environmental controls, ductwork,
interior finishing, etc.
The location of the project will also influence
whether a steel building is even an option. Builders in agricultural or lightly
populated areas generally have fewer code restrictions placed on them. The closer
a building is planned to a densely populated area, the more stringent the fire
codes, building permitting requirements and other municipal standards become.
In some cases steel buildings can not be used in certain areas for this reason.
Other times, fire codes may require steel buildings to be built further apart
than tilt-up concrete structures, requiring a larger plot of land for the project.
This is why, in urban areas, buildings closer to the downtown area are generally
made of concrete and steel buildings become more common on the outskirts of town.
reason steel buildings face greater code limitations is that they generally offer
less fire protection than tilt-up or other concrete buildings. While steel is
not combustible, it is not considered fireproof because it can distort or lose
its structural strength when exposed to heat. Further, a fire on one side of a
metal wall can generate destructive heat on the other side, damaging the property
inside. Steel building designers use a variety of technologies, from sprays to
fire-retardant panels or blankets, to mitigate the fire-resistive problem. By
comparison, a typical 6.5" concrete wall has a fire resistive rating of four
hours or more. Tilt-up and concrete provide superior fire protection for the property
and people inside a building.
The intended use for a building will also
influence whether steel or concrete is the best choice. In general steel buildings
work very well for storage buildings, indoor sports facilities, work shops, and
aircraft hangers, but they are less suited for higher-trafficked buildings. Comparatively
speaking, steel walls are less durable than concrete walls. This holds true in
the face of natural forces (bad weather, earthquakes) as well as for truck or
forklift accidents. When a building is damaged by a vehicle, the damage is generally
more localized and less expensive to repair for a tilt-up or concrete building
than for a steel building. For owners who want to build a warehouse or other facility
where trucks or forklifts will be used, this can be a very important consideration.
Defense contractor facilities, prisons, or other buildings that require positive
security also are much better suited to impenetrable concrete than to comparatively
While steel is reasonably durable, concrete remains the
material of choice for buildings that require less upkeep and maintenance over
the years. Concrete is impervious to corrosion, rotting, rust or insect infestation;
tilt-up concrete buildings created in the 1940s are still standing today with
little apparent wear. The fact that builders in earthquake-prone California now
use tilt-up construction for 90% of their single-story commercial projects indicates
that concrete buildings are cost-competitive and extremely durable.
factoring in potential repairs and ongoing maintenance, it's apparent that the
real dollar difference between operating a steel building and a concrete building
can be significant. Further, the added fire safety and durability of a concrete
building will usually be reflected in lower insurance premiums. If the owner decides
to sell the property, they will most likely find that a tilt-up or other concrete
building depreciates less and than a steel building will.
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