Sponsored by Fuse Commercial Flooring Alliance
Regardless of the type of floor covering in question—be it carpet, laminate,
rubber, tile, vinyl, or wood—nearly every product is affected in one way or
another by the presence of excess water vapor emissions from concrete
and accompanying pH issues. We’ve all seen the dreadful results of flooring
products that have failed due to moisture, as the telltale signs are obvious:
debonded sheet flooring, bubbles, blisters, adhesive degradation or oozing,
cupping, dents or indentations, gaps between tiles, mold growth ... you
name it. If left untreated, the implications to the building and its occupants
can be significant, including the entire floor lifting off of the slab or a host of
health and safety problems that result from the presence of mold and mildew.
Moisture can be introduced to the flooring surface from a leak in the plumbing
or a natural disaster, for example, which requires professional repair and reme-
diation to the infrastructure of the building. But for the purposes of this article,
we will focus specifically on the somewhat less obvious source of moisture: the
natural water vapor present in the concrete slab. The reason for the emphasis
on moisture in concrete is because of a simple, but critical, fact: all concrete
contains moisture, which is not static in nature. On the contrary, water vapor
present in concrete slabs—both new and
existing—will interact with flooring materials
and the environment, and can have a detri-
mental effect like those scenarios described
above if not taken into consideration when
planning and installing the floor.
As stated previously, the industry-
wide financial implications associated
with moisture-related flooring failure are
astronomical. Beyond the obvious price of
purchasing new materials and labor, there
are a number of other factors to consider
when calculating the true cost of replacing a flooring system due to excess
moisture. For example, once moisture-related problems surface, locating the
source of moisture may require the service of a construction professional and/
or a health inspector to determine the extent of the damage to the space.
Permits or other fees may also be involved depending on local regulations.
More importantly, consider the fact that water damage may not be limited
to the floor itself, but may also have compromised other vital building materials
such as studs, floor support beams, and sheetrock. Regardless of the scope
of the damage, site remediation, replacement materials, and labor also need
to be factored into the equation.
Additionally, environmental issues and health hazards may result from the
presence of moisture, which must be addressed before repair and remediation
take place. Mold and mildew have been linked to a number of respiratory
and other health-related issues in occupants who have been exposed to
them, and HVAC systems that have been operating in the area where mold
and mildew have been found will need to be inspected and possibly cleaned
by specialized contractors.
Finally, if moisture-related flooring problems take place in a space that
is occupied, the costs and complexity of the remediation are compounded.
Operations may have to be temporarily suspended or relocated, while
furniture and fixtures may need to be replaced depending upon the extent
of the damage.
Clearly, given the potential failures and costs associated, it is in the best
interest of design and construction professionals to take proper steps to
ensure that the investment in new or upgraded floors is protected. In the
following sections, we’ll explain how.
There are two areas of concern when identifying and preventing moisture-related flooring issues in construction. Depending upon whether it’s new
construction or a renovation project, building professionals need to understand
the underlying issues inherent in both scenarios when it comes to the presence of
moisture in concrete slabs. We’ll address new construction first, including what to
look for and what steps to take when confronted with excess moisture, and then
repeat the process for existing slabs and trenches.
1. NEW CONSTRUCTION SLAB
With any new building project, deadlines and delays mean time is at a
premium, and construction schedules rarely contain sufficient time to facilitate
thorough drying of concrete. This can become a major issue on the floor
surface, as contractors or project managers may push to get product
installed before the concrete has had ample time to eliminate excess moisture
that contributes to failures.
Under optimal conditions, new construction slabs require one month per
inch of drying time for normal weight or hard-rock concrete before installation
of flooring products. The ideal water-to-cement ratio should be between . 45
and .50 under ambient conditions (a minimum temperature of 70° F with a
maximum relative humidity of 50 percent, and constant air movement at 15
m.p.h.). For concrete batched with lightweight aggregate, on the other hand,
the drying time is two months. Lightweight aggregate concrete requires twice
as much time to dry as normal weight concrete of the same thickness due to
the pre-saturation of lightweight aggregates.
One of the reasons design and construction professionals run into moisture
issues with concrete is because they often mistake the curing process with
drying. “Curing” is the chemical reaction that creates the agglomerate better
known as concrete, while “drying” is the loss of water not needed to hydrate
the cement. Curing compounds, commonly used today as an alternative to
keeping the concrete surface physically wet during the initial curing period,
will substantially lengthen the drying period.
According to the Portland Cement Association (PCA), slabs on ground
such as pavement, sidewalks, parking logs, driveways, floors, etc.; and
structural concrete used for bridge decks, piers, columns, beams, slabs,
cast-in-place walls, retaining walls, etc., require a minimum curing period
of seven days for ambient temperatures above 40° F. Alternatively, the
American Concrete Institute (ACI) Committee 301 recommends a minimum
curing period corresponding to concrete attaining 70 percent of the specified
compression strength, which commonly matches the typical seven-day
curing time specified by the PCA. Further, the PCA notes that the 70 percent
strength level can be achieved faster when concrete cures at higher temperatures
(and inversely at longer intervals when curing during lower temperatures)
or when certain cement/admixture combinations are used.
To earn CEU credit, read the rest of the article, and take
an exam, visit interiorsandsources.com/home/CEUs
concrete is the
expensive flooring-related problem,
costing $2.4 billion in