Commercial Job Site Inspections: Where to Check for Potential Flooring Problems
His awareness can help eliminate problems — both before and after the fact — and help determine the cause, or a potential cause, of a flooring failure. I urge you to review the following nine items and consider the bullet points listed with each as food for thought in evaluating job-related problems for possible causes and effects.
Site locationDepth of the water table. Is the water table close enough to the surface to make capillary rise of moisture a concern?
Review a copy of the soils report. Is the soil fine enough to present a capillary rise concern?
Is the site located on an alluvial plain? Essentially, an “alluvial plain” is a valley filled with sand and silts that were deposited by water runoff from higher elevations.
Is the site a hillside lot? A cut into a hillside can present water runoff conditions and exposure of underwater springs that can negatively impact the concrete slab.
Has the site undergone a land-use change? Changes from a low-density to high-density use can impact the runoff of water.
How is the drainage of the area around the site? Is there a swale in landscaping that impedes the flow of water away from the structure?
Beneath the concrete slabIs there a capillary break beneath the concrete slab? A capillary break will serve as a barrier to capillary action from the soil, but it will not serve as a barrier to moisture vapor migration.
Is there a vapor barrier beneath the slab? A vapor barrier should be used not to impede moisture vapor, as well as any radon and methane vapors that might otherwise migrate up through the concrete.
What type of vapor barrier is in place? The type of material used for a vapor barrier is extremely important determinant of the membrane’s effectiveness. A 6-mil Visquene membrane is not a suitable vapor barrier because it can decompose quickly or be easily compromised during the placement of the slab.Barrier thickness. The thickness of the vapor barrier greatly determines its durability and permeability. A good vapor barrier will be 10 times less permeable than Visquene.
Is there a blotter layer on the vapor barrier? A blotter layer will diffuse any moisture that makes its way through a compromised vapor barrier. What type of blotter layer is in place — sand or granular fill? The finer the fill used, the faster the moisture will move throughout the blotter layer. Was the blotter layer wet or dry at time of concrete pour? The water/cement ratio of the concrete mix will be affected by the presence of moisture in the blotter layer. The greater the moisture within a blotter layer, the more the water/cement ratio of the slab will be skewed.
Concrete mix designConcrete sack mix. Have too many sacks of Portland cement been used?
Was a fly ash used to offset the amount of Portland cement in the mix? A type “F” fly ash can be used to control the amount of Portland cement in the mix and to increase the compressive strength of the concrete.
What is the water/cement ratio of the concrete? A lower water/cement ratio proportionately increases the compressive strength of the slab, and decreases its porosity and permeability as well.
Were additives used in the concrete mix? Some admixtures used in concrete mixes impact both bonding and porosity characteristics of the slab’s surface which, in turn, makes adhesive selection vitally important.
What were the results of the concrete slump test? Was the slump at the time of the concrete pour too high for a slab that will receive a resilient floor covering? A slump greater than 4 inches is considered too high.
Concrete slab placementWhen was the slab placed? The time of year during which the concrete was poured greatly influences how thoroughly and quickly the slab dries. A winter-season pour takes twice as long to dry as a summertime pour.
What were the prevailing weather conditions during the time of the pour? Was the pour of the concrete affected by the weather? Rain can create changes in the water/cement ratio of the concrete mix and dry, windy conditions can impact curing of the slab.
How was the concrete finished? The finish of the concrete plays an important role in the bonding of adhesives to the slab surface. The texture of the concrete should be about the same as 80-grit sandpaper, especially when epoxy adhesives will be used.
How are the control joints spaced? Spacing of control joints should be 2 feet apart for every 1 inch in slab thickness for a ¾-minus aggregate, and 2½ feet for ¾-plus aggregate. The control joint is placed in the concrete about 1 inch deep to control slab cracking.
How are the cold joints spaced? Cold joints, also known as “expansion joints,” are of constant concern to the flooring industry. Resilient floor manufacturers recommend that the joints be “honored” (able to expand and contract with temperature change) or have expansion joint covers placed over them.
Are there signs of concrete cracking? If there is cracking of the concrete, a determination must be made to as to its cause. Cracking can occur from drying the concrete too quickly, exposure to excessive bleed water or control joints that have been spaced too far apart.
How was the concrete cured? There are two types of concrete curing: wet and chemical. While the trend is turning back to wet curing, the time required for for this type of curing is sometimes compromised due to the demands of fast-track construction. The time required for complete wet curing is determined by the water/cement ratio. Chemical curing is designed to hold moisture in the slab while the concrete cures. If a curing compound has been applied too heavily, the compound will not decompose in a timely fashion and the drying time of the slab is extended.
The closure of buildingWhen was the structure closed up? The sooner the concrete slab is covered, the sooner the effective drying will get underway.
Was any type of heat source used prior to the installation of the HVAC system? If so, was the heat of the wet or dry variety? Burning propane and heating oils produces a wet heat that retards the drying of a slab.
When was the HVAC system activated? Activation of the HVAC system ensures the stabilization of the concrete slab, and creates an accelerated drying condition and the drying of interior finishes that can affect the flooring installation.
Sprinkler systems. Was the sprinkler system installed too close to the structure or are the sprinkler heads spraying the foundation?
Vegetation. Was vegetation planted too close to the structure? Landscape plants should be kept a minimum of 4 feet from a foundation to prevent moisture diffusion from entering the structure.
Who is responsible for moisture and alkalinity testing?Vapor-emissions testing. Many people think that moisture testing should be performed by a qualified, independent testing agency — and I agree. Both the general contractor and the flooring contractor have vested interests in the test results. Moisture test results should document both the high and low readings. Do not average the results! Areas that exceed manufacturer recommendations for allowable moisture vapor emissions need more time to dry.
Results of pH testing. Slab alkalinity plays a huge role into the success or failure of the installation. The best time to complete an alkalinity test is at the finish of the vapor emissions test.
Start of the floor installationTemperature in the installation area. The HVAC system should be on and the temperature stabilized at least 48 hours prior to the installation. Failure to observe this requirement will impact the stabilization of the concrete, material handling procedures and adhesive open time.
Humidity. Humidity levels also impact the materials, adhesives and drying rates of patching materials.
Lighting. Flooring installers must be able to see what they are doing. Poor lighting hinders the installer’s ability to see imperfections that will show through the finished floor.
Floor traffic. Will the foot traffic of other trades impact the final appearance of the finished floor? Many construction trades leave a trail of damage across a completed floor. Ladders, pallet jacks and heavy rolling loads can destroy a newly installed floor.
Maintenance proceduresHow soon after installation was a floor-maintenance program started? Floor manufacturers recommend that floor maintenance not begin for at least five days after the installation. This interval allows the adhesives to cure to a point where maintenance will not affect them.
Was the floor stripped? Manufacturers do not recommend that their materials be stripped. Strippers are highly alkaline and can have a negative impact on adhesives.
Was the floor sealed? New floors should be cleaned and sealed prior to application of polish. The sealer provides a base over which the polish should be applied.
How many coats of floor polish should be applied? Manufacturers recommend an application of three to five thin coats of floor polish.
Relatively few flooring contractors, and even fewer general contractors, are adequately aware of construction practices that can impact the floor covering installation. Knowledge of these practices is invaluable, especially when problems arise.