Choosing Laminate Flooring - Continued

Voids can also lead to cracked edges. Although "extreme tensile strength" may be listed on product packaging, this refers only to the ability of the mechanical locking edge to resist separation; it does not refer to the material's structural, gap-spanning quality. As with ceramic tile, laminate flooring requires full, uncompromised support from the subfloor. Most subfloor irregularities can be corrected with a feather-edged filling compound.

Standard Wear and Use Ratings
	AC2 (21 Moderate Residential). Suitable for moderate use, such as in a bedroom.
	AC2 (22 General Residential). Suitable for general living spaces.
	AC3 (23 Heavy Residential). Suitable for all residential applications.
	AC3 (31 Moderate Commercial). Suitable for light commercial use.
	AC4 (32 General Commercial). Suitable for general commercial applications, including offices and small shops.
	AC5 (33 Heavy Commercial). Suitable for heavy commercial applications, including department stores and restaurants.
Most laminate flooring products have an AC (abrasion class) rating listed on the packaging. The rating is based on standardized tests that measure impact resistance, stain resistance, burn resistance, the effects of furniture legs or casters, and moisture-induced edge swelling.

Moisture concerns. Because laminate flooring is a wood-based product, it will absorb water. If allowed to stay wet, it can swell or delaminate. Manufacturers address the issue on a number of fronts.

To help stabilize the product under fluctuations in relative humidity, the core is commonly sealed top and bottom with a melamine coating (called "balanced construction" in laminate parlance). Melamine is slippery stuff and therefore reduces friction over the underlayment, allowing the flooring membrane to freely expand and contract with changes in moisture content. Because of this, manufacturers are comfortable extending warranties for most products to bathroom and below-grade installations over concrete, provided they're installed correctly. Says Pergo spokesman Brad Ries: "Most of our installations go into kitchens and baths."

Figure 7.Two years after this floor was installed, obvious heaving appeared in the middle of the room. The problem was a pinhole leak in the hydronic baseboard heat that seeped underneath the floating floor to the lowest point. The flooring shrank after drying, leaving obvious gaps (top). It had to be replaced (bottom).

Part of proper installation is protecting the flooring from water vapor rising from below, especially on installations over concrete slabs (Figure 7). That makes a moisture-barrier membrane a must. The membrane may be as simple and inexpensive as 6-mil poly sheeting, or it may be a costlier foam cushion underlayment with an attached or integral vapor barrier (Figure 8).

Figure 8.Concrete slab installations always require a moisture barrier, typically 6-mil virgin poly sheeting, beneath the foam underlayment. Some manufacturers offer underlayment with an integral moisture barrier. Joints should be sealed with polyethylene tape or integral adhesive strips.

Manufacturers also offer proprietary sheeting for this purpose. If you supply your own vapor barrier, note that low-grade poly sheeting with re-grind (recycled plastic content) won't satisfy warranty requirements; use only virgin 6-mil poly film.

Surface moisture can also cause problems, especially on bathroom and entry-area floors where water may puddle. Joints between glueless planks are impressively tight — tolerances of 1/1,000 inch are normal — and resist water infiltration quite well (Figure 9). Flooring approved for installation in bathrooms and below-grade (basement) floor levels typically features high melamine resin saturation of the HDF core and topical moisture-blocking edge treatments, including paraffin wax and oil (Figure 10). Expect to pay more for materials thus protected, and remember that doing so will always be cheaper than a callback for material failure and a voided warranty.

Figure 9.Mechanical locking joints draw the precisely manufactured edges together so tightly that water can't penetrate.

Once the job is done, you should call your clients' attention to the specific maintenance instructions, which typically discourage wet-mopping, or "submersion cleaning," of all laminate flooring, regardless of its location or special properties. After all, ease of maintenance is one of the major selling points: Sweep or vacuum and damp-mop only. You can distinguish your service, emphasize the point, and say thank you by leaving your customers with a waterless Swiffer mop.

Figure 10.Armstrong is among the few manufacturers that place no usage restrictions on any of their laminate flooring lines for bath and below-grade slab installations (above). In many product lines, the HDF core is impregnated with melamine to make it more moisture-resistant. BHK distinguishes its moisture-resistant core with a green dye, shown here next to an untreated sample (right). The resulting material provides good resistance to wicking and swelling. This type of flooring should be used in kitchens and bathrooms, over concrete slabs, and for all below-grade applications.

Ask Around

Like a scuba diver heading into unknown waters, your safest bet with laminate flooring is to talk to someone who's been there and knows the terrain. Experienced installers will have worthwhile installation tips and cautions that might never occur to a salesperson.

You should also make sure the manufacturer offers good technical support. Robert Gaston, a sales and installation technician in Harwich, Mass., notes, "If I find that manufacturer support isn't readily available, I throw away the samples and avoid the product. It's not worth the hassle dealing with potential issues without good follow-up in the field."

Local flooring dealers should be ready to talk about their favorite lines, what sells, who's buying, and why. Name-brand recognition also tends to be significant, as the older, established companies have been around the block and resolved early quality issues. Newbie producers and importers tend to offer lower prices, but they're also more likely to compromise on quality.

Dave Holbrookis a JLC associate editor.