Installation: Merits of underlayment + attached pad

underlay
MP Global’s QuietWalk Luxury Vinyl is a premium recycled fiber underlayment built for luxury vinyl planks, luxury vinyl tiles and multi-layer floors such as WPC, SPC and rigid core vinyl planks.

By KJ Quinn—A The common theme for innovation in most industries is “better, faster, cheaper”, and flooring installation is no different. An ongoing debate is how products with pre-attached infill compare in the long run to conventional subfloors installed separately.

“Unfortunately, there isn’t really a specific industry body that sets standards for the vinyl planks, tiles and accessories,” said Deanna Summers, marketing specialist and account manager at MP Global Products, a supplier of flooring underlayments. “That’s why we carry out our own R&D to create products that improve vinyl flooring installation.”

The rapid growth of hard-surface floors, especially rigid core and WPC, has been driven in large part by innovations in performance and visuals. In recent years, many suppliers have added subfloors to the planks for convenience. The thought process was: customers would not have to roll out a separate layer on the subfloor before installation if the planks were already backed. However, some experts say that one subfloor shouldn’t preclude the need for another layer.

“Added backfill could provide moisture control properties and allow installers to consider bypassing the otherwise required steps of subfloor preparation,” said David Jackson, director of technical services, DriTac Flooring Products. “Overall, installation could be made cheaper and less time consuming with a confirmed backing option.”

A major selling point of pre-confirmed padding, proponents say, is that it speeds installation, saving end users time and money. “Often these attached underlayments are made of very lightweight styrene or some other variant that bonds easily and delivers a great story to market,” said Chris Palmer, vice president of sales at Leggett & Platt, supplier of flooring underlayments. “The downside, however, is that the actual underlayment is so light that it may not provide long-lasting support.”

Pros vs. cons

Like any product, there are pluses and minuses associated with pre-confirmed padding. The decision to use one or the other (or both) largely depends on customer requirements or the specific requirements of the job site. “Consumer choice will depend primarily on the specifics of the product,” explains DriTac’s Jackson. “The properties of moisture and noise control will vary from product to product, so the decision must be made on a project-by-project basis.”

Cost and convenience are some of the factors in determining whether a moisture barrier that attaches to the subfloor is preferable to buying it separately.

A concern with some pre-attached underlayments is that they can leave insulation gaps between planks. “A consumer may also get the impression that the adhered underlayment can prevent moisture migration, when in fact the cushion is cut to the same dimensions of the floor, negating that advantage,” noted Palmer of Leggett & Platt. “Noise vibrations also tend to find seams and are a channel for channeling sound, which can also be a problem.”

Moisture protection is a big deal, experts say, especially in a world where many hard-surface floors are marketed as waterproof. The general rule of thumb is that workplaces that have a moisture problem or have a concrete subfloor need a moisture barrier. “The exposed seams of the cushioned planks leave a number of vulnerabilities in the floor when it comes to moisture over time,” said Summers of MP Global. “Having full subfloor coverage of a subfloor will help prevent fumes from being trapped and causing problems such as mold growth and alkalinity migration through the cracks from the planks to the floor surface.”

Certain qualities of high-quality subfloors indeed exceed the possibilities of additional filling. “When trying to achieve a certain noise rating, it’s unlikely that enclosed infill is the best solution compared to a separate layer of subfloor,” DriTac’s Jackson said. “Some hard surface coverings can feel firmer or more uncomfortable underfoot with a thin layer of padding adhered than with the added cushion of an underlayment.”

All this begs the question: which option is better? While both attached pad and separate subfloor can be effective, the tiebreakers are often the cost or which solution produces the desired results.

The upfront cost savings for consumers purchasing floors with pre-applied infill is a key selling point. However, most floors with attached backings have a locking system that can be damaged if the product is installed on an uneven surface. “A rough surface, such as pebbles in concrete, fixing heads or uneven joints in OSB or wood subfloors, may need a thicker, more substantial subfloor to smooth out those imperfections,” explains Summers of MP Global.

On some projects it is mandatory to increase the overall height of the floor – a situation where a separate subfloor could be the most cost effective solution. “While the pad attached to your hard floor covering is very similar to a separate foam or rubber underlayment, the development of high-performance, multi-purpose underlayments has evolved far beyond the attached pads,” DriTac’s Jackson reported.

A path for every need

Daltile’s RevoTile has a pre-attached backing along with a click installation system that aims to speed up installation.

Underlayments are made from a variety of materials, such as foam, foam mixed with rubber, felt, and cork, and the price points and benefits vary. For example, Ecore’s itsTRU technology makes it possible to fuse virtually any floor surface onto the vulcanized rubber (VCR) backing. “its TRU technology enables Ecore to combine the inherited performance of VCRs with an endless array of surface layers, including VCRs, grass, vinyl and carpet,” said Bo Barber, executive vice president of sales and marketing. “Ecore products with itsTRU technology have improved safety, ergonomics and acoustic properties.”

Leggett & Platt’s Palmer added: “The constant testing performed on Whisper Step continues to deliver benefits in sound, support and moisture protection.”

Dal-Tile offers a porcelain tile product that offers the best of both worlds. RevoTile has a “backer” that attaches to the tile and an innovative click installation system that allows the product to be installed 50% faster than some traditional tile floors. “RevoTile can be installed over many existing floors, eliminating the need for demolition and removal,” said Patrick Warren, vice president of residential sales, dealership and showrooms. “There is no grout drying time, no two-part grout, and no return visits.”

A separate, non-fastened moisture barrier underlayment called RapidPrep has a shock-absorbing structure designed to maximize the performance of RevoTile’s locking system. “RapidPrep underlayment also improves underfoot comfort, provides compressive strength and thermal insulation, is compatible with many types of underfloor heating and reduces sound transmission,” said Warren.

Suppliers say that during the qualification process, dealers can gain a much better understanding of their customers’ projects, allowing them to advise on which subfloor option will work best. “We recommend following the manufacturer’s installation and maintenance guidelines to maximize the life of your floor,” explains Ecore’s Barber.

For example, an important consideration for multi-family applications is a strict local code or covenant that requires a minimum acoustic rating for Impact Insulation Class (IIC) or Sound Transmission Class (STC). “Some required score numbers can be difficult to achieve without adding an additional underlayment to the rig assembly,” noted Summers of MP Global.

For many consumers, deciding which subfloor will best support their choice of flooring. “The best way is to determine which product offers the highest level of security in the long run,” DriTac’s Jackson says. “However, as multi-purpose underlayments continue to evolve, the moisture containment, noise reduction and cushioning qualities of the attached filling may struggle to meet the same standard.”

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