A bumpy ride

Chris Maskell, NFCA c.e.o.

The sub-floor rollercoaster

Sub-floor preparation, and, in particular, leveling work, has always been a source of contention between the flooring contractor and construction manager. The issue of who will perform the work and who will pay for it bears down during late-stage construction when flooring comes onto the scheduling radar.

At that point, there is little time or budget left to do the work right. “Patch and grind as necessary” is an all-too-often- used phrase in the specifications. Ambiguity like this, when thousands of dollars are at stake, sets the stage for conflict.

Unless there are clear, consistent instructions that allocate work responsibilities where they belong, bids won’t carry the dollars, slab rejection will continue, and good companies will end up in court, accused of default while they try to avoid taking on thousands of dollars of leveling work that are not supposed to be in their scope of work. Saying no to your customer while trying to build a relationship is an impossible situation to be in. Even when the right parties have carried the price, games can be played: “Get it done and we’ll figure it out later….” Invoices for extra work end up not being paid or only partially paid. This is the result of a sub-floor preparation specification that leaves work responsibility open to interpretation.

One solution is NFCA’s Hydraulic Cementitious Underlayment specification guide (updated in 2018). It spells out the process in three parts: General, Product and Execution. This guide needs to make its way into the hands of every design authority in the country. The guide places the responsibility for this work where it belongs — with the general contractor/construction manager/ building owner, not the floor covering contractor. With this done, leveling and subfloor preparation in general can be better understood, agreed to in advance and included in the budget.

Specs drive pricing, guide processes and form contracts, and contracts are legally binding.

The “other” issue

The Floor Flatness/Floor Level (FF/FL) measurement system used by Division 3 Concrete should not be used to determine flatness for the flooring contractor. Flooring contractors use a 10-foot straight-edge or laser to determine if a sub-floor surface meets flooring standards. For most flooring categories, 3/16 inch over 10 feet (slab on grade) is a general industry standard and 1/8 inch over 10 feet for suspended slabs. Meanwhile, Division 3 uses the FF/FL system per ASTM F1155.

Once Division 3 Concrete has delivered (poured) its product, the FF/FL measurement system is used to determine flatness according to ASTM 1155. This is done 72 hours after pour. If measurements meet the tolerance for flatness (and level) then the Division 3 Concrete is considered to have met its responsibility. Fast-forward six months, and the flooring contractor will not necessarily have the flat surface needed to proceed with installation. We know this because concrete slabs curl, creep, deflect (sag) and in general change shape as they strengthen and dry. In addition, the FF/FL measurement system stops recording two feet from walls, construction joints and support columns, and therefore does not determine flatness or slab acceptability from the perspective of the flooring contractor.

What’s the solution?

First, conversation around how must take place at the very beginning, before contracts are awarded. Structural engineers, consultants and owners need to understand the floor covering contractor’s requirements – anticipate slab deflection, plan concrete surface profile, and budgets for corrective work.

Second, we need an understanding of the specifications available and how they work.

Finally, more education around proper priming, mixing and application practices for hydraulic cement underlayment is necessary. NFCA holds leveling training seminars across Canada for all construction parties. For information on all education events, go to www.nfca.ca and click on the education tab.

It’s an exciting time. As we connect to more and more people across the country and develop partnerships with active, likeminded organizations such as Interior Designers of Canada (IDC) and Flooring Consultants and Inspector Training Services (FCITS), momentum is building and the awareness and understanding of the tools available to bring about change is growing.

The National Floor Covering Association (NFCA) promotes industry standards for resilient, carpet, hardwood, laminate, cork and bamboo floor covering installations. www.nfca.ca

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