Rejecting the slab - a bumpy ride for all involved

There is an ongoing disconnect in the construction process that leads good companies into unnecessary conflict regarding sub-floor flatness. This is the Number One reason a flooring contractor will walk off the job late in the construction process when the deadline is looming. Disaster!

NFCA floor installation standards state that it is within the general contractors’ scope of work to provide the floor covering contractor with a flat sub-floor that meets the flooring product manufacturer’s requirements - typically 3/16” over 10’ (straight-edge test method). Yet all too often, the general contractor (GC) will be unable or unwilling to pay for the extra patching and grinding required to meet this standard.

For the floor covering contractor faced with this problem, it’s very difficult to do the right thing and say ‘no’ to the GC who says ‘just get it done’. For the flooring contractor, the GC is the customer, controls payment and is the only line of communication to the construction team.

Thousands of dollars of pre-bought flooring product may be sitting in the flooring contractor’s warehouse awaiting installation. The need to get flooring installed so that invoices can be issued and bills paid can be motivation enough to just give in, dispense with quality and agree to install against better judgement. It’s unfortunate that trying to put quality ahead of the deadline can lose you a customer, delay your payments or worse...get you accused of default of contract and land you in court fighting a battle that should never have been allowed to develop.

On the other end of the equation is the concrete trade (Division 3), where a similar problem of battling for payment can exist. Their responsibility to provide a flat slab ends 3 days after pour, provided their work meets specification. Division 3 contractors are often caught in a loop of having to circle back to work on previously poured slabs that did meet spec, but have since changed shape (curled) because that’s what concrete does as it dries. Worse, they can find themselves back-charged months later by the GC, for extra leveling work done by ‘others’ to meet the flooring manufacturers required 3/16” over 10’ straight edge standard.

Again, tough to argue with your customer when thousands of dollars are waiting to be collected.

On top of this, the system of measurement to determine sub-floor flatness and levelness, FF (Floor Flatness) / FL (Floor Level) used by the concrete contractor, does not line up or correlate in a working way with the system of measurement used by the flooring contractor (the 10’ straight edge method). For example, Division 3’s FF/FL measurements stop 2’ from walls and columns, and don't pass through doorways or cross construction joints. This is why Division 3’s finished and accepted work is rarely meeting the needs of the flooring contractor months later when the floor installation work begins.

For the sub-trades, the problem is obvious and painful. For the building owner, it means any money set aside to do the right thing, such as pay for Hydraulic Cementitious Underlayment, is at risk of ending up in the wrong hands. This ensures quality will suffer because short-changed trades will take short cuts to make up for unfair losses. Not good value for a building owner expecting quality.

Clarity is needed and the answer lies within the specifications. In particular, ‘Section 03-54-16’ (Hydraulic Cement Underlayment). This section should be positioned in the construction schedule so that it can be used to flatten new concrete sub-floors months after pour, when the concrete has dried and changed shape, and yet in a timely manner before the floor covering installation is scheduled.

Seven considerations that will change the outcome

Below are seven considerations to address this long-standing problem. There are many scenarios, and not all are a fit for an immediate solution - but this is where conversation on this topic early on in the process gets everyone understanding and on board. This is where a difference can be made.

1.    Acknowledge the disconnect between the FF/FL measurement and straight-edge measurement systems.

2.    Lower Division 3 costs by lowering the ‘Flatness’ specification. Finish ?” below floor finish level.

3.    Lower Division 3 costs by specifying a rough Concrete Surface Profile (CSP).

4.    Lower Division 3 costs by avoiding ‘Steel Power Troweling’ to a super smooth surface. This in turn will remove the need for an added Shot Blasting process, required to achieve a CSP of 1 or 2 which is needed for flooring.

5.    Include a cash allowance for Section 03-54-16 so it can be planned for and anticipated by the trades effected. This will ensure floor flatness standards can be easily met.

6.   Re-position this work to be done months after pour, after the concrete has dried, shrunk and changed shape - and weeks before the floor covering installation starts.

7.    Remove the confusion and specify NFCA flatness standards, which are outlined in the NFCA Floor Covering Reference Manual. These standards are generic and clearly assign responsibility for providing a flat sub-floor surface to the General Contractor.

8.    Specify the Quality Assurance Program and have a third-party floor inspector represent the specification on site and report on the proceedings to the entire construction team.

I recently attended a construction project where the above procedure had been planned and was being worked on as I walked the site. I talked with some of the trades involved who reported incredible results, a system that benefited everyone, sped the work up and left a better product behind for the next trade.

With this done, disputes on site, delays, court battles, strained customer relations and incidences of contractors rejecting the slab at the eleventh hour will be reduced.