Floor levelness or flatness impacts a resilient floor installation in several ways including the runoff of modular tile which can give the impression of a tile sizing issue. A floor that is not completely level can also create inconsistency in laying tile where some gaps are left purposely in an attempt to keep tile on line. These gaps can fill with water and debris during maintenance and possibly leach under the tile where it can eventually affect the tile bond to the substrate. Additionally, over time these gaps will fill with dirt which can give the false appearance that the tile is shifting or the incorrect impression of tile shrinkage.
An uneven floor can also impact cold and heat welded sheet vinyl seams in a number of ways. With cold welding, an unlevel floor can cause difficulty in double cutting or underscribing seams and the seam sealer can pool in some places along the seam. Once adhered to the substrate, gaps between sheets can be affected in ways similar to those found in tile. The effect on heat welding can cause difficulty in underscribing seams and can also affect the grooving of the seam leading to variations of groove depth. This can compromise the strength and appearance of the seam when it is actually welded. Underscribing and grooving irregularities will affect the final skiving operation and finished seam appearance.
Long term affects also involve maintenance and even the appearance of tile and sheet flooring. Almost all commercial resilient flooring in North America is maintained using rotary machines equipped with flat pads. These pads have a limited ability to follow subfloor contours. Consequently during floor maintenance, high points of the floor are subjected to increased friction from the pads. Friction in a sense is what cleans the floor, literally by abrading unwanted surface contamination from the floor's surface. Prolonged friction after the dirt is removed will abrade the resilient flooring surface. This type of wear is greatly increased when attempting to clean a "low spot" on the floor by tilting the scrubbing / buffing machine on edge to work the pad into what the concrete industry calls a "birdbath."
Some resilient flooring makers offer specially engineered commercial "no-wax" floors that are maintained by cleaning and dry buffing. "No-wax" floors also offer their best performance when the substrate is level and smooth. Undulating floors will vary in light reflectance and gloss level achieved by buffing. This can make for an unacceptable aesthetic appearance. High spots also will wear more quickly as just explained.
The high points of the substrate concentrated the normal friction of the cleaning and buffing process. Damage to the floor is accelerated when the cleaning crews became more aggressive with their buffing techniques and types of pads used.
It is another case where the surface flatness or levelness hurt the finished aesthetic appearance of a resilient floor. Surface undulations also will affect the lay-up of modular flooring products, such as resilient tile.
Installation of resilient tile products over an excessively wavy or undulating concrete slab will unduly burden the installer. They will be compelled to employ cut-backs and other procedures that will slow and complicate the process.
To help minimize this situation, concrete substrates should be manufactured in accordance with the American Concrete Institute's ACI 302.1 R-96 Guide for Concrete Floor and Slab Construction. Minimum F-number requirements for application of thin-set flooring should be specified.