CALGARYCHAPTER

The American Concrete Institute recognizes that there are different tolerances associated with Division 03 and Division 09 floor flatness requirements. Concrete Finishers are held to a quantitative (measured and repeatable) requirement and Floor Covering Installers are held to a qualitative (visual assessment and non repeatable). A scientific calculation using highly accurate measuring equipment versus an informal assessment using age old methods, and this is causing misunderstandings and divisiveness on the project site, and a battle between separate components of the specification that the Owner does not need, nor do they want to pay to resolve.

ACI 117.1R, A Guide for Tolerance Compatibility in Concrete Construction makes a clear distinction between differential tolerances and identifies that the design professional is responsible to identify when tolerances between different trades occurs and describe requirements to bring compatibility into the project documentation.

The National Floor Covering Association (NFCA), Concrete Finishing Contractors Association of Canada (CFCA), Concrete Canada (CC) and Canadian Standards Association (CSA) A23.1 Subcommittee 6, Annex - Suspended Slabs, with additional input from the American Society of Concrete Contractors (ASCC) have identified the factors that often lead to concrete substrate tolerances being declared non compliant when floor coverings are being installed, despite acceptable tolerances when concrete was placed and finished.

There are ways to describe solutions recommended in MasterFormat, using Division 01 to describe work results that cross different parts of the work described in the Project Manual. The last thing that most contractors want from a specifier - is another specification section that 'tells-them how to do their work' - that the content uses too many words or is too long.. and fails to understand that the specification describes 'what is required' not 'how to build' the constructed element. The specifier is wise to inform the contractor that the specification is used to augment the standards referenced in the specifications when detailed content or choices are incomplete or insufficient within the reference standards contained in the work result descriptions.

Cost effective solutions are available, correcting misconceptions is critical and bridging the information gap is as critical to solving the physical gap when it comes to the differential tolerances between the concrete finishing trades and the floor covering trades. Juggling the risk and aligning expectations to the entities best able to manage the risk components of the work.