A roof test cut is a useful and simple diagnostic tool for your flat roof system. A roof test cut uses a tool called a core cutter to extract a sample of a building’s existing flat roof system.

It is difficult and often impossible to determine the composition of a roof system by visual inspection alone – that is – without penetrating the membrane. A test cut sample provides a sample of these materials and how they are installed.

The sample from a test cut allows us to examine the moisture content of the flat roof system- particularly that of the underlying insulation. The moisture content of a flat roof system is a critical indicator of its remaining expected lifetime. The moisture content of the flat roof system’s insulation is a critical indicator of the entire system’s thermal efficiency. As insulation holds more water, it loses its ability to insulate. Water underneath the membrane is a contributing factor to the deterioration of the structural deck holding up the roof.

The presence of water, certain materials, or any combination of the two may lead to deterioration of the deck surface. For example – phenolic insulation – once a popular insulation used in flat roof construction was later found to compromise the integrity of structural steel components when exposed to water. Knowing the condition of the top-side of structural decking is useful information for stakeholders.

A prudent roof estimator always performs a roof test cut prior to beginning any roof replacement or retrofit project. A roof test cut will allow for accurate costing prior to beginning a project- mitigating the chance of unforeseen conditions resulting in “contract extras”. A flat roof retrofit project must always include the detection and removal of “wet” sections of existing flat roof prior to installing the new flat roof system over-top – failure to do so compromises the expected lifetime of the retrofit flat roof.

If the roof system beneath the flat roof membrane is water-logged – it may result in an internal roof leak. An internal roof leak happens when water leaks from the roof system even though it is not raining. This is a frustrating experience for the building owner, tenant, and roofer. A sample from a roof test cut can help determine if a building is experiencing an internal roof leak.

A roof test cut is invasive – it involves breaking the seal of your water-tight flat roof membrane. Alternative, non-invasive, flat roof assessment and inspection tools and methods exist today that often provide the same or similar information as that of a roof test cut. When these options exist- it is best to opt for them instead.