The term “Heel Proof” is used quite often when selecting trench drain grates. This term generally refers to the attempt to keep the heel of a woman’s shoe out of the trench grate opening. While there are few building codes that require this type of opening it has become a very popular type of trench drain grate opening.
The heel proof grate originated from the ASME A112.6.3 standard. In section 7.12 the standard states “A grate designed to resist entry of high-heeled shoes, in which the maximum grate hole size in least dimension shall be 5/16″. (8mm).”
Dura Trench offers heel proof grates in a wide variety of sizes for any application. We do want to mention that this grate standard was created by ASME for “floor & trench drains” and was a specification targeted to drains inside the building envelope. When using a heel proof trench grate inside the building it will often perform quite well. The same heel proof grate outside the building will plug and blind quite easily. A heel proof grate will catch leaves, pine needles, seed pods, grass clippings, cigarette buts, small stones, and almost all other debris. In some cases these heel proof grate openings are seen as an advantage because they screen the debris and keep it on the surface. Unfortunately, they often plug and do not get properly maintained. This can lead to flooding and poor performance of a trench drain with a heel proof grate. When this happens, the heel guard feature can cause flooding and serious safety concerns to moving vehicles. Please consider the true need for this type of grating before demanding a heel guard grate. In many cases an ADA compliant grate is all that is required. These grates resist plugging and blinding about 75% better than a heel proof grate.
Assuming the design truly requires a heel proof grate it is best to discuss this with the owner and put the heel guard grates on a maintenance schedule. The maintenance of a heel proof grate obviously varies with debris loading and required open area for the application. In some cases it is better to oversize the trench grate and plan on a clogging factor of 50-75% when doing your inflow calculations.