One funny thing about waterproofing on roofs is that it is not noticed if it works well. But if it fails, the result will be exposed. A substrate is vital to the functioning of waterproofing systems. A waterproofing deck or substrate is like the foundation of a building. The substrate should be stable and firm. The waterproofing system lasts long, just as the structure in which it is laid on. It cannot be replaced even in two decades, unlike a roofing system. So the substrate needs to fit well and be conducive to the supposed service life of the membrane it is installed on.
Here are briefly answered questions of the need for evaluating roof decks for waterproof application.
How can contractors evaluate a concrete deck before applying a waterproof system?
Roofing experts should evaluate the structural properties of a deck. In the case of new buildings, the deck needs to be sound, dry, and have the right surface profile for the chosen waterproofing system. The moisture properties of a substrate are an essential consideration, and this is affected by several factors. The type of concrete, whether normal or lightweight and its initial drying, are some of the elements. For old buildings, the deck needs to be evaluated for structural issues by a certified professional. Repairs should be done where necessary.
Are there different methods of evaluation for new and old decks?
Absolutely! Evaluating old decks can be more challenging. This is because their real conditions remain unidentifiable until the existing roofing assembly is taken off. Predesign and pre-construction planning, such as test cuts and probes, are essential to reducing unwanted surprises for homeowners. Furthermore, being updated with the kind of roof deck and chosen waterproofing system can guide an expert roofing contractor to predict or anticipate the challenges that may come up.
How can the right waterproofing system be selected for a particular deck condition?
Several factors dictate the considerations for waterproofing membrane component selection. Therefore, every deck condition has its specific solution. A waterproofing membrane is preferred over normal weight concrete. This gives a stable deck and helps to prevent leaks at any time. Notwithstanding, if a wet deck is considered, then the best choice is a loose laid-membrane with relief ports and containment grids. A loose-laid membrane is also recommended if a future cracking or excessive deflection is noticed or anticipated, instead of an adhered membrane that won’t accommodate the thermal movement.
How can a roofing contractor determine the moisture content of a deck?
There are different methods of tests that can be used to determine the moisture content of a deck. Examples are:
1. Turning of hot bitumen on the deck to check if it stays adhered to the deck or froths
2. Drilling small probe holes into concrete decks
3. Taping plastic sheets to the deck to test for condensation
4. Measuring relative humidity
Aside from the bitumen test, no set guidelines or consensus offer roofers a benchmark to determine what the acceptable moisture component threshold is before installing a waterproofing membrane.