Let's Talk About Substrate Inspections

For those unfamiliar with the term, a roof substrate is the base of the roof system. When the term "substrate inspection" is used, it means that an analysis of the roofing system must be taken. One of the easiest and simplest ways of doing this is with a core tool or "core cutter". There is more than one reason to do this. Firstly, you can learn the thickness of the insulation board if you are doing a singly ply installation. Secondly, you can learn what type of roof decking material is installed in the event you cannot see from below. In the world of roof "restorations", we do this for all those reasons AND to determine the moisture content or water saturation levels.

Now let's talk about what all liquid applied products do; they intend to repel water. Whether the product is acrylic, silicone, polyurethane, or asphalt-based, they work by bonding to the exposed roof surface and repel water from getting through. That sounds easy enough, but that is where 99% of mistakes in these systems originate. While these products may all work well in the correct environment for REPELLING water, the substrate underneath is far too often an afterthought.

What can happen with incorrect installation, weather or man-made damage, long-term roof leaks, or age is water saturation in the insulation or substrate. Depending on the type of roof system and extent of this problem, the solutions range in size, scope, and price. There are several issues that can arise from leaving the substrate in that type of state. For example, you may have an asphalt roof system like in the photo above, which is likely to have some form of insulation board like poly iso. When leaks are allowed to persist for a period of time, that insulation board soaks up the moisture and stays saturated. If you were to coat directly over the surface of the cap sheet, even with cleaning and a primer, that moisture is now trapped in the substrate below. Where does that moisture now go? It is likely to want to evaporate thus causing a blow-out of your new coating system. Worse, it could remain trapped, slowly seeping down with gravity to eventually rust your metal deck or rot your wooden one. Not only can this happen, it happens WAY to often. The latter tends to happen particularly with the restoration of a single ply roof system. Since leak entry points are easier to seal, the water is forced to move downward. On smooth built up, cap sheet, or other modified roofs, the tendency for failed adhesion or blow-out is higher. This will cause catastrophic failure down the road for the entire system. This not only is a huge financial liability, it's a legal one as well.

How to prevent all of this? Core samples, moisture scans, thermal, and a couple other options all exist that help to show problematic areas to be concerned about. Core samples however do not lie, and if there is moisture, you already know what needs to be replaced before a restoration can commence. Most manufacturers say that if less than 15-20% of the entire roof has saturation, it is still a cost effective solution to restore and not tear-off. However this does mean you must do your due diligence on the substrate inspection to guarantee that all moisture has been removed. Replacement of roof field drains, and surrounding insulation in ponding areas is always a possibility when restoring a flat or low-slope roof system. It may seem like a lot of work when the customer just "wants a coating", but this is what separates the true restoration from "just a coating".

You'll be both protecting yourself and your customer.