When a Coating Is the Right Call
Restoration coatings work on roofs that are weathered but sound. If the membrane is intact, the insulation below is dry, and the details are in reasonable condition, a coating seals the surface, reflects heat, and buys years of additional service for a fraction of what a tear-off costs. That is a real option and it is underused on commercial buildings in Dallas-Fort Worth.
What decides it is what we find in the cores. We cut test samples in several locations and look at the insulation. Dry board across the roof means a coating is worth quoting. Saturated board over a meaningful portion of the area means a coating would seal moisture into the assembly, and we will recommend against it even though it is the more expensive conversation. That is the honest way to handle it, and it is the same standard we apply to any commercial roof we are asked to restore.
Silicone and Acrylic Coating Systems
Silicone is the choice where water ponds. It cures into a membrane that tolerates standing water without breaking down, which matters on low-slope roofs with marginal drainage or on buildings where the deck has deflected over time. It costs more per square foot and it holds up in conditions that would degrade other chemistries.
Acrylic costs less and performs well on roofs that drain the way they were designed to. It is a water-based system, so application depends on the weather window, and it needs a roof surface that sheds rather than holds. On the right roof it is the better value, and on a ponding roof it is a short-term fix at best.
Both systems need the same preparation: the roof gets cleaned, seams and penetrations get reinforced, and any failed detail gets repaired before coating goes on. Skipping that step is how coating jobs get their bad reputation.
Silicone vs. Acrylic at a Glance
| Feature |
Silicone |
Acrylic |
| Best fit |
Low-slope roofs where water ponds, including roofs with marginal drainage or a deck that has deflected over time |
Roofs that drain the way they were designed to |
| Standing water |
Cures into a membrane that tolerates ponding water without breaking down |
Does not hold up to ponding. On a roof that holds water it is a short-term fix at best |
| Cost |
Costs more per square foot |
Costs less, and on the right roof it is the better value |
| Application |
High solids content builds a thick membrane in a single coat |
Water-based, so the work depends on the weather window |
| Watch for |
Collects dirt over time and is slippery when wet. Very little will bond to it later except more silicone |
Poor chemical resistance, limited ability to bridge cracks, and not built for heavy foot traffic |
What a Coating Will Not Fix
A coating will not dry out wet insulation, will not bridge a structural problem, and will not rescue a membrane that has weathered past the point of adhesion. It also will not correct drainage. If the roof ponds because it was built without enough slope, a coating tolerant of standing water manages the symptom while the underlying condition stays exactly where it was.
Coatings are also distinct from building envelope waterproofing. A roof coating addresses the roof surface. Water entering at a wall joint, a parapet, or below grade is a different scope with different materials. When the source of a leak is not obvious, we diagnose before we specify, because coating a roof that was never the problem is an expensive way to learn nothing.
Waterproof Coatings for Decks and Walls
Waterproof coatings also go on decks and walls, where the job is different from a roof. On balconies, walkways, plaza areas and parking decks, a traffic-bearing deck coating is the waterproofing, built as a base membrane with a wear coat on top. Pedestrian systems use a thinner urethane build with a fine aggregate for slip resistance, while vehicular systems use a heavier build and coarser aggregate to take tire loads. The wear coat typically needs renewing every five to ten years, and the base membrane underneath lasts considerably longer, which is the point of the system. Our deck coating page covers how the concrete is tested and prepared first.
On concrete and masonry walls, the usual answer is a breathable water repellent rather than a film-forming coating. Silane and siloxane sealers soak into the surface and make it shed water while still letting moisture inside the wall dry out. A film over the face can trap that moisture, and it tends to come off in sheets. To check whether an existing treatment still works, spray the wall with water. Beading means it is still working, and darkening as the water soaks in means it is time to reapply. Our concrete and masonry waterproofing page covers the crack and spall repairs that come first.
