Recoats have some common-sense steps to perform before applying the new coating. They also have guidelines specific to the coatings being used. But, regardless if you’re recoating a deck, roof, or floor, you must perform the following steps before applying the new coating:
- Inspect the existing coating.
- Repair or prepare the surface properly.
- Thoroughly clean the existing coating.
- Perform an adhesion test.
All four of these steps are essential for a successful recoat job. Complete instructions for recoat prep can be found in our Application Manuals, but we’ll cover the major points here.
1. Inspect the existing coating
Obvious? Yes. But, be sure to perform a thorough inspection of the existing coating before you begin.
Regardless of the coating or substrate, look for peeling, cracks, exposed substrate, or other damaged areas. Concrete decks and floors should be checked for spalls, divots, and other damage; coating over a broken deck, even if the existing coating is still in place, will lead to problems.
On roofs, also look for spongy or water-saturated materials. And, a moisture survey is a must. Probe the existing system and the substrate for water, and ask the owner if any leaks have occurred.
If the existing coating has serious damage or is degraded to the point where it cannot be properly recoated, then remove the coating. Get down to the bare substrate and start from scratch.
2. Repair or prepare the surface properly
If the substrate needs to be repaired, follow the detailed repair instructions in our Application Manuals. Remember to allow the repairs to cure or set properly before recoating.
Smaller repairs on concrete decks can be made with Neogard 70714/70715 epoxy mixed with sand. That mixture will cure quickly, provide a good surface to coat, and will last. Larger repairs typically require a new concrete patch; again, remember to allow that new concrete to cure properly before coating.
Roof substrates have their own requirements. For modified bitumen and single ply substrates, make certain the sheets seams are sound and detailed. Re-detail the seams if they need it. On spray polyurethane foam roofs, look for blisters in the substrate. Cut out the blisters, then fill with 2.7-lb density foam.
Repair the existing coating where it has peeled, delaminated, has blisters, or shows other defects. For urethane concrete deck coatings, remove the existing coating, then repair with the appropriate base coat material. Cracks should be routed and filled with Neogard 70991 sealant.
On roofs, remove the damaged coating, clean the area, then apply base coat material. Allow that base coat to cure, then apply an appropriate topcoat (urethane, silicone, or acrylic).
Flooring coatings should have any loose, de-bonded material removed. Then clean the surface—see below for info on cleaning—and lightly sand it to provide a better bonding surface for the new coating. Vacuum the resulting dust, then solvent wipe the entire surface with Hempel's Thinner 08080, Xylene or Neogard 7055 odorless reducer.
3. Thoroughly clean the existing coating
If your surface isn’t clean, your coating has no chance to stick. It really is that simple. Before you start applying, clean the surface of the existing coating. Power washing the surface will give great results for typical dirt and grime. For contaminants like grease or oil, Neogard recommends scrubbing with a stiff-bristle broom and our 8500 BioDegradable Cleaner. Be sure to rinse the surface thoroughly, and allow it to dry before you begin applying the new coating. If necessary, clean the coating multiple times.
4. Perform an adhesion test
Adhesion testing is extremely important when applying a recoat. Neogard tests coatings for adhesion to concrete and the various roofing substrates. We test for a few combinations of materials to other materials, but we can’t test for every possible combination, especially when materials from other companies form the existing coating.
Neogard recommends two basic tests to determine if your existing coating is a good candidate for recoating:
- ASTM D903, “Standard Test Method for Peel or Stripping of Adhesive Bonds.” This test, performed with a spring/fish scale, will give a result in pounds per linear inch (PLI). In short, apply the new coating to a clean surface with fabric embedded. After the coating cures, pull the fabric while attached to the scale. A simple calculation gives the PLI results. Urethanes and silicones should score 4–5 pounds; acrylics, 2 pounds. Those numbers are acceptable minimums for recoats.
- Rag Test: This test is essentially D903 without a PLI number. Apply the coating, place the fabric, coat over the fabric, and let the coating cure. Pull the fabric by hand. It gives a rough idea of how well your material is bonded, but isn’t precise.
Applying the new coating
Of course, our Application Manuals have complete instructions on how to apply a recoat. The system builds for deck coatings are variable depending on the materials and existing system. The latest Waterproofing and Deck Coatings manual has specific instructions for using primers, and for FC and FC T systems.
All roofing recoats should be applied in two coats. The topcoat material—7490-CA urethane, 7860-LO or 7870 silicones, or 7251 or 7261 acrylics—can typically be applied direct to the existing coating (assuming the adhesion test went well). Our Roofing manual has DFT requirements for recoats.
Flooring recoats are a bit simpler: Just apply the system according to our Guide Specifications or, yes, the Flooring application manual.
Recoats are a little different from the usual coating application job, but they aren’t difficult to do well. Just follow the guidelines from Neogard, and you’ll have a brand-new surface which will protect the substrate for years.