Flat roof coating and maintenance in Trinidad (20002)

Silver aluminum coating has been the default on Trinidad roofs for decades. It reflects sun and protects the asphalt underneath from drying out. Applied over a membrane that is still flexible and dry, it works well and buys time cheaply.

The trouble starts when coating is used to cover a failing roof. We often find three or four coats over cracked roll roofing, with water sitting in the layers below. A coating seals the top but traps moisture underneath, and the deck rots out of sight. Before recoating, we cut a small core sample to make sure the layers are dry.

If the roof passes, we power-wash, reinforce open seams and flashing joints with fabric and mastic, and then apply the coating at the rate the maker specifies. White elastomeric coatings are another option and reflect more heat than silver. Our guide to what silver coating actually does explains the differences.

Most rowhouse roof failures here start small: a clogged scupper, a lifted seam at the party wall, a cracked spot around the plumbing vent. Catching those early is what separates a 25-year roof from a 12-year one.

We offer roof maintenance visits that cover each of the items below, with photos so you can see the roof without climbing up. Twice a year, in late spring and after leaf fall, is a good rhythm.

• Clear the rear scupper, leader box and downspout
• Check party wall seams and base flashing for gaps
• Reseal vent boots and any satellite or antenna mounts
• Look for blisters, ponding and bare spots in the coating
• Inspect the porch roof and its joint with the front wall

Soft spots underfoot, ponding that lingers for days, blisters that squish when pressed, and leaks that come back after each patch all point to a roof that needs a tear-off. At that point, coating money is better spent toward a new flat roof.

When we replace, DC energy rules usually push a reflective membrane, so the new roof will be white or light colored. We take the roof down to the deck, replace rotted boards, add insulation where possible and install TPO or modified bitumen with new flashing at every wall.

Because Trinidad rows were built in long matching runs, several neighbors on the same block often face the same decision within a few years. When two or three adjoining owners replace at once, the party wall seams become one continuous membrane instead of a patchwork, and staging in the alley is shared. We are glad to price adjoining houses together and walk each owner through their own section.

Modified bitumen in a white granulated cap is a common choice for owners who like the feel of a traditional rowhouse roof but need the reflective surface.

Most Trinidad blocks have rear alleys, which keeps our ladders and buckets off the narrow streets. Street parking fills quickly near Gallaudet University and the H Street corridor, so we bring coatings and roll goods early. Coating jobs usually take a day or two and need a dry forecast, so we schedule around rain and watch overnight temperatures in spring and fall.