Coating a Tar and Gravel Roof in Rio Rancho

avatarby Castagra Products, Inc.Last updated Jun 27, 2019Category: Roof Coating

This beautiful retirement home in Rio Rancho, New Mexico, near Albuquerque was hiding a problem not visible from the street. It may be easy to disregard a leaky roof in a climate with an average of only 50 days of precipitation annually, but, the proverbial “when it rains, it pours” is certainly true here, especially with monsoon season approaching at the end of July.

This property had a built-up roof (BUR) that was hot applied (hot mop) and covered in gravel to protect the layers underneath from sun exposure, which causes cracking and blistering in the asphaltic surface. Tar-and-gravel is the common name for this type of BUR.

Tar-and-gravel is a very common roof type in the Albuquerque area, but the gravel layer can make it difficult to accurately locate and repair leaks. And there’s another issue. The dark color and gravel become a heat sink in the nearly 273 sunny days annually. This can lead to high costs and premature wear for air conditioning systems.

So, the client’s home needed a waterproof, reflective roofing system to protect it from the elements. The homeowner called in Scott Herrmann, owner of Spray-Tech Roofing in Albuquerque, to identify the best option. He recommends against most single-ply products because they simply do not stand up to the harsh desert climate. He also has experience with hybrid systems but said he had to find a more effective solution. That’s when he found Ecodur. With Ecodur’s extreme adhesion, high strength, and ability to receive all reflective topcoats, it was a perfect choice.

For this system, he chose a base layer of Ecodur with a topcoat of reflective silicone.

To begin, he and his crew had to remove six-and-a-half to seven tons of loose gravel.

removing gravel roof

Next, each section of the roof had to be thoroughly cleaned using power brooms, wire brushes, and blowers. The goal is to have everything loose removed and no dust remaining.

Due to a storm on the horizon, they needed to make a quick batch of Ecodur to prevent water incursion in the various weak/leak-prone areas. The rest of the batch helped to start in on some edges. The team also treated vertical seams/gaps with a three-course method (wet Ecodur, polyester tape, wet Ecodur). Ecodur thickened with fumed silica filled gaps on the horizontal deck.

Cleaning tar-and-gravel roofs is dirty work!

The following morning, the roofing team discovered the storm they saw coming was actually a haboob, or dust/sandstorm. This left work areas quite dirty, but every surface should be blown clean at the start of each workday anyhow.

Once all the surfaces were clean, it was time to mix up the first batch of the day. It’s important to mix Ecodur properly. For this project, the crew used a full kit of Ecodur with a foaming agent that allows Ecodur to expand to help self-level on uneven surfaces.

Penetrations, perimeters, scuppers, and other details get coated first.

Then, the field is coated using a squeegee and roller. Due to unevenness on this roof, Herrmann opted for 9-inch rollers rather than 18-inch.

The following morning, with the Ecodur layer cured, the workers again blow all surfaces clean and collect all dirt.

Now the fun really begins! The Ecodur is a perfect base layer for silicone and allows for very smooth application. Just as before, the crew coats perimeters, scuppers, penetrations, etc. first.

With the details done, they made quick work of the 3300 square feet of remaining decking, again using squeegees and rollers and finishing before noon.

At the end of any project, there’s only one opinion that matters: the client’s. They were thrilled and commented that the new roof was beautiful, and they appreciated there was minimal disruption compared to a full tear-off and replacement.

Day 1: Gravel removal
Day 2: Heavy cleaning/preparing for possible rain
Day 3: Ecodur application
Day 4: (½ day) Silicone application

Gravel chute
Dust masks
2 Stihl power brooms
2 Husqvarna backpack blowers
Wire brushes
Ridgid mud mixing drill
30-inch eggbeater style mixing paddle
Midwest Rake Easy squeegee
Painter’s extension poles
Disposable roller frames
Cheap ¾-inch nap roller covers
Cheap 4-inch chip brushes
Lots of rags

Article by Jef McCurdy, Master Roofing Trainer at Coo Ro Co.

Castagra Products, Inc.

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