Understanding Roof Restoration Episode 5 - Restoring Gravel Roofs - PODCAST TRANSCRIPTION

May 16, 2023 at 6:00 a.m.

Editor's note: The following is the transcript of a live interview with Greg Hlavaty and Hal Leland from Western Colloid. You can read the interview below or listen to the podcast.


Karen Edwards: Hello and welcome to the Understanding Roof Restoration Podcast. I'm your host, Karen Edwards from askaroofer.com. The Understanding Roof Restoration Podcast dives deep into the topic of restoring roofs. As the popularity of roof restoration continues to grow, there are many questions that arise. With a wide variety of roofing systems on existing buildings and many available restoration options we turn to the experts at Western Colloid to answer your questions on roof restoration. Greg Hlavaty, Hal Leland, and the team at Western Colloid have been manufacturing and installing these systems for more than 50 years. They have seen it all. We will tackle a different topic each month and answer questions submitted by you, our listeners.

Hi everyone. This is Karen Edwards. Today, I am welcoming Greg Hlavaty from Western Colloid to this episode. Greg, welcome.

Greg Hlavaty: Welcome, Karen. How are you?

Karen Edwards: Good. Now, usually Hal Leland is here with us, but he couldn't make it today, so it's just going to be Greg and I. We are going to be talking about a topic that is really, really interesting and that's restoring gravel roofs. Many people think that it just can't be done.

Greg Hlavaty: Right.

Karen Edwards: That's not true.

Greg Hlavaty: Yep. That's that's correct. I'll give it a little bit of history. Some people that have been around a while know that gravel roofs were restored quite a bit 30 years ago, 20, 30, 40 years ago even. Companies like Tremco leaders in the coding industry for many years and Garland Company in that had products that they used on gravel roofs that were actually called resaturants. Those were originally solvent base and then they mixed some other chemicals with it and made them into water base. Essentially, what they did was is they went over that gravel roof that was all dried out, and cracking, and what have you, and put this, an asphalt, solvent-based asphalt product on it that would lay on there in a very thick layer. The solvents would migrate down into the old asphalt and softened it up. They had a lot of success for some years.

The amount of solvents that were used at with time made that not very desirable, using a solvent based product. Even a water, even turning it into a waterborne it's still heavily solvent based. Then when they dried out, they tended to crack again, because what happens if you swell a roof with anything whether it's an asphalt shingle roof, a wood shingle roof that they spray an oil on. If you swell it up it does good. It softens, it swells, it makes it work a little longer. Then when it dries out it cracks and sometimes it cracks worse. It's like if you've ever painted the fascia on your house and you try to paint it and then when it dries again it cracks even worse. It dries out, shrinks. Same thing with the gravel roofs when they tried to saturate them and rejuvenate them.

Karen Edwards: Let me go back a step. If I'm a building owner how do I know if my roof is considered a gravel roof? What does a gravel roof look like?

Greg Hlavaty: Right. Yeah, that's probably... I should have started there.

If we go back to the earliest forms, modern forms, I say modern in the 20th century back into the early 1900s and that. A roof was built up, as a matter of fact, they called them built up roofs to this day. That is they will take a block of asphalt that is heated to melt it down and they will put it on a roof with layers of reinforcement and membrane water. Sometimes it's waterproofing, sometimes it's just reinforcement. Originally, it was organic felts or in the industry we called them rag felts. In the early days they didn't make paper as much from trees as they used as they do today. They chopped up old rags and made it into paper. That paper was then saturated with asphalt, a form of asphalt, and they would put down hot layer of hot asphalt and broom or roll a roll of felt into that. Eventually, it became fiberglass displaced, the organic felts. The same principle, they built up a roof in two layers, three layers, four layers.

They needed something to surface it with and they had two problems with surfacing a roof. One was the UV degradation in some parts of the country in the northern hemispheres, not as much. They top coated the roofs with asphalt and they used to do what they call a water coating. They would make asphalt very hot and thin and put in every two or three years just like they do a driveway. They would put another coat of asphalt on it and left it, leave it black, let it weather, and it did fine.

That brought up other problems. What about... We started getting into burning with some of the big fires, the Chicago fire, other fires. Now what are we going to do about fire ratings? Underwriters, laboratories, and other testing companies started testing roofs for their flammability. Now, we want roofs that aren't going to not only burn, but help the burn if you got certain forms of asphalt can burn readily. They needed to make those roofs have some fire resistance and have a UV resistance. In parts of the country where we have a lot of direct sunlight that eats up the asphalt will oxidize away in the direct UV sunlight. What are we surfacing with? Well, there's one thing that is almost universal in this around the country, and that's gravel and rock. I don't care if you're in Maine, Florida, Ohio, Oklahoma, California, Washington. You can get gravel.

Gravel does two things. It adds a little bit of weight to the roof for wind resistance and what have you. And it adds... Or three things really. Then it adds a UV resistance, because it's no sun's going to get through that. It doesn't keep the temperature cool if it's a hot day, but it doesn't let the UV, if you keep a good heavy layer of gravel on there, no UV is going to get through and degrade that asphalt. Next it is fire resisting. If you put enough gravel on a roof you can get a fire rating with paper towels. It is a barrier to the heat. There was different amounts of asphalt that were put on in specifications from different manufacturers. Anywhere from 200, 180 pounds per a hundred square feet per square up to 400 pounds per square. They had to build the roofs really beefy, because they put a lot of weight on them and it was inexpensive. Most roofers now think if they buy gravel they're going to get it in most likely in sacks.

Well, in the early days it was delivered by a dump truck dumped on the side of the building and guys had burlap bags that the roofers filled themselves on the side of the building, threw it either and then hoisted it up on a wheel hoist on a ladder up onto that roof. That's how they spread the gravel on a roof. Later on, they pumped it up with pneumatic trucks and all. In the modern days they did a lot of things, but in the early days it was dumped on the side of the building. It was put into burlap bags and haul up on the roof. It did a great job. It did what it was supposed to do and it made it much more resistant to fire and less resistance to the susceptible UV.

Anyway, there's lots and lots of roofs all over the country that were done with gravel. That's not to be confused with granules. Granules is something very small that they put on a cap sheet in a factory and it does the same thing gravel does. It's a barrier and a UV barrier and a fire barrier. Those are still common today in modified [inaudible 00:09:00] and cap sheet roofs.

Karen Edwards: Sure, I'm thinking and hearing your description of getting this big thing of rocks and either way you've got to get them up on the roof.

Greg Hlavaty: Yup.

Karen Edwards: If your roof is nearing the end of its life cycle and they're considering a restoration how labor intensive is that? I would think you've got to get all that gravel off the roof, right?

Greg Hlavaty: That's an issue. For the most part coating was not readily considered as an answer to a gravel roof. Yeah, we can do cap sheet, because it's smooth. We've already talked about doing single supplies, they're smooth. A coating could be adapted to it, but what do we do with this gravel roof that's very rough, very textured. A good portion of the gravel is loose on that roof, but a portion of it is and has to be by the specification and by testing embedded in the asphalt. They put that layer of asphalt, there's a layer of gravel that is uniformly embedded into that asphalt. That doesn't come off very easy.

Karen Edwards: No.

Greg Hlavaty: You want that to be on there. That's an important part of making a gravel roof. If they put gravel on and the asphalt chill, what they call chilled, cooled off too much, they could spread the gravel around on, but it would blow off, because it wasn't held in place by that thing. You want it in the hot asphalt.

Now, what do I do? Well, coating isn't a very good, hasn't been recognized as a good answer, because if you're going to use a coating, coatings are in volume, are expensive. Whether it's acrylic, whether it's a plural component, there are some gravel roofs that they'll put spray foam on. Spray foam has been an answer where they'll... The first thing they'll do though is on a gravel roof they'll sweep it, and vacuum it. We always recommend a vac, sweep, vac. Where they vacuum it, sweep it with either a power broom or a very stiff bruise, then come back and back it again. Get all the loose gravel off, but still can be very rough. Not a big candidate for a coating.

However, for 30 really 40 years we've been doing gravel roofs and that's because we make an asphalt emulsion. An asphalt emulsion is an asphalt that isn't readily flammable. It is relatively inexpensive, so you can use in the higher quantities. If we were to build up an acrylic roof like the acrylics we make, or a plural component like some urethanes or some of the other plural components it would be very expensive, because by the time you covered the gravel and the roughness you would have a very expensive roof with a lot of gallons of that product on there. Those products run from $20 to $100 a gallon depending what you're talking about. It can be not very cost-effective.

With the asphalt emulsion it's high performance underwater it. We line lakes with asphalt emulsion. It has water 365 days a year for 30 years and it withstands it in heavy enough layers. Asphalt emulsion, as we've talked about before is a combination of a straight run distilled asphalt. One that's not been oxidized like hot mopping asphalt. It's distilled in left in its more pure form. It is mechanically ground with a bentonite clay, which hence colloided. It becomes a colloid product and water. Once the water evaporates, it's a combination of bentonite clay and asphalt. That does two things, it's very waterproof. It is low cost. It's a low cost product and it is a very resistant to water it. In that form...

Another problem that we've had with asphalt is the fumes. They don't like hot asphalt because of the fumes and what have you. Well, asphalt to emulsion is used at ambient temperature and by ambient, I don't 60 degrees, or 70, or 80. It's never heated. Some of the early asphalt coatings and some of them that are still used today in some areas have to be heated. They're solvent based and in order to use them, if it's cool out or the temperature, they don't flow very well. Where asphalt to motion can be sprayed easily and it can be built up in heavy gallonages. It doesn't give off fumes. It's zero voc.

Asphalt has been getting into bad wrap, but I look at it... I compare it to plastics. They say, "Well, asphalt, do they have benzene... If you burn it can be... If it's hot you know can get the fumes." Well, if you burn plastic it's toxic. It'll kill you. It doesn't stop us from brushing our teeth with a plastic toothbrush or doing all the things we use plastic for it's just used in its proper place. That's why we like the asphalt of emulsion at ambient temperature we can pump it and put it on heavy gallonage over that gravel and build it up to not a perfectly smooth surface, but a relatively smooth surface using the right amount of gallonages.

Karen Edwards: This podcast is brought to you by Ask A Roofer and Western Colloid Fluid Applied Roofing. When you're looking for answers for your roof what better place than askaroofer.com. If you are looking for answers on restoring your commercial, industrial, or low slope roof? Look no further than Western Colloid. For over 50 years they have been bringing old roofs new life. Together we're helping contractors, building owners, property managers, architects, engineers, and consultants. Choose the best commercial roofing system. Find Western Colloid today on askaroofer.com.

Yeah. That's what I was going to ask, because it seems like it's becoming more appealing now. Oh, we can take the gravel off. Then, yeah, it's not even, but... How is the asphalt emulsion applied and how difficult is it to know how much to put on where to try to get that smooth as smooth as possible as you can? Is that challenging?

Greg Hlavaty: We have specifications, but are even our specifications vary dependent... Gravel size all used in different parts of the country or even in the same part, it depends on the specification, or what's readily available. A lot of gravel here in the west we have what they call four or five grit. Very small 1/4 inch, 3/8 at the most, but most of it's 1/4 inch. That vacuums often leaves a pretty easily done, but you get 3/8, then you get 1/2 inch gravel. A lot of areas have 3/4 inch gravel. Areas that have coal tar pitch used 3/4 or larger gravel. If that's still embedded that's a very rough textured service. That takes a judgment. It isn't just, "Hey, give me a speck and I'll go do this gravel roof." It's learning what to do. We have guys that we send out and try to help guys, help contractors when they're learning to do gravel.

It isn't the first thing I recommend a person that's going to do fluid applied roofing do, because it goes against the grain. When you're going to put on... Most of our specifications end up using on a gravel roof between a minimum of 18, but usually 24 to 30 gallons of emulsion. They said, "Oh, I'm putting all that. How much weight am I putting up there?" "Well, I just took off 200 pounds of gravel and I'm going to put back on 40, 30 or 40 pounds of coating." We're not even getting close to what we took off when we clean the gravel. The weight is not the issue, but putting that amount of volume on is something that's hard. Most guys that have used spray rigs they're used to spraying. That's slight light duty. You're not putting on a lot. This is put on in heavily volume. Usually 10 to 12 gallons per a hundred square feet for a light gravel, very light gravel. That's just for the flood coat before we start putting the plies on. It could be two passes at that 12 gallons to get it done right.

It's still inexpensive compared to tearing off and what have you. And the production can be good. Done with a regular or a roof rig sprayer, a Graco roof rig or another rig that is made to pump at 10 or more gallons per square, 15 is better. The 15 gallon roof rigs will pump that and you use a much more open tip. You flood that roof, you let it dry, and then you'll come back and start with the plies.

The other part of it is as one of the drawbacks to judging asphalt emulsion on a roof is that it is 45, between 40 and 45% solids is all. It's not high solids product, which means 55% of that evaporates away as water. It leaves less than half of the volume that you put on there. When you spray it on and look, "Boy, I put a lot on there. That's 3/8 of an inch thick," but when it dries it's an 1/8 of an inch thick. It isn't all that thick. You have to keep that in mind that you're putting on a lot more than what you think, because a lot of that is going to dry, evaporate away. It does take some training and letting us maybe work with somebody.

We've helped other manufacturers, because we put acrylic top coats on either in just the acrylic top coating after we put... We'll put a asphalt emulsion flood coat on a gravel roof, let that dry out, cure well, and then come back with at least two plies of polyester fabric in asphalt emulsion, and possibly one ply in acrylic. At least a top coat of acrylic. Depend on drainage, depends on the part of the country, if there's a lot of pounding water, one spec doesn't fit all. For one thing, we never do a light spec on gravel. Where we might do a one ply of polyester reinforcement over a good cap sheet roof slope. We would never do one reinforcement over a gravel roof. You need redundancy. You have to... This isn't a bandaid roof. This is a fairly substantial reinforced coating system that you're putting on there. It's going to have multiple plies on that thing for it to perform. It can be done with other technologies.

Karen Edwards: It sounds like the right equipment is going to be really important here. Especially, when applying that asphalt emulsion, because you talked about it's so different from what someone may be used to. I'm curious, we've put the flood coat on we're ready to come back and start doing the plies. You said one, but usually two. What kind of amounts are you cutting back from what you used in the flood coat or are you still putting it on?

Greg Hlavaty: We're not cutting back. We may even be adding.

Karen Edwards: Okay.

Greg Hlavaty: For instance, if we did a gravel roof and when it dried out it was a little more textured than we thought, where our normal first ply of asphalt emulsion, embedding that first ply of polyester in is normally six gallons on a cap sheet roof, what have you. It would be at least that six gallons, but it might be seven or eight to help fill a little more of those voids. We're using an inexpensive product. We're not cutting corners here. We want to put on as much as we need and maybe more than we need if possible. We'll put that first ply on. In some cases, both the first and second are put on simultaneously in warm weather. It's done like a built up roof. It can be shingled in where they're half lapped.

It isn't always done in cooler times of the year. They'll put one ply, let it dry, put a secondly on. That's a lot of water to evaporate away from a roof. That's one of the caveats to do in water-based systems is that water has to evaporate, and that roof has to dry, and cure. There's no real shortcuts on that. We're up to a mother nature as part of...

Karen Edwards: True.

Greg Hlavaty: ... and physics. We're the evaporation room. That that's the first steps. We're finding other manufacturers, that we're actually working with, that are putting plural component systems over asphalt emulsion put into gravels. They've been held back from those gravels, because of the cost. Now, they find, oh, well we can put a intermediate layer in there that isn't too cost costly of the asphalt emulsion and build that up and still be able to use our technology that we make, which is a plural component. Whether it's urethane, which might be a single component urethane or a plural, or some of the two component systems that they've used. It just...

We choose the acrylics. We like the waterborne, because we're on the Western US and we find that they work well. Especially, if they're reinforced on a roof like this. We have some very successful roofs. This isn't like a five or six year old sys systems. We've been doing this for 40 years. We've got roofs that are... Vicki did a little post on our deal about a roof that was originally built in World War II as barrack, or storage, or whatever in southern California. Barrel roofs, but they were gravel roofs. In the old days they graveled even sloped roofs.

Karen Edwards: Yeah.

Greg Hlavaty: Not just flat roofs like they do today. That was a barrel roof. Somewhere in the 70s, we believe, we don't have the exact date. We just know that that gravel was swept off and there was a chopped glass and emulsion roof put on with Western Colloid, the original owner and founder of our company actually did it with his contracting company when he first started. That was redone in 2000... 1999, 2000, or 2001 I can't remember which a third time with another layer of chopped glass, and emulsion, and aluminum. Here we've got a gravel roof that's been on since World War II.

Karen Edwards: Wow.

Greg Hlavaty: Hasn't been torn off, but has been redone a couple times. It kept going. It's been done for a long time.

One of the things that I do caution, because there's some other great coating companies out there. We're not the only one around, but they are being new to the gravel they don't realize the volumes it takes to do it. We've seen other companies out there specifying what they think is a lot of emulsion on them, put six or seven gallons on, sweep it, and six or seven gallons, and then apply a polyester on it. We went through that the hard way back in the 70s and 80s. You can't light coat a gravel roof you got to go after it with all the product it needs. In the end, you end up with a really good rock solid roof, and a well-performing roof, and a economical roof.

It can be very, I think, we've talked about it before, but we did a very large, well-known building in Texas some years ago that was done with a combination of... It was a flood coated gravel roof, that then had chopped glass and emulsion, and then polyester and emulsion, and polyester and acrylic put on it. It was my understanding that it was almost a million dollar savings, because it had a heavy insulation on it. They were going to have to tear off the entire roof and the insulation and redo it. It was a very costly roof, but a big money savings for them.

Even our gravel roofs, we've gone to FM. We have FM ratings with multiple systems, both with chop fiberglass reinforcement and polyester reinforcement over gravel and hail tests. That building in the Dallas area withstood that huge hailstorm that came through with five inch hail.

Karen Edwards: Wow.

Greg Hlavaty: Came through with flying colors did a great job. It's been around. It isn't a brand new thing we're just trying out. It's just a brand new thing you're hearing about that. A lot of people don't know that there's another alternative.

Karen Edwards: Yeah. That's fantastic. It's really impressive that you've been doing it so long. I think, it's also equally important, you mentioned just a few minutes ago, how there's other manufacturers that maybe are newer to the game or newer to the industry and don't understand, like you said, the amount of asphalt emulsion that has to be put on there. We need to, I think, all work together as an industry to make sure we're meeting those standards. That's when you get a bad like, "Oh, I know somebody that did that and didn't work." Well it wasn't that it didn't work. It wasn't installed properly.

Greg Hlavaty: Right. All of us in the coating industry have gotten black eyes from the coating industry. People that are back in the very beginning of the reflective part of California's energy codes. Everybody in... It was the new gold rush in California. Everybody that could make a white coating was in California. You might be making it in South Carolina, and New Jersey, in Michigan, but I'm out... I got guys in California selling this white coating, because they're mandating it. When it first hit it wasn't a boom to everybody, because those of us that actually had manufacturing plants here and lived side by side with our building owners that we put on their roofs. We kept getting the, "Oh yeah. I tried that. It was a nightmare." "Oh, that didn't work then I couldn't find him." "Oh, the guy who is no longer around. It was..." You have to live with it. Sometimes we can be our own worst enemies by not doing it the right way.

I'm pretty friendly with most other manufacturer. I've had other ones call and I say, "Look, call me up. I'm an open book. I'll tell you what it took for us to do it the right way." You get salesmen out there that are used to selling coatings and they can be very good salespeople. If all of a sudden you throw them up against a gravel roof they're not sure what to do and how to do it. If you're a contracting company that's not comfortable with it then that's fine. Don't do it. I don't think everybody... Some people will... They'll walk by our booth at the trade show and look at our sample of our system over the gravel, and chuckle, and walk away. It's like, "Oh, that looks very scary." If that's the case, then that's fine, but it can be very successful and we have millions of feet on to prove it.

It can even be done over coal tar pitch. This is something that you don't find with cap sheet and what have you. Asphalt emulsion, I'll just throw this out there real quick, because lots of gravel roofs in the south were dead level roofs and they were done with coal tar pitch. Cold tar pitch was an amazing product that was self-healing, got hot every time. Every year when it got hot, it got soft. It resealed all its old cracks and brewers and all that, but there's still cold tar pitch roofs around. You could... One of the big no-nos with cold tar pitch is you never put asphalt in combination with cold tar pitch. They do not mix. You could couldn't use a hot asphalt to repair a coal tar pitch roof. Asphalt emulsion is benign to...

We have hundreds of thousands, maybe millions of feet of asphalt emulsion over coal tar pitch roofs. That bentonite clay and non-oxidized asphalt does not react with a coal tar pitch, so we do gravel roofs even over coal tar pitch. Many of the roofs here in San Diego are, where I'm at, that were cold tar pitch at the Hewlett Packard facilities. I don't know what they are now. They've been bought, sold, and what have you.

Karen Edwards: Yeah.

Greg Hlavaty: In the early days there were many cold tar pitch roofs out here and we did asphalt emulsion over them for years. Many of those are still going. I'm talking about 20 plus years ago. Gravel can be done. That needs to be done in the right way. Don't just get a spec, and buy a drum, and try to do it, but talk to us or some...

Karen Edwards: Yeah. I think, you finished by saying you finish it with acrylic coating. That can provide a nice, sustainable, highly reflective, finished roof system for that building and that building owner, which does all kinds of great things like bring down energy costs, heating and cooling costs...

Greg Hlavaty: Sometimes we do more than just coat it. Many gravel roofs are built to be flat. Now, some of them have a little bit of slope, and if they do, great, that helps it. If they're flat and they have some pounding on them, then we would use a reinforced acrylic surface, which... A lot of people say, "Ah, we don't like acrylics in pounding, because they peel or they wrinkle." They can if they don't cure right. If they're not done. One of the things acrylic can do, acrylic can perform just as well as a urethane, or plural component, or any of the others in pounding when it's reinforced. We put down a polyester fabric in the acrylic. Then it becomes reinforced concrete. It lays there and it can with stand pounding for decades.

Karen Edwards: Nice.

Greg Hlavaty: We have that for decades. Even in pounding conditions an acrylic surface can be put on. It's just a heavier surface.

Karen Edwards: Excellent. Wow, this was a great conversation today, Greg. Thank you so much. I hope that we've helped educate some folks out there that yes, you can restore a gravel roof, but there's very specific needs, and conditions, and application methods to be aware of. The team at Western Colloid is always available. You've always said, "Just reach out to us." You're there to help. You'll help with specs, you'll help look at buildings. There's pretty much whatever assistance someone needs your team is there to provide it.

Greg Hlavaty: You bet.

Karen Edwards: Excellent. This podcast is going to be available on askaroofer.com, on westerncolloid.com, also on any platform that you listen to your podcasts. We encourage our listeners to submit their questions. Go to either of our websites. If you have a question that you want to ask about roof restoration then send it in. If we use your question we'll send you a gift that's always nice to get a gift. Next month we're going to be talking about best practices for applying. We talked a little touch on that today, but I'm sure that there's enough things to think about and keep in mind as you're installing and applying that we'll dive deeper into that next month. Hopefully, Hal can join us for that conversation, as well. We love his insight. Thank you, Greg.

Greg Hlavaty: Great. Thank you, Karen.

Karen Edwards: Bye-bye.

Greg Hlavaty: Appreciate it.

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