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How can I make a perfect spray pattern on a roof? Post New Topic | Post Reply

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Posted: Dec 16, 2008 08:59 AM
How can I make a perfect spray pattern on a roof?
Hi Guys

I have been spraying roofs for a little over a year and have become decent (Probably a 7 on a scale of 1-10) at setting a flat pattern. Every now and then an overlap spray will have a slight bump.

The other day, I was able to take a look at a roof that a large competitor did and was pretty amazed with their work. It was a wide open 15,000 sq. ft roof with 2 ac units and a couple of vents.

They were very precise on their detail work with clear lines, which is always good. The one thing that I noticed was not a bump anywhere on the entire roof. No overlaps, gully's not even a 1/2 inch difference anywhere on their spray pattern.

The application was done by one sprayer and no robots were used.

My question is how do these guys spray a perfectly flat roofs with no bumps anywhere? Do you guys think that they are that good or are there some tricks such as planning or scarfing the bumps out before coating that I may not know of.

I have seen quite a few roofs even the Superdome, but never one that looked as if someone laid out cement in a drive way and was very close to being perfect.

Any advice would be greatly appreciated!


Posted: Dec 22, 2008 04:42 AM
To spray a perfect roof a lot of things must come into play , perfect weather durring the application is a BIG help , clean material , the right choice of spray gun and tip size for the project at hand , the right heat and presure , all equipment must been in great working order , and years of practice. Remember SPF is a art.
Roger Morrison
Posted: Dec 22, 2008 01:44 PM
From an SPFA tech tip:

"In order to apply spray polyurethane foam (SPF) to form a smooth surface profile and produce specified physical properties, a proper application technique must be used. The spray gun should be held as perpendicular to the substrate as possible. Spraying at a severe angle will cause the SPF to roll and exhibit a 'tree-bark' surface profile. This profile may cause the SPF to exhibit poor physical properties and significantly increases the surface area of the SPF to receive protective coatings.

You should feather your passes at the outside edges. This will leave a taper on the outside edges that will blend in smoothly with the subsequent pass. The application of the SPF should be installed at a consistent rate to allow approximately 80 percent of the spray pattern to overlap the previous lift. This will eliminate any washboard undulation (see Figure 1) and create a smoother surface profile. The SPF should rise smoothly and uniformly.

Your tie-in to the adjacent pass will vary depending on your natural pass width. The tie-in pass should carry onto the previous pass by 10 to 20 percent of your pass width (see Figure 2). Try using the following technique to control your tie-in detail. Spray a full length pass (30 - 40 linear feet). Start your new pass immediately adjacent to the first pass. After approximately 10 linear feet, stop spraying. Get on your hands and knees and observe the pass line. The elevation of the SPF at the pass line should match the middle of the pass. If there is a ridge between the two passes, take a half of a step away from the first pass and continue spraying. If there is a valley, take a half of a step towards the first pass. If there is a 'tree-bark' surface at the pass line, narrow your pass width. With practice, these techniques become automatic. Your foam application will look much better, require less coating and provide better drainage."
Posted: Dec 22, 2008 03:04 PM
Thanks for the SPFA Tech tips. I am going to overlap my tie ins by 10 to 20 % as suggested and if I do it right, it should eliminate that bump that I have been having.

philip mullins
Posted: Jan 02, 2009 04:39 AM
now that youve read that article, send a fat check to the spfa, get accredited, and you very well may be more "qualified" than the guy who actualy sprayed that roof!

slow in a hurry. wyatt earp wrote a book that is still used by the fbi for training today. when he describes his quick draw technique he states that he never practices pulling his weapon quickly. instead, practice unholstering your weapon slowly. using deliberate and efficient motions to bring the sights on target. practice pulling your weapon AND hitting your target over and over and over. speed will follow consistencey. you will develop a smooth and calm technique with no wasted motion that will deliver bullets on target.

maybe step back down to a 01 tip. work on a slower more consistent pattern and when you get real good then step up to a 02 or 03. get ur eyes trained as far as where too look to watch ur pattern.when to look ahead of ur pattern. when to follow it. i never look directly at my edges. i tend to watch out of my peripherial vision for stop and start, if that makes any sense. i dont care for any wide tips myself. by no means would i call myself an experienced roofer. i dont claim to be the best or even good for that matter. this is just a philosiphy that works for me. probably cause i read that book when i was just a kid that liked to play with my single 6 out on whites bayou.

and yes, they make a machine for that. it looks like a lawn mower. has several cool attachments for cutting gutters and valleys, or a wire brush for smoothing.

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