PaintPRO, Vol. 9, No. 6
November/December 2007
PaintPRO, Vol 9 No 5

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Other articles in this issue:
Painter of the Month
Clear Wood Finishes
Project Profile: Miami City Hall
Product Profile: Yolo Colorhouses
Business Strategies
Tools: HVLP Sprayers
Finishing Touch: Going for Gold
Paint Industry News
Product News

PaintPRO Archives — Estimating, Etc.
Painting Irregular Surfaces



Getting a handle on irregular or configured surfaces

by Len Hijuelos

I was checking on a usual source of information ( and again came up with an article I thought would be of interest to some of PaintPRO’s readers. The question posed was how to deal with irregular or configured surfaces. Unfortunately, the individual posting the question was not very specific, but I got the impression that he was probably referring to surfaces like metal roofing and siding.

The main thing to remember about these kinds of surfaces is that any time a flat surface is changed into a configured surface, additional paintable area is added, and obviously, this additional area has to be accounted for in your pricing structure. That seems so elementary that we shouldn’t even be talking about it, but you might be surprised how often somebody will argue the point.

I have heard on more than one occasion that since the surface is to be sprayed, the configuration doesn’t matter — this is wrong, as we will try to demonstrate. Light steel framed structures such as rigid frame and purlins will usually utilize corrugated panels for roofing and siding. These corrugations are about 5/8 inch in depth. This, then, will add approximately 10 percent to the flat surface. For example, a side of a building 200 feet long by 10 feet high would be 2,000 square feet. Add 10 percent and the total area to be painted would then be 2,200 square feet. On other types of siding or roofing or roof decks (the underside of the roof) where metal sheeting is used, rather than corrugated metal, these figures could be decidedly different. Depending on the profile and depth of the configuration, you could be looking at an add factor of 1.5 to 2.5; for example, if you have a roof deck where the profile shows a 4 1/2-inch depth, your add factor would be approximately 2.5, so that same 2,000-square-foot wall would now be 5,000 square feet. This is a substantial difference.

Painting Irregular SurfacesAnother factor to consider is an increase in the labor cost. These surfaces, regardless of the configuration, lend themselves quite well to spray application and that is usually the application method of choice. The corrugated surface will usually have only a small impact, if any, on production, and can basically be ignored, as long as you have the additional area included. The other surfaces, however, are a different story. You cannot spray these surfaces in one pass — because of the profile, the gun will have to be angled from two to possibly four different ways to cover all the surface area. This has a definite impact on production and has to be accounted or allowed for.

More often than not, repainting of metal buildings involves, or may be limited to, the painting of exterior roofing and siding. An exterior application can have a major impact on material consumption. Sometime ago, our company was awarded a contract to pressure-wash and repaint several quite large metal buildings in a manufacturing complex that happened to be sited in close proximity to the Mississippi River. Because of the size of the project as well some other factors, we decided to very carefully monitor the material usage for future reference. The results were as follows:

Interior walls and roof deck: 278 square feet per gallon
Exterior siding — sheltered: 246 square feet per gallon
Exterior siding — exposed: 178 square feet per gallon

On days when the wind was blowing a bit, everything was shut down; we probably would have gotten something like 50 square feet per gallon.

These are all real numbers, from the add factors to material usage, and the math doesn’t lie. No matter how much you rationalize or how much you argue, the additional area is there and the associated costs for these areas have to be included in the pricing. For those readers who might be interested in exploring this subject a bit further, I would refer you to the PDCA Estimating guide, where they provide illustrations and tables.


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