Estimating Material Requirements
Accurate Material Estimation for Roll Door Painting
Published on
August 29, 2024 at 3:32:14 PM PDT August 29, 2024 at 3:32:14 PM PDTth, August 29, 2024 at 3:32:14 PM PDT
Bidding low may land you a painting contract, but will you make money? Properly estimating the materials you need for a job is a key skill, and one you have to get right.
Overview
Estimating the amount of paint needed for a roll door repaint project can seem daunting. With hundreds or even thousands of doors to repaint, all with corrugated curtains and different-sized door openings, it is hard to know where to start. However, when broken down, it is not that complicated.
Steps to Estimate Requirements:
- Determine the actual square footage of each door:
- Door Measurement: Multiply the width by the height of the visible door curtain to get the beginning square footage.
- Corrugation Factor: Most roll door curtains are corrugated, adding an average of about 12% to the total surface area. This needs to be added to the actual door size. Review the actual doors on the job to ensure the corrugation factor is accurate.
- Waste Factor: Spraying extends beyond the edge of the door curtain, requiring an additional waste factor. Typically, an additional 3 inches sprayed around the perimeter of an 8'x8' door equals 6 sq. ft., or about 10% of the door's total footage. Sloppy spraying can increase material usage, so aiming for less than 3 inches of overspray is recommended. A good rule of thumb is to add a minimum of 6 sq. ft. per door as a waste factor.
Formula for Calculating Surface Area:
- (Door width x height) + (12% Corrugation Factor) + (6 sq. ft. Waste Factor) = Actual Surface Area
Example:
- A 7' x 8' door is 56 sq. ft. Adding 12% for the corrugation (approximately 7 sq. ft.), plus another 6 sq. ft. for the waste factor, results in 69 sq. ft. Use this figure of 69 sq. ft. for your material calculations.
Now that you know how to calculate the actual surface area of a door, you can use that to calculate paint material usage.
Calculating Material Usage
To calculate the amount of paint needed for a project, you can divide the surface area by the coverage. For example, if you're painting a 8’x8’ roll-up door with a coating with a coverage of 400 square feet per gallon, you'll need 0.22 gallons of paint (8'x8'/400=0.22 gallons).
Here are some other things to consider when calculating paint material required:
- Number of coats
The number of coats required will affect how much paint is needed. Products like Chem-Bake One-Step generally cover with one coat, even over color changes.
Note: Depending on the paint product you choose and how extreme the color change is, additional coatings may be required. In these cases or you decide that the underlying paint requires primer, a bonding primer tinted to a similar shade as the new color can be much less expensive than using two coats of a more expensive performance paint.
Chem-Bake One-Step 1201- Highly durable abrasion and impact resistant
- Excellent color fastness and gloss retention
- Self-Priming with superior adhesion on most surfaces
- Corrosion resistant - salts, acids, solvent, alkalis
- Low VOC Low HAP
- Applied via airless sprayer or brush & roller*
- Available in a nearly unlimited array of fade resistant colors.
Theoretical coverage
Theoretical coverage can be reduced by factors such as losses from catalyzing more paint than can be used before the pot life expires, and other waste detailed in previous sections.
Additional Resources:
We have a link to a simple paint calculator on the store using these calculations, which can help with our paint products.
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Spraying Technique for Roll-Up Doors
This outlines one experienced painter’s method for spraying self-storage roll-up doors. There are many ways to do the job, but this is a solid approach—especially for skilled painters who haven’t worked extensively on corrugated roll-up doors with silicone-modified polyester (SMP) or Kynar coil-coated surfaces, which are notoriously difficult to paint. The technique helps avoid many common problems and is efficient. It’s worth reviewing whether you’re just getting started or already seasoned; even experienced painters may pick up a tip or two. This method works well with three or four doors at a time. Start by applying a tack coat, working up the door and focusing on the bottom of each rib. By the time you reach the third or fourth door—whichever point allows the first door to tack up (tacky to the touch but no paint smears on your fingers)—you return to the first door and begin a top-down pass, focusing on the top of each rib. When executed properly, this approach ensures the top, bottom, and face of each rib are fully painted. It’s a fast, efficient method that reduces the risk of under- or over-painted areas, drips and sags, and excessive passes or angle changes just to cover the face. Disclaimer: This video is for general information only and is not a training program or a specification. All decisions regarding product selection, surface preparation, masking, application methods, safety procedures, protection of surrounding areas and other considerations are the sole responsibility of the painting contractor. Contractors must follow manufacturer instructions, applicable codes, and industry best practices. No warranty or guarantee of results is expressed or implied.
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Disclaimer: The information provided in the Self-Storage Learning Center is for general informational purposes only. While we strive for accuracy, All From 1 Supply makes no guarantees regarding the completeness or reliability of the information. Use of this content is at your own discretion, and we encourage independent verification before making decisions based on the material.
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