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Sealant being applied in a joint over a backer rod

How to Use Sealant Calculators to Estimate Product Needs

Predicting how much sealant or caulking you need for a construction job can be difficult. To alleviate this challenge, many manufacturers and distributors offer online sealant calculators to approximate how much product is required for your application. This sealant calculator guide walks through when and how to navigate these programs so you get the most accurate estimate for your project. 

The Best Applications for Sealant Calculators

Sealant calculators estimate the amount of necessary product needed for an application regardless of its technology (silicone, urethane, hybrid, etc.). Calculations are based on the volume of a traditional sealant bead, a rectangular prism that is later tooled to an hourglass shape, common in basic vertical and horizontal expansion joints, utilizing the recommended 2:1 width-to-depth ratio.

Additional calculations can be made to accommodate cove or triangle beads of sealant and expandable foam sealants that are used in control joints and window perimeters.

Sealant calculators are not suitable for detailing or flashing applications, as the product is often tooled flat so the volumetric-based calculations would not be appropriate, either significantly overestimating or underestimating your needs. Contact a Sales Representative for anticipated product needed for these or other caulking applications.

Common Sealant Calculator Fields

Sealant Joint Calculations-2The results of a sealant calculator are only as good as the values entered. The product approximation depends on your joint dimensions, so be sure you know which numbers go in which sections of the calculator. Most programs will allow you to toggle between metric (meters, millimeters) and imperial or English (inches, feet, etc.) measurements so double check that you have the correct one selected for your job. Here is an explanation of the common fields you will see in sealant calculators. 

  • Length/Linear Feet/Linear Meters- These refer to the entire length of your joint/s, measured in feet or meters. This will be the largest of the numbers you enter.

  • Joint Width- The width, in inches or millimeters, indicates how far across your joint runs.

  • Joint Depth- The depth, in inches or millimeters, is measured from the top of your joint to the top of your backer rod or bond breaker.

  • Inefficiency Factor- also referred to as “percent waste” or “wastage”, is an approximate percentage of the sealant that will be lost during the product application. This number varies depending on the individual applicator and their skill level, so below are the general range recommendations to enter in the calculator. If you aren’t sure the experience level of those who will be applying the product, an inefficiency factor of 10-15% is a safe estimate.

    • 20-25%- new applicators
    • 10-15%- average applicators
    • 0-5%- very experienced applicators

After you’ve entered your joint details, the sealant calculator will report how many tubes, cartridges, sausages, or buckets of product you will need for your application. Again, make sure you select the appropriate packaging type for what you are looking to purchase. 10 cartridges will not equal 10 sausages.

If the project has multiple joints with the same width and depth, you can add up their lengths to calculate how much product is needed for them all. However, if your joints have different widths or depths, it is best to input the values of each joint separately first and then combine the amount of product needed.

How to Reduce Sealant Waste

The first way to minimize unused sealant and unnecessary cost is to only purchase as much sealant as you will need. Therefore, having the exact dimensions of your joint upfront will return the most precise output of the sealant calculator.  

Once you have your product in hand, there are additional strategies you can employ to decrease waste, whether due to applying too much sealant or installing it incorrectly and having to tear out and recaulk the joint. For basic steps on how to apply sealant, refer to this blog post.

It is important to note that you cannot simply tool caulking in a joint and move the remainder to another area of the job as this may cause contamination which will diminish the sealant’s elongation and durability performance, causing premature failure of the joint seal. 

Proper substrate preparation and the use of primer, if needed, are indicated in the product’s application instructions and are critical to avoiding sealant waste due to lack of adhesion. To verify the adhesion of an existing joint seal, the field adhesion test can indicate the quality of the application and identify potential problems such as contaminated or expired sealant, improper cleaning, or extreme substrate movement. 

Vulkem_116_retail_croppedUtilizing the proper tools in the right way will also minimize wasted material. When using a caulking gun, cut your nozzle to the appropriate size by first inserting the nozzle tip into the joint and marking where it hits joint face. Cut diagonally across just short of that line so the sealant bead will be slightly smaller than the joint and fully fill the cavity. Otherwise, the sealant may just float on top of the joint and cause inconsistent wet-out. When you go to tool with too much sealant, you will find excess product on the top and sides of the joint to ultimately wipe down and remove. Taping the sides of your joint can make this process easier and give a cleaner appearance but it will not reduce the waste. 

In addition, the right size tool is necessary for the tooling process. Caulk spatulas and sealant finishing tools come in various shapes and sizes. For typical expansion joints, you will want a tool that just barely fits into the joint width to maintain the hourglass shape of the sealant bead.  

A final consideration is the time of day that the product is installed. During the mid-point temperature of the day, the joint will be at its mean joint size, the average width during its natural expansion and contraction cycle. If you apply the product in this timeframe, the sealant will experience consistent expansion and contraction during the cure period which prevents cracking and bulging. 

Sealant Calculators in Summary 

Sealant calculators, like the one provided by Tremco CPG, are a great tool for forecasting how much material you will need for a typical caulking joint. To best utilize these estimates, it is essential to know the joint dimensions and how to input them into the calculations. From there, proper substrate preparation and sealant application will reduce waste and ensure you have enough product for the job.