A blower door test upon job completion will show the improvement of air exchanges per hour, as well as determine if the air sealing has made the house “too tight.” If the air exchanges are below the minimum ventilation requirement, make up mechanical ventilation must be added to the HVAC system. Having a blower door test certification with measurable results reflects credibility to your customer.

Listen to Your Customers and Ask Questions

The first meeting with the customer is arguably the most crucial time. It’s important to listen to them as you walk through the building, as they provide you with a vast amount of information. Areas that will be most fundamental in discussing include where the cold or warm spots are in the building, where the most time is spent and which rooms are not used. Determine and address their core concerns such as reducing energy bills, improving comfort, etc.

Start at the Top

A basic air seal for a house starts in the attic. In the attic there are three options: a critical seal on the attic floor; covering the entire floor; or spraying the underside of the roof deck. A critical seal includes using low pressure spray polyurethane foam (SPF), like Handi-Foam® E84 Class 1 foam, on any penetration, interior top plates, can lights with 3-inch clearance, bathroom fans, and exterior or perimeter top plates.

Alternatively, you can cover the entire attic floor with 1 inch of low pressure SPF. Consider estimating both ways so you can show your customer a “good” and “better” option. Additionally, you will also need to decide whether to move around existing loose fill or batt insulation or replace it once the air sealing is complete. In regions where air conditioning units are typically housed in the attic, spraying the underside of the roof deck will allow one to bring this area into the conditioned space.

Move to the Bottom

Next is the basement rim joist or crawlspace. Each rim joist space will typically be 1 square foot, so if there are 150 feet of exterior walls, you will have 150 square feet of space to insulate. It’s important to remember to look at all exterior wall spaces, as sometimes the wall that runs parallel with the floor joist will be missed. If the joist is against the wall, you need to determine how to seal that area and whether to drill holes or cut out small areas of the mud sill.

Check for Gaps

The final areas to consider are usually larger holes caused by remodeling or covered up during the construction process. These areas are common in sink bases, vanity cabinets, and bathroom storage areas above staircases. As the blower door test is being performed, walk around and check for these areas. A strong breeze is a good indicator of air infiltration; this can be seen easily with the use of a smoke pencil.

For each area, you will need to determine the depth of foam needed. An air seal can be accomplished with a ½ inch of SPF, but by using 1 inch you will achieve an R-value of six. Handi-Foam E84 Class 1 SPF can be used up to 2 inches thick in air sealing applications. Check with your local inspector to determine if an ignition barrier is required.

Another option may be to do a hybrid system, which includes 1 inch of SPF and a more efficient insulation such as fiberglass or cellulose to help obtain the required R-value. Again, it’s ideal to offer your customers options so they can make a decision that will help air seal and insulate but also fits with their budget.

Estimating the Job

When it comes to figuring cost, you need to look at the entire job and materials needed. Each area requires different labor and materials, so it is important to carefully examine all aspects of the job.

Always remember each square foot of foam 1 inch thick equals 1 board foot. So, if you are figuring 2 inches of foam over 100 square feet, it will be 200 board feet of foam.

When estimating, remember to add in the following:

Attic:

• Spray polyurethane foam (estimate by board footage).

• Removal of existing blown or batt insulation and installing new blown in or batt insulation.

• Don’t forget to add in the cost of additional materials (can light covers, baffles, etc.).

Basement:

• Spray polyurethane foam (each square footage of rim joist at 1 inch thick of foam = 1 board foot).

• R-19 batts for rim joists (check local codes).

Air sealing with low pressure SPF is an easy addition to your HVAC business, and it can save you time and money versus subcontracting out the work to high pressure polyurethane foam providers. Using low pressure SPF for an air seal requires less material, only one applicator, and shortens re-entry time from 24+ hours to just one hour. High pressure foam is dispensed too rapidly for the accuracy required to seal just the critical air infiltration points. The time and money savings of low pressure spray polyurethane foam make it easy to give your customers more options.

Don’t Forget

Always make sure to perform the blower door test at the end of a job to show the improvement in air exchanges per hour and determine if mechanical ventilation is required. Additionally, always remember to protect your customers’ property with drop cloths and plastic and take all waste with you at the end of the job.

Safety is a top priority when working with low pressure spray polyurethane foam, and contractors should always use the proper personal protective equipment.

Publication date: 3/18/2013