ACH50 stands for air changes per hour at 50 pascals of negative pressure. Pascals are a standard unit measure of pressure comparable to pounds per square inch (PSI). ACH is a calculation of the cubic volume of space divided by air volume moving in and out per hour. For ACH50, a blower is used to measure the infiltration of outdoor air into a structure to compare the relative "tightness" of that structure. The measurement used is 50 pascals of negative pressure in reference to outside pressure. A higher number means that more air can infiltrate the structure (loose), whereas a low number means less air can infiltrate (tight). This number doesn't reflect air moving in and out of the space when it isn't pressurized.

FAQs Archive

Q: When can construction work recommence?

The area needs to be aired out for 30 minutes after the sealing is complete. This is done by opening doors and windows while running the fan. During this time, the sealing equipment and coverings are removed.

Q: Is it safe for inhalation?

Yes, but not during application. If a technician has to enter the space while it is being sealed, they wear personal protective equipment (PPE). After the sealing is complete, the area is safe to enter without protective gear within 20 to 30 minutes.

Q: To what extent can it create a secure seal, and is this sealing method safe?

Aeroseal Envelope has sealed houses to as low as 0.19 ACH50. But the value is in the system’s ability to allow builders to seal a home as tight as it is designed for. Aeroseal Envelope can meet any IECC, Passive House, LEED, Well Standard, ENERGY STAR, or Net Zero requirement. A home that is too tight can be a bad thing if the space isn’t designed for that level of tightness. The popular saying “build tight, ventilate right” applies here and works both ways. Building tight without proper ventilation could cause issues with indoor air quality (IAQ) in the space. On the flip side, a leaky home with proper ventilation could cause the mechanical system to not work as it is designed. Because Aeroseal Envelope can dial in the desired tightness of the space it removes the guesswork and ensures that the home is only as tight as the space is designed for.

Q: What size of leaks can this product effectively seal?

Aeroseal Envelope seals holes as large as 1/2”, and as tiny as human hair. Aerosol sealing is extremely effective at sealing narrow gaps and extremely small holes that are typically not cost-effective to seal manually, or that are missed using manual sealing techniques.

Q: What is a passive house?

A passive home is one that requires minimal heating and cooling. In essence these homes are very energy efficient reducing its ecological footprint. The "Passivhaus" concept was developed in Germany in the 1980's. It includes superior insulation, airtight construction, high performance windows, ventilation with heat recovery, elimination of thermal bridges or paths where heat can flow through the building, utilization of passive solar heating, energy efficient appliances and lighting, and monitoring that the building meets a standard. As a result, Passive Houses typically use up to 90% less energy for heating and cooling compared to conventional buildings.