Duct Leakage Testing

Call us today:

973-544-6800 for NY, NJ, & PA

or

202-852-4000 for DC MD & VA

Info@BuildingSciencesLLC.com

We provide duct testing for new construction and retrofit installs when called for.  We are certified in testing ducts and can actually help you pass this test.  We serve northern and central NJ.  

Duct tests may also be called air test, or pressure tests by your local building official.  What they are looking for is that the ducts are sealed properly and the air is not leaking into crawl spaces and attic.  This is a tough test, so you really have to make sure all your ducts are sealed properly.  

To do the tests, we seal the registers and pressurize the ducts.  Leakage through the ducts will be noted on our equipment and should be minimum.   

Once we are done with the testing, we provide a certificate right on the spot, that you can take to your building department.  

Ready to start? Call us 

973-544-6800

OR

202-852-4000

Want More Details?  See below:

Background: Why seal ducts?   When new ducts are installed, they should be sealed tight. Sealing ducts allow for the right amount of air, at the right temperature, to be delivered to the right room.  Result? Homeowner comfort!. 

Above: Ducts get sealed and then pressurized. The leakage at that point is total duct leakage 

Above: Technician prepares a probe to be inserted into the supply duct that has been sealed off

This was not the norm for a long time, and ducts were not sealed, equipment cabinets were not sealed and filter slots were left open allowing the attic and basement, and garage and crawl space air to enter into the ductwork and then spread throughout the house resulting in many problems for the occupants.  Leaky ducts result in some or all of the following:

• Higher utility bills - yes up to 30% higher in gas, electric, and oil bills!
• More humid in the summer and drier air in the winter indoor air
• Uneven heating and cooling - hot or cold rooms.  Air does not get to the right rooms in the right qualities. 
• Indoor air quality can suffer - contaminants can enter the home through leaky ducts
• Pre-mature equipment failure - higher repair bills

Who Can Use This Service?  Homeowners who believe their system is not performing or if you want an independent company to check the work performed. HVAC contractors, builders, and General Contractors.  

Above: An example of ductwork that has been sealed.  All the ducts get sealed and then pressurized. Any leakage then is duct leakage and we can measure that.  

The right way to install new ducts - All ducts should be sealed at the point of connections - along with all connections with mastic - "a dime deep".  All connections of any kind in the ductwork should be sealed. This includes the trucks that are connected to the equipment, and in between components of equipment - like coils as they sit on top of the furnace.  The filter slot or cabinet should likewise be sealed.  

Is this Code? NJ's energy code R403.3.3 requires all ducts to be sealed and then tested to 4 CFM per 100 sq ft of conditioned floor space.  That is 4% of sq ft.  That is a very tight standard but good for the consumer.  

When is the duct leakage test performed?  Typically in the rough-in stage but can also be done post-construction.  The standard is the same.  For homeowners, this test can be done at any time. 

How is the duct testing done? All the duct registers and returns are sealed with special tape. Ducts are sealed and then pressured with a special machine called a Duct Blaster. The amount of air recorded on a sealed system is the total air leakage. See pictures below. The test takes about 30 mins of preparation time, setting up the equipment and sealing the ducts. And all of 5 mins to actually run the test.  Passing tests are given a pass certificate on the spot. 

Above: After all the preparation is done, a technician performs the actual duct leakage test.

What is Pass and what is Fail? Ductwork must be tightened to 4 CFM per 100 sq ft of conditioned space.  So any number of CFM over 4 CFM per 100 sq. ft is a fail.  Anything at or less than 4 CFM is considered a pass.  

What if the test fails?  If we are getting a reading of higher than 4CFM over 100 sq. ft of conditioned space, then our technicians will run a few quick tests to identify where the leak is. If the HVAC contractor is present, they can make the necessary repairs. And we will re-test the ducts immediately. If we have to return and set up the test all over again, then a 2nd full test fee will apply. 

Tips for Preparing for the Duct Pressure Test: It is preferable to run this test in the rough-in stage when all ducts are accessible (in case more sealing is required).

What to use to seal the ducts: You can use U181 tape or mastic. Mastic is preferable on so many levels and should be applied nickel thick. For spaces or openings larger than that, those spaces must first be wrapped in mesh tape.

Believe it or not, duct tape is not made for ducts and should not be used for ducts. It will come loose in about a year.

Mastic can be applied with your hand or with a brush.

All joints and seams in the system including collar connections, take-offs, and boots should be sealed. All seams at the air handler including the removable pan at the bottom of the blower cabinet should be sealed. The connection of the boot to the subfloor should be sealed with caulk or mastic.

If using a flex duct, do not rely on a zip tie to provide a seal that can potentially crimp the duct and cause leaks. Apply mastic over the transition, then pull the inner liner over the mastic, then mechanically fasten the liner with screws, pull the fiberglass back over the liner, and then use a zip tie over the fiberglass. Also, use this method when a sheet metal sleeve is used to join 2 pieces of flex duct.

If you have a filter slot, it should be sealed. One easy way to do this is to use a filter slot cover. You can purchase it here.

So if you have questions on this or would like us to test your ducts please call us at 973-544-6800.