Air Leak Testing for Existing Homes

Cold rooms, drafts, or a heating bill that jumps every winter? We put your house under pressure with a blower door, then use a thermal camera to show you where the air is getting in.

Call (253) 802-8738 · Book a Leak Test

Retrotec blower door equipment · FLIR thermal camera · Based in Sumner · Testing only, nothing to sell you

Most of our tests are for new homes that need to pass the energy code. But you don't need a permit to want answers. If you've lived in your house a while and it never feels warm enough, a blower door test is the quickest way to find out how leaky it is and where the leaks are. You come away knowing what to fix first.

We set a fan in an exterior door and pull air out of the house. That pulls outside air in through every gap at the same time, so small leaks you'd never notice become easy to find.

The test tells you two things:

• How leaky the house is overall. We measure it, so you have a number to compare against after any sealing work.
• Where the air is coming in. We walk the house with you while the fan runs.

Places we often find leaks in older Puget Sound homes:

• Attic hatches and pull-down stairs
• Recessed can lights and bath fans
• Top plates and wiring holes into the attic
• Rim joists over the crawlspace or basement
• Plumbing and vent holes under sinks
• Fireplaces and chimney chases
• Gaps around windows, doors, and trim
• Ductwork in the attic or crawlspace

We bring a FLIR thermal camera on every leak test. With the house under pressure, outside air cools the spots it comes through, and those spots show up on the camera as darker streaks. That lets us point to the actual leak instead of guessing from a draft.

The camera works best when it's cooler outside than inside, so fall and winter are a good time to test. In warm weather we can still find leaks, it just takes a little more looking.

Air leaks are one of the main reasons a house feels drafty or has one room that never warms up. Cold air coming in low and warm air escaping up through the attic means your furnace or heat pump runs longer to keep up.

Sealing the biggest leaks is usually one of the cheaper upgrades you can make to an older home, and the test shows you which leaks are worth sealing first. We won't promise a dollar amount on your bill, because every house is different. What we can tell you is where the air is going.

Air leaks can also carry moisture into walls and attics. If you've noticed musty smells, condensation on windows, or damp spots in the attic, mention it when you book.

• One or more rooms are always colder or hotter than the rest
• You feel drafts at outlets, baseboards, or windows
• Your heating bill seems high for the size of the house
• Before you hire an insulation or air sealing contractor, so you know what needs doing
• After air sealing or insulation work, to see if it helped
• Before or after a remodel, a window replacement, or a new heat pump
• You just bought an older home and want to know where it stands

• A measured air leakage number for your house
• A walk-through with you while the fan is running, so you see the leaks yourself
• A short list of what to seal first. You can do it yourself or hand it to a contractor.

WA Blower Door is a testing company. We don't sell or install insulation or air sealing, so what we tell you isn't tied to a sales pitch. If we see something structural, like rot, sagging framing, or water damage, our engineering team at Dow Engineering PLLC works out of the same Sumner office. → Dow Engineering

A short homeowner checklist. The full builder checklist is on Residential Testing.

• Close all windows and exterior doors. Leave interior doors open.
• Clear a path to one exterior door where we can set up the fan.
• Turn off the furnace, heat pump, and water heater (or set them to "vacation" or "pilot"). We'll help if you're not sure.
• Put out any fire in the fireplace or wood stove and let ashes cool. Close the damper. Cover the ashes or keep the glass doors shut.
• Turn off bath fans, the kitchen hood, and the dryer.
• Make sure we can get into the attic hatch and crawlspace if you want those checked.
• Pets in a closed room or out of the house while the fan runs.
• Make a list of the rooms or spots that bother you most. That's where we'll start.

Apartment buildings, townhome blocks, and commercial spaces need more air than one fan can move. We run dual-fan and multi-fan setups with Retrotec FanTestic software logging every fan together. If you manage or own a larger building with comfort or leakage problems, give us a call and we'll talk through what the test would take. → Multi-fan testing

Is the test safe for my family and pets?
Yes. It's a fan in a doorway running at modest pressure. It's loud, so pets are usually happier in another room. We ask you to turn off fuel-burning appliances during the test so no exhaust gets pulled back into the house.

Do I need to be home?
Yes, or have another adult there. The walk-through is the most useful part, and we'll want to show you what we find.

Do you do the air sealing?
No. We're testers. We'll show you where the leaks are and what to tackle first, and you can do it yourself or hire someone.

Will the results help with a rebate?
Some utility or state programs ask for blower door results. Check your program's rules first, then tell us what they need and we'll help where we can. We can't promise a rebate.

Is this the same test new homes need for permits?
It's the same equipment. For new construction and permitted remodels, see Residential Testing. If you need energy code paperwork for a permit, our partner Build Sherpas handles that. → Build Sherpas Energy Code

Where do you work?
We're based in Sumner and test homes across Pierce County, King County, and the South Sound. See our Sumner, Tacoma, Puyallup, Auburn, and Pierce County pages.

Give us a call, book online, or send a note. Tell us a little about the house and what's bugging you.

Book a Leak Test · Call (253) 802-8738 · Send a Message

Email: office@dowengineeringpllc.com

WA Blower Door, a tradename of Dow Engineering PLLC · 16202 64th St E Ste 117, Sumner, WA 98390 · (253) 802-8738 · office@dowengineeringpllc.com