Avoid This Common Mistake: Unsealed Range Hood Exhausts

If you're a general contractor working on new residential or commercial construction in Las Vegas or Clark County, passing your building’s thermal envelope test on the first try can save you time, money, and headaches. One of the most common reasons projects fail this test is a simple one: poorly sealed range hood exhausts.

How Range Hood Exhausts Cause Air Leaks

During a thermal envelope inspection, one of the key things we look for is unintended air leakage. The range hood exhaust is often a problem area. If the duct isn’t properly sealed where it passes through walls or ceilings, it leaves gaps that allow outside air in and conditioned air out.

Even a small leak can impact the blower door test results. In tight, energy-efficient builds, especially those aiming for code compliance in Clark County, these minor leaks add up quickly.

What This Means for Your Test

If air is escaping around the range hood duct, your thermal envelope may not meet the required air leakage limits. That means you fail the test and have to go back and fix the issue—usually with extra labor, delays, and a return trip for the inspector.

How to Seal It Right

Before your inspection, double-check that the duct is sealed where it penetrates the building envelope. Use durable, code-approved materials like mastic or foam sealant to close up any gaps. Caulk may work for smaller cracks, but avoid relying on it for larger openings—it doesn’t always hold up over time.

Also make sure the vent cap on the exterior is properly installed and sealed to prevent outside air from leaking in around the edges.

Get It Done Right the First Time

Paying attention to details like this can help you avoid re-inspections and project delays. As third-party energy inspectors in Clark County, we’ve seen range hood exhausts become a repeat problem on job sites. Take a few extra minutes to seal it properly, and you’ll be one step closer to passing your thermal envelope test the first time.