Currently Reading

Draftstopping for Optimal Home Energy Efficiency

Quality Matters

Draftstopping for Optimal Home Energy Efficiency

Insulating and air sealing unseen and hard-to-reach pockets is critical to energy-efficient homes

By Richard Baker January 9, 2017
Draftstopping best practices around a bathtub
Builders should also pay attention to draftstopping in places in the home that aren’t so obvious, such as behind the bathtub. (Illustration: IBACOS)
This article first appeared in the January 2017 issue of Pro Builder.

You’ve probably heard the term “draftstopping” but perhaps aren’t sure what it means. It sounds like a good idea, right?

Mitigating interior drafts is a theory of good thermal performance and energy efficiency, though we tend to limit our frame of reference to walls and other areas we can see. Those details are critical, no doubt, but they’re also obvious and are usually adequately addressed.

I’m talking about the places that aren’t so obvious—at least once the home is finished: wide swaths of uninsulated or unsealed construction that are often neglected or aren’t considered in the overall scheme of whole-house energy efficiency. You wouldn’t leave a window wide open and expect good thermal performance, so don’t expect a quality thermal envelope without paying close attention to all areas of the wall.

Picture the framing cavities of an exterior wall below the rim of a bathtub, for instance. Because the tub is typically set in place before the insulation crew do their thing, it can be difficult (at best) to effectively insulate, air-seal, and encapsulate that now-hidden wall section.

The same is true for areas behind prefabricated fireplaces, chimneys, and mechanical chases, as well as double-wall and attic knee-wall assemblies. The result? When using fibrous insulation such as fiberglass or cellulose, convective heat transfer can reduce the R-value of those assemblies, their overall thermal efficiency and comfort, and the effectiveness of the HVAC equipment.

The solution is relatively simple, though a different sequence, trade, or both may be needed. Before the cavities and other voids are covered up or made inaccessible by a tub or shower enclosure, chimney flue, or fireplace insert, have the framer or the product installer add insulation and encapsulate it with a rigid, full-height, and completely sealed panel to serve as an air barrier. That kind of assembly renders convective loops far less likely.

Discuss and settle details and performance expectations beforehand with your trades so that everyone knows the drill, and educate and inform your building inspector before he visits the site so he doesn’t red-tag the work or make you tear it out.


Draftstopping_Quality Matters_bathtub_energy efficiency.png

Draftstop behind the tub: Use the illustration above and follow this best-practices checklist for draftstopping behind a bathtub, and check out this reference from the Building America Solution Center for fireplace and chimney assemblies.

1.] Insulation: Fill the entire wall cavity with insulation to the code-compliant (or better) R-value.

2.] Air barrier panel: Cut sheathing material—such as fiber-cement board, paperless or glass-mat drywall, thin-profile sheathing, or rigid insulation—to fit so it covers the entire exterior wall surface behind the tub, and encapsulate the cavity insulation. If necessary, add blocking between the framing members to fully fasten the air barrier.

3.] Air barrier sealant: Apply a thick bead of sealant to the exposed surfaces of the framing members, including the plates and any blocking.

4.] Air barrier fastening: Nail or screw the air barrier material to the framing.

5.] Joint and seam sealant: Apply sealant or expanding foam along joints and to seal seams and any holes made through the air barrier material. Once the tub is installed, seal any holes around the tub drain.

Richard Baker is a program manager on the Builder Solutions team at IBACOS.


Related Stories


Climate Change Is Driving Up Demand for Stormproof Homes

The mounting consequences of climate change are forcing many homeowners to weatherproof their homes with more resilient materials

Quality Matters

Construction Details for Trouble-Free Stucco Overhangs

Transitions where horizontal and vertical stucco surfaces intersect are prone to moisture problems. Attention to proper detailing will help you avoid issues with water intrusion

Green Projects

This Off-Grid Colorado Project Lays the Groundwork for Green Housing’s Future

The resilient and energy efficient VISION House offers a glimpse into the future of eco-conscious construction


More in Category


Create an account

By creating an account, you agree to Pro Builder's terms of service and privacy policy.

Daily Feed Newsletter

Get Pro Builder in your inbox

Each day, Pro Builder's editors assemble the latest breaking industry news, hottest trends, and most relevant research, delivered to your inbox.

Save the stories you care about

Lorem ipsum dolor sit amet lorem ipsum dolor sit amet lorem ipsum dolor sit amet.

The bookmark icon allows you to save any story to your account to read it later
Tap it once to save, and tap it again to unsave

It looks like you’re using an ad-blocker!

Pro Builder is an advertisting supported site and we noticed you have ad-blocking enabled in your browser. There are two ways you can keep reading:

Disable your ad-blocker
Disable now
Subscribe to Pro Builder
Already a member? Sign in
Become a Member

Subscribe to Pro Builder for unlimited access

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.