Framing & Air Sealing Pony Walls for Engineered Floor Trusses
Today, we’re demonstrating how to build pony walls on a subfloor foundation to support floor trusses. These engineered trusses, visible above, are critical for structural support. We’ll walk you through the process of framing and air sealing to show how everything fits together.
The first step involves drilling holes into the bottom plate of the pony walls and installing Titan HD bolts. These 5/8-inch bolts are drilled four feet on center and anchored into a 12-inch deep footing. It ensures the bottom plate is securely fastened and stable for further framing.
Next, a pony wall is framed on the anchored bottom plate. The studs must be cut and measured accurately using laser levels or string pulls to align perfectly with the top plate. This precision is essential for the floor trusses to flush with the top of the wall.
Air Sealing and Anchor Bolt Details
Air sealing plays an essential role in building efficiency. We recessed the washers and anchor bolts using a two-by or three-by plate. This allows the bolts to sit flush, securing the bottom plate tightly. A combination of DAPS Extreme Stretch caulking and seal sealers creates a strong, airtight barrier.
Zip Liquid Flash is also applied to the bottom of the exterior sheathing. This further seals the subfloor to the foundation, making the crawl space airtight. These details are beneficial for conditioned crawl spaces and ensure long-term durability.
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Floor System Design and Vapor Barriers
The floor system uses engineered trusses spaced 16 inches on center, spanning 28 feet across the foundation. These trusses are designed to clear-span the floor, leaving a clean, open crawl space beneath. The subfloor sheathing is glued and screwed to the trusses for added strength and stability.
To address moisture control, a Tremco 250GC vapor barrier is installed under the plates and extends six inches up the stem wall. This connects seamlessly to the radon system‘s Visqueen wrap, creating a continuous barrier against vapor intrusion.
Conditioned Crawl Space Features
This home has a conditioned crawl space, meaning no perimeter vents are installed. Instead, an Energy Recovery Ventilator (ERV) circulates fresh air into the space, keeping it dry and preventing issues like frozen pipes or pests. The system ensures a clean, efficient crawl space environment.
Learn More
If you’d like to learn more about building custom homes, request a project consultation with us. Take a look at our comprehensive collection of similar videos on our YouTube channel, The Real Property Show.
