Built Right Detail 03: Thermal Bridges in Wood Framing

A builder’s net zero envelope course by Xerox Builders · October 2026

Studs, plates and headers carry heat around the insulation, so an R22 batt never makes an R22 wall. This Detail shows how much of a wall is really wood, the difference between nominal and effective R-values, and the advanced framing and exterior insulation choices that fix it.

Why framing matters

Wood insulates far less than the batt beside it, so every stud, plate, header and block is a shortcut for heat around the insulation. On the inside, the framing runs colder than the rest of the wall, which means cold spots, a higher risk of condensation and sometimes dust marks on the drywall. The aim is simple: less wood in the wall, and an unbroken blanket of insulation over the wood that is left.

The framing factor

The framing factor is the share of the wall area taken up by framing instead of insulation. Corners, studs, plates, headers, jacks and cripples add up quickly.

Values adapted from the National Building Code user’s guide. In a typical house, roughly a fifth to a quarter of the wall is wood.

Nominal vs effective R-value

The number on the batt is the nominal value. What the wall delivers, once the framing is counted, is the effective value. For a 2×6 wall at 400 mm on centre with R22 (RSI 3.87) batts, the Canadian Wood Council’s effective R calculator gives the stud-and-batt layer an effective value of about R14.5 (RSI 2.55). The studs cut the batt’s value by about a third.

Add 25 mm (1 in) of extruded polystyrene outside the sheathing and the whole assembly, with all its layers and air films, comes to about R21.3 (RSI 3.75). Insulation outside the studs is not interrupted by framing, so it counts in full; only the cladding fasteners pass through it. The Part 9 energy requirements work in effective values, so this is the number your energy advisor and building official care about.

Advanced framing

• 600 mm spacing: 2×6 studs at 24 in, stacked in line with joists and rafters so loads go straight down.
• Two-stud corners: drop the third stud that only backs the drywall; use drywall clips and insulate the corner.
• Ladder blocking: flat blocks where partitions meet exterior walls, instead of a three-stud channel.
• Right-sized headers: sized to the real load, plies pushed to the outside with rigid insulation behind, and no header in non-bearing walls.
• Fewer extras: no jacks or cripples that the design does not need.
• Single top plate: only where the framing stacks and the engineer and building official accept it.

Building Science Corporation reports that advanced framing can bring the framing factor down from about 25% to about 15% while using fewer pieces of lumber. Wider spacing changes the sheathing, drywall and structural design, so confirm details with your designer and engineer before framing starts.

Getting it built

Advanced framing fails when it is only on paper. Put the framing layout on the drawings: stud spacing, corner and intersection details, header sizes and where headers are left out. Walk through it with the framer before the lumber order goes in, because habits such as triple corners and full-depth headers are hard to break once the crew is moving. Tell the drywall contractor that clips and ladder blocking replace some backing studs. And if the engineer specifies extra posts or hold-downs, plan how insulation will fit around them rather than leaving them as solid wood columns.

Cold framing and moisture

Framing that runs cold on the inside face is more than an energy loss. In a humid house it can show up as shadow lines of dust on the drywall over studs, or as damp corners behind furniture. Fewer, warmer framing members are part of a durable wall, not only an efficient one.

Continuous exterior insulation

The best fix for framing is a continuous layer of insulation outside the sheathing. One layer covers studs, plates, rim joists and headers at once, and keeps the sheathing warmer. Keep it unbroken at floor lines, corners and openings, and plan the cladding attachment, because screws and clips through it are small bridges too (Detail 10).

The bridges that matter most

A thermal camera used during a blower door test on a cold day shows these bridges clearly, along with missing or compressed insulation. For the heat-flow physics behind this, see our Building Science Deep Dive.

Site checklist

• Advanced framing plan reviewed by designer and engineer
• Studs at the planned spacing, stacked in line with joists and rafters
• Two-stud corners with drywall clips; no closed pockets
• Ladder blocking at partition intersections
• Headers sized to load and insulated; none in non-bearing walls
• No extra studs, jacks or cripples beyond the plan
• Corners, headers and small cavities fully insulated, batts not compressed
• Exterior insulation tight with staggered joints, unbroken at floors and openings
• Thermal camera scan during a cold-weather blower door test
• Every wall photographed before drywall

Test yourself

Try to answer each question, then click it to check.

Next: Detail 04, Slab Edges & Under-Slab Insulation. See also our Building Science Construction Guides.