Framing and Structural Work
Framing transforms your foundation into a three-dimensional structure. This is when your ADU really starts to take shape, with walls rising, roof trusses going up, and the skeleton of your new living space becoming visible. Proper framing is critical for structural integrity, energy efficiency, and everything that follows.
Quick Summary
Timeline
2-4 weeks
Cost range
$15,000-40,000
Key inspection
Framing inspection
What Happens During Framing
Framing is the process of building the structural skeleton of your ADU using wood or metal studs. This phase typically takes 2-4 weeks for a standard ADU and involves multiple stages, each requiring precision and adherence to your approved plans.
Floor Framing (if raised foundation)
Floor joists, rim boards, and subfloor create the base for walls. Crawl space and pier foundations require this step.
Wall Framing
Exterior and interior walls go up with studs typically 16 inches on center. Window and door openings are framed with headers.
Roof Framing
Roof trusses or rafters are installed, topped with sheathing. This defines your ADU's final shape and interior ceiling heights.
Shear Walls & Hold-Downs
Structural plywood shear panels and metal hold-downs provide earthquake and wind resistance as specified by engineering.
Critical Framing Elements to Watch
Wall Studs and Spacing
Standard residential framing uses 2x4 or 2x6 studs spaced 16 inches on center. Some areas allow 24-inch spacing for energy efficiency (more insulation space). Check your plans for the correct specification.
- • 2x4 walls: Standard, allows R-13 insulation
- • 2x6 walls: Better insulation (R-21), often required in cold climates
- • All studs must be straight, crown up, properly secured
Window and Door Headers
Headers carry the load above window and door openings. They must be properly sized for the span width. Common materials include doubled 2x lumber, LVL beams, or engineered headers.
Common issue: Undersized headers can cause sagging over time and lead to windows and doors that stick or won't close properly.
Roof Trusses vs. Rafters
Trusses are pre-engineered and factory-built, while rafters are cut and assembled on-site. Each has advantages depending on your design.
- • Trusses: Faster installation, engineered for load, limited attic space
- • Rafters: Allow vaulted ceilings, more flexibility, more labor-intensive
- • For ADUs, trusses are more common due to speed and cost
Shear Walls and Seismic Requirements
In earthquake and high-wind zones, structural shear panels provide lateral resistance. These are typically plywood or OSB sheets nailed in specific patterns to designated wall sections.
- • Nail spacing must match engineering specs (often 3-4 inches at edges)
- • Hold-downs connect walls to foundation with metal straps and bolts
- • Simpson Strong-Tie or equivalent hardware is typically specified
- • Inspector will check all connections carefully
The Framing Inspection
The framing inspection is one of the most critical inspections in your project. It must be completed and passed before you can cover walls with sheathing, insulation, or drywall. The inspector verifies structural integrity and code compliance.
What Inspectors Check
Common Framing Problems to Avoid
Walls Out of Plumb
Walls that aren't perfectly vertical cause problems with drywall, cabinets, and trim. Use a level frequently during framing to catch issues early.
Rough Openings Wrong Size
Windows and doors need precise rough openings. Too small and they won't fit; too large wastes material and creates air sealing challenges.
Missing or Wrong Nails
Shear walls require specific nail types and spacing. Using the wrong nails or spacing them too far apart compromises structural integrity and will fail inspection.
Not Following Plans
Any deviation from approved plans requires approval. Field changes without proper documentation can cause inspection failures and permit issues.
Pro Tips for Framing Success
Order materials early: Lumber prices fluctuate and delivery can take time. Order 10-15% extra for waste and mistakes.
Protect lumber from rain: Wet lumber warps and can develop mold. Cover materials and frame quickly after delivery.
Document everything: Take photos before walls are covered. This helps with future repairs and inspections.
Plan for utilities now: Coordinate with electrician and plumber about wire and pipe runs before walls are closed.
Frequently Asked Questions
Can I do the framing myself to save money?
Technically yes, but it's not recommended for most homeowners. Framing requires significant skill, proper tools, and understanding of building codes. Mistakes can be costly to fix and may not pass inspection. If you have construction experience, you might assist, but leave critical structural work to professionals.
What's the difference between stick framing and prefab panels?
Stick framing builds walls on-site piece by piece. Prefab panels are assembled in a factory and delivered ready to install. Prefab is faster but requires crane access and may have transportation limitations. Both methods meet code when done properly.
Why is lumber so expensive, and will prices go down?
Lumber prices fluctuate based on housing demand, mill capacity, and transportation costs. After the 2020-2021 spike, prices have normalized somewhat but remain higher than historical averages. Get quotes from multiple suppliers and consider timing if flexibility allows.
What happens if the framing inspection fails?
The inspector will provide a correction list specifying what needs to be fixed. Common issues include incorrect nailing, missing hardware, or deviations from plans. Make the corrections and schedule a re-inspection. Most jurisdictions allow one free re-inspection.
Ready for the Next Step?
Once framing passes inspection, you're ready to make your ADU weather-tight with roofing installation. Getting the roof on protects all your framing work from the elements.