Failing your framing inspection can be expensive, especially if you have to stop work to fix mistakes--and then go backward and tear out work you thought was complete. Here are some of the most common framing mistakes that can cost you a red tag. Don't be surprised at how sic some of these are--framers are still messing up on some of the most obvious details.
Sill Plates on Concrete
For houses on slabs, the bottom plates of all exterior walls and interior bearing walls must be pressure treated lumber secured to the foundation. Exterior walls must have concrete-embedded anchor bolts 6 feet on center with an anchor within 12 inches from each end--in each section of bottom plate. If the bolts don't land within a foot of the wall's end (they rarely do), you must install a powder-actuated fastener in place of the missing bolt. Interior bearing walls should be attached with powder-actuated fasteners at 32 inches on center.
A beam or girder bearing on a wall must have a column beneath it at least the same width as the beam. This adequately transfers the load through the wall and into the footing.
Shim gaps between the bottom of the header and the trimmer at window and door openings to achieve solid load ransfer. Standard wood shims compress under load. You're required to use steel shim stock or steel washers. Hammer the shims/washers in tight.
The Universal Building Code specifies nailing patterns for structural wall sheathing of 12 inches on center in the field and 6 inches on center along the edges. Adjust your air pressure or your nailer's depth of drive to avoid penetrating the skin of the sheathing with nail heads.
Boring and Notching Studs and Plates
Architects love to draw 3-1/2-inch stud walls in bathrooms that have to accommodate 3-inch-diameter vent pipes. Once the pipe is through your wall, there isn't much left of studs or plates. To pass inspection, you can add studs on either side of the piping or use specially designed metal plates to reinforce the bored-out studs.
Fire Blocking/Draft Stopping
Install fire blocking in walls, floors, and ceilings to prevent creation of concealed space more than 10 feet long. If you frame a wall with 10-foot studs, you must fire block it to reduce the concealed space. If you have back-to-back walls with an air space in between, you need a full-height draft stop between the walls at 10 feet on center. When a drop ceiling intersects a wall, a row of fire blocks must be installed to block the drop.
When joining two sections of plate end-to-end to create one long wall, the top piece of the double top plate must overlap the joint in the bottom piece at least 4 feet onto the next wall section.
For walls intersecting at a 90-degree angle, there can't be a joint in either top plate within 4 feet of the intersection. If there is, you must add metal strapping to the top plate to tie the two walls together.
Engineered floor and roof systems won't stand up without lateral bracing, as detailed in truss suppliers' drawings. The building inspector examines those drawings. If you don't brace the exact location called for, you'll fail inspection.
Engineers must design a specific fix for damaged truss webs and provide an engineering stamp for each incident. A fix for broken truss "G3" on the last house doesn't necessarily apply to other similar damages. The inspector must see the manufacturer's paperwork on site.
Boring and Notching Beams
Beams aren't supposed to have holes in them. If your plumber or electrician drills through your beams you'll need an engineer to re-calculate the decrease in the beam's efficiency. Keep the paperwork that shows the beam still supports the load it was designed for on site.
If you're installing 2x12 joists, don't try to use those leftover 2x6 hangers; they won't pass. Nail off joist hangers completely--fill all of the holes with approved hanger nails. Hanger nails are designed with longer heads than regular 8d and 10d nails, which won't pass inspection.
Check that your rise and run are correct and consistent, especially the first and last riser. Make sure they match your typical rise or at least don't vary by more than 3/8 inch. Check for adequate headroom. Fire block the wall running parallel with your stringers. And, if your stringers are 10 feet or longer, fire block between them so you don't create a diagonal fire chase.
Are You Really Ready?
Have you received your plumbing, electrical, and mechanical inspections and are the tags on site?
Is the building weather-tight?
Are all of your approved drawings, building permits, copies of all prior inspection reports, and other relevant paperwork on site?
Build What the City Approved
If you change the approved plan, you must incorporate that change into your drawings and have the changes approved. If inspectors find you've deviated from plans, they won't approve the work.
Framer and contributing editor Michael Davis with Atanacio Maldonado, chief inspector for the City of Albuquerque, N.M. The authors' recommendations are based on experience and on the Universal Building Code. Before beginning work, be sure to consult local building officials and to follow the rules outlined by the International Code Council.
Published in TOOLS OF THE TRADE Magazine, January/February 2003