Framing Corners
A survey of methods and materials used to build warm, inexpensive and strong corners.
Synopsis: This well-illustrated guide to framing corners offers a number of alternatives that reduce the amount of dimensional lumber needed, while allowing plenty of room for adequate insulation. The author also includes a couple of ways to frame corners that meet at an oblique angle.
Unless you are a builder who always builds round houses, chances are pretty good that a portion of your building career will be spent framing comers. Until recently, framing a comer was a straightforward task that didn’t present too many options. The typical stick-framed comer was, like its predecessor the timber post, a massive piece of wood. It was sturdy, and you could drive nails into it anywhere you pleased. These days, the traditional three-stud corner is not gone but may soon become as rare as solid-chestnut timbers. For a variety of reasons, there is now more to consider than just providing nailing support for siding outside and drywall inside.
A change in framing corners
The primary reason is economics. The price of framing lumber has nearly doubled in the past ten years. The prevailing opinion holds that the lumber’s quality has slipped considerably, too, which is an economic factor if you have to spend 20 minutes digging in the pile trying to find a straight 2x for a sill or a plate. The cost of heating a house has also changed the way people frame corners. During the energy crunch of the 1970s, some architects and builders began to think harder about more efficient ways to insulate houses and switched from 2×4 to 2×6 walls for their greater R-value potential. Comers, always notorious cold spots, came under scrutiny, too. If built with 2x6s, the older style solid comers not only required more lumber than the 2×4 version, but they also created a bigger area in the wall that couldn’t be insulated and suffered more from thermal bridging. Thermal bridging is the transfer of heat energy through solid materials; in a house, cold is usually conducted from the outside sheathing to the interior walls through any solid material, most notably the framing.
In the interest of both economy and energy efficiency, researchers and builders have been searching for better ways of framing comers using less wood and more insulation. Here are some of the methods that they’ve come up with.
The three-stud corner is traditional and sturdy
The three-stud corner is a direct descendant of the timber post and is favored by many builders. Its main advantages are that it is quick to assemble, it is strong and it gives the carpenter plenty of support for nailing exterior corner boards and siding. You can make it two ways: Nail three full studs together, or use 2x scrap from the site as blocks between two full studs. A single end stud on the abutting wall is nailed on the inside corner. The main disadvantages of three-stud corners are that they use more lumber, are difficult to insulate and create a wide thermal bridge to the interior. These corners are not effective when built with 2x6s. Connecticut framer Mario Sapia uses this corner because he like the mass of the construction; he reduces the thermal bridging by wrapping the exterior of the house in 3/4-in. rigidfoam insulation.
For more photos and information on the different ways to frame corners, click the View PDF button below.
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