How to Frame a Wall Corner - A Complete Guide
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How to Frame a Wall Corner – A Complete Guide

How to Frame a Wall Corner – A Complete Guide

How to connect walls when framing

The big advantage of doing a project yourself is that you have full control to make sure the job gets done right. And when it comes to rough framing, the importance of a job well done cannot be overstated. When building a house, adding a room, or just adding a wall, raw framing creates the skeleton of your home, and the attention to detail will pay off in the long run.

one of eht’s readers recently asked about recommended methods for framing a corner in a new room. This article will focus on corner framing techniques that not only remain structurally strong, but also take into account the often overlooked aspects of raw framing, such as wiring and insulation.

90 degree inside corner

When framing a wall corner, the two initial factors to consider are structural integrity and providing a good surface for nailing interior siding or wall cladding. A standard method often used for interior wall corners is called a “tri-stud corner.” in this case, the corner is built with three studs nailed together or two studs sandwiching blocks that function as spacers.

at the end of the wall where your design began, nail the three studs and install them into the wall while assembling them on the floor. Secure all corners with 16d nails every 16 inches, nailing boards flush to all surfaces. At the opposite end of the wall, where the plates are 3 1/2 inches from the edge of the foundation (due to overlapping walls), place a single stud.

maze 350

This method provides adequate structural integrity for the wall, but also creates a solid block of wood in the corner that is not very friendly to the electrical wiring installation process. if wiring is to be routed through the corner, sandwich block between the two corner studs. the gaps between the blocks leave enough room to drill holes and run the wires through the corner more easily.

alternate inside corner

Not all corners are created equal. sometimes it’s cool to be square, but other times you might want to take a new angle on things.

Non-square corners can be constructed with studs that are installed at 90 degrees to the respective top and bottom plates of the two intersecting walls (see diagram #2). the studs will meet inside the smallest angle of the corner. the top and bottom plates extend beyond the studs and are cut flush at the intersection of the walls. the top plate is duplicated, with one of the layers of the second plate extending past the junction of the first top plates and cut to be flush with the edge of the studs.

This method creates a gap between the wall studs on the opposite side of the corner. the gap formed from this angle provides a poor nailing surface where the wall sheathing will intersect. this is often overlooked by “builders on the run”, but should be addressed by the competent diy’er.

Instead of leaving this gap and simply hiding it with the wall sheathing, miter cut two additional studs to fit the space, adding additional strength and a suitable nailing surface for the wall sheathing.

This wide-angle corner is built with mitered supports.

This wide-angle corner is built with mitered supports.

Again, this process will create a thick block of wood that, while very strong, creates a thick obstruction for running any sort of electrical wires. If the wall is intended to house any wiring, use mitered blocking installed in the gap rather than continuous mitered studs. This will allow space to more easily drill holes and install cables, while still providing a proper nailing surface.

90 degree outside corner

A common framing mistake when building a wall is to overlook the importance of insulation in the small spaces created by framing the corners of exterior walls. wood itself doesn’t do a good job of insulating your home, and untreated spaces allow mother nature to intrude through these nooks and crannies, which will ultimately reflect on your energy bill.

In a 90 degree outside corner, the “three stud” method does not leave enough room to install insulation. to accommodate this, install individual studs at the end of each wall. the first stud will cover the outside of the exterior wall, while the intersecting wall stud will be installed perpendicular to the first “cap” stud (see diagram #3). nail these intersecting studs with 16d nails every 16 inches.

Next, you’ll need to brace the corner with a third stud while still allowing room to add insulation and electrical wiring. On the inside edge of the wall with the outside “cap” stud, install a third stud parallel to the stud on the intersecting wall.

Instead of stacking this third stud flush with the corner of the wall, install it about 1 inch from the “cap” stud. nail this third stud to the second corner stud. this creates a 1-inch gap that allows for easier installation of electrical wiring, as well as sprayed or closed-cell foam insulation, which works great in small spaces. this corner treatment creates a strong intersection while remaining functional for the installation of other amenities. plus, this provides a solid, nailable surface for wall cladding on both the interior and exterior sides of each wall.

alternate outside corner

When adding window alcoves, hexagonal room additions, or any other out-of-square corners on an exterior wall, you will again be faced with the space created behind intersecting studs. Instead of installing solid studs or blocking, fill the corner space with spray-on or closed-cell foam insulation.

cut or spray insulation in the corner to weatherproof the inside of your home. When installing the insulation, trim it back about an inch before it is flush with the corner studs on the exterior side of the wall. then use the remaining space to cover the insulation with 1-by-4 or 1-by-3 boards cut to fit each side of the intersection (see diagram #4). the 1 by 4 will run from the top plate to the bottom plate. this provides a strong, insulated, navigable corner for installing electrical wiring, while also providing a solid surface for nailing at the edges of each corner, both on the inside and outside of the corner.

the extra effort

insulating corner voids and providing a solid nailing surface are often overlooked by professional framing crews who erect walls and ceilings on a daily basis. it takes more time and effort to properly build a strong, insulated corner. but the extra effort means the siding can be installed more strongly. and the insulation will help protect against heat loss and minimize cooling costs. These corner building techniques are the best bet for those extreme DIYers who insist on building it themselves and doing it better.

some framing tips

  • You may find it helpful to assemble the wall on the floor, nail it together, and then snap it into place. work on a level surface to help set the walls flush. try to avoid butting walls on the floor and keep your work surface clean and free of obstructions.
  • place the top and bottom plates on edge, inserting the wall studs between the plates and nailing them into place on ends of studs.
  • check squareness by measuring diagonally from each corner after each wall is assembled.
  • at 90 degree corners, after siding is installed and the wall is placed. up, the end of one wall will cover the corner of the other.

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