How to Build the Walls of a Detached Sunroom

Exterior Wall Framing

• 1

  Measure the length of each exterior wall, as determined by the footings or concrete slab. Record the length of each wall section, subtracting 5 1/2 inches from two of the walls, either those running lengthwise or from side-to-side. This reduction allows for the thickness of the walls to overlap the shorter walls, since each 2-by-6 is actually 1 1/2-by-5 1/2 inches thick.

• 2

  Cut one treated 2-by-6 to the length of each wall needed. This will form the sill plate, which is the wall's bottom, horizontally running framing member. Cut two more plates from untreated 2-by-6s to create the top wall plates for one wall. Doubling the top plates creates rigidity and strength. For four walls, make four top plates the proper wall length. Cut two to measure 4 inches shorter than the wall and the other two 4 inches longer than the wall. When attached, the top layer of plates will stagger across wall sections for added strength.

• 3

  Align the bottom plate for one wall with the accurate top plate, laying them together, on edge, with the ends even. Mark the plates, using a tape measure and square to cover both at once. For the longer walls, draw a line at 4 1/2 inches, 12 1/4 inches and again with each additional 16 inches. On shorter walls, which rest between the longer walls, mark 1 1/2 inches, 16 3/4 and every 16 inches thereafter. Omit stud marks where doors or windows are desired. End each stud wall as it begins, with either a single stud 1 1/2 inches from the end or three studs 4 1/2 inches from the end. Make an X to the right of each stud mark made to notate the right edge of the stud, once installed.

• 4

  Cut one stud per stud mark, except for the three in a row at either end of the longer walls. Subtract 4 1/2 inches from the wall height desired to determine stud length. Attach, one at a time, to first the bottom wall plate then the marked top plate. Drive two 16d nails through the plate, into the stud end. Nail the top plate on the free stud ends similarly.

• 5

  Frame the rough opening for all windows and doors. Add 5 inches to the width of the desired door and mark the plates to notate. Add 3 1/2 inches to windows and mark accordingly. This allows the clearance for the studs framing the opening as well as the window or doorjambs and framework.

• 6

  Attach studs flush with the rough frame marks on either side of the opening. Nail through the bottom plate into the stud ends and through the top plate similarly. These studs form what are known as the "king" studs.

• 7

  Build headers to span the width between the king studs. Designed to support the load above, headers replace the skipped studs. Consult building plans or a structural engineer to determine the height of header needed. In general, a header must be 1 inch high for every foot of opening. For most purposes, three 2-by-12-inch boards with a sheet of 1/2-inch-thick plywood between each board is adequate. Glue and nail the header together to support openings up to 4 or 6 feet in width.

• 8

  Insert the header at the appropriate height between the king studs: 2 inches above the door height and 1/2 inch above the window. Toenail through the header into the king studs, driving the nails at an angle. Cut a 2-by-6-inch board to the same opening width and toenail, at the proper height, between the king studs to create the sill plate. Doors don't require sill plates, in contrast.

• 9

  Cut two 2-by-6s to create "jack" studs, running from the header down to the bottom plate, for doors. Run additional boards, called "cripples," between window sill plates and bottom floor plates as well as above window and door headers. Nail each addition to the surrounding framework. Space cripples every 16 inches. Not only do they help support the weight of the structure above, but they also provide nailing surfaces for wall sheathing.

• 10

  Attach the final, top wall plate. Stagger the plates so that the longer plates overlap onto the adjacent wall. Glue and nail in place.

Finishing and Erecting the Walls

• 11

  Cut sheathing to span the outside of each stud wall section. Use either 5/8-inch OSB, particle board, plywood or other suitable sheathing. Nail to the wall framing to attach. Cut out each window or door opening. Cover with building paper to create a water-tight exterior.

• 12

  Walk each wall up to erect in place. Brace the wall with additional boards, wedged between the floor and wall, while working. Secure the bottom plate to the concrete pad or footings with anchors permanently attached to the concrete surface. Add concrete anchors every 6 to 8 inches, drilling through the bottom plate into the concrete to attach.

• 13

  Tie adjacent walls together by nailing end studs together. Reinforce with steel tie plates, attached half to one wall plate and half to the other, at top, bottom and a couple places in between. This increases wall stability.

• 14

  Continue constructing the wall, tying into the roof when added. Cover the outer wall surface with siding or desired sheathing. Insulate the interior wall, add a vapor barrier, and sheath with drywall or desired material.