Framing exterior openings precisely will make installing the windows and doors a breeze.
Synopsis: Windows and doors are inserted into the areas of a framed wall known as rough openings. Framing the rough openings isn’t a matter of throwing a bunch of studs together with a nail gun, though. Rough openings need to be framed properly so windows and doors can be shimmed level and plumb. Seasoned builder John Spier shows us the correct way of framing rough openings from layout through assembly. His approach involves simple steps and framing basics to achieve accurate, well-built rough openings for any job.
Although the name suggests otherwise, rough openings demand plenty of precision, especially when they are framed in load-bearing walls. Properly done, rough openings provide a place for windows and doors to fit securely, unaffected by the critical structural work being done by headers, king studs, trimmers, sills, and cripples (or sill jacks). After years of building, I’ve learned that getting rough openings right makes the rest of the job go smoothly.
Check the plans first
Although the rough openings for doors and windows are specified on the plans, these dimensions are worth double-checking. It’s important to note that sizes always are described width first, then height. I like to look up rough-opening dimensions in the tables provided by window and door manufacturers. These tables are excellent, and I’ve learned not to second-guess them. Getting this information correct is the first step in avoiding serious frustration a few weeks down the line.
Occasionally, circumstances can require rough openings to be modified. Non-standard floor thicknesses, specialized flashing elements, and applied sills are just a few details that can affect rough openings and should be thought through. If the building details are particularly unusual or complicated, it’s smart to test the scenario as a mock-up before committing to a whole project.
Verify rough-opening locations
In conventional platform framing, headers typically are sized so that the opening is at the correct height with the header tight to the top plate. Sometimes this placement needs to be modified, either by using cripples above the header or by moving the header up into the plates.
Lateral locations of rough openings usually are specified from the edges of the building to the centers of the openings, and between centers when several rough openings appear next to each other.
Before transferring layout marks to the lumber, I give the entire plan a final check. Confirm clearances, and make sure that the rough-opening layout will maintain symmetry within and between floors, if that’s a priority. When there is room to move left or right, it’s nice to make sure that trim details fit cleanly without ripping and squeezing.
Gather all the pieces
All the wall components that define a rough opening need to do their part in making the opening solid and square forever. The king studs on each side of the header should be straight in all directions (for example, no bow, crown, or twist). The header needs to be sized appropriately and should provide room for insulation, if possible.
Trimmers need to be continuous from the header to the bottom plate. In some areas of the country, this detail is required by code. Even if it isn’t required, I still maintain that this practice is the best. Interrupting the trimmers with sills is not a good idea because the ends of the sills eventually can crush under the load. Multiple gaps, even of the slightest dimensions, can allow settling to occur. Lateral resistance of the wall is better with continuous trimmers as well.
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From Fine Homebuilding #176