In Construction, what is a Trimmer?

Mary McMahon
Mary McMahon

A trimmer or trimmer stud is a component of a framed structure that provides additional support for an opening such as a door or window. Trimmers are needed to ensure that the structure remains stable and retains its structural integrity despite the creation of openings, because openings can create weak points in a structure. These structural members are usually required under the building code and a contractor may opt to exceed the needs of the code by using a larger size than called for if it appears necessary.


In a basic framed wall, a series of studs run the length of the wall, connecting with the floor and roof joists. A network is created to distribute the weight of the structure, ensuring that no hot spots develop where structural members are called upon to support disproportionate amounts of weight. As soon as an opening is created, it disrupts the arrangement of studs and can make the structure weaker, vulnerable to high winds, earthquakes, and other problems.

Trimmer studs, along with other supportive members like king studs, distribute the weight of the structure above the opening around the opening, ensuring that it dissipates evenly through the floor. This reduces the strain on the wall created by the opening. It also reduces the risk that the wall will fall out of plumb, potentially making it hard to open and close the door or window.

A trimmer can be made from wood or metal, depending on the structure. It is built into the framing around the opening and can be installed in several different ways. It is possible to install separate trimmers to support the header and the sill, and this may be done for structural integrity and to make it easier to replace or repair the sill. A contractor can make a decision about which trimmer layout would be best to use on the basis of the structure, the architectural plans, and other factors, like the likelihood that windows will be moved or replaced.

With some framed structures, the framing may be done flat on the ground, with the framing being raised when it is finished. This technique can be easier, especially for people working on small crews, than trying to frame upright. As the structure is built and the roof supports are installed, it will become increasingly sturdy and the structural supports installed to hold the framing up during construction can gradually be taken away.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I don't have much sense when it comes to building things, but I can see the need for a trimmer now. For all my life, I have never once considered what keeps a house from collapsing over windows and doors. Now that I think about it, certain types of openings would need extra strong trimmers.

If you had those big bay windows that cover half a wall and sometimes extend almost all the way to the floor, you would really need to provide extra support around the frame. This could be a really vulnerable area when strong winds whip through the yard.

The same thing would apply to sliding glass doors. They cover such a wide area, and a trimmer would help support the weight of the house over the glass.

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