Window Header Size Calculator

Think about a bedroom. Imagine standing in a quiet room, looking at a perfectly good wall; then think about wanting to put in a window. You look at the wall and think, this is going to be an easy hole to cut, and suddenly the wall overhead doesn’t vanish. There’s something called a header that you has to install which will become a bridge carrying the load of the walls on either side of opening, plus the floor above and the roof. To get that bridge correct means knowing what it has on top of it, not guessing.” After you input your rainfall information and roof size, the rest are done by the calculator.

You no longer have to guess at conversions and coefficients. Tributary loads is broken down, meaning it figures out how much total floor and roof area rests on this particular piece of wall. The window header needs to hold not only the dead weight of the floor system, but also all the snow on the roof and any furniture or people in second-story bedroom right overhead. Many times people ignores the floor load, resulting in headers that will easily hold up the roof but can’t prevent the floor from sagging.

How to Choose the Right Window Header

“Framing has its issues with deflection. For example, you pick a beam based off bending stress; it won’t break, but when loaded, it’s bending more then you want it to be. And now your doors is sticking, and there are cracks in the drywall over the window.” The tool also lets you specify a maximum deflection amount (such as L/360, which is typical for keeping visible distortion out of the finish). If you go up one level (say, L/240), then it’s going to tell you you need a stronger (or deeper) member. A more rigid member may mean using laminated veneer lumber rather than ordinary dimensional lumber; you’re trading money against durability.

You’ll have to decide before you cut anything that this isn’t something you can ignore. So the material matters. Standard spruce-pine-fir lumber, Douglas fir, and engineered wood products like LVL all behave different. And then there’s what species you use. Species stiffen differently. They bends differently. Take a look at this chart to see how they all compare in stiffness and bending strength. A 2×8 of Southern Pine can take far more load than an equivalent sized piece of Hem-Fir. To get similar capacity you may have to move up to a higher grade material, or perhaps even stack your plies if you’re limited in height. It’s not just a question of whether something will fit into a hole. It’s a question of meeting a performance requirement inside some physical constraint.

Finally, there’s a little thing called jack studs (the ones on the end of the header… That hold it up vertically). Depending on how much weight the header carries, one jack stud could of been crushed or bent from the pressure. This ratio is what the calculator check for as well, to make sure your jack studs can bear the reaction force. If not, you’ll need more jacks OR increase the width of your bearing surface. A small detail, but if you fail here, you’re going to have settlement issues that won’t become apparent until months after project is complete.

And in the end it gives you the visualization of how the structure realy works. It shows how the abstract code actualy turns into real numbers. For complicated circumstances, talk to an engineer. Check your local codes. But at least you have some idea going into the hardware store so you’re not totally blind. And yes, we all want to make sure our house doesn’t fall down when we go frame that window. You also want to make sure the finish remains intact. That’s what a good header does. It holds things up while keeping them level, all behind the scenes.