Why I Cut Kerfs Inside My Birdhouses

When I first started building birdhouses, I kept running across the word kerfs. I didn't know much about them at the time, so I did what most people do. I read a little, watched a little, and tried to figure out why they mattered.

Turns out it was pretty simple.

A few shallow cuts inside the front of the box give young birds something to grip when it's time to climb toward the entrance hole. Basically, a small ladder cut into the wood.

Once I understood that, adding them just made sense.

I've never actually watched a young bird struggle to get out of one of my houses. But I also didn't want that to be the reason I started adding kerfs later, so I began cutting them from the start. It only takes a minute or two, and then it's done.

I keep the cuts shallow and don't worry much about making them perfect. Cedar is soft, and it doesn't take much to leave a little texture behind. Most days I grab a Japanese pull saw because it's nearby. Other times I'll use a small router if I already have it out.

Either way, the result is about the same. The birds just need a little something to grip as they climb to the entrance hole.

Once the box is together, I don't really think about the kerfs anymore. They're hidden inside, and most people would never know they're there unless they opened the house up and looked.

But the birds know.

And for me, that's reason enough to keep cutting them