How deep can you cut into a tji joist?

You can typically cut into a TJI (Truss Joist I-beam) joist up to one-third of its depth without compromising its structural integrity. For example, if you have a 10-inch deep TJI joist, you should avoid cutting more than about 3 inches deep. Always refer to the manufacturer's guidelines and consult a structural engineer before making any modifications, as specific joist models may have different requirements.