 Let's see what's on thinking man's mind today. Is there any difference between undercut and clearance under a fire door? That's a great question. It's one that I get a lot. And I just got this recently. So come on in and let's check it out. As defined by NFPA 80, clearance under the bottom of the door shall be a maximum of three quarters of an inch. And that clearance is from the bottom of the door to the top of either a raised threshold or the floor. And so when you look at the difference undercut is from the bottom of the door to the bottom of the frame. And if you've got a raised threshold that is half an inch high, then you could have an additional three quarters of an inch above that, or an actual undercut of an inch and a quarter. This one on the screen happens to be the question was, can I have an inch and an eighth undercut on a fire door. And yes, you can, because this has a threshold a raised non combustible or listed threshold. Or it could be over the flooring material again as long as it's no more than three quarters of an inch from the bottom of the door over the top of the flooring or the threshold. So what happens if you do have a greater gap? Pemko for one makes door gap solutions where you don't even have to take the door off in order to install this one is an aluminum but they make them in stainless steel. And they have an intumescent built in to close the gap in excess of the three quarters of an inch. If you happen to have that problem. For more information and continuing education opportunities, please visit also obloy academy by clicking in the link in the comments below. Please click like and subscribe to this channel. You can follow me on Twitter at our consultant and or connect with me on LinkedIn for updates. If you have a code question, you can email me at Catherine dot flower at us obloy.com. Thanks for joining me in the code corner today. My name is Katie flower and my goal is to help you achieve safe purity in the built environment.