Finally got the draft under my front door sorted

I ran into something similar last year, but my door was an older, hollow core model, which made the screw-in sweep a nightmare to install without damaging the frame. I eventually had to go for a simple rubber door sweep that clamps on with a metal bracket instead of being screwed in. It was much easier on the surface and didn't require me to find solid, unwarped wood for the mount.

My door settled a bit over time, and that little gap at the bottom started getting huge in the summer becasue of the humidity causing the jamb to swell. The clamp-on sweep handled that shift much better than the fixed screw-in type did for me. I used a small piece of thin scrap wood behind the clamp to help keep it tight against the bottom of the door and the threshold.

It felt more robust and didn't worry me about splitting the wood when I tried to drive the screws in before. It keeps the cold air from creeping in near the threshold when the temprature drops. If you have a hollow door, seriously consider the bracket and clamp setup. It saves a lot of frustration when you don't have solid wood underneath you.

My expirience with this was diferent. I spent a year dealing with whistling drafts and thougt the door itself was the only reason. But I figured out the issue wasn't the bottom of the door, but the threshold itself. My floor is perfectly flat, so the door is hitting the base at the wrong points. I found that the wooden threshold running along the wall was warped by the damp, creating a subtle bow in the middle. It wasn't dramatic, just uneven. To fix it, I used a very small piece of heavy-duty rubber shim, about an inch thick, and slid it under the metal guide of the threshold right in the middle. This leveled the whole entry point, and suddenly the door ran perfectly flush against the gap. It was just about getting the base level before even thinking about the seal.

I disagree with the idea that a clamp-on sweep is necessarily superior for handling wood movement. While your approach sounds like a headache for hollow doors, relying on a clamp to adjust to a massive shift in the jamb is actually risky. My experience was that when the gap widened due to humidity, the clamp just slid across the opening rather than creating a tight seal. A high-quality, heavy-duty seal should be designed to compress even if there is a bit of minor shifting, not just rely on a bracket that holds in one spot. Have you tested how the clamp performs if the gap gets extremely large? I worry it just loses all contact.