As winter arrived, I noticed my garage door’s threshold (you know, the part of the door that’s on the bottom that you step over every time you go through the doorway, and sometimes trip over when carrying things that block your view) had started to rot and degrade.
First thing I did was take measurements of the threshold including height inside, height outside, width, and length. Measuring length is tricky as the threshold likely will go under the side door jams making it actually longer than what you can see. So to be sure, you’ll want to buy a longer threshold than the visible part you measure just to be sure. You’ll end up cutting it shorter, but you cannot make it longer of course.
So, I figured it was time to replace it. Since I had no idea how it was installed and didn’t have any of the correct tools, I started out watching several YouTube videos on the subject. In the end, I found that my situation had slightly different characteristics than all of the videos I had watched.
So, I started out on Amazon purchasing several tools, parts, and other items I didn’t readily have available. Here are those items I ended up buying after carefully reading the reviews to be sure they would work in my situation. Thankfully I have Prime so shipping was free, fast, and returns were easy in case the products didn’t work for one reason or another.
Purchase Parts, Tools, etc.
- (Hammer) Drill: I wanted a corded drill to avoid batteries running out of power in the middle of the job, plus when you don’t use the tools often, the batteries end up not being able to hold a charge after a long period. I also needed a hammer drill to drill into the concrete, so I purchased a 2-in-1 drill/hammer drill combo. Well worth the price.
- 3" Cut Off Tool: This tool was for cutting the threshold. I also purchased a hacksaw but when I tried using that it was so slow cutting, and was thankful I had purchased the cutting saw.
- Oscillating Tool: This was for cutting into the side door jambs in case any widening of the space to insert the new threshold was needed, either vertically or horizontally. Well worth the price and purchasing it.
- Long Power Drill Phillip & Slotted: These were needed I found when to unscrew the old threshold out, one screw at the end was right next to the vertical door jamb and a short Phillips would not have worked to remove (or install the new threshold if a screw was close to the edge).
- Self-Drilling Anchors: For placement into the holes drilled into the concrete needed to hold the threshold in place.
- Caulking Gun & Caulking: Recommend caulking that is compatible with concrete, wood, metal, etc. so it can be used for this entire project. Important note, do not buy self-leveling caulking for concrete, that is of consistency equivalent to goo/water and will not hold shape vertically.
- Face Shield: Be sure to purchase a more sturdy shield, not the kind used for today’s pandemic. It needs to hold its place and be sturdy enough to deflect any shrapnel that may fly at your face from a saw disk breaking apart, coming off the axle, or pieces of aluminum coming off the threshold as you’re cutting it. SAFETY FIRST.
- Composite Shims/Levelers: Usually shims are made of wood, but after I saw the rot in the old threshold made of wood, I decided to go with something that would not rot to avoid issues related thereof. I hadn’t initially ordered these and found that they were needed because my garage was sloped (for drainage) as it was on the side of the garage. This delayed completion of my installation by a week waiting for them to arrive the next weekend.
- Aluminum Adjustable Threshold: Highly recommend metal material or composite. Wood will just rot eventually, not to mention attract termites too. Also, adjustable height is a necessity because you really won’t know how you may need to adjust the threshold’s height. But, be sure the adjusting range covers the measured maximum height or lowers to at least the minimum height you may need to clear the door and the sweep attached to the bottom of the door. (The sweep is what comes in contact with the rubber insert that goes into the threshold so they meet and make an air tight seal.)
Remove Old Threshold
Once all parts have arrived, you are ready to remove the existing threshold. You want to be careful removing it so as not to destroy and of the side door jamb or other parts that are not part of the threshold itself. My old threshold was made of wood connected to metal (outdoor part). The wood was almost all rotted. It had 4 screws that I removed first. Then I slowly pried the rotted wood out with an old, large flathead screwdriver. I thought the screws went all the way into the concrete, but they ended up only going into wood that was glued somehow to the concrete surface.
Once you remove the threshold and sweep what you can way, be sure to scrape any glue/caulking residue off the concrete well. (Note if you do not have a concrete foundation as I do, you may need to research what to do if you have a wooden foundation.) Next, you will want to either mop the area to remove any dust (otherwise any caulking you apply to the concrete will not adhere well). Let it dry completely for several hours or a day.
Next, measure the length where the new threshold will go, including the distance into/under the door jamb where the previous threshold was. After measuring twice and assuring you measured the correct length, you’re ready to cut the threshold to the desired length. When cutting the threshold, you will want to cut from both ends to keep the screw holes centered and not end up with a screw hold right at an end.
Cut New Threshold
The new threshold will likely have a removable adjustable part, and rubber gaskets along the edges. Before taking the parts apart, mark them left and right so you know exactly how they were assembled. Also, measure the length of the new threshold and subtract the length measured on the foundation that is needed. Divide that total by 2 and that is the length you will remove from each side of the new threshold to keep the screw holes centered.
Now, take the adjustable part out of the base if applicable. Remove any rubber gasket seals, if part of the assembly, as well as the vinyl seal that fits on top of the threshold. Put on your face shield. Using either the cut off tool or hacksaw, remove the length from each side of the threshold base and adjustable part. Next, cut the removed rubber gaskets and vinyl seal to length and re-insert them. Re-assemble the threshold to assure fit and measured length is correct. File or sand any sharp edges as desired, and assure no cut areas have bent metal pieces that could interfere with re-assembly.
Dry Fit Assembled Threshold
Always dry fit! Once re-assembled, place the threshold into the location where the previous threshold was installed. Assure the fit at the door jambs is acceptable.
- Close the door and check that the vinyl seal snugly meets the sweep on the door bottom and no air passes through (test using a flashlight or daylight and see if any light passes through.
- Check that the distance between the vinyl seal to the sweep is consistent and the same the entire length. If it is not, you may need to add shims underneath the threshold to level it out as needed. If shims are added, be sure to mark precisely where they are located on the concrete foundation as well as on the threshold using a sharpie or other marker. Also, you want to be sure the shims are not under any screw holes on the threshold.
- Check that the vinyl seal is centered directly under the sweep so they touch one another completely without excess overlap inside or outside.
- Now, mark where the screw holes are onto the concrete foundation to mark where you will drill holes to hold the threshold in place. Double check the marks.
Drill Foundation Holes
Using the drill/hammer drill, you will take a masonry bit that is just larger than the diameter of the threshold screws (since you will be putting screw anchors into the holes) and drill holes into the concrete to the length of the estimated distance they will need after going through the threshold. Once the holes are drilled, using the appropriately sized anchors (meaning the screws will fit into them), insert the anchors into the holes. Again, be sure to wipe all dust away from the drilling with a wet cloth and allow to dry.
Dry Fit Again
Next, dry fit the threshold atop the shims, and adjust the threshold height as needed (you’ll need to remove the vinyl seal if you had fully inserted it into the threshold). Partially screw the threshold screws through the threshold holes into the anchors in the concrete to assure all screw holes are lined up properly. Gently insert the vinyl seal to check height. Do not fully tighten yet.
Assure all spacing is as desired and a snug fit is between the door when closed and the sweep/vinyl seal make a snug air tight seal. If all fits well, remove the screws and threshold.
Caulk Shims to Concrete, Fill Space Between Shims
Using concrete compatible caulk, adhere the shims to the concrete foundation where you had precisely marked their locations. If layers of shims are used, caulk them together on top of one another as dry fitted. You can let the shims dry overnight or for several hours so they don’t move easily. Or just use caution not to move them if continuing.
Next to prevent pests, air flow, etc. from going under the threshold due to the added shims, fill in all spaces between shims and make the caulking layered high enough to meet the entire base of the threshold so it will make a complete seal. Also put caulking on top of the top shims to adhere to the threshold. Now, place the threshold on top of the caulked shims and make sure there is an air tight seal between the threshold, past the shims, to the concrete foundation. Add caulking as needed if no sealed.
Fasten Threshold
Screw in the threshold screws into the anchors in the concrete just barely. Now, adjust the adjustable part of the threshold until desired height reached. Check with door closed that it forms a tight seal. If acceptable, now tighten the threshold screws into the anchors in the concrete, careful not to overtighten/strip the anchors.
Double check the seal from door bottom sweep to vinyl seal and all potential gaps under threshold. If all fits well, you may need to then add caulking to the sides of the threshold where it meets each door jamb in order to fully seal from pests and air flow. Let dry for several hours before closing, otherwise the caulking will move and smear. If closing the door at night, try to re-open next day or two to continue allowing the caulking to dry completely.
Clean up, put tools and spare parts away. Don’t worry too much about the cost of the tools if you have to buy them, they are very robust and can be used on many other projects and repairs.
Hope you have found this informative and helpful!
