Welp, we had some rot. Specifically, the trim around one of our exterior windows was rotting away. How can you tell if window trim is rotting away? It feels like a sponge when you poke it. Wood is not supposed to resemble a sponge. Since winter is coming (don’t laugh, we have embarrassingly short summers!), Mrs. Frugalwoods and I are trying to knock out a few needed projects on the exterior of the ol’ Frugalwoods home and this rotted window trim quickly ascended to the top of the list. Our reasons for replacing it were not entirely cosmetic–rotten window trim can let water infiltrate behind your sheathing (the board, plywood, or OSB layer underneath your siding). If water gets to your sheathing, all sorts of bad things happen: mold, rotting insulation, and in the worst cases, rotting framing members. We’re lucky because the window itself is a relatively new vinyl replacement window. Vinyl window are awesomely weather resistant so I knew we didn’t have actual window issues.
If our windows were wooden frames, we’d likely have a bigger problem on our hands. Fixing it isn’t rocket science, but the going local rate for this project is $350-$500. Knowing that this cost is almost entirely labor, we figured we could do better, and we did! Demolition is my favorite part of any home improvement project. Nothing like bashing things with hammers to make me smile! For this project through, you’ll want to be gentle. First try and figure out which trim sections are rotten. Our window had both a flat board (sometimes called a “brick mold”) as well as a decorative molding. I originally thought it was only the brick mold that was rotten, but it turns out the molding was also getting soft in spots. Poke around with a screwdriver and you’ll quickly note which components are in need of repair. If it feels like wood, great! If it feels rubbery or spongy… then it’s time to tear it out! Once you’ve determined which components need to go, use a small pry bar to start removing the pieces.
Your goal is to expose enough of the boards to get accurate measurements. Once you can clearly see what’s where, take a photo and measure the dimensions. If you can keep the trim pieces from falling apart as you demo, it will make cutting your new pieces to fit all that much easier. Now finish removing all trim boards and pray to the god of old houses that you don’t find additional rot as you delve deeper into your wall. If you do find rotten sheathing or even framing… then you have bigger problems. Not insurmountable, but also maybe not a weekend project. If that’s the case, then you should go find another how-to post 🙂 Now that you know the quantity and size of trim boards necessary, head to your local home store and make a beeline for the construction supplies. Here’s a pro-tip: Most of the pros are pretty nice. If you are confused, ask the guy in the filthy shirt with giant bulging muscles for advice. Dude will almost always hook you up. In our case it was a very nice Eastern European gentleman with forearms the size of cantaloupes who explained the finer details between brands of cellular PVC trim.
It’s time to inspect and insulate around the window. If you have a house built in the last 50 years, it won’t look like this. Modern houses use plywood or OSB (oriented strand board) as their sheathing. Besides being cheap, strong, and not requiring the destruction of old growth forests, OSB and plywood also make for very tight window installs. Old houses like ours have board sheathing. In addition to being expensive, weak, and requiring the wide-scale deforestation of most of the United States, board sheathing tends to be poorly fitted around windows. C There’s probably a better way to do this, but wow do I love spray foam. The stuff is magical, especially for filling giant irregular voids. Four extremely important things to know about spray foam: So have a plan! Move quickly and evenly apply a light layer of foam wherever your voids are deepest. Keep working your way around the window filling cracks, voids, holes, and whatever else gets in your way. In our case, we had giant voids to fill. I
f you have a newer home you might only have the area immediately adjacent to the window frame to insulate. In either case, insulation is worth the money while you have the window opened up. Might as well do it right. After you’ve foamed all there is to be foamed (plus some stuff that probably shouldn’t have been, but you know how it goes…) take a break while the foam hardens. It should be fine to continue working after 20 minutes or so. If your house was built correctly, you won’t need to do this step as you’ll already have flashing. As for us, we needed it. Flashing a window is a way to seal the area around the window from water infiltration while allowing any water that gets behind the trim boards to exit the wall structure. You can use all manner of materials as flashing: plastic, aluminum, lead (yes, and it works great!). We chose a flexible, sticky asphalt product commonly know in the trade as “Ice and Water Guard.” This stuff is really easy to use. J
ust cut your pieces to size, peel the backing paper off, and stick it up. You’ll want to apply the various pieces around the window from bottom to top. That is, you want water to be able to travel down the face of the flashing and never find an overlapped seam facing upwards. For the top strip of flashing, try to get it as far underneath the layer of siding above as possible. For the flashing on the sides, try to end the flashing on top of the bottom course of siding. This sounds great in theory, but reality can prevent it from being perfect. Just try the best you can. Now measure for your trim and cut. I like working from the top down, but I have no idea if that’s actually better. Our old brick mold wasn’t mitered in the corners so I followed the pattern and butt jointed it. Yes, I just said butt joint. It’s a carpenter’s term, for real. To cut a straight line with a chop saw or miter saw is simple. If you are making the cut with a circular saw, draw a straight line on the board with a carpenter’s square to make sure you don’t wander. D
on’t be a cowboy, you and I both know you can’t eyeball it. While the left side and top of the window was a dead ringer for 1×5, the right side was juuuust too small for me to wedge it in there. Oh the joys of old houses! So I scribed the 1×5 to match the variation in the siding edge and ripped it with the circular saw. This I did mostly eyeball because I knew I would be covering the crappy edge with the decorative molding. Screw the boards in place with your nifty special screws (they are actually pretty neat) and step back and admire how much more like a window it looks already! Unlike your trim board brick mold, decorative molding is pretty ugly in the corners unless you cut it on a 45 degree angle–aka a miter joint. When faced with cutting a miter joint, normal folks would go out and buy a miter saw. This makes it really easy to cut perfect miters every time, but will run you a couple hundred dollars. If you are like me and a member of team “if it can’t be done with a circular saw then you shouldn’t be doing it,” then read on. C
utting a 45 degree miter is not much harder than a 90 degree straight cut. The trick is getting a good line in place, and for that the carpenter’s square is essential. Measure carefully to the outside of the miter (the longest part) and check your marks twice before cutting. It’s really easy to get confused and draw your 45 degree line in the wrong direction (ask me how I know this…). Once you have your line in place, carefully follow it with your circular saw. If you go slowly and check your measurements, no one will ever know you didn’t use a miter saw. Now screw in your molding and admire your handiwork! Oh you thought you were finished? Nreak out the caulk and run a bead on all of the joints. Smooth each joint with a moist finger (no joke, the best way to get a good caulk line). Don’t forget to add a dab of caulk to each screw hole as well. Once the caulk is dry you can decide whether you want to paint. So far we haven’t, because the new white trim matches our existing trim pretty well.
Now you are actually done. Bask in the glory of saving hundred of dollars. Revel in the new confidence you built in your DIY skills. Or just take a shower. You probably need a shower real bad by now. We’re focused on building (hah!) a sustainable life, both from a skills-learning perspective AND from a stable financial perspective. Our immediate goal is to “retire” early to a homestead in Vermont and leave our city jobs behind. As part of that plan, we’ve embarked on a journey of radical (sometimes hilarious) frugality. Sometimes it’s trimming a window, other times it’s cutting my wife’s hair at home (way scarier for me than window trim!) Want to know more? Check out our About page to investigate the radical frugality journey so far. Hope your own window trim project goes well! Feel free to ask questions in the comments — we still read and respond to them even though this post is nearly a year old. Never Miss A Story Sign up to get new Frugalwoods stories in your email inbox.