Four years ago I replaced the rotten threshold of my back door. I took a plank from a pallet, sawed and planed it to fit, caulked, applied two coats of Thompson's sealer, and painted.
Before long, the wood was getting wet. It soon rotted.
What's a better way to make a threshold?
Don't wet it.
Thompson's is junk. Never use the stuff. If you want it to last in a wet environment use a wood rated for ground contact.
As Keith notes- best plan is to make it stay dry. chances are you are rotting out the nearby sill 7 god-knows-what-else. And you're throwing money away with Thompson's.
Then I'd make it out of Mahogany, Ipe, or even PT Yellow pine. [I made one 25 yrs ago from whatever red mahogany-like wood was found in an old castro-convertible sofabed- It still looks like new.
Most [domestic] pallets are made from twisted elm. Hard stuff to break, but not known for its decay-resistance. Come to think of it, a friend worked in a BeechNut factory in the 60s. All the gum came from south America and was on Mahogany pallets or in mahogany boxes-- lots of the boards were 5/4x12- but never more than 3-4' long. Me made a lot of bowls and trinkets with it, though. I doubt you'll find mahogany pallets these days.
If you like the wet-wood look that you get with Thompsons- mix Boiled Linseed oil & Turpentine 50/50 & apply until it will take no more.
Jim
Make it out of white oak and fix whatever's causing it to stay/get wet.
gl
If it rotted so is more you cant see below, treated wood, concrete, an awning are ideas I have stone ones.
You could use pressure treated wood. Might last longer.
Concrete.
Plus, take the door frame out and reinstall it properly with flashing and sealing in the appropriate places. Seen a lot of rotted thresholds in my life, and almost all were due to ponding water from outside, because whoever added the porch didn't hold it down an inch or two like you are supposed to, and didn't seal or flash under it. (rim joist right under door in basement usually has visible water marks.) Most of the other rotten thresholds were from water entering at top or sides of door frame, traveling down the gap between jamb and rough opening, and ponding on subfloor under threshold.
-- aem sends...
When I replaced a rotted threshold, I discovered severe damage to the sill beneath it going a few feet in both directions. It was a major repair.
Any rain that hits the storm door ends up on the sill. I have kept it dry by cutting open a plastic bag and taping it inside the door along the bottom so that when the door closes the skirt drapes over the sill. That's not a permanent solution.
The threshold is 7" above a concrete step. When I replaced the threshold, I replaced the sill and put on a pressure-treated fascia board with an airspace behind it to help keep moisture from reaching the sill.
I knew that the threshold, unlike the fascia board, would be exposed to standing water. I thought wet pressure-treated wood could cause rotting in adjacent wood. Swelling and freezing could also cause damage. Metal flashing didn't seem feasible, so I tried paint over a penetrating sealer. I don't know if it could work with the right wood, the right sealer, and the right paint.
I replaced my rotten window sills with redwood. That was 15 years ago.
Jimmie
Pressure-treated wood is far better than any "pallet" wood you scrounged up.
Windows and doors these days are installed with drain pans at the bottom. These are sometimes plastic membranes like SealRite, IIRC. Go to web sites for the better manufacturers, typically JeldWen, and review the installation instructions. Alternate systems of drain pans can be fabricated from copper flashing along with plastic window screen to permit moisture flow, a method I have used successfully. The copper also discourages growth of nasties that rot the wood. First, however, rebuild your structure to a proper level of soundness with treated lumber, not the cheap wet stuff used for for backyard storage sheds. The better boards are southern yellow pine, ACQ treated for example. Then when you have a decent rough opening, install the frame and door, finally dealing with the exposure to casual water by using a storm door or adding a portico.
Joe
Use an "outdoor" wood and protect it with a polyurethane.
I replaced a rotted oak threshold with some solid vinyl trim, still looks new three years later. It may not wear as well but its never gonna rot.
That could be a practical solution for me. What sort of trim should I look for? Is it thick like a board?
I want to keep moisture from penetrating at all. Pressure-treated wood wouldn't rot, but moisture penetration could still cause trouble. Thompson's in the kind of wood I used didn't work. Now I'd be reluctant to trust Thompson's in any kind of wood.
What is "outdoor" wood? If it holds polyurethane well, what else matters? Does polyurethane stand up well to UV?
Figuring out how to keep the water out is the best solution.
I've used pieces of that composite 5/4" deck board for various things where I though it may get wet. As another posted mentioned cedar and redwood are good choices.
The wood from a pallet is the cheapest low grade wood you can find. Probably pine. You leave a piece of untreated pine wet for a year and it's be rotten to mush.
The original Thomsons was great stuff - but about 15? years ago they had to change the formula and now whizzong on it would likely do as much good.
Have not seen a pine (or other softwood) pallet in years. Usually assorted hardwoods - ash, maple, birch, and rough oak are pretty common - and I've even gotten some ironwood.
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