We all want cheaper lumber, right? Well, you may not want “cheap” lumber, but you certainly don’t want to pay any more for your materials than you have to. And that’s where finger joint lumber comes in. While it can save you a lot on your lumber and molding costs it may not be the best choice for your project.
Finger joint lumber was the lumber industry’s way of creating the long pieces of wood that we need for non-structural things like trim and casings. Sure you can buy non-finger joint versions which are usually called stain grade, but they cost a lot more than their finger jointed cousins. Why?
How is Finger Joint Lumber Made?
Wood manufacturers take some left over lengths of wood that are too short to use anywhere else and cut the ends of them with a finger joint profile. It’s not complicated, you can make your own finger joint profile with a finger joint router bit if you wanted to. It’s a great way to make a piece of wood extend to almost any length by adding more and more pieces to the end.
The finger joint is then glued with a wood glue or other adhesive and clamped together to cure. Once the glue is cured and the clamps are removed you can sand or plane the wood smooth so that the joint lines up perfectly and once painted the joint is usually invisible (for a time).
Finger joint lumber is cheap because the manufacturers can use small lengths of leftover wood to assemble full length of moldings. That equates to cost savings sure, but what does it do to the performance?
Finger Joint Performance
This is just my opinion from working around the stuff for years. Sometimes I’ve installed it myself, but more often I’m the one removing it when it fails. It can work well, in larger pieces when there is ample gluing surface to help hold the pieces together, but it still has one fatal flaw.
Wood moves. Wood expands and contracts in response to the conditions in the environment around it like heat, cold, and moisture. The problem with finger joint lumber is that every piece of wood moves differently and the piece of wood on one side of the joint vs. the other side will almost always expand and contract at different rates. This results in the joint weakening and pushing apart over time.
Even if there isn’t failure of the joint the expansion and contraction often results in the joint projecting through the paint where it can be clearly seen. Can you say, “ugly”?
Joints like in the picture at the top of this post tend to perform best because of the large glue area, but small finger joint moldings like door stop, cove molding, quarter round and other similar items often don’t even have the strength to survive transport from the store to the job site.
Should You Use Finger Joints?
I certainly won’t yell at you if you do. NOOOOOOOOOOOOO!!!! Just kidding! Finger joint lumber should never be used for anything structural or exposed to the elements, but if you want to save a little to put some new casings in your closet then sure go ahead. Just be aware that you get what you pay for and it is much cheaper than solid wood. What does that tell you about the quality you are getting?
My thinking is very much in line with what Benjamin Franklin famously said, “The bitterness of poor quality remains long after the sweetness of low price is forgotten.”
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I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.
I used finger join to cut Victorian baseboards with my router table. They worked great for the non structural 1×8 boards because there were no knots so less jitter. I had a bit more to finish but the lumberyard ran out, and now sells only primed finger join which is total crap. The only real reason they sell pre primed is to hide the garbage knotty wood. So never ever buy pre primed finger join unless you like to be ripped off.
Correction. Douglas Fir (From the NW) is more structurally sound then any finger jointed lumber. Speaking as a structural engineer.
What? I don’t understand what you’re saying, because the two examples you’re comparing aren’t mutually exclusive. Finger-jointed lumber can be made from Douglas Fir from the northwest… I don’t get it.
From Engineering point more the joints; lesser the strength of structure. Failure of any joint leading to failure. Also, wood as strong as weakest joint.
I worked at Sierra Pacific back in the early 80’s. I tailed off and ran the cut back saw that the company used for finger joint molding. Our good stuff went overseas. Finger joint to my knowledge is not for exterior use. European’s would not accept any shipload that had even one board with a pitch pocket that wasn’t repaired
I think besides making a dollar or two, it was as you say for the longer boards. But they are supposed to be primed and painted. The molding division I worked at used oil based primer.
The theory was the coverage would help protect the white glue. We didn’t have the selection of glues available today. And as for pine not lasting, perhaps the new growth which is not as stable. But we have old growth pine that’s as hard as cement and a bear to drill through…
Do I use finger joint lumber – nope. I know how to use a coping saw
So, yeah, I agree.
Two years ago I re-sided my garage with a lot of expensive red cedar shingle. I used finger joint lumber for the corner boards and orange store pine for other trim boards. This summer I noticed the finger joints are becoming visible through the paint. So I’ll be spending good money after bad to fix the issue. The rest of the trim looks fine. But it’s well protected with roof overhangs. Don’t know what I was thinking with the finger jointed stuff. I guess it was dirt cheap at the local Builder’s Surplus.
I’m re-siding my house now, red cedar, stained with BM solid stain. Never chips or peals. Goes 10 + years before a re-coat is needed.
I’ll be using mahogany for the trim boards. Oh, that’s expensive! people have said to me. And overkill as well. Approximately $1800 total for entire house.
BTW, I live in Cranston, Rhode Island. Close to Providence.
So let’s see. typical orange store piece of 1x6x8. They call it Select Kiln-Dried Square Edge Whitewood Board. Cheap pine in other words. Properly prepared it may last several years. How many? I don’t want to find out. Cost: $2.34 per board foot.
L. Sweet Lumber. Been around longer than anyone can remember. High quality materials and some say rather pricey. You know the old adage.
1×6 Philippine Mahogany (Meranti). $3.45 per board foot.
Easy to work with. Has rot resistance similar to Cedar and Redwood. Is not too heavy. Takes a finish well.
I am overly confident that this wood will outlive me twice over if primed on all 6 sides, installed correctly and painted on a regular basis.
But you know what will happen. I’ll croak and the next person who buys my house will slap vinyl all over it cuz they hate maintenance.
You are definitely going to be appreciated by the next guy!
My husband has been saying this very same thing. We have actually seen brand new homes that have this lumber in it for all the supporting structure. Some of the pieces were already coming apart and warping. Why would you risk the structural integrity of your home or someone else’s home with wood that was not made for this purpose? Plus, these were $300K homes. SAD.
It’s everywhere these days!
they are actually making finger jointed 2x structural material now. its not going to be seen so its not a issue for aesthetics. and its stronger than any piece of #2 spruce you’ll find on the market