# Accounting for Wood movement in joinery



## Eric_S (Aug 26, 2009)

So I'm getting ready to start designing nightstands and since I'm new to woodworking I'm a little confused on wood movement in regards to joinery. I understand wood moves more across its width, and some species more than others. I also understand that quarter sawn is more stable than rift, and rift is more stable than flatsawn.

What I am confused about though is joinery. I keep watching online videos from finewoodworking and wood whisperer and whenever they do mortise and tenons or dovetails or any other joints, they are always very tightly cut so that the joints are strong, yet I always hear to account for wood movement. So is it always necessary? How do I make a mortise and tenon that allows for woodmovement while still keeping a strong/tight joint? Same for lap joints and pretty mucha ll other joints. Can anyone help me on this? I want to make sure I design the joints correct the first time. I live in Indiana.

Eric


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## mstenner (Oct 6, 2009)

The short answer is this: when two pieces of wood are joined with opposite grain directions, but only over a SHORT DISTANCE, then you don't need to worry about it. What's a short distance? A few inches (typical joinery sizes) are fine. I've heard 12 or 18 inches tossed around. For example, if you're putting a breadboard end on a table, you typically only glue it in the middle and use pegs/dowels that can move on the ends. If it were only 10 inches long, you could probably just glue the whole thing.

Note that dovetails are almost always done so that the cross-grain directions of the two pieces are in the same direction. That is, a drawer might get taller or shorter but the boards will do that together. The change in thickness of a 1/2" drawer side will be completely insignificant.


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## Eric_S (Aug 26, 2009)

Thanks mstenner, that helps a bit and makes perfect sense.

I found this article on finewoodworking for online subscribers (14 day free trial) http://www.finewoodworking.com/fwnpdf/011165044.pdf that shows how to do mortise and tenons and other joints to account for woodmovement. He is showing tenons of less than 5" wide being pinned and glued only at the top. Really? Is this truely necessary? This article is whats causing my confusion.


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## mstenner (Oct 6, 2009)

Yeah, that seems a little extreme to me. Maybe extra care is taken there because it's such a stressed joint. Perhaps the wizened old graybeards can shed some light on the middle ground. I've seen in many cases people recommending gluing the entirety of a 3" tenon. Realistically, the "middle ground" is probably the sort of territory where either approach will work.


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## Eric_S (Aug 26, 2009)

The tenoned joint he shows is from a bed headboard so maybe it does take extra stress? So realistically I should be fine gluing up the entire joints in a nightstand except for the top? I still havent' decided if I'll do frame and panel sides yet or slab. Also in that article, it shows the bottom of a slab chest loosely sitting in a groove similar to a frame/panel and resting on the aprons. Would I need to do this for the bottom of a nightstand that would probably measure 30" x 15-20".


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## DanLyke (Feb 8, 2007)

I have no actual empirical evidence to back this concern up, but my guideline is that I become concerned about wood movement with more than 2 or 3 inches of cross-grain joint. In thinking about it this is probably way too conservative, because many people make their tenons 2 inches wide, but there's no way I'd go five or ten inches with a glued cross-grain joint unless I knew specifics about how that wood will expand and contract, and for 4 inch wide frame pieces I'd make the tenon smaller than that and only glue the tenon..


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## scottishrose (Sep 25, 2009)

I'm a newbe to woodworking myself, but if you are designing side tables and you are putting panels in a stile and rail type frame allow a bit of room and only glue the stiles and rails. You might want to take into consideration where you live and the time of year you are building it. For instance I live near Seattle where the winters are damp and summers are dry so while building in winter the wood is more swollen so put stain or color on the hidden part of the panel before glueing up so it doesn't show in summer when it gets dry. That is the opposite that one would do say in Minnesota where it gets very cold and dry in winter and humid in summer. In either case you have to leave room for panel movement and gluing just the joints lets the panel move freely with the change in humidity.


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## mosaicwes (Sep 14, 2010)

I see a lot of projects posted on LJs that I'm sure are doomed to failure and often wonder if a person should point it out to the newbies or not. What's the protocol?

Don't want to sound like a crotchety old know it all but hate to think that some newer woodworkers might make the same mistakes several times before learning the hard way, over time.

If we're talking about fine woodwork, as in furniture etc., I would never expect a cross-grain joint of most solid wood types, of more than 3 or 3 1/2" across max, to hold for more than a few years at best and perhaps not very long at all at worst. 
Certainly there's a difference between a very dense wood like Eastern Maple and a softer more porous wood like poplar or Western Maple but…. all wood moves seasonally. I would never do a cross-grain joint of 4" with just glue and expect it to hold longterm. If it's a tenon, break it up into two smaller ones. 
Cross grain edging on a table or tray or breadboard… use a breadboard joint. Some sort of movable mechanism for the panel to expand and contract, like dowels in a slot, and glue only the center 3". 
There are metal fasteners specifically for this purpose where they can be hidden, under a tabletop for instance.

Spend some time in an antique store and study the traditional ways of furniture building. There's good reasons for all those techniques and short cuts can lead to disaster down the road.


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## LeeBarker (Aug 6, 2010)

Good answers. Oh, and a good question, Eric! How about this:

Pick a number for yourself, based on this sample and or others, and build two nightstands. While you're at it, make a dummy piece with several widths of joint involved both smaller and larger than what you decided on, and take it in the house and stick it under the bed. (Maybe do this in several species, too.) Or wherever, just so it's a heated place. In a year, drag it out and take a look at it. You'll become the local expert on Area Wood Movement.

Meantime, relax and build the nightstands. That's a great project-door and drawer, but nothing overwhelming. Have fun. Let the anxiety fly out the window and just dance with the plan and the tools and the wood.

Kindly,

Lee


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## rsdowdy (Aug 25, 2009)

I don't know about the protocol, but if I posted a project, I would really like corrective input into the project. If the corrective input is severe, then I would perfer it in a personal email/mail/note to me with a kind critisim to the viewing public so I won't look so much like a left shoe. Oh, what am I talking about, if the shoe fits then let me have it, but this is what I try to do in other things I am more profecient at than woodworking. A gentle helpful reproach, and if something is muderous, I would send a a personal mail stating they might want to delete their post and here are the reasons why, and if they want more help, please email me. Like our pastor has said, if you see a problem and open your mouth, congratulations, you have just volunteered to fix said problem.

Royal


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## gargey (Apr 11, 2016)

I think wood movement is overblown.

Don't glue/screw table tops, or mismatch length & width in other LARGE scale or EGREGIOUS applications.

Evidence of exploding furniture is sorely lacking.


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## Unknowncraftsman (Jun 23, 2013)

Every woodworking project should start with.This is what I am going to make.What wood will I use and do I have enough.Plus extra for back up since we never know for sure how certain parts of a plank will behave until we start cutting into it.
What jointery will I be useing is my wood right for this build.
Color, weight, durable 
So I think it's a good sign when someone's asking these questions at the beginning of any build.Being sensitive to how to work wood is what separates us from junk furniture that's sold to the majority.

Aj


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## mosaicwes (Sep 14, 2010)

Gargey: There is absolutely no aspect of wood joinery that is as non-understood as wood movement. 
I've repaired everything from high end guitars to solid wood furniture of all kinds that have had failed joints, 
not necessarily because of improper builds, but simply as the result of wood movement. 
Look in the dumpsters behind apartment buildings and you'll find tons of evidence of exploding furniture.

If you live in a desert it's of little consequence but if you live near the coast, as I do, it's a huge issue that needs always to be considered when planning a build.


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## gargey (Apr 11, 2016)

Wes & Aj2,

There is no shortage of poorly built ANYTHING these days. Most of the exploded furniture behind apartment buildings is likely due to poor build quality (materials and joinery) rather than a lack of consideration for wood movement; good luck finding solid wood in most of it.

I'm not suggesting that we should disregard the phenomenon of wood movement. It deserves consideration. I am suggesting that the OP (and others) should not freak out about *small scale* grain mismatches if the joinery is otherwise well considered. By and large it will not matter (in the opinion of gargey). It is common for people to learn something new, and then get carried away…

..

Wes, you mentioned failed guitars… For the culprit to be wood movement, in your opinion, can you describe what joint failed? I'm just curious. I assume it would have to be some plainly face-glued piece glued cross-grain, with no other fastening (i.e. not a great joint)? How can you be sure that heat, water, impact, were not contributors? Sincere questions.


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## mosaicwes (Sep 14, 2010)

Heat and water, as you put it are not just contributors, they are the very real cause.
It's called weather and has nothing to do with projects left out in the rain.

On a bright and clear sunny day here on the coast, the humidity can be 95%. 
Warm are hold more moisture than cold air. 
In the winter, it could be raining and relative humidity is only 40%.

Unless you have a system of humidifiers and dehumidifiers like they do in guitar factories,
the moisture content of the air is constantly changing and even wood projects with a heavy varnish on them,
will contract and expand in response to those changes. 
Like I said, if you live in a desert, this isn't a factor.

I fixed and older, good quality classical guitar just yesterday.
The fretboard had let loose for about 10 inches from the headstock towards the body.
Rosewood on mahogany, both pieces running the same direction obviously.
The mahogany neck (still no wear thru the varnish after 40 years) had expanded 
slightly more than the the fretboard.
Only a tiny bit but nevertheless, enough to cause the joint to fail.

In antique stores you see all kinds of failures even tho the guys who built the furniture, knew what they were doing. 
No glue, can hold a joint forever if the wood is moving at slightly different rates. 
It doesn't have to be cross grain to fail.
Virtually all chairs built with round mortise and tenons (rungs) will fail eventually because the hole expands and contracts into an oval shape and so does the rung.

I'm a retired, ticketed joiner. Also used to teach joinery at a trades college.


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## BulldogLouisiana (Apr 12, 2015)

> Wes & Aj2,
> 
> There is no shortage of poorly built ANYTHING these days. Most of the exploded furniture behind apartment buildings is likely due to poor build quality (materials and joinery) rather than a lack of consideration for wood movement; good luck finding solid wood in most of it.
> 
> ...


I too doubt wood movement caused the furniture to be thrown out behind most apartment buildings. Mainly because doesn't wood movement only really effect solid wood? On this forum, I'd hope wood movement is more of an issue. It's possibly given too much consideration, but I'm not experienced enough to have a real opinion.


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## BulldogLouisiana (Apr 12, 2015)

Oops


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## Unknowncraftsman (Jun 23, 2013)

I do see your point I think.
Since the op's question was wood movement in jointery then the answer has to be yes.Have you ever made a mortise and tenon joint too tight.Or maybe the mortise too deep and the tenon too long.And when you added glue it nearly impossible to close the joint.
That's wood movement.


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## MadMark (Jun 3, 2014)

Download & read this: USDA 'Wood handbook: Wood as an engineering material'

M


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## Texcaster (Oct 26, 2013)

I did my cabinet making training in SoCal (coastal desert). Our rule of thumb was 1/8 in movement per 12 in of width. The only time movement is a problem is if the movement is not allowed for. There is tried and true body of knowledge to allow for movement, that is the heart of the trade.

Which brings me to guitars. Carved top guitars, mandolins and the violin family can survive very long periods because of only having longitudinal bracing or tonebars. The strength is in the arch, these instruments can handle a bit of movement.

Flat tops go against every rule of allowing for timber movement. It is highly recommended to build at relative humidity 40%. Flat top is a misnomer because top and back are domed to help with seasonal changes. The dome can flatten or swell.

I've only built two flat tops and I'm working on 3 and 4. I've built 11 archtop instruments.

Flat top #2 modified OM



















Flat top #1 carving the braces of a OOO










Quarter sawn timber with no runout is a must for string instruments.


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## rwe2156 (May 7, 2014)

> And when you added glue it nearly impossible to close the joint.
> That's wood movement.


This is hydraulic pressure of the glue preventing a joint from closing caused by too tight joint not allowing adequate squeeze out.

Eric -

mstenner offers a good, practical answer which I agree with 100%. 
scottishrose has the right perspective IMO.

My experience: I've never been concerned about wood movement inside a standard M/T joint and I've never considered it an issue except a very wide apron or a breadboard edge. Have to see the exact design of your project.

I think there is a lot of "analness" and overkill regarding wood movement. One of the first things I ever built almost 30 years ago was a coffee table. All put together with dowels, not a thought about movement. Even though now I know it violates everything I know about mounting a tabletop, it has never cracked, split or bowed to this day.

If you take a look at the FWW video on building a highboy by Phil Lowe, you will see a piece with maybe 24" high sides and back MT'd to the legs. You could never glue a tenon that wide. I have seen similar examples of antique furniture with splits across the side panel because they were glued up entirely.

Way more important to keep in mind is where you build your project vs. where will it reside? There can be a big problems building a project in a shop subject to high humidity, then moving it inside the house, especially with drawers and doors.


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## gargey (Apr 11, 2016)

> Heat and water, as you put it are not just contributors, they are the very real cause.
> It s called weather and has nothing to do with projects left out in the rain.
> - Wes Giesbrecht


Don't be an ass.


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## a1Jim (Aug 9, 2008)

I always send my students this link regarding joinery and wood movement.

http://toddpartridgedesign.com/sr_pages/documents/UnderstandingWoodMovement.pdf


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## KnickKnack (Aug 20, 2008)

> I always send my students this link regarding joinery and wood movement.
> 
> http://toddpartridgedesign.com/sr_pages/documents/UnderstandingWoodMovement.pdf
> 
> - a1Jim


Great article Jim - thanks for that.


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## Jon_H (Jun 21, 2016)

I reside in the land of moderation.

Living conditions are much different today than when those antiques were built and the hardcore rules for dealing with wood movement had their genesis. Homes were drafty at best with little to no HVAC to speak of. So furniture back in the olden days was subjected to more of the seasonal climate changes than pieces residing in relatively modern abodes. Any home built in the last 50-75 years is still light years ahead of anything constructed when George Washington was alive in terms of moderating temperature and humidity. Homes built in the past decade or so are practically hermetically sealed with very efficient and effective temperature and humidity control systems. The pieces we build today are subjected to much less of the climate than the antiques we like to compare them to.

The materials we work with have also advanced considerably since the era of the powdered wig. There was no kiln dried lumber 200+ years ago. A lot of furniture was built with lumber that still had a lot of moisture in it. Take a piece of furniture that was constructed with green wood in the middle of a hot, humid summer and put it in the corner of a log cabin in the midst of a frigid, arid winter, and stuff's gonna move! I would also venture to guess that modern polys and lacquers also protect our modern furniture from the elements much better than the oils and varnishes of yore.

That said, modern technology has not obliterated wood movement, nor changed the laws of physics. So there is still a need to account for wood movement. I think some consideration for the size of the project, the types of joints being used, grain direction, and the atmospheric conditions in the pieces intended resting place should all be considered. Personally, I don't blindly apply all of the sage advice regarding wood movement to each and every project, and engineer my pieces to death out of fear of wood movement . I'm not acutely anal about wood movement. Not that there's anything wrong with that, it's just my opinion and approach. I have yet to have a piece damaged by wood movement.

For a night stand that's going to reside in a reasonably modern home, there's not much concern for wood movement. Apart from the top, the component pieces really aren't going to be wide enough to have a great deal of movement. I would consider how you're going to attach the top to the base and account for some movement there. Ditto for any shelves wider than 4 or 5 inches that may be fixed to the main carcase or frame.


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## Unknowncraftsman (Jun 23, 2013)

rwe you are half right sometimes It can be hydraulic pressure.Some wood will also swell up when you add glue making the joint too tight.
Dovetail joints are a good example.
Drawers are also a good example of building for seasonal movement.Unless they are plywood.
That's been my experience.

Aj


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## peckawood (Dec 1, 2017)

Great topic. I am researching this also as I am building an entry table. My design for the top has end grain pine, 1-1/4" x 2-1/2" by 1-1/4" thick pieces, alternating grain pattern glued together to form a 5" x 34" piece. I planned to glue 5/4" x 3-1/2" pine to each side to increase the width to 12". Is this a mistake to glue the wood to the sides of the end grain piece? I am unsure how much movement I can expect from the end grain piece. Any advise is appreciated.

Thanks, Ed


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## sawdustdad (Dec 23, 2015)

Having a little difficulty trying to understand what you are proposing to do. How about a diagram or picture?


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## Unknowncraftsman (Jun 23, 2013)

Alternating grain patterns what does that mean?


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## splintergroup (Jan 20, 2015)

From what I understand of your top, attaching long grain sides to an end grain top will have problems. You can attach the wood "breadboard" style as this allows the two sections to move independently of each other.


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## peckawood (Dec 1, 2017)

Thanks for the responses. I have posted the image of the end grain panel and i am showing the wood that will border each side. I appreciate any input.

=146975573&filters[recent]=1&filters[publicOnly]=1&sort=1&o=1]http://s38.photobucket.com/user/peckawood/media/IMG_1110_zpswrr4sc0v.jpg.html?filters[user]=146975573&filters[recent]=1&filters[publicOnly]=1&sort=1&o=1


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## sawdustdad (Dec 23, 2015)

You will have issues doing what you are proposing to do. The end grain blocks in the center will expand and contract both ways, in the length and width of the table. It will eventually break any joints at the corners of the long grain boards wrapping around the center. Just a bad idea.


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## peckawood (Dec 1, 2017)

Thanks, I was unsure of how much movement to expect with the end grain piece.


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## Lazyman (Aug 8, 2014)

> Thanks, I was unsure of how much movement to expect with the end grain piece.
> 
> - peckawood


Rule of thumb is that the greatest movement is in the direction of the rings when looking at the end grain, though there are exceptions of course. This is why quartersawn lumber is usually more stable where the rings are oriented in the shortest dimension (thickness) of the board so you have the least possible movement in that dimension. So if you oriented all of the end grain blocks so that the rings go side to side, you would at least minimize the amount of movement towards the ends of the table. You may still have a problem, since it may not be possible to orient them all perfectly and even if you can, it will still be greater than the movement in the length of the flat boards.

By the way, you can calculate a rough idea how much movement to expect in any given dimension by looking up the shrinkage percentages at wood-database.com. If memory serves, the tangential factor is the one that gives you the percentage in the direction of the rings and radial is the one that goes at a right angle to the rings. Compare these to the longitudinal factor to see why this can be a problem.


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## revanson11 (Jan 5, 2012)

This is a timely subject for me. I am in the process of making a large QSWO coffee table that has a lowershelf with an 11" wide through tenon. I have made the tenon to fit tightly within the mortise (who wants gaps in their through tenon's?) From some of the thoughts here, some seem to think that this shouldn't be a problem while other think that I should prepare for catastrophic failure. Those of you that have made projects with large through tenons what have your experiences been. Thanks to all for participating in this forum.


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## Lazyman (Aug 8, 2014)

Randy, You might get better response in a new forum topic. A lot of people don't bother with old threads like this (2009). Also, there are several variables that you may need to specify such as is the tenon going through another piece of QSWO oriented the same way or will the mortise be in a stretcher. Were you planning to glue it or are you going to use wedges or some other method to secure it?


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## Dust2dust (Apr 28, 2019)

What about farmhouse bench tops? Building table with solid pine and used table top fasteners to allow expansion across 40+" but bench tops are 16". Do I still need to allow for expansion using tabletop fasteners or is it small enough so that it isn't necessary?


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## Lazyman (Aug 8, 2014)

There are several variables to consider but you can use the Shrinkulator to estimate the theoretical amount of movement to expect based upon current wood moisture of the wood species you are using and the expected change over time.

Instead of using table top fasteners, you could just make the holes a little oversized which will give you some room for movement and if you use glue, apply it only towards the middle of the width. You can also minimize the impact by moving the attachment points closer together. If for example you have the attachment screws only 8" apart, you only have to worry about half of the amount of movement so that it is probably negligible.


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