Why is it always that the stile is the mortise and the tenon is the rail?

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Forum topic by zdwiel posted 02-27-2013 09:58 PM 1325 views 0 times favorited 13 replies Add to Favorites Watch
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4 posts in 1931 days

02-27-2013 09:58 PM

Topic tags/keywords: mortise tenon stile rail windows doors joinery

I’ve looked at many doors and windows the past few weeks and every single time, the vertical stile is the mortise and the horizontal tenon is the rail in the mortise and tenon joint in the corners. Is this purely stylistic or is there a functional purpose to this arrangement?

13 replies so far

View HorizontalMike's profile


7754 posts in 2908 days

#1 posted 02-27-2013 10:02 PM

Good question. I have NO clue though. I suppose it has something to do with standardization of practices/procedures, in order to eliminate any confusion.

-- HorizontalMike -- "Woodpeckers understand..."

View Loren's profile


10373 posts in 3642 days

#2 posted 02-27-2013 10:04 PM

I think it’s traditional. It makes the door most stable in
its longest dimension. If you look at old board and batten
doors you’ll see that they move in width only, and I
reckon that as frame and panel doors evolved it became
traditional to do it that way.

Also, with an entry door with a 6” stile capped by
a rail, the joint is going to move a bit like a breadboard

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404 - Not Found

2544 posts in 2963 days

#3 posted 02-27-2013 10:07 PM

I would imagine water run off comes into it as well

View teejk's profile


1215 posts in 2678 days

#4 posted 02-27-2013 10:09 PM

End grain gets hidden that way. Few applications do you ever look at the top or bottom of a door. Plus stability.

View zdwiel's profile


4 posts in 1931 days

#5 posted 02-27-2013 10:19 PM

That all makes some sense. My first inclination was actually that you’d want it the other way around so that if there was water on your sill or threshold you would get minimal end-grain exposure, but that doesn’t seem to be important since the traditional method exposes more end grain on the top and bottom edges.

I like the idea that in both doors and windows you are more likely to be looking at the stile edge than the rails and it might look nicer to not see the joint.


View kdc68's profile


2657 posts in 2270 days

#6 posted 02-27-2013 10:56 PM

I believe too, it have to do with physics (gravity). The shoulder of lets say a blind mortise and tenon joint provides rigidity of downward forces that may be applied to a door or window. If the the tenon was at the end of the rail, then any downward force applied to the stile would fail the joint….Sorry for the crude drawing

-- Measure "at least" twice and cut once

View REO's profile


928 posts in 2068 days

#7 posted 02-27-2013 11:15 PM

had to rethink this a little. on doors of equal sized frame members there would really to no advantage but on those with larger dimensions for the tops or bottoms there would be quite an increase in strength when the tennon has a longer surface on the endgrain. it does eliminate endgrain exposure also.

View TCCcabinetmaker's profile


932 posts in 2348 days

#8 posted 02-28-2013 12:08 AM

1 it allows for wood movement.
2. it increases the stength of the joint for the tenon to not run against the grain of the wood.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View kdc68's profile


2657 posts in 2270 days

#9 posted 02-28-2013 12:15 AM

I reread my post and I thought it didn’t make much sense. I knew what I meant :-) So I thought I’d try again. As you can tell I’m not at all gifted in SketchUp….so sorry again for the crude drawings

-- Measure "at least" twice and cut once

View BenI's profile


332 posts in 2172 days

#10 posted 02-28-2013 12:15 AM

I think if the end grain had a mortise it would make it very weak and easy to split/break.

Also, if the stile had a tenon then the starting width of the board (for the stile) would have to be the width including the tenon.

-- Ben from IL

View bondogaposis's profile


4717 posts in 2345 days

#11 posted 02-28-2013 12:33 AM

It is because of gravity. Glue sometimes fails and and weight of the door would tend to cause the bottom rail to slip off of the tenon if the rail was mortised. kdc68 has it right.

-- Bondo Gaposis

View kdc68's profile


2657 posts in 2270 days

#12 posted 02-28-2013 12:37 AM

bondogaposis....thanks for that ! I really need to work on my SketchUp skills !

-- Measure "at least" twice and cut once

View rockindavan's profile


299 posts in 2630 days

#13 posted 02-28-2013 12:40 AM

It also makes putting on hinges easier and stronger. Otherwise hinges might fall between the long and end grain and the screws wouldn’t hold as well.

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