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 at 01:58 PM 702 views 0 times favorited 13 replies Add to Favorites Watch
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4 posts in 574 days

02-27-2013 at 01:58 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


6928 posts in 1551 days

#1 posted 02-27-2013 at 02:02 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


7464 posts in 2285 days

#2 posted 02-27-2013 at 02:04 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 1606 days

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

I would imagine water run off comes into it as well

View teejk's profile


1208 posts in 1321 days

#4 posted 02-27-2013 at 02:09 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 574 days

#5 posted 02-27-2013 at 02:19 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


1968 posts in 914 days

#6 posted 02-27-2013 at 02:56 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


611 posts in 711 days

#7 posted 02-27-2013 at 03:15 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


925 posts in 992 days

#8 posted 02-27-2013 at 04:08 PM

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.

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1968 posts in 914 days

#9 posted 02-27-2013 at 04:15 PM

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

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326 posts in 815 days

#10 posted 02-27-2013 at 04:15 PM

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


2498 posts in 988 days

#11 posted 02-27-2013 at 04:33 PM

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

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1968 posts in 914 days

#12 posted 02-27-2013 at 04:37 PM

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

-- Measure "at least" twice and cut once

View rockindavan's profile


283 posts in 1273 days

#13 posted 02-27-2013 at 04:40 PM

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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