Tenon Width query

[John Moorhead]

Folks -

I am making some screen doors out of QS Doug Fir. The bottom rail is almost

10" wide. I am going to go with MT joints, but I am wondering if I should divide it into two or three tenons to allow for wood movement, also, I am wondering if I should glue the middle section of each tenon if I do two tennons, or glue up only the center tenon if I do three. The tenons themselves will be 1/2 wide in stock that is about 1 1/8 thick, and they will fit the depth of the mortise, just under 3" in a stile that is 3 1/2" wide. So, is this long enough, or should I flip the stile over and drill the mortise through, giving me a joing that is the full width of the stile?

The wood is kiln dried and the doors are outside, though covered and out of the direct elements.

I'd appreciate any remarks... well, ON topic anyway...

Thanks in advance!

John Moorhead

[George]

Divided tenons puzzle me. If they're all attached to the same board, what's really gained? Answer, I feel, is less chopping in the days before routers.

You glue/fast pin the dimension you want to keep constant. In the case of a door, it would be the bottom. Check the grain orientation, but you could have to allow for over 1/4" of movement floating up into the panel. It's the shoulders of the tenon that count for strength, so draw-pinning the tenon in a slot is as good as glue.

Hell, if you're a Normite, sliding dovetail.