I'm building two exterior redwood gates, 34.5" x 62", using a frame of
2x4s and a z-brace. I understand that the z-brace should go from the
bottom hinge side, so that z-brace is in compression. Does it matter
how the diagonal of the frame is aligned with the edge of the z-brace?
I can think of five different arrangements, from attaching the brace
to both rails and both stiles, to attaching it to only to the rails,
Is it purely a matter of aesthetics, or are some arrangements
structurally superior? Intuitively, I would think that attaching the
brace to the upper rail and the hinge-side stile would be strongest,
but perhaps it would look odd being off center.
In most stile and rail situations the rails go between the stiles, but
on a gate the stiles should go between the rails.
Many folks don't do it this way because it doesn't look like what
they're used to, but when you think of the applied stresses, it starts
to make more sense.
The diagonal that forms the Z should be double mitered so that the
point fits into the intersection of the stiles and rails. This allows
you to pin the brace from both directions, and adds rigidity to the
If you really want to get good service life out of the gate, let
corner irons into the interior of the stile and rail intersection.
This gives you the opportunity to get a good face grain connection for
your screws, rather than going through the face and into end grain.
Your diagonal will hide these and, in conjunction with a dab of
exterior construction adhesive between it and each of the pickets,
give you a strong and long lasting job.
It is worth your time to seal the end grain of all members before
assembling your gate. Even redwood will open and close on the end
grain and the mechanical effect will degrade the joints.
Tom Watson - WoodDorker
Is it that the applied stresses are different with a gate and with,
say a cabinet door? Or is it that for a small door, the stresses are
small and so the difference doesn't matter, and "rails between stiles"
is conventional or aesthetically more pleasing? I noticed that all my
1908 house's interior 5 panel doors have rails between stiles.
I guess I don't properly understand the applied stresses. I always
thought that "rails between stiles" was because gravity would have to
pull the stile farther down to disconnect it from the rail, assuming
the tenons are shorter than the rails are wide.
Cabinet doors and residential doors use joinery that relies on face
grain to face grain contact that is pinned by glue.
A typical gate relies on mechanical fasteners that join face grain to
edge grain, and the failure profile is different.
You've already cottoned onto the idea of the Z brace going from the
bottom hinge side to the upper latch side, and there's a good reason
The stresses are greatest at that high inside point and the frame
wants to sag away from that.
If you live near farm country, drive around and try to find a "Can't
Sag Gate", which could be as much as twelve feet wide, although only
three feet high.
A gate wants to fall apart from side to side. Running your screws
from the top of the rail into the stile gives you a better shot at
resisting the implacable desire of gravity, aided by by long term
impact forces, to tear your gate apart.
My previous description involved techniques that would provide face
grain to face grain fastening, which is way more resistant to
withdrawal than face grainto edge grain joining via mechanical
Now, all that being said, you could choose to use mortise and tenon
joinery for your gate, which would give you the face to face contact
that was optimal. Then the reason to run the stiles between the rails
would be that you don't want edge grain to face up towards the
Tom Watson - WoodDorker
Thanks for your long insightful comments. This is the one thing I
don't understand the reason for, though. I assume you mean
side-to-side in the plane of the gate. My naive reaction is that
gravity pulls down. Where does side-to-side come from? Considering
the gravitational torque about the bottom hinge?
Wayne Whitney (in firstname.lastname@example.org) said:
|| In most stile and rail situations the rails go between the stiles,
|| but on a gate the stiles should go between the rails.
| Another question: are screws stronger in resisting pullout or in
On pullout, it's the small amount of wood around the threads that
tears. In shear the wood either has to split or allow a large chunk to
be torn out - or the screw has to break (normally unlikely).
The answer may depend on the wood and the direction of grain relative
to the shearing forces. If you want a best try at one answer fits all,
I'd say that screws are stronger in resisting shear.
DeSoto, Iowa USA
You might be confused now because you often see the advice never to
put shaer stresses on screws, but that comes from mechanical
engineering in metal parts, where you would anyway not rely on a screw
to fix a position but would rather use a pin.
May I offer the suggestion of a Gate Kit. I have built my last z braced
gate as all have eventually sagged. As the wood dries out and weathers it
tends to shrink. The gate kits let you build your gate frame out of 2x4's
for framing but also include hinges and steel reinforcement in all 4 corners
to prevent sagging. About $35 Home Depot.
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