BuildingGateMedium

Braced Gate Frame

A 900 x 1800 mm cedar gate that stays square: three rails and one diagonal brace, every joint bolted through, because a gate with no brace is a gate that sags within a year.

Designthe dimensions everything else is derived from

Leaf size
900 wide x 1800 mm high
Stiles
2 off 1800 x 70 x 45 mm
Rails
3 off 760 x 70 x 45 mm
Brace
1 off 1825 x 70 x 45 mm, rising from the bottom hinge stile to the top latch stile
Rail positions
top, middle and bottom, evenly spaced
Exposure
fully external, hinged at one stile only

Cut list sizes are finished sizes. Add 5 mm to the width and 25 mm to the length of every solid-wood part for saw kerf and planing, and buy boards oversize by one thickness so a bowed board can be flattened rather than relegated.

Materialswhat each part is made from, and why

All materials
Cedar (Western Red) · 2 stiles, 3 rails, 1 brace
Low movement and natural durability. A gate is a frame that has to stay square in the weather, and a timber that moves a lot will not.
Stainless Steel A4 (316) · every bolt, washer and nut
A gate is outside and in constant movement on its hinges, which is the worst case for a fastener that could corrode.

Cut listfinished sizes, worked back from the design

PartQtyFinished sizeStock
Stile21800 x 70 x 45 mmCedar (Western Red)
Rail3760 x 70 x 45 mmCedar (Western Red)
Brace11825 x 70 x 45 mmCedar (Western Red)

Fastenersquantities and lengths that follow from the joints

All standards
ItemQtyGripStandard
M10 x 160 hex bolt, A4 stainless12140 mmISO 4014
M10 x 130 hex bolt, A4 stainless4115 mmISO 4014
M10 plain washer32—DIN 125 A
M10 nylon-insert nut16—DIN 985

Grip is the sum of the clamped thicknesses. A bolt has to clear the nut by two full threads, which is what sets the length that appears in each row — not a preference.

M10 x 160 hex bolt, A4 stainless · grip 140 mm
Two at each of the six rail-to-stile joints. Grip is the rail (70) plus the stile (70). ISO 4014 →
M10 x 130 hex bolt, A4 stainless · grip 115 mm
Two at each end of the diagonal brace. Grip is the brace (45) plus the stile (70). ISO 4014 →
M10 plain washer
One under each head and each nut across all sixteen bolts. DIN 125 A →
M10 nylon-insert nut
A gate slams. Every slamming cycle is a shock load on every joint in the leaf, and a plain nut will not survive a season of it. DIN 985 →

Toolsand what each one is for on this job

All tools
Drill
Boring 11 mm clearance holes through 70 mm sections.
Twist Drill Bits
11 mm for M10 clearance, plus a countersink to break the hole edges so they do not split.
Circular Saw
Cutting the frame parts; the brace is cut to the diagonal and does not need a mitre.
Socket Set
Sixteen nuts.
Combination Wrench
Holding the head on the outer face, which is the face on show.
Tape Measure
Checking that the two diagonals of the frame are equal before the brace goes in. The brace holds the frame square; it cannot pull it square.

Order of workthe sequence, and where it is not free to change

  1. Cut two stiles, three rails and one brace. The brace is 1825 mm, which is the diagonal of a 760 mm run and a 1660 mm rise.
  2. Lay the frame out on a flat surface and clamp it, with the diagonals measured equal.
  3. Check the diagonals again after clamping. This is the moment the gate is either square or not.
  4. Bore and bolt the six rail joints, snug only.
  5. Fit the brace so it rises from the bottom of the hinge stile to the top of the latch stile. Fitted the other way round it will pull the gate out of square rather than holding it in.
  6. Bring all sixteen bolts to torque, then hang the gate.

Where it goes wrongthe three failures worth designing out

  • Leaving out the brace, on the reasoning that three rails are enough. Three rails make the frame rigid in bending and still completely free to rack; the brace is the only part resisting that.
  • Fitting the brace the wrong way up. It must rise from the hinge side to the latch side, so the load path runs into the hinge rather than hanging off the latch.
  • Bolting the frame together before checking the diagonals. Bolted timber does not pull square; the frame has to be square first.

Frequently asked questions

Why is the brace cut to a diagonal and not mitred?

Because it is bolted through the stiles rather than housed between them. A plain square-ended cut is bolted flat against the stile face, which is both stronger and simpler than a mitre that adds nothing.

Can a lighter gate be built with two rails?

Yes, and the brace is still not optional. Rail count follows the depth of the leaf and what it has to resist; the brace answers a different question, which is racking.

What about the hinges and the latch?

They are hardware, not fasteners under a dimensional standard, so they are outside this database. What the database does cover is the bolt pattern in the frame that the hardware then hangs off.