Racking - a rectangular frame distorting into a parallelogram.

A rectangle with pinned corners has no inherent resistance to being pushed over.

Adding a diagonal turns it into two triangles.

A triangle cannot change shape without a side changing length.

That is the whole principle.

It is why bracing works where adding corner fasteners does not.

Direction of loading - a brace typically works in compression.

A strap works in tension only and buckles the other way.

A brace pushes back against the frame trying to fold.

Fitting a strap where a brace is needed achieves nothing in one direction.

It is a common misunderstanding of what each part does.

Some systems use tension bracing in opposing pairs instead.

At the corner between a post and a beam.

They triangulate that specific joint.

Pergolas, carports and open frames use them commonly.

So do pole structures with no sheathing to brace them.

The brace angle affects how effective it is.

Shallower angles give less resistance for the same member size.

They tie a gable end wall back into the roof structure.

A gable is tall, triangular and often unbraced out of plane.

Wind acting on that large surface pushes it inward and outward.

Bracing shares that load with the roof rather than leaving it to the gable.

Unbraced gables are a recognised failure mode in high winds.

The bracing is part of the roof design rather than a wall detail.

It is genuinely common and a frequent cause of poor performance.

Bracing gets removed to fit a door, a window or for appearance.

The structure then performs far below what was designed.

Nothing looks different until lateral load arrives.

Removal should be referred back rather than decided on site.

Alternative bracing can usually be arranged if the need is identified early.

Properly, no - it is part of a designed system.

Requirements come from the lateral loading for the site.

Brace position and size are calculated rather than judged.

A brace in the wrong place transfers load somewhere unintended.

It can overload a post or a connection that was not sized for it.

Where a frame genuinely feels weak, that is a reason to check the design rather than add members.

Yes, and the connections carry the load the brace develops.

A brace is only as effective as its end connections.

Compression braces need proper bearing at each end.

The fastener schedule carries the rating as always.

Angled ends need connectors suited to the geometry.

A well-sized brace with inadequate connections resists very little.