Because a nailed joint relies on fasteners in withdrawal, which is the weakest way to use them.

A connector converts the load into bearing and shear.

That is far stronger and far more predictable.

It also gives the joint a published capacity rather than a guess.

That figure is what an engineer designs to and an inspector checks.

Toe-nailed joints have no rating anyone can rely on.

By which force the joint has to resist, which narrows it faster than dimensions do.

Hangers support a member where it meets another.

Ties and straps resist tension along a line or around a corner.

Bases and caps transfer load between a post and what it meets.

Braces triangulate against racking, and holdowns resist overturning.

Size and capacity are settled after the load path is identified, not before.

Yes - the published capacity assumes a fastener in every hole provided.

Filling half the holes gives a connection with no known capacity.

It is the commonest reason a connector fails to perform as designed.

Some connectors do have holes designated for optional or seismic use.

Those are identified in the manufacturer's literature.

Where a hole cannot be filled, the connection needs re-checking rather than accepting.

Not without invalidating the rating.

Capacities are tested with a specific fastener in a specific size.

Screws are not a general substitute for the nails a connector was tested with.

Some connectors are specifically approved for proprietary screws.

Using a longer or thicker fastener is not automatically safer.

The manufacturer's fastener schedule is part of the product rather than a suggestion.

Because modern timber preservatives are far more aggressive to steel than older ones.

A standard galvanised connector in treated timber outdoors can corrode quickly.

It can fail well within the structure's design life.

Heavier galvanising and stainless options exist for that reason.

Fasteners must match the connector's corrosion class.

Mixing stainless fasteners with galvanised connectors can accelerate corrosion rather than prevent it.

No - ratings, approval marks and the codes behind them differ by market.

A figure published in one jurisdiction does not transfer to another.

Test methods and safety factors differ between regimes.

Products may be certified in one market and not recognised in another.

The local code and the manufacturer's tables for that market govern together.

Where a structure is engineered, the engineer's specification is what applies.

Bending, cutting or drilling a connector voids its rating.

The steel is formed and the holes placed as part of the tested product.

Field modification changes behaviour in ways nobody has measured.

Some connectors are specifically designed to be skewed or bent within limits.

Those limits are stated and are narrow.

Where nothing standard fits, a skewed or custom connector is ordered rather than made.