MGP10 Guide

Single vs Continuous Span: What the Tables Mean

Updated 2026-02-21 · MGP10 Span Tables

Single vs Continuous Span

Open any span table and you will see two sets of values for the same member: single span and continuous span. Picking the wrong one is one of the easiest and most consequential mistakes in the whole exercise. Here is what the distinction really means.

A single-span member bridges one gap; a continuous member runs over three or more supports and can often span further.

Single span

A single span member is supported at its two ends only and bridges one gap. It is the simplest arrangement and generally the more conservative table column. If your member just sits across two supports, this is your column.

Continuous span

A continuous span member runs over three or more supports as one continuous structural element — think of a long joist crossing several bearers. Because the intermediate supports share the load and the member helps itself across them, a continuous member can often span further than the same size in a single span. That is why the table lists higher values in the continuous column.

Where joints belong

If you must join lengths to make a continuous run, the joints or laps must be made at or near the supports and detailed as AS 1684 specifies — never out in the middle of a span. A mid-span join breaks the continuous action and the continuous-span numbers no longer apply.

Which column should you read?

Member across two supports only → single span.
Member unbroken (or correctly lapped) across three or more → continuous span.
Not sure, or joints fall awkwardly → use single span (the safer, lower value) or get advice.

When in doubt, reading the single-span column is the conservative choice. Reading continuous when your framing is not truly continuous is the dangerous one.

Keep going

See this in context for joists and bearers, and make sure your wind class and load width are right too.

Frequently asked questions

What is a single span?

A single span member is supported at its two ends only, bridging one gap. It is the simplest case and usually the most conservative column in the table.

What is a continuous span?

A continuous span member runs over three or more supports without a break in its structural action — for example a joist crossing several bearers. Because the supports share the load, it can often span further than a single-span member of the same size.

Can I always use the continuous span column?

Only if your member is genuinely continuous — properly continuous over the supports, or correctly lapped or joined as the standard requires. If joints fall in the wrong place, the continuous assumption no longer holds and you must use single-span values.

Where should I join or lap continuous members?

Joints and laps must be made at or near supports and detailed as the standard specifies, never mid-span. Incorrect jointing turns a 'continuous' member back into weaker single spans — follow AS 1684 and your engineer's direction.