MGP10 Guide

MGP10 Lintels and Beams: Spanning Over Openings

Updated 2026-02-09 · MGP10 Span Tables

MGP10 Lintels and Beams

Every door and window punches a hole in a load-bearing wall, and something has to carry the load that would have gone straight down. That something is the lintel. Lintels are also where DIY span-table use most often goes wrong — because of what lands on top of them.

A lintel carries the loads above an opening across to the supports each side.

A lintel is only as simple as its load

A lintel over an internal, non-load-bearing wall carries little. A lintel in an external wall under a roof, or under an upper floor, carries a great deal. The span you can achieve depends entirely on what is bearing down on it. Identifying the real load above the opening is the first and most important step.

Point loads change everything

When MGP10 is not enough

MGP10 lintels are common for modest openings under ordinary loads. But as openings get wider or loads from above increase, an MGP10 member of sensible depth runs out of capacity. The usual answers are:

Step up to a higher grade (MGP12, MGP15).
Use a built-up member designed for the job (not just two boards nailed together on a hunch).
Use an engineered beam such as LVL or glulam, designed for the span and load.

Deflection over openings is visible

Sag over a window or door is not just a structural concern — it cracks linings, jams doors and is plainly visible. Deflection limits matter as much here as strength, which is another reason to size lintels from the proper table rather than by eye.

Approaching the lookup

For a simple MGP10 lintel: establish exactly what loads bear on it, confirm there are no point loads, set the opening width (the span), apply your wind class, and read the size that meets the span from the current table. If there is any point load or the opening is large, stop and get an engineering design. The Span Spec Builder helps you record the case clearly for that conversation.

Keep going

Brush up on deflection and the most common span-table mistakes before you finalise any beam.

Frequently asked questions

What is a lintel?

A lintel is the beam over an opening such as a door or window that carries the loads above it across to the supports on each side. It must be sized for what it carries — wall, floor and/or roof loads above the opening.

Can I use MGP10 for a lintel?

For modest openings carrying ordinary loads, MGP10 lintels are common. For wide openings, loads from above (like a roof or upper floor), or any concentrated point load, you may need a higher grade, a built-up or engineered beam, and an engineering design.

What is a point load and why does it matter?

A point load is a concentrated load landing at one spot — for example where a beam or post above bears onto a lintel. Standard span tables generally assume uniformly distributed loads, so point loads usually require specific engineering.

When do I need an engineer for a beam?

Whenever the situation falls outside the standard table assumptions: large openings, point loads, beams carrying other beams, unusual geometry, or anything load-bearing you are unsure about. When in doubt, get it designed.