'M'
| Mansard Roof | - | Form of pitched roof designed to provide more space for rooms |
| Megger | - | Test meter used by electricians |
| Mezzanine | - | Extra floor - possibly inserted between floor and ceiling of very tall room |
| Mitre | - | Angled joint (similar to joint in picture frame) |
| Module | - | Dimensional co-ordination of components |
| Muck | - | Brickie term for mortar |
| Mullion | - | Upright post in window |