| Rafters | - | Series of structural timbers rising from eaves to ridge to support pitched roof covering |
| Rail | - | Horizontal member in door or fence |
| Rainwater Gutter | - | A channel along the edge of a roof to collect rainwater |
| Rainwater Pipe | - | A pipe which takes rainwater from a roof or gutter |
| Relieving Arch | - | An arch constructed above a lintel or beam to take weight of wall above |
| Render | - | External sand-cement coating for walls |
| Reveal | - | Vertical side of door or window opening |
| Ridge | - | Top of a pitched roof |
| Ring Main | - | Power circuit for sockets |
| Rise | - | Vertical distance between two adjacent stair treads |
| Riser | - | Upright part of a stair OR vertical water pipe from the mains |
| Roof Truss | - | Prefabricated structural timer framework to support roof |
| RSJ | - | Rolled steel joist |