Hardware and parts
Thresholds and seals
Thresholds and seals are the parts at a door's edges that close the gap to the floor and frame. They include threshold plates, brush strips, drop seals, compression gaskets and, on fire doors, intumescent and smoke seals. Each must suit the door's use and any fire rating.
Where does it work well?
Draughty or wet entrances, doors that let dirt or rain in, fire doors needing intumescent and smoke seals, and entrances being improved for wheelchair access with a low or level threshold.
Pros
- Reduces draughts and rain entry
- Low-cost upkeep item
- Can improve level access
- Smoke seals help contain smoke on fire doors
Cons
- Brushes and gaskets wear
- A raised sill can obstruct access
- Fire door seals must match the door's test evidence
How long does it last?
Typically a few years on busy doors, with brushes and gaskets replaced as routine upkeep.
What should you check when buying?
For accessible entrances, Approved Document M describes a threshold of no more than 15 mm, with upstands over 5 mm chamfered. Check drainage at the threshold on exposed sites. On fire doors, use only seals that match the door's test evidence.
Common questions
How high can a shop door threshold be?
Approved Document M defines an accessible threshold as level or no more than 15 mm high, with upstands over 5 mm chamfered. That guidance applies to England. For an existing shop, the Equality Act 2010 may call for reasonable adjustments, such as a ramp.
Why does rain come in under my shop door?
Usually the threshold has worn, the seal no longer touches, or drainage is blocked. Wind-driven rain on an exposed frontage can also beat a simple brush strip. A better seal, drip or threshold plate normally fixes it.