Will a flush threshold on bifold doors leak?
It can. A flush (non-weathered) threshold has no upstand lip, so weather performance cannot be guaranteed, while a low weathered threshold seals better. Use flush thresholds in sheltered areas only, and install drainage with the external surface falling away from the door.
What is the difference between the two thresholds?
A weathered threshold has a lip the bottom seal presses against. One manufacturer quotes an upstand of only 14 mm. A non-weathered threshold sits flush with the floor and has no lip, so it is better for sheltered or internal use.
How do you stop a flush threshold leaking?
- Fit face or concealed drainage to carry water away from the track.
- Set the external surface to fall away from the door.
- Add a channel drain in front of the track where exposed.
- Seal the cill to the structure with a suitable membrane.
When is a flush threshold the right choice?
Where level access matters, such as for wheelchair users or older occupants. Tell the customer the weather risk. MLI Building Products can supply bifold doors with both threshold options. Confirm the product’s water tightness rating first.
Need a trade price? Call the trade counter on 01903 262 636 or visit us at Unit 1, Friar Walk, Worthing. We offer free delivery within 30 miles.
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