Problem and fix
How to stop a letterbox flapping and banging in the wind
Short answer
A letterbox flaps in the wind when the outer flap's spring has weakened, its hinge pin has worn loose, or there is nothing on the inside to stop air pressure pushing it open. Fitting an inner flap or brush cover usually stops the banging. If the spring or hinge has failed, replace the letter plate with one sized for your door.
Why it happens
When wind hits the front of the house, air pressure builds on the outside of the door. If the letter plate flap is only held shut by a light spring, gusts lift it and let it drop again, and that is the clack you hear at night. Pressure changes inside the house play a part too: opening a back door or window can suck the flap inward.
Over years the spring loses tension and the hinge pin wears, so a flap that used to stay shut starts to lift in lighter winds. On older doors the plate may simply be a lightweight design that never had much tension.
Fixes to try, from simplest up
- Check the screws: a loose plate rattles on its own. Tighten the fixings from inside.
- Fit an inner flap: an internal cover plate with its own flap blocks the air that pushes the outer one.
- Fit a brush cover: an inner cowl with brushes breaks up the pressure and cuts the noise.
- Add a small self adhesive pad where the flap meets the frame to soften the contact.
- Replace the letter plate: a plate with a stronger spring or a sprung hinge holds shut far better.
Replacing the plate the right way
Letter plates come in several cut out sizes, and the replacement needs to cover the existing slot in your door. On composite and uPVC doors the plate is often part of the door hardware range, so measuring the fixing centres as well as the outer size avoids a plate that does not line up with the old holes. Choosing a plate with a sprung flap and an internal cover in one set solves both the flapping and the draught at the same time.
When it is really the door
If you can hear wind and feel cold air around the edges of the door as well as the letterbox, the seals may have hardened or the door may have dropped. In that case the letterbox is only part of the problem. A door that needs a shove to close, or rattles when you push it, needs its hinges and keeps adjusting. If the door is past adjusting, a new uPVC door is £799 fully fitted and a composite door from £1,099, both with a letter plate chosen to suit.
Common questions
Get a free fixed quote
Call 07925 319937, open Monday to Sunday 9am to 6pm, or send the form.