Letterbox Sealing for Energy Saving
Why Sealing Your Letterbox Matters
Up to 15% of home heat loss can come through doors and windows — and letterboxes are often overlooked. A poorly sealed letterbox allows warm air to escape and cold air to creep in, making your heating work harder and increasing your energy bills.
Option 1: Brush Strip Seals
Brush strips reduce direct airflow and are cheap to install. However, the bristles allow some air movement and degrade over time — especially with frequent use during winter months when heat retention matters most.
- ✅ Low-cost and simple to install
- ✅ Reduces light draughts
- ❌ Bristles flatten and let air through over time
- ❌ Not fully airtight for winter energy savings
Option 2: Spring-Loaded Flaps
These are often fitted as part of standard letterboxes and provide basic closure. However, they don't insulate or seal well and may actually contribute to heat loss due to air gaps or rattling movement during wind.
- ✅ Built-in on many door types
- ✅ Auto-closing feature
- ❌ No insulation against cold
- ❌ Common source of draughts and noise
Option 3: Foam/Rubber Pads
Often used as a DIY gap filler, these solutions are inexpensive and temporarily useful. But they compress, lose shape, and rarely seal well enough to stop thermal leakage through a letterbox slot.
- ✅ Quick temporary fix
- ✅ Affordable for short-term use
- ❌ Low durability
- ❌ Doesn’t hold up to cold/wet weather
The Magflap: A Thermal Sealing Upgrade
Unlike basic sealants, Magflap uses magnetic closure to maintain a tight, consistent seal every time the flap closes. Designed with energy efficiency in mind, its rigid, enclosed design limits air exchange far more effectively than brush or spring flaps.
- ✅ Strong magnetic seal to minimise heat loss
- ✅ Durable finish made for winter performance
- ✅ Sleek and subtle visual design
- ❌ Higher upfront cost than foam or strips