Is the sun warping your door and window frames?

In the UK, we’re used to talking about rain, not record-breaking temperatures. But as climate change brings longer, hotter summers, homeowners are starting to notice the not-so-sunny side of extreme heat—especially when it comes to wooden window and door frames.

Timber windows and doors offer classic charm and great insulation, but they can suffer under the strain of prolonged heat and UV exposure. If your windows face direct sunlight for much of the day, they could be at risk of warping, cracking, or swelling, which doesn’t just affect how they look—it could compromise your home’s security, energy efficiency, and comfort.

Let’s take a closer look at how heat affects wooden window frames, and what you can do to protect them.

How does heat affect wooden windows?

Wood is a natural, breathable material. That’s one of its greatest strengths—but also one of its weaknesses in extreme conditions.

Here’s how heat and sunlight can impact timber windows:

• Expansion & Contraction: Wood absorbs moisture and expands in the heat, then contracts as it cools. Repeated cycles of this can lead to permanent distortion over time.
• Warping: High temperatures can cause timber to bend or bow, especially if one side of the window is consistently exposed to direct sun.
• Cracking or Splitting: As the wood dries out and contracts, it can develop surface cracks or deeper structural splits.
• Paint or Finish Damage: UV rays can break down protective coatings, leaving wood vulnerable to weathering, fading, or rot.

If your windows become misaligned or start sticking, it may not just be a minor inconvenience—it could signal that your frame has warped.

Why window warping is a problem

While it may start as a cosmetic issue, a warped window frame can have wider consequences:

• Draughts and energy inefficiency
• Security risks if locks don’t align properly
• Difficulty opening and closing windows
• Increased exposure to moisture, which can lead to rot
• Lower property value due to visible damage

It’s especially important to pay attention if you live in a home with older wooden frames or south-facing windows that take the brunt of the sun.

How to prevent timber windows and doors warping in hot weather

1. Use UV-protective finishes
   Treat your wooden frames with a high-quality, UV-resistant varnish or paint. These coatings act as a barrier against sun damage and moisture loss.
2. Install external shading
   Awnings, shutters, or even external blinds can help reduce direct sun exposure—especially on south- or west-facing windows.
3. Ventilate your home
   Good airflow helps to regulate internal temperatures and reduce stress on the wood from rapid temperature changes.
4. Maintain the wood regularly
   Inspect your windows at the start of each summer and re-treat the timber every few years to keep it protected.
5. Don’t ignore signs of trouble

If your window is sticking, looks uneven, or the lock doesn’t align properly, get it checked by a professional before the damage gets worse.

Need repairs? Rocks Locks can help

If heat has caused your window frame to warp, Rocks Locks offers repair services to help realign or replace affected areas. We also provide single-unit uPVC glazing repairs if your window pane is cracked—helping you avoid the cost of a full replacement.

Our services cover Camberley and surrounding areas in Surrey, Hampshire and Berkshire, and we can assess both security and structural issues caused by extreme weather.

Don’t let the heat compromise your home

As UK summers grow hotter, protecting your timber windows from warping and cracking is more important than ever. With the right maintenance and timely intervention, you can keep your windows beautiful, functional, and secure for years to come.

Contact Stuart at Rocks Locks on 07900 335525 for a free window inspection or advice on maintaining and securing your timber frames in hot weather.

Secure your windows before the next heatwave hits!