03.07.2024 · Words by Myles

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How Can I Repair a Crack in a Composite Door?

How can i repair a crack in a composite door

How Can I Repair a Crack in a Composite Door?

Composite doors are tough. They keep intruders out and keep the warmth in, with a design to maintain these functions for over three decades.

Despite this, your composite door occasionally feels the heat, making it susceptible to odd creaking noises and some cracking during its long lifespan.

Why do composite doors crack, and how should you fix a cracking problem? Let's take a closer look.

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What Causes a Composite Door to Crack?

Before we go any further, let's clarify something: All types of doors can crack, so you shouldn't assume it's a problem exclusive to composite doors.

There are several reasons a door cracks, and unfortunately, there's not much anybody can do to avoid it. The best we can do is deal with the problem as it arises.

Doors crack for one or more of the following reasons:

Accidental damage

Even a brand-new door isn't immune to cracking by accident. Composite doors are rugged and highly durable, but exterior cracks can occur if something hard makes contact with your door by accident.

Of course, using an abrasive and harsh cleaning agent can also cause small cracks in a composite door's Glass Reinforced Polyester (GRP) exterior coating. This tiny crack would likely widen as the composite materials expand and contract with temperature changes during warmer months, making the problem worse.

One positive point, however, is that GRP coatings on composite doors are in place to protect the materials within, so any surface cracks that appear indicate that the protective layer is fulfilling its purpose.

Weather conditions

Why do people tend to blame everything on the weather? In this instance, there's a valid reason for doing so, as inconsistent weather conditions, especially substantial temperature fluctuations, can drastically affect exterior doors - especially if they're south-facing.

If you live in an area with a more unstable or unpredictable climate, your composite door will likely feel the effect of the weather conditions more than a home in a temperate weather zone.

The issues are that, as already mentioned, doors that face the elements expand and contract as temperatures change, and composite doors are no exception.

Hot weather will cause your door's composite material to expand, which will contract when the temperature drops again. During the summer months, you might find your composite door more challenging to close during the day, indicating its expansion in the heat. This constant expansion and contraction could be the cause of your door cracking.

You might get woken in the night by unnerving creaking noises from your front door area, which can be scary - until you realise what they are. Yes, they're the sound of your door contracting as the night temperature drops.

Your door frame

You might be ready to contact the professional installer who installed your door when you read that your door frame might cause your door's cracking problem, but hold on a moment before picking up the phone. You might be contacting your installer for a different reason.

If a cracking sound is evident every time you open and close your composite door, or there's cracking around the door frames, there is a chance your problem relates to your door frame's size.

The installation may have been perfect when your professional installer originally fitted your composite door and frame.

With the expansion of your door in the heat, the framed opening might now be too small for the door, and this tight fit is causing it to crack.

If the extra pressure applied to your door's perimeter is ignored, more and more visible cracks may appear on the exterior of your composite door. Feel free to contact your installer from UK Composite Doors to adjust your door frame any time you need!

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How Can I Fix a Crack in My Composite Door?

If you find your composite door cracking, you should first assess the extent of the cracks before springing into action. Mostly, they're likely only small cracks in the door's surface. These are easy to repair, and we'll tell you how:

How to fix surface cracks in your composite door

You should acquire a GRP cleaning agent, a plastic filler, a putty knife, and some medium and fine grit sandpaper for small surface cracks.

  • Clean the cracked area and surrounds Use the GRP cleaning agent to clean enough of the area surrounding the crack to avoid getting any grime or grit intermingled with your later repair. Aim to remove all built-up dirt from the crack and the immediate area. Give the cleaned area time to dry before proceeding to the next step.
  • Apply the filler There are many decent plastic fillers available from retailers, so your local hardware shop will be able to assist you with door repair kits. Most plastic, composite door fillers include a powder and a liquid, which you'll need to mix to make a filler compound, as per the filler's included instructions. Be ready to act immediately, as plastic filler compounds set quickly. When the combination is mixed, use the putty knife to apply the mixture to the cracks, making sure to fill them completely.
  • Sand the set compound Ensure the compound is well set before you begin to sand it down. Depending on how much excess filler compound you applied, use the medium grit sandpaper to remove the excess filler, but switch to the fine grit as you get closer to the repaired area. Wipe down the finished repair to remove any excess dust.

Once you've finished the repair, you should only be able to notice the restored cracked area on close inspection. You can touch it up with paint if you want it to blend in better.

You may consider replacing the GRP coating where the composite door cracking is more extensive or near the door locks.

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Can composite materials be repaired?

When manufacturers identify a fault, bolted, bonded, or injection repair work is completed depending on its nature.


In Closing

A composite door is robust and durable, but still susceptible to cracking (and the odd creak or two). Fortunately, these surface cracks are usually easy to repair and won't impact the door's strength. Remember, however, that although these hardy doors may crack like other doors, composite doors don't fade in the sun!

Visit UK Composite Doors for more about composite doors and how to get the perfect one for your home.

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