Referencing the Australian Standard AS:2688:2017. This standard outlines what is considered acceptable and what is not regarding door warping and bowing.

What is Warp/Bow?

Warping or bowing refers to the cupping or twisting of timber within the door itself. It does not pertain to the door’s relationship to the jambs or the frame in which it is hung.

Standards and Acceptable Tolerances

According to AS:2688:2017:

• For doors up to 2150mm high, a warp/bow of up to 4mm is not considered a defect.
• For doors between 2150mm and 2400mm high, a warp/bow of up to 6mm is acceptable.
• Doors exceeding 2400mm in height or 1020mm in width are not covered by this standard or the warranty and are not guaranteed against warp/bow or twist.

You can determine cupping by applying a straight edge to the concave face of the door, or identify a twist by placing the door face against a true plane surface.

Factors Leading to Warping/Bowing

Several factors can contribute to the warping or bowing of doors, including but not limited to:

Atmospheric Conditions: Humidity, heat, and dampness can cause the timber to expand or contract, leading to warping. Warping is more noticeable in the spring and summer months when wood that has been wet starts to dry out.

Improper Storage: Doors stored in unsuitable conditions before installation are more prone to warp.
Keep doors flat and fully supported on a level surface to prevent bending or twisting. Avoid leaning them against walls or other objects.

Moisture Conditions: Adverse moisture levels during the door’s life can cause it to warp.

Colour and Finish: Using dark or multiple colours (paint or stain) can exacerbate the warping process.

Door Size: Taller doors are more prone to warping than shorter doors.

Preventative Measures

The best way to combat warping is to take preventative measures when you install a door:

• Let the door acclimate to its new environment by placing it in the room for 48 hours so it can adjust to the moisture content in that room
• Apply several coats of sealant to the door, at least two coats, keeping the door flat during this process. Ensure the sealant is applied to all six sides of the door, with special attention to the top and bottom, which are prone to absorbing moisture.

Addressing Minor Warps

If you notice early on that one of your doors is starting to lose its shape:

• Remove the door from its hinges.
• If painted, remove any paint using a heat gun if necessary.
• Smooth and fill any cracks, and remove the coating or varnish, especially around the bottom and top of the door.
• Apply at least two coats of sealant to the entire door, including the hinge areas.
• Once the sealant is dry, you can repaint the door.
• When rehanging the door, ensure you seal the door frame to prevent the frame from expanding and causing the door to stick.

Addressing Severe Warps

For doors with a significant warp:

• Lay the door flat on a pair of saw horses or similar supports.
• Weigh it down with heavy towels or blankets.
• Leave the door for several days until you notice it correcting itself. Wet towels can be more effective.
• If the warp is extreme, add additional weights.
• Once the door is straight, let it dry and ensure you follow the sealing steps outlined above.

Important Consideration
Please note that making a new door will only necessarily solve the problem if the environmental conditions causing the warping are addressed. Maintaining consistent environmental conditions and ensuring proper storage and handling is essential to minimise the risk of warping or bowing.

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