How to Install Gas Struts on Cabinets & Flap Doors
Upward-opening flap doors and lift-up wall cabinets are popular choices in modern kitchens, utility rooms, and bespoke storage units. However, holding a heavy cabinet door open while reaching inside requires reliable mechanical support. Installing gas struts provides a smooth, controlled lifting motion and keeps the door safely elevated until you are ready to pull it down. Whether you are upgrading an existing overhead cupboard or building a new storage unit from scratch, this practical guide walks you through the essential steps for accurate fitting and long-term reliability.
Choosing the Correct Hardware and Ratings
Before installing a gas strut, it is crucial to ensure you have selected the right hardware for your cabinet dimensions and door weight. Cabinet gas stays are rated by force, typically indicated in Newtons (N), where 100N roughly corresponds to supporting 10kg of weight over a direct lever arm. Fitting a strut that is too strong can strain hinges or prevent the flap from closing properly, while an underpowered stay will fail to hold the door open.
- Door Weight and Dimensions: Weigh the door panel (including handles) and measure its height to calculate the necessary Newton rating.
- Single vs. Paired Struts: Narrow or lightweight cabinet doors may only require a single stay, but wider flap doors (typically over 600 mm) benefit from two struts mounted symmetrically to prevent twisting.
- Mounting Brackets: Ensure you have the appropriate circular or flat base plates for timber carcasses and narrow aluminium frame adaptors if working with metal-profile doors.
Tools and Materials Required
To carry out the installation accurately, gather the following items before starting:
- Gas struts with corresponding ball-joint mounting brackets
- Short wood screws (usually 3.5 mm x 16 mm, ensuring they do not breach the exterior carcass)
- Tape measure and steel rule
- Pencil for marking fixing points
- Cordless drill and a 2 mm pilot drill bit
- Pozi-drive screwdriver
Step-by-Step Guide to Installing Gas Struts
Accurate positioning is the most critical part of installing gas struts. The mounting points dictate the opening angle—typically between 75 and 100 degrees—and determine whether the door closes flush against the carcass frame.
1. Mark the Carcass Mounting Point
Open the cabinet flap to your desired resting angle. On the inside of the cabinet side panel, mark the position for the carcass bracket. A common trade standard is to position the centre of the mounting plate roughly 200 mm to 250 mm down from the top internal edge and 25 mm to 30 mm back from the front edge. Always check the template supplied with your specific hardware, as geometry varies between stroke lengths.
2. Fix the Carcass Bracket
Align the carcass bracket over your pencil marks. Drill small pilot holes to prevent the chipboard or MDF from splitting, then secure the mounting plate firmly using wood screws. Ensure the plate sits completely flush against the cabinet wall.
3. Position and Secure the Door Bracket
With the cabinet flap propped securely at the target angle, extend the piston arm of the strut to identify the corresponding position on the inside face of the door. The door mounting bracket is usually fitted between 70 mm and 100 mm down from the top hinge line. Mark the fixing holes, pre-drill shallow pilot holes (taking care not to drill through the front face), and secure the bracket with screws.
4. Attach the Strut
Most modern cabinet gas stays use snap-on ball socket ends. Position the strut cylinder with the thicker body mounted to the carcass and the thinner piston rod pointing downwards when closed. This orientation ensures internal lubricants keep the seals conditioned. Push the ball sockets onto the mounting studs until they click into place. If your hardware features retaining spring clips, ensure they are seated correctly.
Testing and Alignment
Once fitted, gently test the movement of the door. The flap should open smoothly without binding against the carcass top or straining the concealed hinges. When closing, the stay should provide consistent resistance rather than snapping shut. If the door fails to close fully, the door bracket may be set too far forward, preventing the piston from retracting to its minimum compressed length.
Frequently Asked Questions
Which way round should a gas strut be fitted?
Install the strut with the main body (the thick cylinder) attached to the cabinet carcass and the extending piston rod attached to the door. This allows the internal damping oil to lubricate the rod seal whenever the cabinet is closed.
Can I replace just one gas strut on a double-stay flap?
It is always best practice to replace both stays at the same time. Installing a gas strut alongside an older, worn unit creates an imbalance in lifting force, which causes the door to rack and places unnecessary stress on the cabinet hinges.