Building a Storage Bench: Which Lid Stays and Concealed Hinges Do I Need?

A functional and safe storage bench requires the precise combination of concealed hinges for smooth pivoting and gas struts to assist with lifting the heavy lid.

Those looking to make efficient use of living space often plan custom-built furniture. A bench that integrates seamlessly into a larger wall unit or stands as an independent feature in a hallway offers immense storage capacity. However, the critical aspect when building such a storage bench is the lid mechanism. A heavy lid made from 18 mm chipboard or even solid wood requires hardware that reliably supports the weight, prevents uncontrolled slamming, and allows for precise installation.

This guide explains the technical criteria used by joiners and skilled installers to choose the correct hinges and lid stays for a storage bench.

Key Purchasing Criteria for Lid Stays and Hinges

Before ordering your fittings, the physical requirements of the bench must be determined. Hardware selection is based on specific technical criteria:

• Weight of the lid: The weight determines the required lifting force of the struts, measured in Newtons (N). A spring that is too weak will not keep the lid open, whilst a spring that is too strong will push the lid open forcefully and prevent flush closing.
• Dimensions of the lid panel: Width, depth, and material thickness define the number of hinges required. From a width of 900 mm upwards, three hinges are generally necessary to prevent sagging.
• Opening angle: How far should the lid swing upwards? If the bench sits directly against a wall, the angle must be restricted to prevent damage to the plaster.
• Type of overlay: How does the lid sit on the carcase? This decision determines the design of the hinge required.

Concealed Hinges for the Bench: Which Overlay Is Correct?

For the rotational movement of the lid, the concealed hinge (cup hinge) is the standard in furniture construction. It is mounted invisibly on the inside and can be adjusted in three dimensions. The standard diameter for the cup hole is 35 mm. Suitable designs can be found under concealed hinges 35 mm.

For a bench, there are primarily two construction methods for the lid, requiring different hinges:

1. The lid rests on top of the side panels

This is the most common and robust construction method for a bench, as the weight of seated individuals is transferred directly through the side panels. For this setup, you need a hinge for a full overlay. When closed, the lid completely covers the carcase edge. Suitable models can be found under full overlay concealed hinges.

2. The lid sits flush between the side panels

For aesthetic reasons, the lid is sometimes designed to sit between the side gables of the bench. In this case, you require an inset hinge. Note that in this design, seated weight must be supported by additional internal battens within the carcase, not by the hinges. Corresponding hardware is available under inset concealed hinges.

The opening angle

If the bench is freestanding, a standard hinge with 110° can be used. Suitable models are listed under concealed hinges / cabinet hinges 110 degrees. However, if the bench sits flush against a wall, the lid would strike the wall at 110° and tear out the hinge. In this scenario, an opening angle of exactly 90° is strictly required. Suitable solutions are available in the concealed hinges / cabinet hinges 90 degrees section.

Lid Stays and Gas Struts: Calculating the Force

The hinge acts as the joint of the chest, whilst the strut provides the muscle to lift the weight. To safely open the lid upwards and hold it in place, lid stays are used.

The most common and dependable option is the gas strut. It assists in opening and dampens the downward movement. Important: A gas strut should not be confused with a standard furniture damper (soft-close buffer). The latter only cushions the impact over the final few millimetres, whereas the gas strut exerts continuous force throughout its entire stroke.

The rating of these struts is specified in Newtons (N). As a rule of thumb, 10 N corresponds roughly to the holding force for 1 kg of weight. Calculating the required force depends on the lid's weight. A lid made from 18 mm thick chipboard measuring 1000 mm x 400 mm weighs approximately 5 kg.

• For light lids (up to 5 kg), two struts rated at 50 N to 60 N each are often sufficient.
• For medium-weight lids (6 to 8 kg), select two struts rated at 80 N to 100 N each.
• For heavy lids made from solid wood, specialised hardware is required. You can find these in the gas struts for heavy lids range, offering forces of 120 N, 150 N, or more.

An overview of all standard ratings can be found under gas struts. It is essential to always install two struts (left and right), otherwise the lid will warp over time and place uneven strain on the concealed hinges.

Decision Guide: Which Fitting for Which Application?

To simplify your selection, here are specific scenarios for constructing a storage bench:

• If you are fitting a lightweight lid (MDF, 16 mm thick) to a freestanding bench, then choose full overlay concealed hinges with 110° and combine them with two 60 N gas struts.
• If the bench sits directly against a wall and the lid is made from heavy oak (22 mm), then you must use 90° concealed hinges (at least three units for widths over 1000 mm) combined with lid stays rated at 120 N or higher.
• If you require maximum closing comfort, then choose hinges with integrated damping. These can be found under concealed hinges / cabinet hinges with soft close. They absorb residual force as the gas strut allows the lid to descend.

Installation Notes for Fitting

Installing concealed hinges and gas struts requires precision. The following tools and materials are needed:

1. Forstner bit (35 mm) for the hinge cup drillings in the lid.
2. Cordless drill/driver with a suitable bit (typically PZ for cross-recess screws).
3. Chipboard screws (e.g. 3.5 x 16 mm or 4 x 16 mm) to secure the cruciform mounting plates and strut brackets. Ensure the screws do not pierce through an 18 mm thick lid.
4. Folding rule and square.

The cruciform mounting plate for the concealed hinge is attached to the carcase side. When drilling according to the System 32 hole pattern, the front drilling sits exactly 37 mm from the front edge. The gas strut must be installed in accordance with the supplied dimension sheet. The mounting points on the carcase and lid dictate the angle at which the strut delivers maximum force. Follow the manufacturer's millimetre specifications precisely.

Frequently Asked Questions (FAQ)

How many concealed hinges do I need for a 1200 mm wide storage bench?

At least three. At a width of 1200 mm, the support of two hinges at the outer edges is insufficient, causing the lid panel to sag in the centre. Position the third hinge exactly in the middle.

Can I combine standard concealed hinges with gas struts?

Yes, this is standard practice. The concealed hinge guides the rotational movement, whilst the gas strut distributes the load. Both hardware systems operate independently but complement each other perfectly.

What does the N rating on a gas strut indicate?

The N stands for Newtons and specifies the extension force of the gas strut. 10 N roughly equals the force required to hold 1 kg of mass against gravity. A strut rated at 100 N can therefore support approximately 10 kg of weight.

Why does my lid not close fully and remain open by a centimetre?

This is almost always due to gas struts that are rated too high. If the lid weighs 5 kg but you have installed two struts rated at 100 N each (designed for approx. 20 kg), the weight of the lid is insufficient to compress the gas within the cylinders. Replace the struts with lower-rated models.

Do I need to install heavy-duty drawer runners on a storage bench?

No, runners (such as full-extension runners or single-extension runners) are only used if you are designing pull-out drawers rather than an upward-opening lid. For a traditional chest-style bench with a lid, you only require concealed hinges and lid stays.

Suitable Hardware Categories for Your Project

To find the correct fittings for your storage bench project, explore the relevant hardware ranges:

• For the pivoting lid axis: concealed hinges / cabinet hinges
• For lifting assistance: lid stays
• For heavy solid wood lids: gas struts for heavy lids

Measure your timber panels carefully, calculate the total weight, and select fittings matched strictly to the required Newton ratings and opening angles. This ensures smooth, reliable, and safe operation for your custom-built bench.