Laying floorboards: Aluminum or wood substructure?

Wooden substructure

Wooden decking substructures are still widely used today. The traditional wooden substructure is often popular due to the affinity with wood as a material and not least because of the material costs, which at first glance appear to be low.

Wooden subfloors made of larch, pine or Douglas fir are mainly used in conjunction with wooden floorboards and visible screw connections, e.g. using Terrafix . With visible fastening from above, the plank covering has hardly any scope for swelling and shrinkage behavior, which is to be compensated for by the similarly functioning wooden substructure. In the long term, however, it turns out that not all types of wood for the top layer are equally suitable for this type of floorboard installation. The less the covering “works” afterwards, the lower the risk of screws shearing off or the creation of unsightly tripping hazards. These properties generally apply more to hard tropical woods, which are often sold at a considerable price and do not necessarily meet the sustainability requirements of many consumers. However, when it comes to laying larch, pine or ash on a wooden substructure, the type of fastening, sufficient protection against waterlogging and good ventilation of the surface play an even more important role in ensuring that the decking is still intact after 10 to 15 years. As the self-drilling screw required to fasten the wooden boards often becomes the weak point of the decking, invisible screw fastening using special fasteners, such as Terraflex or Clipper, in combination with protective tape for the substructure makes sense.

Another essential characteristic of wood, which is not necessarily an advantage in the case of the UK, is the uniqueness of the structure. As a result, part of the wooden substructure is often crooked, resulting in significantly more rejects and more additional work during assembly. In addition to the argument of the well-known material, the lower unit price compared to aluminum is also often cited, which we will compare in more detail in the next section.

Aluminum substructure

Aluminum is a versatile material that is nevertheless light in relation to its stability and can be shaped as desired. We have made use of precisely these properties and developed our CLIP rails from them, which, thanks to the cavities and specifically placed struts, produce a considerable load-bearing capacity and span with little weight. In combination with the connectors, the aluminum UK can be extended endlessly and enables installation without cutting. Production under dimensional control ensures that all rails meet our standards and that material quantities and installation plans can be planned with millimeter precision. Thanks to the dark tone coating, the UK not only disappears visually into the background, but is also optimally protected against salt water, chlorine, weathering and waterlogging.

Due to the non-corrodible nature of the substructure, the old covering can be removed and the new one simply fitted back onto the same substructure if a fresh covering is required. There is no need to repair or replace individual rails, as would be the case with a wooden substructure. This aspect alone leads to lower costs and effort in the maintenance of a terrace in the long term, but there are other reasons why investing in an aluminum substructure pays off on closer inspection. This eliminates waste and offcuts and the precise quantity planning means that no more material than necessary has to be purchased.

It should not be forgotten that the high load-bearing capacity of the aluminum rails means that significantly fewer support points or contact points with the floor need to be created, which results in significant savings on decking bearings, which are indispensable for standard decking. And finally, the time factor must not be ignored, especially if the installation is carried out by professionals, because time is money. If you save time on sorting, cutting and straightening wooden beams, as well as the effort involved in setting up and aligning decking supports, you will notice the difference. This shows that a simple comparison of the unit price is simply not meaningful enough to choose the cheapest overall option for the desired quality standard.


The right decking substructure material therefore obviously depends entirely on the requirements and demands of a terrace: How much budget is available? How long should the terrace last at least? What type of decking and the associated type of fastening is required? Is the terrace exposed to particular weather conditions, e.g. pool, pond or weather side of the house? Will the surface be installed by yourself or by a specialist? Is the area used privately, commercially or publicly?

If you consider the increased demands on contemporary decking, you are generally on the safe side when choosing an aluminum substructure. Our CLIP system consisting of CLIP rail and CLIP decking support represents the standard for a high-quality and professional substructure that meets all the requirements for high standards and legal requirements thanks to coordinated accessories.

If in doubt, it is always worth getting a comparative offer from a specialist dealer. They can use our online planner to calculate exactly how much decking storage and other accessories are required in each case and are on hand to answer any questions you may have.

Did you know?

Decking construction requires expert knowledge and is subject to generally recognized regulations, such as the brochure “Decking and balcony coverings” from GD-Holz. Don’t forget to find out about local building regulations for successful planning and installation and pay attention to the installation instructions for the boards and fixing materials.

When a terrace is walked on and the boards are in heavy use, forces act that can shift the entire substructure. For this reason, a permanently stable attachment is essential. The following illustrations show how a terrace can be installed in a torsion-resistant manner: