Rhombus slats compared: Larch or Douglas fir – which slat suits your facade?

Anyone planning a wooden facade with rhombus battens will quickly face the first question: Larch or Douglas fir – and how much material do I actually need? In the Gunreben assortment, you will find two rhombus battens: Canadian larch in grade A/B and Douglas fir in grade I/III. This article shows the differences between the two variants and which projects they are each suitable for.

You can find all available battens and lengths in our Rhombus profile collection.

A quick guide to help you decide

• Canadian larch A/B (27 × 68 mm): uniform, fine-grained wood texture for a calm, high-quality facade appearance. Available in lengths up to 6.10 m – ideal for large surfaces with few joints.
• Douglas fir I/III (26 × 68 mm): warm, reddish hue and more lively wood texture. Handy lengths from 3.0 to 5.0 m – well suited for garden sheds, carports, and privacy screens.

Regardless of the wood type, the following applies: A rhombus facade only works as a system consisting of the batten, sub-structure, rear ventilation, and appropriate fastenings.

What is a rhombus batten anyway?

Rhombus battens have a parallelogram-shaped cross-section: both longitudinal edges are cut at an angle. When mounted with spacing, an open facade with uniform shadow gaps is created. When mounted horizontally, the slanted edges point outwards and downwards – this allows rainwater to run off well, and the view into the rear ventilation layer is largely concealed depending on the viewing angle.

Typical areas of application include ventilated facade cladding on residential buildings, extensions or garages, garden sheds and carports, privacy walls, as well as cladding for wheelie bin enclosures, balcony railings, or roof overhangs. Both types of wood can be used untreated outdoors and will develop a silver-grey patina over time.

Canadian larch rhombus batten: the batten for large facades

The rhombus batten made of Canadian larch is available in the 27 × 68 mm format in grade A/B. Canadian larch grows slowly, which means the wood is fine-grained and has grown uniformly – the facade appears calm and high-quality.

Its main strength is the lengths: Larch is available in 3.05 m, 3.66 m, 4.27 m, 4.88 m, 5.49 m, and 6.10 m. With these long lengths, even wide house walls can often be clad without joints – this saves work and ensures a continuous joint pattern.

Suitable for: Facades on residential buildings and extensions, large contiguous surfaces, and projects where a calm, uniform appearance is the priority.

Douglas fir rhombus batten: warm, lively, and manageable

The rhombus batten made of Douglas fir in the 26 × 68 mm format in grade I/III is impressive due to its warm, reddish hue and a livelier wood texture. Douglas fir is a proven alternative to larch and fits particularly well with natural-style gardens and outbuildings.

Douglas fir is available in 3.0 m, 4.0 m, 4.5 m, and 5.0 m. These manageable lengths are easy to transport and work with – ideal for smaller projects and surfaces that are interrupted by windows, doors, or posts anyway.

Suitable for: Garden sheds, carports, privacy walls, cladding in the garden, and facades with a natural-rustic character.

Overview: Larch and Douglas fir in comparison

How many rhombus battens do I need per square meter?

The requirement depends on the batten width and the chosen joint width. The rule of thumb is:

Linear meters per m² = 1 m ÷ (Batten width + Joint)

With a 68 mm batten width and a 10 mm joint, this results in a center-to-center distance of 78 mm. 1 m ÷ 0.078 m = approximately 12.8 linear meters per square meter. Also plan for about 10% for waste, window connections, and corners.

Example: For a facade area of 30 m², you need about 30 × 12.8 × 1.1 ≈ 423 linear meters. Using larch in 6.10 m lengths, this corresponds to about 70 battens; with Douglas fir in 5.0 m lengths, about 85 battens.

What matters during installation – for both wood types

Sub-structure and rear ventilation

A rhombus facade is always installed with rear ventilation. The sub-structure creates the necessary air gap so that the wood can dry off quickly after rain. Matching the respective batten, the Canadian larch sub-structure 44 × 70 mm or the Douglas fir sub-structure 42 × 72 mm are recommended. Center distances of about 50–60 cm are common. If the rhombus battens are mounted vertically, a counter-battening is additionally required so that the air can circulate unhindered from bottom to top. You can find further squared timbers in the Sub-structure collection.

Fastening

For larch and Douglas fir, use only stainless steel wood construction screws. Galvanized or bright steel screws can lead to dark discolorations around the screw head in combination with the wood's ingredients. Batten joints should always lie on the sub-structure and be arranged offset across the surface.

Joints and insect protection

A spacer or a simple installation gauge ensures uniform joints over the entire surface. At the bottom and top ends of the rear ventilation, a ventilation/insect screen prevents insects or birds from nesting.

Please note: Depending on the building, federal state, and fire protection requirements, additional regulations may apply. In case of doubt, have larger facades planned by a specialist company.

Care: leave untreated or oil?

Larch and Douglas fir can be left untreated. Under the influence of weather, the surface grays into a silvery patina – this is a natural process and not a quality defect. In sheltered areas, such as under roof overhangs, the graying process happens more slowly, so color differences may be temporarily visible. Those who wish to maintain the warm wood tone should treat the facade with a suitable wood oil or a stain for outdoor use – however, this must then be renewed regularly.

Which rhombus batten fits which project?

• Are you cladding a house facade or a large wall surface? Then the Canadian larch rhombus batten with lengths of up to 6.10 m is the first choice.
• Garden shed, carport, or privacy screen? The Douglas fir rhombus batten with its manageable lengths and warm hue fits particularly well here.
• Do you desire the calmest, most uniform facade appearance possible? Then there is much to be said for the fine-grained larch.
• Are you also planning a wooden terrace? You can find tips on wood selection in the article Douglas fir or hardwood: Which terrace board fits?

Conclusion

Both rhombus battens offer the typical advantages of a wooden facade: they are weather-resistant and usable without treatment, provided there is structural timber protection and rear ventilation. The differences lie in the appearance and lengths: the Canadian larch impresses with its calm, fine-grained wood texture and lengths up to 6.10 m, while the Douglas fir impresses with its warm hue and manageable lengths for smaller projects.

Crucially, it is not just the batten that matters, but the entire system of sub-structure, rear ventilation, and stainless steel fasteners. Compare all lengths now in our Rhombus profile collection and assemble the matching sub-structure right along with it. For larger project quantities, feel free to contact us.