BauBuche For components under high load

How does it differ from the standard solid structural timber and glulam?

BauBuche has significantly higher strength and stiffness properties compared to solid structural timber and glulam. For example, the bending strength of BauBuche GL75 is almost three times greater than that of standard solid structural timber C24 or glulam GL24. As a result, significantly smaller cross-sections can be used, and more slender construction can be carried out.

What construction requirements need to be taken into account by carpenters?

The processing of BauBuche beams is practically identical to that of conventional softwoods. Carpenters mainly have to pay attention to moisture protection. If the BauBuche is subjected to weathering during the construction phase, this could lead to swelling and the formation of stains. We therefore recommend applying a hydrophobic treatment as protection for transport and assembly (e.g. BauBuche varnish from Koch und Schulte GmbH & Co.KG). Trimming can be easily performed using conventional joinery machines. All of the screws need to be predrilled. Fully ground drills should be used for drilling (such as the HSS-G wood drill from Famag).

What benefits are there for carpenters?

BauBuche provides carpenters with a high-performance material. BauBuche beams are extremely well-suited for components under high loads:

Broad dropped beams can be produced with more slender dimensions thanks to the high bending strength and the high modulus of elasticity. And in limited spatial conditions, as is the case in restoration, the lower cross-sectional height also opens up a number of important benefits.

The compression strength along the grain of up to 70 N/mm² allows for more slender columns.

The high compression strength perpendicular to the grain of up to 10 N/mm² makes BauBuche the perfect material for thresholds. The support areas can be reduced in main and secondary beams. Steel transverse pressure reinforcements can usually be omitted when using BauBuche.

The BauBuche is supplied with a wood moisture level of approx. 7%. The shrinkage of components under pressure, and the associated subsidence that often occurs with glulam (wood moisture level on delivery approx. 12%), does not occur with BauBuche.

What benefits can carpenters promise their clients?

Carpenters can offer their clients a more slender structure with an elegant hardwood look. Matching board materials and BauBuche Flooring are available for interiors or furniture. The components are also very resistant to mechanical damage thanks to their high densities. And all of that at similar prices to those for conventional softwood products.

The superior strength and stiffness of BauBuche allows smaller cross-sections, which in turn means major savings in material consumption. The material savings differ depending on the application, as different properties take precedence during the dimensioning. In the case of single-span beams, deformation (modulus of elasticity) is generally the key factor, whereas with continuous beams, it is bending strength or shear strength; and with columns and frameworks, it is compressive and tensile strength.

Their high load-bearing capacity means that BauBuche GL75 beams are suitable replacements for steel beams. This helps to prevent thermal bridges and means that costly connections to the steel structure are a thing of the past.

Working with BauBuche – An experience report by the project manager Jens Moser, Gumpp & Maier GmbH (timber construction company)

How did your first timber construction project involving BauBuche go?

The Eurogen office building was the first project for which we used the new BauBuche material. When I took over management of the project, I was surprised by the small cross sections of the columns and beams. And I am still fascinated by just how streamlined constructions with BauBuche are. This is what makes BauBuche so special in my opinion. Processing and assembly were not without their complications. We had to go through an in-house learning process. Nevertheless, we would certainly use BauBuche again. And I am already looking forward to the next project.

What was your experience of trimming BauBuche?

After we received delivery of the first beams, I was of course struck by the high deadweight. The density of BauBuche is around 800 kg/m3 and the material boasts a corresponding strength. We trimmed the beams on our Hundegger K2. To keep the cutters on course, we had to set the speed of the joinery machine to the lowest track speed. This worked well.

Since all the screw holes for BauBuche had to be predrilled, there was a lot of drilling to be done. How was this?

We essentially made the drill holes with a diameter of 6 mm by hand. Spiral drills were great for this. Given the great hardness of BauBuche, the drills became very hot quickly. That's why the colleagues always worked with numerous drills. After each drilled hole, the machine was changed to allow the drill to cool down. As an alternative, the drills can also be cooled down in an oil bath. I would not, however, recommend this since the oil drops can quickly soil the wood. Compared to softwood, significantly greater drill wear must be anticipated.

Recommendation from Pollmeier: When drilling in BauBuche, fully ground drills ensure the best results; e.g., FAMAG wood drill HSS-G long.

Assembly – An experience report by the project manager Jens Moser, Gumpp & Maier GmbH (timber construction company)

BauBuche is extremely sensitive to moisture. How did you cope with this?

That's true. Moisture sensitivity is the central issue when assembling BauBuche. We produced the pockets in the main beams with an excess width of 2 mm so that the secondary beams would fit into them easily even if they have swelled slightly. Furthermore, all the columns and beams were given a moisture protection coating (BauBuche varnish from Koch und Schulte GmbH & Co.KG). When applying the BauBuche varnish, particular attention should be paid to the end faces. The beams were carefully stacked with laminated wood and wrapped in foil to ensure moisture protection during transportation and at the building site.

Recommendation from Pollmeier: BauBuche varnish is highly recommended as a protective coating for transportation and assembly. The layer thickness to be applied is 120 ml/m², that is the equivalent of one coat. Particular attention should be paid to the end grain areas – the end faces of the beams: Here we recommend 2 to 3 coats of BauBuche varnish. This is particularly important in the case of columns since the horizontal end faces can be subjected to rough weathering conditions.

How did assembly go?

Despite the many days of rain, assembly of the beams and columns went well. The protective coating more than proved its worth. Despite the varnish we still covered the structure in tarpaulins whenever it rained. The ceiling boards BauBuche Q, on the other hand, were cut to size and delivered untreated directly to the site by the manufacturer Pollmeier. Moisture protection proved more difficult here: We constructed a temporary, rain-proof storage box for the boards on site. The boards were only assembled on rain-free days and, immediately after they were laid, bitumen foil (BauderTEC KSD Duo) was applied to provide protection from the elements.

Were there still water marks on the boards?

Yes, despite our best efforts, there were still a few water marks. These can be removed with oxalic acid, which we did successfully.