Wooden Façades and Fire Safety by Linda Makovicka Osvaldova

Author:Linda Makovicka Osvaldova
Language: eng
Format: epub
ISBN: 9783030488833
Publisher: Springer International Publishing

Longitudinal joints are joints where a batten or a beam are lengthened. It can also be incorporated in façade elements. This lengthening can be carried out using a butt joint or a scarf joint. A butt joint is the weakest type of joint and it is necessary to brace it. A butt joint is a method of joining two members end to end. If the joint cannot be braced, we should use another type of joint such as the scarf joint.

A scarf joint is much stronger than a butt joint since it does not need to be braced. This joint is made as follows—we hollow out a part of a batten or beam which we are going to join and we make an inverse hole in the second piece of wood. By combining these gouges, we will get a compact piece of wood, which can be secured against movement in many different ways, i.e. by using nails in the diagonal of the gouge in the one-third distances. This joint may take different forms: half lap, beveled, dovetailed, tabled etc.

We only need a chainsaw or electrical saw to make such joint. When making such a joint, the most important thing is to keep the dimensions of sheets the same at both ends of the beams, which we want to connect. Joint can have various forms, depending on which material we are going to use to stabilize it since the joint itself is not stable on its own. We can either glue it or use different fasteners such as nails, screws, threaded bars with washers and nuts or truss plates [3].

The type of joining material affects the properties of the joint significantly. In addition, the position of the joining material is of crucial importance as well, mainly in the case of truss connector plates which could be placed on the side or on the top of the joint. Considering its properties, the main advantage is that it is easy to manufacture, it has good properties under load i.e. flexural strength. If we want to spread this joint, its properties are affected by the fasteners used. Screws and glue are better than wedges. Under torsional strength, this joint is not very resilient and quickly disintegrates [4].

It is becoming more and more popular to use adhesives and various glues. These joints are very firm but quite expensive. Some types of working joints are additionally glued (e.g. mortise and tenon joints). Glued joints are very tough, solid, flexible and waterproof. On the other hand, they require precise preparation and stronger pressures if pressed.

The adhesives are mostly synthetic thanks to their positive characteristics (water resistance, biological resistance) and user-friendliness. These adhesives are slowly replaced by animal glue and casein glue. Before gluing, wood must be planed, sanded and dust must be removed. After applying the glue onto the joint, the joint has to be pressed or clamped using stiffeners and clamps. Ideal compression pressure depends on the type of adhesive but in general, it should range between 0.

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