The Journey of the Batten

Jul 26, 2013 Off Comments in General News by
The Journey of the Batten

Just exactly how does a timber roofing batten become a batten that is suitable to use on a roof? This introductory article is intended to illustrate the “journey” that begins with a tree and ends up with a product that is used all over the UK in its tens of thousands every month, and for the next five months we will be exploring all issues relating to battens.

Wood – as most of you are probably aware – grows on trees: and the battens which roofers use almost every day of their working lives come from two particular types of tree which grow in European forests, the Pine and the Spruce. These trees are of a type known to the timber industry as “Softwoods” – and they are essentially the “workhorses” of the construction industry: being used for floor joists, framing, roof trusses, standard doors, windows and trim (architraves and the like) in most of the houses that we build every year.

The vast majority of the battens that we use here in the UK are imported (because we don’t grow enough trees ourselves: we just don’t have the land to spare for large forests and therefore cannot produce enough timber sustainably); and the ones we bring in to our docks mostly come from Sweden and the Baltics. SR Gold is produced and imported from Latvia, which is the middle of the three Baltic States – just to the West of Russia. SR Gold battens are made primarily from high quality Spruce: a timber that is known commercially as “whitewood”, on account of its very pale colour. (Gold battens are treated with a wood preservative containing a dye, which gives them their distinctive orange-yellow colour.)

After forest management, the journey from tree to batten really begins in the sawmill, where the felled trees are brought in as cut logs from the forest. They are typically about 25 – 35 cm (10 to 14 inches) in diameter and about 5 metres (15 feet) long. After sorting for shape and size, the logs are de-barked and then they begin their “conversion” – as the process of cutting them into various pieces is known – in the sawmill proper.

First of all, two outer “slices” (called side boards) are removed by a very large diameter saw; and these side boards are then sent by conveyor to a machine called a “splitter”, which is a bank of small circular saws, set very accurately at the required spacing to produce a number of 25mm thick battens. (Typically, a side board can be split into 4 or 5 battens, with a small amount of “waste” at the edges, where the curve of the log and any remaining bark makes it difficult to produce a good rectangular section). Typically, the wood going is in 103mm wide and as the saw diameter is no more than 3mm wide, a true 50mm wide batten can be produced.

The main part of the log is then flipped onto its side flatwise, and two further partially-rounded side boards are sliced off it, leaving a rectangular chunk of the log – now called a “cant”. The additional side boards are immediately sent off for splitting, whilst the cant is then moved along to another large saw and sliced into rectangular boards: either 38mm or 50mm wide, depending upon the required batten width. These new, square-edged boards are then passed by conveyor to another splitter, where they are divided into 4, 5 or 6 battens of 25mm thickness, depending upon the width of the particular board. A typical log will thus produce about 25-30 battens.

At every stage of this simple-but-effective process, any battens which are not square-edged, or which may be bent or otherwise unsuitable for use, are removed from the production process and sent for “chipping” into wood residue (which is sold for other uses). All other acceptable battens are then moved onto the next stage: which is grading.

Every single batten that is produced in Latvia for SR Timber will have been inspected for acceptable quality by experienced, trained personnel; who are checking to make sure that no defective material gets through the system. The top quality battens – which meet the criteria for so-called “BS battens” (to the rules of the appropriate British Standard, plus some additional quality requirements imposed by SR Timber to improve appearance and performance) will be packaged and marked as “SR Gold”; whilst all other battens which are of an acceptable level of quality and appearance are packaged and marked as “Premium Green”. SR Gold battens – which fully meet and exceed the BS 5534 requirements – are stamped with their dimensions and timber species code.

The very last production stage is preservative treatment: where the battens are impregnated with preservative to the required level of “Use class 2” (that is, suitable for roofs). The SR Gold battens receive a coloured preservative, as we said earlier, whilst the Premium Green battens are treated with a standard copper-based preservative, which leaves them with a greenish tint.

After a suitable period of natural air drying, the final journey of the battens is then onto a ship, bound for a UK port, and – at last – to a roofing merchant depot for sale to the trade.