Generally the most common cladding style due to the wide range of choice in terms of suitable board profiles (all available profiles can be used given the right design), the option of open or tight (flush) joint types and the ability to cover large areas either by staggering end joints to create a 'brickwork' type effect or aligning them to give a more 'panellised' effect.

 

Fixing battens only need placing vertically. Boards should be no more than 150mm wide, allowing a vertical overlap of at least 25mm for square or feather edged boards and 15mm for rebated or shiplap boards (used where a flush surface is required).

 

Tongue and groove boards should have a reduced coverage than overlap or rebated boards. The tongue should face upwards with the shoulder of this edge chamfered whilst the trailing edge with the groove should be left square and not vertically jointed.

 

Horizontal boards can be used open jointed as a rainscreen with the top and bottom edges chamfered at different ends, thus reducing air pressure and thus wind driven rain. If the edges are overlapped this will also reduce any possible UV effects on the membrane. This design gives a strong shadow line that will tend to hide the effect of shrinkage if the boards are used green.

 

The attractive chevron designs that can be produced with diagonal cladding make this style a popular choice although it does carry several design limitations. Longer spans of board are required for the main diagonal axes and this may necessitate either use of a thicker board or close batten centres (no more than 400mm) to compensate. Butt jointing of shorter boards should be avoided as these are liable to leakage, as should arranging the boards in a 'V' profile as this can give drainage problems due to collection of water runoff at the bottom.

 

If a chevron effect is required the boards should be arranged as an inverted 'V', allowing the water to drain away from the centre.

 

As a diagonal design is more vulnerable to water penetration a flush fit is required. Therefore open joints should be avoided and a shiplap board profile is preferred.

 

This style is ideal for curved surfaces, using narrower boards the sharper the curve, and is also very tolerant of variations in dimensions. In addition a variety of surface modelling can be achieved by using the 'board on board' construction method - where a layer of inner boards are spaced apart over the battens and an outer layer of boards are fixed over these to cover the gaps - by varying the widths of the inner and outer boards.

 

The 'board on board' construction method also allows for good ventilation and an open jointed design can be used here, although this will allow more rainwater penetration than with a horizontal arrangement. Rebated or tongue and groove boards will give a flush vertical joint ensuring that there is enough overlap to allow for shrinkage. Square cut timber can be used but requires a minimum 25mm overlap.

 

Vertical butt joints should be avoided due to the risk of swelling in the end grain of the lower boards where joints are not completely flush, therefore the available lengths of different timber species need to be considered.

 

If boards are tight jointed then horizontal bearers and vertical counter battens are required. Batten centres should be no more then 600mm.