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External Larch Cladding

How to install and maintain larch cladding

How to install and maintain larch cladding

As timber cladding becomes more popular and in demand, more varieties and styles are available. As part of our wide range of cladding available at Ruby, we have both Home Grown and Siberian Larch. Our home-grown larch is sourced from efficiently managed forests improving carbon footprint whilst maintaining sustainability throughout. The boards are a dark pink colour. The Siberian Larch is a very durable and vigorous cladding, perfect for those exterior buildings and uses, commonly finished off with a straw like tone. Both types of larch contains prominent and bold growth rings with straight grains throughout. Because of the oily, resinous and dense properties that larch has, it does not need to be treated and therefore a very popular choice. However, within this blog, we will be providing you with some tips and pointers to take on board to help with the maintenance of your larch cladding, keeping it in great condition for many years to come. We have many different products to help with the instalment, maintenance and design features of your larch cladding structures so do check them out as we go along.


Maintaining your Larch Cladding 


Overtime, your larch cladding boards will start to change colours from the pink  and yellows that it once was to grey, silvery colours due to the UV rays coming from the sun. This occurs with both home grown and Siberian options. To help minimise and stop this from occurring, we highly recommend using Osmo UV protection larch oil. The oil has pigments within it which optimally match the colour of the wood ensuring that the colour is kept throughout its lifetime. As well as this, it is water and dirt resistant, regulating moisture levels within the timber to stop swelling or shrinkage and does not flake, peel or blister. Applying this protective oil every 12 weeks is recommended to keep your boards in superb condition throughout its long life. It's important to consider the direction that your cladding is facing as this will help to determine the number of regular maintenance checks and coats of UV Protection oil needed. South or West facing structures are more prone to increased sun light and large amounts of rain and will therefore have an affect on the boards causing them to weather quicker. On the other hand, Northern and East facing structures will need more maintenance due to the lack of sunlight.


Over a long period of time, larch timber can warp and twist because of changes in climate and weather conditions. The twisting and warping will occur when drying so make sure even air flow is accounted for and make sure all cladding boards are firmly fixed onto battens. It is necessary to clean your larch cladding, both Siberian and Home Grown, in order to keep the quality structure and aesthetically pleasing look. Use warm soapy water to clean the boards ensuring you do not completely soak the boards causing them to swell dramatically. Once cleaned and dry, make sure to apply Osmo larch UV protection oil to ensure protection against the sun. The better you clean and prepare your boards, the longer it will be until they need another wash. The wood will also need suitable and even air flow throughout the structure to aid on going drying.


When wanting to use your larch cladding boards to create sheds and outer buildings, it’s important to make sure all edges and joints are sealed ensuring that minimal water and moisture is entering. Sealing the joints can be done using Osmo Larch UV Protection Oil   and End Sealing Wax that we have available here at Ruby. Painting your larch is not necessary to ensuring a long life and protection from the elements, however if wanting to change the colour, we would recommend staining the timber, especially with Siberian larch because of the grain, bringing out a beautiful natural design. If there is any sap or resin content on the outer boards, stain blocking primer or knotting agent can be used to remove the contents and stop it from happening in the future. Siberian larch is known to have high resin contents within the wood so do look out for it carefully. It is recommended that both home grown, and Siberian Larch need to be completely dried out before being used for exterior uses as larch is prone to swelling and shrinkage during constant weather changes and temperature.


To increase fire safety standards, zero flame treatment can be applied to your external larch cladding minimising fires from occurring and spreading. A water based clear solution that soaks into the timber without affecting the appearance or nature of the wood. In terms of larch timber, it’s important to work towards a complete coverage of is 3.7m²/L to achieve Euro Class B and Class 0 spread of flame and fire propagation. When using this zero-flame treatment, it’s important that the boards have not been sealed to allow the liquids to be absorbed by the timber. Make sure all sides of the boards have been coated to ensure a higher level of safety and efficiency. Also available at Ruby UK is our rodent and insect mesh used to prevent pests entering your outer buildings by covering up small gaps and spaces in the outer layer. Whilst still providing efficient air flow into the building, the mesh is not combustible nor corrosive. The mesh can be fixed using staples, battening, tacks or a bead of silicone.


Installing your Larch Cladding 


When coming to fit your larch cladding, it’s always best to start at the bottom ensuring that all lower boards are completely level making it easier to fit the boards above. When securing the boards to the battens, we would recommend using tongue-Tite Plus screws as the boards can split easily when using nails. Pre drilling the holes is a great way to ensure that the boards aren't damaged or split also. Do be careful when choosing your fixings due to the acetic acid that can be present within larch cladding and will therefore corrode your fixings causing large amounts of rust. Therefore, it's recommended to use the best quality fixings available to create a sound and sturdy structure that also looks aesthetically pleasing. These fixings should finish flush with the surface of the board to create a smooth finish and minimise any water sitting pockets. In terms of the positioning of the screws, two fixings should be fitted 25mm in from the side edges and at least 20mm from the top edge. With boards under 100mm, only one screw is needed which can be fixed halfway across the width of the board. Every time a board crosses over a batten, one or two fixings will need to be applied depending on the width.

Here are some key pointers to take away from this paragraph:

  • Start installing your cladding at the bottom as Larch is quite a heavy and dense material. Make sure the boards are completely level at the bottom as this will help guide you on the higher boards
  • Pre drilling your fixing holes is a great way to stop the boards from splitting
  • Where a board crosses over a batten, fixings should be put in place to create a strong and vigorous structure
  • Position the fixings 25% in from the edges of the boards
  • Use high quality fixings to stop corrosion and weakening of the structure


The larch cladding should be fixed to treated battens ensuring that battens are perpendicular to the cladding for example, if you wanted your cladding to be horizontal, the battens must be vertical and vice versa, creating a vigorous, durable structure. The battens should be spaced out with 600mm centres and have the same life expectancy as the chosen cladding boards. There are two main ways of battening depending on if you want the cladding horizontal or vertical. Vertical battens can be fixed straight to the outer wall or alternatively, horizontal battens should be fixed to supporting battens which run vertically and therefore perpendicular. See our diagram below. It's recommended that cladding boards are installed horizontally, however if you do decide to have them vertical, please make sure top edges are angled to increase the effectiveness of drainage. Where two ends of the boards meet (abutting boards), two battens should be put in place, which means adding a small batten which extends the width of the joint and board.


The way in which you fit your Siberian and home grown larch boards to exterior walls and buildings will depend on the structure. You need to take into consideration factors such as insulation, cavities, battens and design of cladding. Applying an insulation layer to your exterior wall before cladding may be required to reach good thermal properties. Ideally, this is done in two ways depending on the design structure. An insulation layer can be directly applied to the exterior wall and then the battens fixed straight onto the insulation layer or alternatively, a double layer arrangement can be used which will be fixed within a framework using I-joists or battens. When two insulation boards meet, there should be a minimal gap no bigger than 5mm. Once the insulation stage has been carried out, you will need to add a cavity to allow sufficient water drainage and air ventilation. To create this cavity between the wall and boards, battens can be used by fixing one batten to the other perpendicular and creating a structure which has a channel in between the cladding and wall. This channel will need to be open at the top and bottom so do leave a small gap between both the ground and roof and boards. To stop insects and pests entering these small gaps, we have available insect mesh which will restrict access but still allow sufficient airflow throughout the structure. 

To sum up this paragraph, here are some key points to take away:

  • Applying your insulation can be done by securing it straight to the exterior wall using fixings and then the battens can be screwed and hung from the insulation.
  • Alternatively, you can use a double layer arrangement which will be fixed to the exterior wall within a framework of battens or I-joists.
  • Where two boards meet (abutting), a second batten will be needed which will run along the gap and whole width of the board to ensure strength and durability between the two boards
  • Air and drainage cavities are essential and only need a gap of 8mm
  • The cavities will need to be open spaces and so leave a gap at the top and bottom between the roof and floor
  • Insect mesh is extremely useful and covers the gaps whilst providing efficient air ventilation and circulation


When wanting to cut your larch boards to create the right size and fit any gaps, make sure to use End Sealing Wax to ensure all cut ends are protected and no water enters the wood from exposed areas. On top of this, when cutting your vertical boards, do make sure to cut them at a slight angle to allow any water or moisture to run off the ends and stop water sitting at the top. Because of the durable and strong features of larch, cutting the material can be a difficult job. We would therefore recommend placing a small amount of oil on the saw or cutting when wood is frozen. Where an end board meets the corner or edge, please do allow a minimum of 8mm in between to reduce chances of water sitting on the end grain.


Economic, lightweight and easy to install, Vistalux is a versatile corrugated rooflight. It is easy to cut, drill and install with standard DIY tools and is available in a choice of corrugated profiles in clear or translucent tint options with a 10-year warranty! We also offer an environmentally friendly roofing options which include Coroline corrugated bitumen sheets. These sheets are tough, lightweight roofing and cladding materials made from bitumen saturated organic fibres. The Coroline is 2.6mm thick.


We hope you have found this useful and helps to keep your larch cladding in great condition throughout its lifetime. Please do take some advice on board to help preserve those larch cladded buildings and check out all the accessories and products related to larch cladding. If you have any more questions or queries, don’t hesitate to contact our sales team on 01409231763, and they will be happy to help.

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  • I have to reclad one side of a garden office as there is rot and woodworm damage . Would like to know what treatment I could use to prevent future rot /woodworm

    Charles Oldham on

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