Composite Timber Cladding Installation Guide

Tested repeatedly and accurately to ensure safety and reliability for use, composite timbers are produced by extruding a unique composition of cultivated wood, high-density polyethylene and some engineered stabilizers, such as UV inhibitors and mould resistance. These make composites ideal for outdoor use as the outstanding properties provide durability against harsh weather and resistance to breakage, mould, and decay. Laboratory tests have shown that composites are much stronger and durable than natural timber.

The combination of strength and attractive wood-like appearance of composites is a result of achieving great balance between wood fibres and plastic resin where temperature and speed are optimised during manufacturing.

Installing Composite Timber Cladding

Composite timbers are easy and very simple to install. However, to ensure best performance, quality, and lifespan, it is recommended that a professional tradesman complete the installation. Installing composites is very similar to installing natural timbers; however some key areas where care must be taken are outlined below.

It is important to know that the installation guideline presented below may not cover every event that may occur during installation. A professional is recommended to do the installation in order for easy adaptation if anything unexpected occurs. It is also recommended that a licensed architect, engineer or local building official review your design. Another is to make sure that local building codes are met before beginning the installation.

1. Ensuring Safety for Everyone

Keep children away from the work area until the job has been completed and tools have been stored safely.Refer to operators manuals for all power tools safety guidesWhen handling WPC (Wood Plastic Composite) timber always wear gloves and eye protection and work in a well-ventilated area.Do not burn WPC off-cuts. Dispose of them safely as refuse.Wear goggles when pressure washing or scrubbingAlways use eye protectionPreparation - Avoid exposing planks to direct sunlight when storing. Weathering may lighten or darken colored cladding. However, this will stabilize after approx 3 months.

Note - Composite cladding is NOT intended for use as columns, support posts, beams, joist stringers or other primary load-bearing members. A code-compliant substructure must support the composite cladding. While composite cladding products are great for re-cladding (removing old cladding planks and installing cladding on code-compliant substructure), composite cladding should not be installed on top of existing cladding.

2. Prepare Fixings

Composites should be fixed and secured with quality products. It is recommended to use stainless steel fixings to ensure quality and stability. Use of pneumatic nail guns is not recommended.

3. Installation & Fixing

Composites are designed for simplicity and easy installation. While a tradesman is recommended to complete the job, basic DIY skills and the appropriate tools are all that is needed to do it yourself.

Starter battens

On external walls, the starter batten should be fixed at or above DPC level and checked for levelAt junctions with flat or lean-to roofs, consideration should be given to the installation of the necessary flashingFix cladding to a substantial timber framework, secured to masonry or timber substrate.Horizontal cladding requires battens spaced vertically at a maximum of 400mm centres.For vertical or diagonal cladding battens should be horizontal.Sufficient battens should be utilised and positioned to support trims and plank ends.Over two storeys high, fix centres should not exceed 400mm. Battens on plywood sheathing must be fixed directly into studdingCladding should be secured with A2 (marine grade) stainless steel screws.Battens should be a minimum of 19 x 38mm and should be treated with suitable preservative. Irregularities on the backing surface should be removed and reduced where possible to create an even finish.Clear air space of at least 25mm must be provided behind the cladding, with cross battens used to keep the gap clear if insulation is to be used.8 gauge screws should be used. Holes of 6mm should be pre-drilled into each fixing cladding plank to allow for expansion and contraction.Work from the centre out when screwing to ensure flatness and fix ends with 4mm clearance at each end for expansionTop planks may be cut down to fit the remaining space but allow sufficient clearance to engage the tongue into the grooveFit subsequent planks in the same fashion ensuring that the tongued and grooved joints are firmly closed. Lightly tap the plank down to cover the screw with the overlapStagger the joints and position them at least one fixing centre apartUse a Arbosil 9010 sealant around perimeter junctions and openingShould the cladding be used on timber studding, walls which are not weather tight or walls which are very exposed, the cladding can be backed by a permeable membrane which complies with BS4106: 1972Planks and trims should be secured by jagged plasterboard A2 (marine grade) stainless steel screws. Fixings should be through the lip as this is then hidden by the next plank. Trims should be secured prior to installation of cladding with the final part added upon completionPlease refer to expansion and contraction guide to measure the butt joint gapping requirements Additional battens are required at base and head and for direction changesIrregularities in the substrate will be adversely reproduced in the cladding installation unless the battens are properly aligned. Packing pieces should therefore be placed behind the battens where required.

4. Gapping - Allowing For Expansion (And Contraction)

Composite cladding planks expand and contract according to temperature. Expansion and contraction are more active in areas where extreme temperature changes occur. Installing planks according to the gapping requirements noted below will accommodate this.

Remember that changes in length can occur if working in extreme temperatures during installation. Cutting planks when the temperature is hot and then letting them cool overnight is a good example. A small contraction may occur so it is recommended that planks are fastened as soon as possible after cutting.

Gapping Requirements

Allow 5mm minimum gap where the planking meets any adjoining structure or postFollow all supplied butt joint gapping guidelines for all composite cladding planks.

5. Pre-Drilling

Composite cladding planks require an over-drilled fixing hole of 6mm slot to allow the board to expand and contract. The screw must not be screwed in so tight, as this can restrict the ability of the material to expand or contract. If these are not followed, the cladding plank may bow as a result of material expansion.

6. Cutting Tool Options

Chop Saw

(Any wood cutting blade can be used, although Fine Teeth are highly recommended)

Used for simple straight cutsIdeal for cutting obtuse and acute anglesPerfect for cutting mitres

Jigsaw (Any Bosch Wood Blades Can Be Used)

Used for simple straight cuts, radius edges and for intricate shapesUseful for notching out sectionsA proficient Jigsaw operator is capable of absolute precisionCircular Saw (Any Wood Cutting Blade Can Be Used, Recommended Fine Teeth For Professional Finish)For cuts that exceed 1 metre and provides a perfect straight line cutUsually quicker than using a jigsaw but limited to cuts in one direction at a timeCan be sourced from Dewalt, Bosch or Hilti etcâ?¨A proficient Circular Saw operator is capable of absolute precision

Standard Fixing Tool Options

Drills

Used for creating clearance holes using appropriate sized drill bit depending on the size of the fixing (clearance hole should be big enough for the fixing to pass through the object it is fixing)Used for screwing fixings through clearance holes to firmly secure objectDrill can also be used with attachments such as Hex (Allen) key tool or a socket to the correct diameter of the fixing to enable rapid tightening of the fixings

There are a number of power tool manufacturers such as Dewalt, Bosch or Hilti