Presentation on theme: "Timber Wall Cladding Systems"— Presentation transcript:
1 Timber Wall Cladding Systems In Residential Buildings
2 Timber Cladding Systems allow Design freedom – not regimented – almost anything goes!- Traditional styles- Modern styles, and- Unique personal stylesEase of handling – light and user friendlyLarge range of finishes, plusThe natural beauty of timber!
3 Other BenefitsTimber claddings have built in flexibility – helps to resist the stress and strains of foundation movements due to reactive soils and mine subsidence, wind storms and earthquakes!Can be designed with excellent thermal propertiesHave natural sound damping properties
4 Cladding SelectionToday’s designers can choose from a wide variety of timber cladding products. When choosing the type to use, there are a number of points which must be considered:• The appearance required by architectural style• Availability and cost• Ease of installation and maintenance
5 Cladding Selection (Cont.) • Prevailing climate and thermal performance required for a building, including buildings in a bush-fire prone area• The importance of additional strength given to the structure by some types of cladding• Local government regulations or statutory requirements
7 Timber claddings have the option of being: Structural – i.e. designed to carry loads e.g. bracing, as required by the BCA– e.g. structural plywoodor solely as decorative - not carrying loads
8 SarkingSarking is a waterproof material that is fixed to the studs directly behind external claddingThe primary function of sarking in walls, is to direct any water that may have penetrated the cladding back to the outside of the structureIt also provides a draught proof barrier to keep wind driven rain or dust out of the wall cavity
9 Sarking (Cont.)Wall sarking is fixed on the outside of the studs, from the top plate down and over the bottom plate and flashing, and/or in accordance with the manufacturers instructionsOnly vapour permeable, fire-retardant, building paper should be used as sarking behind timber cladding – don’t use aluminium foil type sarking - as trapped vapour may wet the back of the cladding and then cup and distort the cladding
10 Vapour barriers The need for a separate vapour barrier depends on the: type of construction,the intended use of the buildingand the climate at its location.Note: Install vapour barrier on warm side of all insulation
11 Vapour barriers (Cont.) Note: When large temperature differences exist between indoor and outdoor environments there is potential for condensation of water vapour within a frameShowers, baths, dish-washers, clothes-washers, driers, cooking, indoor plants - and even people - generate large amounts of water vapour within a building
12 Vapour barriers (Cont.) Some of this vapour will move outward through plaster, wood and other permeable materials until it either:disperses into the atmosphere (this could be the wall cavity)reaches an impermeable barrieror meets a surface cold enough for it to condense into liquid
13 FlashingFlashing over wall openings, at corners and vertical joints is essential water proofingEnsure flashing is fixed at least 25 mm under the sarking/cladding
14 Flashing (Cont.)Over openings flash over the ends and the framing of the opening
15 Moisture ContentAll kinds of timber will take up or lose moisture, and adjust dimensionally, in keeping with changes in the local humidityThe actual timber equilibrium moisture content (EMC) will vary from place to place and from season to season, so that timber in service may have a moisture content ranging from about 6% to 18%Timber cladding will usually be supplied as “dry”, “kiln dried” or “seasoned” and will have a moisture content in the range 10-15%
16 Moisture Content (Cont.) Chamferboard and ship-lap cladding profiles will usually be supplied as seasonedHowever, cypress and hardwood weatherboard profiles, as well as some western red cedar profiles may be supplied unseasonedUnseasoned boards wider than 200 mm should not be used
17 Moisture Content (Cont.) Wider unseasoned boards may develop slight cupping across the face unless restrainedUnseasoned hardwood boards should be fixed as soon as possible after delivery to reduce the risk of cupping or splittingAs unseasoned cladding will shrink as it dries, an allowance must be made for shrinkage by increasing the overlap of boards (see AS2796 for details)
18 Moisture Content (Cont.) When machined profiles are produced from seasoned timber the design of the edge-joint will allow for movement due to seasonal changes in equilibrium moisture contentOther than exercising proper care and good workmanship during installation, no special precautions need be taken to compensate for light expansion and contraction in service
19 Moisture Content (Cont.) When fixing, it is important that nails are placed so that movement of boards caused by changes to equilibrium moisture content during different seasons (or the drying of unseasoned boards after installation) does not create stresses sufficient to cause splitting of the timberIndividual boards must not be nailed together at the lap
20 Storage & HandlingIt is important to keep cladding clean and dry - dirt marks and stains can’t be hidden by stain finishes, + any wetting may cause problems with movement at a later stageMake sure cladding is kept covered, stacked level, well clear of the ground, and that stacks are evenly supported at 450 mm intervals to prevent bowing and saggingSome cladding e.g. western red cedar, is relatively soft and require care in handling to prevent minor denting
21 Pre-FinishingDepending on the final appearance required, a priming coat of either water repellent, stain or paint should be applied to all surfaces before fixingIt is also advisable to apply an undercoat colour matched to the final coat so that movement lines will not be apparent after any shrinkage or movement
22 Solid Timber CladdingSawn timber weatherboards are available in a wide range of species, sizes and profilesFixing can be horizontal, vertical or diagonal with a large variety of profiles and widths
28 Installing Horizontal Cladding First - choose a method of joining the timber at internal and external corners.Usually it is timber stops - external corners boards can either be cut in neatly to a stop or left to run through - then cut off to a straight edge later - then fit the stop.
29 Or cladding can be mitred Or cladding can be mitred at external corners and scribed at internal corners - time consuming method and requires precisionWhere cladding abuts masonry - leave clearance to prevent moisture from masonry entering the boards – or seal cladding ends and protect joint with a cover strip set in mastic
30 Installation Details Select the first board to be fixed If using weatherboards, undercut the bottom edge to an angle of about 15 degrees so that water will be shed readily.
31 Installation Details (Cont.) The first board should be laid to a string line, mark out the width of one board on both corners of the wall to be clad - partly drive a nail at these points and run a string line between themPartly drive nails into every third or fourth stud along the string line - remove the string line - the first board is placed against this line of nails and fixed
32 Installation Details (Cont.) Chamferboard and ship-lap profiles are laid similarly with the tongue facing upwards - rebate or tongue & groove are brought tight together using a chisel as a leverWeatherboards will require a full-length packing piece under the first board and as necessary over openings
33 Installation Details (Cont.) Weatherboards are fixed with only one nail per stud. This nail should be driven as closely as possible to the butt of the board but it must miss the thin end of the board underneathLap hardwood and treated pine boards 30 mm and nail them 35 mm from the buttLap western red cedar boards 20 mm and nail 25 mm from the butt - a gauge block can be used to keep the boards at the same spacing.
34 Installation Details (Cont.) Apply a primer to all freshly cut ends and seal all joints, including the stopped ends, with a paint/stain compatible mastic or silicon sealantPlace the mastic on the ends of the boards before fixing themNails should be driven with care - heavy and excessive nailing distorts the wood and may cause splitting during weather changesSome cladding boards may require pre-drilling of the nail holes at the ends to avoid splitting.
35 Installation Details (Cont.) Joints are placed over studsTight fitting joints are achieved by cutting a board slightly over-length, bowing it to get it into position and then snapping it into place.
36 Installation Details (Cont.) Progressively, take measurements at the ends of walls, beside openings and at 1800 mm centres along the wall to ensure the cladding is still runs parallel - very important either side of openings if the cladding continues above the openingIf necessary to correct this – it is best to catch up over a number of boards if the difference in parallel is greatCladding around window and doorframes need not be stopped if the butt jointing is neatWhen fixing cladding on the next wall around a corner, make sure the boards are in the same line
38 FastenersHot dipped galvanised or other non-corrosive nails (of suitable shank size and length) should always be used to fasten timber claddingPlain steel nails should not be used - as rust makes unsightly stains + causes gradual deterioration of timber around the nailFlat head nails are recommended to provide additional restraint for treated pine and Western Red Cedar claddingSilicon bronze nails (although expensive) produce a superior appearance when Western Red Cedar is coated with a natural or stain finish
39 Fasteners (Cont.)When fixing weatherboard profiles ensure nails are placed so movement of boards caused by wetting and drying do not create stresses sufficient to cause splitting of the timberThus one fixing per stud is best - ensure individual boards are not nailed togetherEdge-joint design in seasoned cladding profiles usually allows for minor seasonal movement thus two nails per stud may be usedSpacing of supports (studs) should not be more than 650 mm centres measured along the board
40 FinishingAfter fixing, one or two finishing coats of stain or paint should be applied - where cladding is to be painted, nail holes may be punched and filled prior to application of the finishing coats.Filling of nail holes in cladding that is to be stained is not recommended.
41 Plywood CladdingApart from the style and warmth of timber structural plywood has:Cross laminated strength – resists impact and edge damageChoice of face veneer to suit applicationDurable glue bond
42 Other practical advantages of structural plywood cladding are: Can be bent to suit curved finishesGood acoustic propertiesEfficient thermal performanceGuaranteed quality and safety
54 Hardboard Cladding • Reconstituted, natural hardwood • Environmentally friendly - only sustainable new growth hardwood used• Contains no knots, gum veins, cracks or splits• 25 year guarantee not to rot, split or crack• Hidden joining system suitable for on and off stud joining• No scarf joining• Limitless cladding and lining design solutions
55 Panel Sizes 3660 x 1196mm 3050 x 1196mm 2745 x 1196mm 2440 x 1196mm Thickness: 9.5mmAvailable in smooth of rough sawn
64 Technical Resources Program – Supporting Timber Education & Training AcknowledgementPrepared by:James MacGregor ConsultingThis educational resource has been prepared as part of the Forest & Wood Products AustraliaTechnical Resources Program – Supporting Timber Education & Training