Specification for the application of TRW Foam Installation Board System (TRW Fibreclad System™)

Introduction

This specification has been set out as near as possible to the actual construction sequence and it must be read in conjunction with the TRW Installation and Application manuals.

TRW Fibreclad System™ is a cavity-based Exterior Insulating and Finishing System which is used as a versatile, cost effective exterior wall cladding system for residential and light commercial construction. The TRW Fibreclad System™ is made up of 75mm expanded polystyrene sheets that are fixed to timber or steel framing over the surface of a self draining 25mm cavity. The polystyrene sheets are then reinforced with fibreglass mesh and over coated with a range of specially blended renders before the walls are painted with a 100% acrylic membrane system.

TRW Fibreclad System™ provides a primary and secondary means of weather defence against water penetration by separating the cladding from the external wall framing with a nominal 25mm drained cavity. This ensures long lasting durability even in Australia’s most extreme weather conditions.

TRW Fibreclad System™ has been tested and certified with double sided RFL to carry an R value of 4.01 (winter) and 3.69 (summer).

Framing Set Out (Timber Or Steel)

Timber framing must comply with AS 1648 National Timber Framing Code. There are four Wind Zone categories: Low, Medium, High and Very High. The Building Wind Zone for the job must be clearly understood before the installation of TRW Fibreclad System™ and the frame must be constructed and braced accordingly. In all cases studs must be set out at 450mm maximum centres. Noggins must be flush fitted at maximum 800mm centres. Edge fixing for the polystyrene sheets must be provided. All eve junctions, openings, wall/roof junctions and foundation details must have support for the sheet edges. Timber framing must have a maximum moisture content of 24% at the time cladding commences. For steel framing the minimum framing specification is ‘C’ section studs and noggins of overall section size 75mm web and 32mm flange. Steel thickness must be a minimum of 0.55mm. TRW Fibreclad System™ requires a straight and true frame to be fixed to. We accept no responsibility for variations in horizontal or vertical straightness of walls due to the frame not being straight.

Building Wrap

A building wrap complying with AS/NZS4200.1 must be used in all circumstances. Building wrap must be installed horizontally and be continuous around corners. The wrap must be lapped 75mm minimum at horizontal joints and 150mm minimum over studs at vertical joints. Flexible sill and jamb flashing tapes complying with Australian standards must be used around all penetrations. All penetrations must have internal air seals applied.

Head Flashings

Head flashings must be installed over all window heads and door openings. If head flashings cannot be used, an acceptable alternative flashing must be provided.

Flashings in General

Joists designed to carry decks need to have a continuous flashing fitted before the polystyrene is fixed. Check if there are any special back flashings required where the TRW Fibreclad System™ joins another substrate or curtain wall construction.

Roofing

Where areas over roofs are to be fitted with TRW Fibreclad System™, the roof/wall flashing must be installed prior to the commencement of cladding.

Pipes & Meter Boxes

It is critical that pipes are flashed appropriately in accordance with AS/NZS 2904. All pipes must have the building wrap turned to the outside of the building and have the building paper taped to the outside of the pipe. All pipes must have a downward rake of a minimum of 5 degrees and must be sealed in place using Sikaflex or another approved equivalent both before the installation of the TRW Fibreclad System™ and after completion. All meter boxes must be correctly flashed. Particular attention to detail and workmanship must be given to the weatherproofing details relating to flashing and sealing building penetrations or junctions with other building materials. All junctions between the TRW Fibreclad System™ substrate and dissimilar technical literature materials must be correctly flashed and sealed with Sikaflex or another approved equivalent. The sealant must be installed in strict accordance with the manufacturer’s requirements and must be left to properly cure prior to rendering.

Eve,Gable Ends & Unlined Walls

Eves shall be fixed into place before the cladding is installed and allowance made to close off the cavity with framing or battens to stop airflow into the roof space. After the TRW Fibreclad System™ has been completed a 5mm bead of Sikaflex should be installed at the eve polystyrene intersection. Reverse raking eves or eves less than 450mm wide must be flashed. To ensure the EPS substrate is not affected by timber shrinkage in areas that are not traditionally lined (e.g. gable ends), it is highly recommended that the internal walls of these areas are adequately braced with a thin sheet of plywood or an alternative bracing material. Alternatively, the timber in these areas must have a moisture content of no greater than 18% and must remain that way throughout the entire construction process.

TRW Fibreclad Battens

TRW Fibreclad System™ battens for use under an EPS substrate are manufactured from high density (Class H) expanded polystyrene with an approximate density of 24kg/m3 and measuring 25mm x 45m. All battens must be stapled vertically to the framing or alternatively glued to the chosen building paper in accordance with the batten layout shown in the detail data sheets. Additional vertical battens are required at internal and external corner s and openings. At the eve and external corners the airflow must be blocked off and gables must be lined or incorporate an air barrier.

TRW Starter Foam

TRW Starter Foam has been designed to eliminate the use of cavity closers. TRW Starter Foam will leave a 2mm-3mm gap between the flashing and the back of the Starter Foam. (Minimum 1000 sq/mm air gap per lineal metre). This will allow any water to escape and air flow to dry any condensation that may occur on the back of the foam. The bottom edge of TRW Starter Foam is pre coated to prevent UV rays and the elements degrading the foam. The bottom edge is also cut with an upward 25 degree rake to act as a drip edge and minimise the gap between the foam and the flashing on pitched roofs. TRW Starter Foam should be fitted after battens and before any other foam is fitted. On first storey applications a 15mm-20mm gap between the bottom edge of the starter foam and the roof is desirable. On each corner stud measure up the desired distance for the top edge of the starter foam to leave a 15mm – 20mm gap at the bottom edge, then flick a chalk line across the battens. This will ensure the bottom edge is straight. TRW Starter Foam must be mitre cut and glued at all internal and external corners. For ground floor applications TRW Starter Foam must be left 75mm above ground level.

TRW Sills and Reveals

TRW Sills are cut on a 25 degree fall to ensure water runs away from windows. The top edge of the sill and the internal edges of the reveals are pre coated eliminating the need for external angle beads around windows. 5mm gaps should be left between all joints. Window components should be fitted after battens and starter foam.

Fixings

Polystyrene sheets are fixed through the cavity battens and spacers to the studs with 130 x 4mm hot-dipped galvanised screws topped with a 42mm washer. All horizontal joints must be fixed 50mm either side of joint. Fixings must be maximum 400mm centres on every stud and 150mm centres on all external corners.

Steel Framing

The same fixing centres apply as for timber framing. 6 gauge screws in defined Corrosion Zones 1, 2, 3 and 4 and Grade 304 Stainless Steel 6-gauge screws in the sea spray zone. The screw length must allow a 10mm minimum penetration through the steel framing.

Fixing Polystyrene sheet

The sheets must be butt jointed except at corners where one sheet may overlap the other to form a straight finish. Additional framing will be required at eves, internal and external corners and window and door openings for the support and fixing of sheet edges. All sheet joints and edges must be supported. Sheets can hang 50mm below the supporting frame. Construction joints are needed in walls longer than 5 metres or higher than two stories. This doesn’t apply to two storey houses with a gable end that does not contain a penetration. All joins between the EPS sheets must be flush filled with adhesive spray foam prior to render being applied. Any oxidization on the surface of the polystyrene must be removed with a stiff broom and water, and then the cleaned surface must be scratched to provide a key before rendering begins.

Aluminium Angles

All external corners must be protected by a TRW Fibreclad System™ aluminium angle. The angles must be glued on at 200mm centres with TRW angle adhesive.

Mesh Coat

Aluminium angles should be meshed first using TRW Fibreclad System™ 100x10x10mm 160g/m2 alkali resistant mesh followed by all the flat areas of wall using TRW Fibreclad System™ 1000x10x10 160g/m2 alkali resistant mesh. All mesh must overlap any adjacent drop by a minimum of 50mm. At the corners of all openings, a second layer of mesh 100 x 300mm (butterfly) must be applied and embedded in the base coat render on the diagonal to reduce the chance of any subsequent cracking at these high stress points.

Base Coat

TRW Fibrelite™ High Impact base coat must be applied 4mm-5mm thick and floated with a plastic diamond float

Finishing Option

There are two finishing options once the mesh and base coat have been applied:

Option1:Stucco Testure
TRW Fibrelite™ base coat render can be sprayed through a hopper gun to achieve a heavy stucco render finish.

Option2:Texture Finish
Texture finish is a modified Acrylic Top Coat Render which is towelled on and floated flat to achieve a fine granular finish. The smooth render will not cover up background imperfections, particularly when walls are subject to side lighting at certain times of the day.

Painting

A full membrane system must be used over TRW Fibreclad System™ to make the system weather tight and give the desired finish colour to exterior walls. TRW membrane is 100% acrylic-based membrane that has been specially formulated and must be applied in accordance with the paint manufacturer’s specifications and instructions. Other paint systems are not covered by this specification sheet and TRW will not warrant the use.

Internal Plastering

Installing internal plaster board and final fix of windows and door jams after TRW Fibreclad System™ is finished is often a course of cracking in the render, created by plasters and carpenters hammering the frame. Internal Plastering also adds stability to the frame acting as additional bracing. Internal Plastering and architrave fix should be fitted after EPS has been fitted and before final render coat is applied to ensure a crack free surface

Curing

Curing
The curing time of finishing render will vary due to ambient temperature, relative humidity, surface temperature, surface porosity, application methods, and/or the thickness of the material. All freshly applied material must be protected from inclement weather for a minimum of 24 hours after application. It is the responsibility of the render applicator to determine if the product is cured and/or dry prior to applying any additional coats that may be required or exposing the applied product to rain, snow, dew, and/ or any other inclement weather condition that may have a detrimental effect. Although all the finishes contain cement and will not fully cure for 28 days, as long as it is lightly hosed down with fresh water 12 hours prior to painting, it can be painted after the finish coats have cured for a minimum of 3-4 days.

Site Storage

Products in dry form must be stored in a dry area, off the floor on a timber pallet and it must be protected from the weather and from mechanical damage. Stock must be rotated to ensure that the oldest material is used first. Render stock that is older than six months must be discarded. EPS sheets, battens, flashings and profiles must be protected from direct sunlight and physical damage. They should be stored flat and under cover. Liquid components must be stored in a frost free area.

Maintenance

Any membrane film damage must be repaired as soon as possible to prevent water penetration and ensure that the high strength properties of the fibreglass mesh are maintained. Any impact damaged areas must be thoroughly cleared of any loose material and repaired with TRW Fibrelite™ render. This will ensure a positive bond between the original render and the repaired area. Repaint within the following week. The wall cladding system should be regularly cleaned, at least annually, by washing with clean water to remove dirt and to maintain the finish appearance. Grime may be removed with warm water and detergent. Rendered walls should be recoated with an approved paint system in accordance to the paint manufactures specifications to maintain weather tightness. Regular checks, at least annually, must be made of the system to ensure that the weather resistant coating is maintained watertight, and that the sealant, flashings, and other joints continue to perform their function and do not allow water to penetrate. Failure to correctly maintain the system may void any long term warranties offered with the system. Any accidental damage to the cladding must be repaired immediately TRW materials.

Advantages

• TRW Fibreclad System™ carries a 7 year warranty, backed by TRW
• The TRW Fibreclad System™ has been developed as the result of over two decades of cladding history in Australia and overseas research and incorporates flashings to ensure all windows and doors are adequately sealed to stop water intrusion. The penetration flashings that are required for this system are installed by the licensed contractor.
• As TRW Fibreclad System is not a rigid system like fibre cement or traditional stucco renders, the fastinings can move slightly within the polystyrene backing sheets and the cavity battens. This ensures that the stresses that can occur as anew building settles and moves or during temperature fluctuations will not transmit through the cladding and cause undue cracking in the exterior.
• TRW Fibreclad System is a cavity based system that allow any moisture that may penetrate behind the cladding system for any reason to escape uninhibited without wetting or affecting the structural framing of the building. The cavity also enables air flow to dry any condensation that may occur.
• The TRW licensed contractor takes full responsibility for creating the cavity behind the polystyrene.
• It is a scientific fact that the external location of the polystyrene insulation puts the insulation in the best place: as far toward the outside of the building as possible where the temperature fluctuates. This reduces the amount of energy that is needed to maintain a constant temperature inside the home, and does not leave cold spots like some in-wall insulation that tends to slump over time.
• The TRW Fibreclad System™ is not jointed on the outside surface. The raw polystyrene sheets are glued, meshed and rendered on site. This feature allows designers and architects to readily achieve a monolithic look without the risk of being able to see any type of sheet uionts.
• The polystyrene in the TRW Fibreclad System™ is 75mm thick and with the batten ends up 100mm therefore giving the appearance of a rendered masonry or block construction but at a fraction of the price.
• As the TRW Fibreclad System™ is extremely lightweight (approximately 9kg per m/sq) and remains slightly flexible, it is well suited to pole structures or areas with poor quality soils and foundations.
• The TRW Fibreclad System™ offers tremendous design versatility and flexibility. The polystyrene substrate can be bent, rasped, curved and carved to create different shapes.
• When the TRW Fibreclad System™ is used for recladding older or damaged buildings, the surface of the polystyrene substrate can be rasped and filled to ensure the finished surface of the cladding is completely flat and livel prior to the rendering system being applied.
• The level of toxicity of expanded polystyrene in a fire is no greater than that of burning timber and other commonly used building materials, Although a lot of soot (smoke) is created, tests carried out in accordance with European standards show that it produces fewer toxins than burning radiate pine. Confusion is often created between polyurethane and polystyrene, which are two distinctly different products. Polyurethane foam can be toxic in a fire but it is not used in the TRW Fibreclad System™
• Under full scale testing, the TRW Fibreclad System™ has yielded an ignitability index of zero. This means that the materials used in the TRW Fibreclad System™ do not contribute to a fire.
• Polystyrene is an inert organic material that will not rot, will not hold water and is highly resistant to mildew. It also provides no nutritive value to ants, termites or rodents.

Limitations

DO NOT apply render when the anbient or surface temperature is below 4 C or above 30 C or will be in that range for the 24-hours period after application. When hot, dry, or windy conditions exist, moist curing and protection must be provided. Material that is allowed to freeze or material that dries too quickly may suffer irreparable damage.

DO NOT add any other material to the renders used with the system or deviate from the mixing or application procedures outlined in any of TRW’s technical data sheets without written approval from TRW.

DO NOT apply any TRW material unless the substrate has been properly cleaned and prepared.

DO NOT add any more water than prescribed by the technical data sheet for the individual products.

DO NOT wet the wall prior to the application of any render.

DO NOT reactivate any render with more water once it has begun to set.

DO NOT mix more render than you can use in 45 minutes.

NOTE: Failure to follow the manufacturer’s written specifications could result in the following but not limited to spalling, cracking, peeling, chipping, delamination, discoloration, wash off, and overall system failure.

Warranty

TRW warrants your products to be free from defects in material and workmanship for a period of 7 years from the original date of purchase. If you discover a defect covered by this warranty, we will repair at our option using new or refurbished components, or if repair is not possible, replace the item. All Foam Insulation Board, fibreglass mesh, fixings and render products used for the TRW Fibreclad System™ must be supplied by TRW or one of its certified distributors. The recommendations, suggestions, statements and technical data provided by TRW are based on the best current knowledge available and are given for information purposes only without any responsibility for their use. It is expressly understood and agreed that the buyer’s sole and exclusive remedy shall be the replacement of defective products, and under no circumstance, shall TRW be liable for incidental or consequential damages. TRW neither assumes, nor authorizes, any others to assume for it any liability with respect to furnishing of the product. Handling and use of the products are beyond the control of TRW; therefore, no warranty is made, expressed or implied, as to the results or on site quality that can be obtained from the use of the product. The long-term durability of the TRW system is dependent upon the correct preparation and application of all of its components in strict accordance with all the relevant written instructions and detail sheets. On-site application is beyond the control of TRW and it cannot guarantee workmanship or the correct preparation and application of its products or systems. The Certified TRW contractor shall take the overall responsibility for on-site supervision, staff training, installation, and quality control.

Technical Assistance

Technical assistance and information is available by calling TRW at 1800RENDER