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Application

  • Suitable for new build and refurbishment projects.
  • Suitable for high, medium and low rise properties.
  • Also suitable for use on solid walls.

Description

Render Carrier Board Silicone Render System.


Features and benefits:

  • Developed exclusively by WBS, the EPSITEC External Render Carrier Board System has been designed to satisfy the need for render only systems incorporating a drainage cavity, for use on lightweight steel or timber frame construction.
  • Lightweight steel and timber frame structures are extremely robust and can be assembled in a matter of weeks using factory production methods.
  • Once the framework has been assembled, and has been clad with an external weather-grade building board, the EPSITEC system can be installed directly to these boards ensuring the timber batten / RagRail locate the studs behind.
  • This innovative technique offers many advantages compared to traditional masonry methods, including increased speed in construction and it also allows internal contractors to commence works much earlier in the building programme, resulting in reduced build time and associated cost savings.
  • Following NHBC Guidelines, the EPSITEC System has been designed to incorporate a drainage cavity between the board and the system allowing any moisture to naturally drain away.
  • Depending on the projects requirements, Intumescent strips can be installed horizontally at floor levels to close the cavity in the event of a fire. For party walls and openings the NVFB Fire Barrier can be installed, fully closing of the system within these areas.
  • Once the render carrier board has been installed (as per manufacturer’s instructions), the system is finally completed via the use of a wide selection of coatings and textures, which gives the completed project a hard-wearing, attractive, weatherproof finish.
  • NHBC/ Zurich approved drainage cavities can be achieved on steel/ timber frame constructions (in accordance with EN ISO 6946: 1996).
  • Can be applied to uneven surfaces and used to level the substrate.
  • BBA Certified.
  • This system has an assessed anticipated lifespan in excess of 30 years. 

General information

Material

Silicone

Warranty description

Ten year

Guidance for specification option:

On BBA approved systems

Uniclass

Ss_25_45_72_28 External wall insulation systemsPrimary

CAWS

M21/20 External wall insulation system . . . . . .

M21/210 External wall insulation system

Product range

External Wall Insulation Systems On Support Rails

Specification data - External wall insulation systems

System performance

Durability: 30 years; Fire performance: To BS EN 13501, A2-s1, d0; Strength and stability: When designed in accordance with the guidance located within the systems certification, the system can adequately resist the wind loads and impact damage likely to be met in service.

Guidance for specification option:

The systems can be expected to have a design life in excess of 30 years.

Manufacturer guidance

The system can also contribute to a limiting risk of interstitial and surface condensation. For further information, please see the system’s BBA Certificate.

Preparation

Not required.

Biocidal wash.

Manufacturer guidance

Ensure substrate is clean and structurally sound. The substrate must be completely dry and not damaged by rain or frost. Consult the board manufacturer and redo pull-out tests before continuing if rain or frost damage is evident.

Sheathing boards must achieve minimum pull out requirements to be suitable for the system application. Ensure sheathing boards or panel substrates are line and level to allow RagRails to be installed flush to the substrate. Slight variances in the substrate can be overcome by using suitable packers to ensure the system is installed line and level. All sheathing boards must be securely fixed, correctly jointed and sealed (where required) as per the board manufacturer's instructions.

If the walls are not line and level, the fixing lengths must be checked to ensure adequate embedment into the sheathing board/ frame substrate. This will need to be confirmed on site prior to the installation of the Wetherby system. Sizing of flashings trims and beads also require alterations.

Existing timber or steel cladding - remove any defective areas of the existing substrate and where required make repairs to ensure the surface is ready to receive the EWI system. Clean the existing walls to the satisfaction of the Contract Administrator to remove any friable material algae or lichen. WBS Biocidal Wash can be used to treat areas of moss algae and mould growth.

Support rails and brackets

-

Fixing method

-

Material

15 mm RagRail Cavity Spacer Rails.

Guidance for specification option:

Rails or Timber Battens should be installed vertically at 600 mm cts and around windows ensuring the Render Carrier Boards are fully supported. RagRails are to be fixed down one side of the rail and through the centre of the rail hitting the studs at 300 mm cts. The above would all be subject to Job Specific Detailing, including Pull Out Tests and Wind Load Calculations.

25 mm RagRail Cavity Spacer Rails.

Guidance for specification option:

Rails or Timber Battens should be installed vertically at 600mm cts and around windows ensuring the Render Carrier Boards are fully supported. RagRails are to be fixed down one side of the rail and through the centre of the rail hitting the studs at 300mm cts. The above would all be subject to Job Specific Detailing, including Pull Out Tests and Wind Load Calculations.

25 mm Timber Battens.

Guidance for specification option:

Rails or Timber Battens should be installed vertically at 600mm cts and around windows ensuring the Render Carrier Boards are fully supported. Timber Battens are to be fixed at every 150m cts. The above would all be subject to Job Specific Detailing, including Pull Out Tests and Wind Load Calculations.

Manufacturer guidance

The RagRails or Timber Battens create a drainage cavity between the Sheathed frame and Render Carrier Board. This cavity will then allow for any moisture located within these areas to track down and drain out, either from the bottom of the system or into specifically designed drainage boxes.

Bracket fixings

LS 5.5 (steel frame).

R-QCP (timber frame).

Manufacturer guidance

The actual fixings of the Rail / Battens will need to be appropriate for the substrate that the system will be installed over. Fixings and their frequency will be subject to pull out tests and wind load calculations. 

Boards

-

Material

WBS Approved Render Carrier Board, minimum 12 mm.

Guidance for specification option:

1200 x 2400 mm, insert requirements.


The framed substrate must be sheathed using a Wetherby approved sheathing board ensuring that they achieve minimum pull out requirements to be suitable for the system's application. These boards must be fixed as per their manufacturer’s instructions using their approved fixings. Please see table located in systems BBA certificate for further information. Render Carrier Boards must be externally fixed to the Timber Batten / RagRail using approved WBS fixings.

Fixings

WBS approved mechanical fixings.

Guidance for specification option:

WBS approved render carrier boards to be fixed using WBS approved mechanical fixings in accordance with board manufacturer’s instructions / any pull out tests and wind load calculations completed for the project.


Please note: 3–5 mm gaps must be left between render carrier boards with approved sealant installed. Designated mesh strip (100 mm) to be installed over board joints which must be encapsulated with 1–2 mm scrim adhesive.

Insulation

-

Additional mechanical fixings

Mechanical only.

Manufacturer guidance

  • Where mechanical fixings are required, the length, type and number of fixings into the substrate required can only be determined following an on-site pull out test.
  • Secondary pinning may be required on high-rise applications. Please consult with WBS Technical Support for recommendations.

Fire barriers and stops

-

Material

Tenmat Intumescent Strip.

Guidance for specification option:

Intumescent strips should be screw fixed in place at 250 mm max centres, using a non-combustible screw with a head of no more than 11.5 mm diameter. They should be mechanically fixed at agreed locations to form horizontal and if specified vertical fire breaks in the cavity.

Tenmat NVFB Fire Barrier.

Guidance for specification option:

Vertical cavity closer detail and cavity closers around openings (where required) – Tenmat NVFB Non-Ventilated Fire Barrier

Mechanically fix the NVFB through the centre of the barrier at distances no greater than 250 mm from each end, using a stainless steel screw, with a head diameter between 12 and 14 mm maximum width (no washer required). The depth of the screw should be sized according to the substrate to which the screw will be anchoring in to but must allow for the screw head to be compressed 5–10 mm into the surface of the NVFB barrier. Ensure that NVFB pieces are tightly abutted together and are aligned flush with each other. Point in any small gaps (up to 5 mm) with intumescent sealant if required. The Render Carrier Board is to be installed over the NVFB fire barrier ensuring the NVFB is adequately compressed.

Manufacturer guidance

Systems can incorporate cavity closers/fire barriers if required. NVFB’s and Intumescent Strips are required on all projects 2 storeys and above as per BRE Report BR135:2013. Building Control would also need the confirm the positioning and the requirement of the cavity fire barriers/ intumescent strips.

Fixings

TKE Range – Steel Frame - Stainless Steel Screw.

Guidance for specification option:

Typically used to fix intumescent strips to their agreed locations (Rail / Sheathing Board / Steel Frame).

JT3-FR6 Stainless Steel Screw.

Guidance for specification option:

Typically used to fix NVFB fire barriers to their agreed locations (Sheathing Board / Framed Substrate).

Manufacturer guidance

Fixing type, length and frequency are all subject to pull out tests, job-specific detailing/requirements and wind load calculations. 

Movement joints

-

Form with

Not required.

WBS Stainless Steel Movement Joints.

WBS PVC Movement Joints.

WBS Stainless Steel Surface Mounted Render Stop Beads.

WBS PVC Surface Mounted Render Stop Beads.

Manufacturer guidance

All structural movement joints must be mirrored through the Render Carrier Board System. As a minimum, incorporate the movement joints every 7–10 m vertically and at every other floor level horizontally. Structural Engineers will be required to confirm how much movement will occur and where movement joints are located in the substrate. All movement joints and surface render beads must be fully meshed in, applying silicone sealant where necessary. 

Sealant

Compriband sealing tape between the render carrier boards.

Guidance for specification option:

Where movement joints are required.

Render carrier or reinforcement

-

Material

Glass Fibre Reinforcement Mesh.

Guidance for specification option:

Trowel apply a 4-6 mm thick coat of scrim adhesive to the entire surface of the boards. Lightly run a notched trowel through the scrim adhesive at a 45 degree angle to ensure the correct thickness of adhesive is applied. Bed WBS Alkali Resistant Scrim Cloth into top third of the wet adhesive, overlapping joints by 75 mm minimum. The scrim cloth must be overlapped around building corners and returned into all reveals and heads. All beads must be fully scrimmed in. Install additional 500 x 250 mm minimum pieces of scrim cloth diagonally across corners of all wall openings. If required install secondary fixings through the wet scrim adhesive and WBS Alkali Resistant Scrim Cloth whilst adhesive is wet. 100 x 100 mm scrim patches to be installed over each secondary fixing head. Finally, smooth out scrim adhesive using a spatula.


When initial layer of scrim adhesive has hardened, trowel apply a further 2-3 mm coat of scrim adhesive ensuring all alkali-resistant mesh is covered. Level the scrim adhesive using a spatula/damp sponge float to achieve a uniform flat and even surface ready to receive the WBS final finish.

 

Allow sufficient drying time before applying the Primer. Cold conditions and high humidity will result in the basecoat taking longer to dry/cure. The basecoat must be fully hardened with no signs of moisture visible. Moisture trapped in the basecoat can potentially damage the curing of the Primer/Silicone Render causing failure after completion of the system.

Mesh size

Guidance for specification option:

50 m² roll.

Fixings

JT3-ST-2 6.0.

Guidance for specification option:

Typically used for the stainless-steel secondary fixing installed through the mesh at a rate of 1 per m2. Can be specified to be fixed into the render carrier board only or through it into the Rail/ Batten located behind. The positioning/fixing type would be subject to job-specific detailing, wind load calculations and pull-out tests. 

Render

-

Application

Primer and finish coat.

Material

EpsiCoat Primer.

Guidance for specification option:

Apply Wetherby EpsiCoat Primer with a brush or lamb’s wool roller as per manufacturer’s printed instructions.

Decorative finish

WBS Silicone 'K', Grain size ___ mm.

Guidance for specification option:

Mix and apply Wetherby Silicone Textured Finish strictly in accordance with the manufacturer’s printed instructions. The topcoat should be applied with a stainless steel trowel to the thickness of the grain and finished with a plastic float. Apply in a continuous application always working to a wet edge and in the same direction to ensure consistency of finish. Wherever possible, entire elevations should be completed in a single operation to avoid joint marks in the finish. This can often be achieved by working to natural breaks in the building or working to breaks in colour or texture.

 

Do not apply Wetherby Silicone Textured Finish with differing batch numbers on the same elevation. Care should be taken to avoid texture changes at different levels. Prior to setting, polish render with plastic float to give an even texture and remove all trowel marks.

WBS Silicone 'R', Grain size ___ mm.

Manufacturer guidance

  • WBS flexible silicone & acrylic thincoat finishes are supplied pre-mixed and are available in 100 standard colours. Special colours and colour-matching to other manufacturer's palettes may be available on request. WBS silicone and acrylic finishes are available in four standard grain sizes in the 'K' range and two grain sizes in the 'R' range. Other grain sizes can be acquired on request.
  • WBS Silicone & Acrylic systems are certified for European Technical Approval from the DIBT, Germany. ETA is an EEC wide accepted equivalent to BBA. Standard.
  • WBS Silicone & Acrylic systems are BBA approved on the Epsitec system.
  • Please consult with WBS Technical Support before specifying any dark colours with a lightness value of less than 20.

Colour

-

Manufacturer guidance

Any NCS or RAL reference, insert requirement.

System accessories

None.

WBS Sealing Tape.

Guidance for specification option:

Pre-compressed, expanding waterproof sealing tape.

WBS Firtree Fixings.

WBS Jointing Pieces.

WBS End Caps.

WBS EVO-STIK Silicone Sealant.

Manufacturer guidance

Relevant tape and jointing to be specified as per board manufacturer’s guidance/instructions.

Samples required

None.

Submit samples of textured Wetherby silicone finish for approval. Keep approved samples on site for the duration of the contract for inspection and comparison purposes.

Manufacturer guidance

The manufacturer offers a product sample service, providing a small sample of the finished build-up, colour and texture before a final decision is made. Contact the manufacturer for further information.

Execution

Install system as per manufacturer’s instructions.

System completion

Inspection of completed installation.

Documentation for insulated render systems.

O&M manuals and data sheets relevant to the system installed.

BIM objects

BOS

NBS BIM Object Standard

This BIM object has been authored to meet the requirements of the NBS BIM Object Standard.

Find out more about the NBS BIM Object Standard.

Platform Compatible Version
Revit
 -

2

IFC
 -

2

Literature

Wetherby New Build Systems

Wetherby New Build Systems

Clay Brick Slip Systems

Clay Brick Slip Systems

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