Ravenscroft Plastics Limited Green Lane Newtown Tewkesbury Gloucestershire GL20 8HD Tel: 01684 292272 Fax: 01684 299124 e-mail: email@example.com website: www.cavalok.com
Designated by Government to issue European Technical Approvals
Agrément Certificate No 00/3673 Second issue*
CAVALOK CAVITY CLOSURE SYSTEM Patron Chablone
• THIS CERTIFICATE RELATES TO THE CAVALOK CAVITY CLOSURE SYSTEM, A PVC-U CAVITY CLOSER AND WINDOW ACCEPTOR USED AS A TEMPLATE TO FORM AN OPENING IN MASONRY CAVITY WALLS DURING CONSTRUCTION AND SUBSEQUENTLY, IN CONJUNCTION WITH A STAINLESS STEEL CLIP, AS A FIXING FOR PVC-U WINDOWS. • The product closes the cavity at openings without forming a thermal bridge and provides a damp-proof barrier between inner and outer wall leaves at the point of closure.
Regulations 1 The Building Regulations 2000 (as amended) (England and Wales) The Secretary of State has agreed with the British Board of Agrément the requirements of the Building Regulations to which cavity closers and sub-frame fixing profiles can contribute in achieving compliance. In the opinion of the BBA, the Cavalok Cavity Closure System, if used in accordance with the provisions of this Certificate, will meet or contribute to meeting the relevant requirements. Requirement:
Dwellings Buildings other than dwellings
When the product is used as detailed in this Certificate, adequate provision will have been made to limit the thermal bridging which occurs around the opening of which it forms a part. The detail will therefore contribute to meeting the requirement of limiting the heat loss through the fabric of the building and the risk of surface condensation on the reveal will be minimal. See section 10.1 of this Certificate.
Resistance to weather and ground moisture
The product prevents the passage of moisture from the outer leaf to the inner leaf of a cavity wall at window openings. See sections 11.1 to 11.4 of this Certificate.
Materials and workmanship
The product is acceptable. See section 15 of this Certificate.
Readers are advised to check the validity of this Certificate by either referring to the BBA’s website (www.bbacerts.co.uk) or contacting the BBA direct (Telephone Hotline 01923 665400).
In addition to the contribution which the product can make to meeting the relevant requirements, the following comments should be noted: Requirement:
• The product is for use in masonry cavity walls with cavity widths of 50 mm and 75 mm. • It is essential that the product is installed and used in accordance with the conditions set out in the Design Data and Installation parts of this Certificate.
When used in conventional masonry cavity walls, the product will transfer back to the structure wind and impact loads imposed on the window. The walls require conventional ties between the inner and outer leaves at window openings.
Internal fire spread (structure)
The product is acceptable. See sections 12.1 to 12.3 of this Certificate.
2 The Building Standards (Scotland) Regulations 1990 (as amended) In the opinion of the BBA, the Cavalok Cavity Closure System, if used in accordance with the provisions of this Certificate, will satisfy or contribute to satisfying the various Regulations and related Technical Standards as listed below. Regulation: Standard:
Fitness of materials and workmanship Selection and use of materials, fittings, and components, and workmanship
The product can contribute to a construction meeting this Standard. See the Installation part of this Certificate.
Selection and use of materials, fittings, and components, and workmanship
The product is an acceptable material. See section 15 of this Certificate.
Comment: Regulation: Standard:
When used in masonry cavity walls, the product will transfer back to the structure wind and impact loads imposed on the window. The walls require conventional ties between the inner and outer leaves at window openings.
Regulation: Standards: Standards:
12 D2.1 and D2.2 D6.1 and D6.2
In conjunction with a cavity barrier, the product can satisfy these Standards. The product does not constitute a cavity barrier. See sections 12.1 to 12.3 of this Certificate.
Resistance to moisture Resistance to precipitation — Resistance to precipitation
Walls incorporating the product can comply with the requirements of this Standard. See sections 11.1 to 11.4 of this Certificate.
Resistance to condensation Condensation — Interstitial condensation
The risk of damage due to interstitial condensation associated with the product will be minimal. See section 10.2 of this Certificate.
Structural fire precautions Structural protection — Principles Concealed spaces — Principles
Condensation — Surface condensation
The risk of condensation on the inner surface of a reveal containing the product will be minimal. See section 10.1 of this Certificate.
Conservation of fuel and power Buildings in purpose group 1 — Limiting thermal bridging at junctions and around openings Buildings in purpose groups 2 to 7 — Limiting thermal bridging at junctions and around openings
Walls incorporating the product can satisfy these Standards. See section 10.1 of this Certificate.
3 The Building Regulations (Northern Ireland) 2000 In the opinion of the BBA, the position of the Cavalok Cavity Closure System, if used in accordance with the provisions of this Certificate, will satisfy or contribute to satisfying the various Building Regulations listed below. Regulation: Comment: Regulation:
Fitness of materials and workmanship
The product is acceptable. See section 15 of this Certificate. C4
Resistance to ground moisture and weather
Walls incorporating the product can contribute to meeting this Regulation. See sections 11.1 to 11.4 of this Certificate.
The risk of harmful effects on the building due to interstitial condensation associated with the product will be minimal. See section 10.2 of this Certificate.
When used in conventional masonry cavity walls, the product will not adversely affect the structural stability of the walls. Use of the product does not obviate the need for conventional wall ties between the inner and outer leaves at window openings.
Internal fire spread â€” Structure External fire spread
The product is acceptable. See sections 12.1 to 12.3 of this Certificate.
When the product is used in an opening, adequate provision will have been made to limit the thermal bridging which occurs around the opening of which it forms a part. The detail can therefore contribute to meeting the requirement to make reasonable provisions in the fabric of the building for the conservation of fuel and power. See section 10.1 of this Certificate.
4 Construction (Design and Management) Regulations 1994 (as amended) Construction (Design and Management) Regulations (Northern Ireland) 1995 (as amended) Information in this Certificate may assist the client, planning supervisor, designer and contractors to address their obligations under these Regulations. 5 Description (5.10).
5.2 The PVC-U sections of the frame are box profiles, sealed at the open end with a polystyrene plug (see Figure 2) and joined together either by welding or mechanically, with a push-fitted corner joint (see Figure 1). Sections for use at the jamb and, for externally-installed windows, at the sill, have an upstand against which the window frame is positioned (see Figures 3 and 6).
Technical Specification 5 Description 5.1 The Cavalok Cavity Closer is a three-sided, U-shaped, PVC-U frame with a temporary timber head brace (removed after installation) (see Figure 1). Figure 1
Typical closer section
5.3 PVC-U sections are available to suit 50 mm and 75 mm wide cavities and various applications (see Figure 3). 3
Typical closer sections externally-installed windows upstand
jamb and sill
jamb check reveal
5.4 Polypropylene ties are available from the manufacturer for fixing the frame into the surrounding masonry, and stainless steel clips for securing the frame to the closer (see Figure 4).
Approved fabricators 5.7 Approved fabricators assemble the closer frames to size. 5.8 Corner joints are made by mitring and welding, or by cutting square and fitting with an ABS injection moulded corner joint (see Figure 4).
5.5 A suitable double-sided glazing tape is used to seal the joints between the window frame and closer upstand (see Figure 6). However the tape is not a part of the specified system and is outside the scope of this Certificate. Security glazing tapes covered by a BBA AgrĂŠment Certificate would be suitable.
5.9 The head is temporarily braced with a timber strut, screwed to the closer upstand for externallyinstalled window applications (see Figure 1), and to a PVC-U angle (see Figure 4) fixed into the body of the closer for check reveal and internally-installed window applications. A suitable double-sided glazing tape is applied by the fabricator to the face of the closer upstand which will be in contact with the window frame.
5.6 The PVC-U closer sections are produced by conventional extrusion procedures. Quality control checks on the extrusion include heat ageing, heat reversion and dimensions. 4
from which the window is to be installed (see Figure 5). The clips must protrude a minimum 8 mm above the level of the frame. If this is not possible due to an excessive rebate depth, then packing strips must be used. A plastic cover (see Figures 4 and 5) is fitted over the sharp edges of the stainless steel clip as a safety measure prior to installation.
plastic clip cover
Window with clips
6 Delivery to site and storage 6.1 Closer sections are transported to the approved fabricator in shrink-wrapped bundles of fifty 6 m lengths. Ancillary items are despatched in bags or boxes. The packs bear product identification, a manufacturing reference and the BBA symbol incorporating the number of this Certificate.
tie PVC-U angle (bracing connection)
6.2 The closer frame and window frame with protected clips fixed in position are despatched to site from the fabricator as individual units, with the fixing ties in bags. Care should be taken to ensure that the clips protruding from the window frame are suitably protected from damage during transit. 6.3 Closer and window frames should be handled with care and stored under cover in a clean area, and suitably supported to avoid distortion or damage.
polystyrene end block
Design Data 7 General 7.1 The Cavalok Cavity Closer is suitable for use in masonry walls with cavity widths of 50 mm and 75 mm for fixing PVC-U windows.
7.2 The product provides an effective means of closing the cavity without forming a thermal bridge, and avoids the need for cutting bricks and blocks.
5.10 An approved fabricator is also responsible for preparing the window frame. This is constructed to allow 5 mm expansion all round with the sill attached in accordance with the manufacturerâ€™s recommendations. Stainless steel clips are screwed to the jambs and sill of the window frame (up to 100 mm from each end and at maximum 300 mm centres). The clips are positioned against a stop or datum line scribed on the frame, with the angled leg of the clip pointing out towards the direction
7.3 The product is suitable for use in flush-jamb and check reveal applications, and can accommodate externally- and internally-installed windows. 7.4 The product can be used as a template, to form an opening around which a wall can be constructed. 5
Scotland Technical Standards J4.1 and J9.1
8 Practicability of installation Installation of the product is straightforward and can be carried out by tradesmen using traditional skills, provided the installation instructions are followed.
Northern Ireland Technical Booklet F, Paragraphs 1.33 and 1.34. (1) In determining the set-back position, the glazing tape is taken to be a part of the window frame.
9 Structural stability
Scotland and Northern Ireland 10.2 Under normal domestic conditions the level of interstitial condensation associated with the product will be low and the risk of any resultant damage minimal.
9.1 The Cavalok Cavity Closer must not be used to support loads from the masonry. Lintels are required above window or door openings. 9.2 The product will not have an adverse effect on the structural stability of brickwork or blockwork walls, constructed in the conventional manner in accordance with normal good practice as defined in BS 5628-3 : 2001. Use of the cavity frame does not obviate the need for conventional wall ties around the openings.
11 Weather resistance 11.1 The Cavalok Cavity Closer is effective as a vertical damp-proof barrier at jambs of window openings in masonry constructions, where a brick/block closer and dpc detail would normally be used. The product is also effective as a horizontal damp-proof barrier at the sill.
9.3 PVC-U windows fixed to the closer frame with retaining clips, to the masonry or lintel at the head, and, where necessary, to the inner leaf at the sill (see sections 16 and 17), will satisfactorily transfer to the structure the wind loads likely to be encountered in the UK. It is recommended that window frames are reinforced, particularly those: • with side members over 1 m in length • used in exposed areas • with an opening light at the jamb.
11.2 With externally-installed windows, the product is suitable for use in exposure categories up to at least ‘severe’, as defined in Table 11 of BS 5628-3 : 2001 and depicted as exposure zones 1, 2 and 3 in the map shown in section 3.1 of BRE Report BR 262 : 2002 Thermal Insulation: avoiding risks. 11.3 For windows installed internally into a flushjamb detail, the product is suitable for use in exposure categories up to at least ‘severe’ as described in section 11.2, subject to satisfactory performance of the glazing tape.
9.4 For opening light windows there is a tendency for the frame to distort under the forces exerted by the clips, when the window is opened. This is particularly so for unreinforced window frames. To prevent this distortion, additional screw fixing of the frame to the closer is recommended, as detailed in the Certificate holder’s Cavalock Technical Manual.
11.4 For very severe exposure conditions, as defined in the Standard and Report (see section 11.2), the use of the check reveal version of the product is recommended. However, satisfactory performance in this application will depend upon the performance of the glazing tape and its silicone seal (see Figure 6).
10 Hygrothermal behaviour 10.1 Provided the closer and window frames are installed in accordance with provisions of this Certificate and, in particular, that plasterboard minimum 13 mm thick, and window board, minimum 22 mm thick, are fixed on a minimum 5 mm plaster skim at the reveal and sill respectively, with the plaster skim finishing at least 25 mm from the window frame (see Figure 6), then thermal bridging and the risk of local surface condensation around openings will be acceptable, and meet the following requirements, where the window frame is positioned against the closer upstand (see Figure 6) and thereby set-back 30 mm or more(1) into the wall cavity, and the junctions between the walls and the front and back of the window/door frame incorporate an effective sealant. England and Wales Approved Document L1, Paragraphs 1.30 and 1.31 Approved Document L2, Paragraphs 1.9 and 1.10
12 Properties in relation to fire 12.1 The Cavalok Cavity Closer will not contribute significantly to the growth of a fire. On exposure to fire a surface char rapidly forms and inhibits further combustion. 12.2 The product does not constitute a cavity barrier against the penetration of smoke and flame in the context of the Building Regulations. This does not prevent its use in England and Wales or Northern Ireland, where cavity barriers are not required around openings. In Scotland, however, the product is only suitable for use in conjunction with a cavity barrier meeting the performance requirements defined in Technical Standard (D1.3), Table 1. 12.3 The use of the product does not preclude the need to provide suitable fire protection to steel lintels where this is necessary to satisfy the Building Regulations. 6
13 Security against intrusion
Removal of the window from outside is virtually impossible as the retaining clips cannot be disengaged from outside and the head is fixed to masonry or a lintel.
Closer frame 17.1 The cavity wall is built to the sill level. 17.2 The closer frame is placed correctly, in the sill cavity and propped vertically, with the box up against the outer leaf.
14 Maintenance To ensure the maximum weathertightness, the silicone seals to the external window joints must be checked regularly and repairs or renewal carried out promptly.
17.3 The box should be a tight fit in the cavity. If not, it is recommended that, after installation, the closer frame or window frame should be fixed back to the inner leaf at the sill with a rigid strap fixing or equivalent, particularly for installations involving larger windows (above 1 m wide) and/or in exposed conditions.
15 Durability The product and accessories(1), protected within the cavity, are assessed as durable and, when installed in accordance with this Certificate, will not suffer degradation during the normal expected life of a building.
17.4 Masonry is built up around the closer to lintel height and fixed to the closer frame with ties, fitted into the closer channel and embedded in alternate mortar courses of the outer brick leaf (every sixth course) and inner block leaf (every other course).
(1) Excluding the double-sided glazing tape (see section 5.5) — outside the scope of this Certificate.
17.5 When the mortar has set, the timber bracing is removed from the closer frame and the lintel positioned at the head ensuring that it is supported only by the masonry, ie the closer must not bear any weight.
Installation 16 General 16.1 Installation of the product must be carried out in accordance with the manufacturer’s instructions.
PVC-U windows 17.6 The protective plastic clips are removed from the stainless steel clips on the window frame.
16.2 Reference should be made to the typical installation details shown in Figure 6, when reading the installation details given in section 17. Care needs to be taken to ensure that when the 50 mm closer is used in externally-installed applications it is positioned the correct way round such that window/door frames are set-back by at least 30 mm over the cavity.
17.7 The backing paper of the double-sided glazing tape on the closer upstand is removed immediately prior to installation. 17.8 The window frame is pushed centrally into the opening ensuring that it locates against the closer stop at jamb and sill and that all clips engage.
16.3 The clip fixing system has been approved for use only with PVC-U windows.
17.9 Plastic packers are pushed under the frame at the sill.
16.4 The closer frame must be assembled by an approved fabricator.
17.10 The head of the frame is fixed back to the masonry or lintel.
16.5 The closer is selected to suit the application (see Figure 6), ie: • 50 mm or 75 mm cavity width • check reveal or flush jamb • internally- or externally-installed window.
17.11 Where necessary the window frame is fixed to the inner leaf at the sill (see section 17.3). 17.12 Where necessary, the frame of an opening light is screwed to the closer (see section 9.4).
16.6 The installation details required to meet thermal requirements (see section 10.1) must be observed.
17.13 A silicone sealant is applied at appropriate positions around the window frame (see Figure 6). 17.14 Plasterboard, at least 13 mm thick, and window board, at least 22 mm thick, are fixed on a minimum 5 mm plaster skim at the reveal and sill, respectively. In each case the plaster skim must finish at least 25 mm from the window frame (see Figure 6).
externally-installed horizontal position (sill)
externally-installed vertical position (jamb)
internally-installed horizontal position (sill)
1 3 1
check reveal vertical position (jamb)
1 10 2
1 silicone sealant 2 22 mm window board 3 7 mm plaster skim set back at least 25 mm from the window frame
check reveal horizontal position (sill)
internally-installed vertical position (jamb)
4 5 6 7
glazing tape 3 mm plaster skin 13 mm plasterboard brick line flush with upstand
8 glazing packer 9 foam strip 10 5 mm deep air space
19.1 An assessment was made of the hygrothermal properties of constructions incorporating the product. In making this assessment, reference was made, as appropriate, to the ‘Robust Construction Details’(1) BRE Report BR 262 : 2000 Thermal Insulation : avoiding risks and BRE Information Paper IP 12/94 Assessing condensation risk and heat loss at thermal bridges around openings.
The following is a summary of the technical investigations carried out on the Cavalok Cavity Closure System.
18 Tests 18.1 Tests were carried out on PVC-U extrusions to determine: • shrinkage on heating
(1) Limiting thermal bridging and air leakage : Robust construction details for dwellings and similar buildings TSO 2002.
• gelation by immersion in acetone
19.2 A window installation was inspected to assess the practicability of the installation.
• tensile impact, before and after heat ageing.
19.3 Factory visits were made to assess the manufacture and quality control of the extruded profiles.
18.2 Tests were carried out in accordance with the methods defined in MOAT No 1 : 1974, on a combined closer and PVC-U window, installed in a test rig, to determine: • air permeability
19.4 An assessment was made of: • durability of all materials and components used in the construction of the product • weathertightness of the product when installed in accordance with the manufacturer’s instructions • fire resistance and structural stability of walls incorporating the product
• effect of cyclic wind loads to ±1250 Pa • effect of temperature variation (–5°C to 55°C) on resistance to wind loading • resistance to wind loads of ±3000 Pa (Safety test)
• weatherability of the exposed closer upstand in the internally-installed window application.
• resistance to wind gusting from 0 to 750 Pa.
(a) are maintained at or above the levels which have been assessed and found to be satisfactory by the BBA; (b) continue to be checked by the BBA or its agents; and (c) are reviewed by the BBA as and when it considers appropriate.
Bibliography BS 5628-3 : 2001 Code of practice for use of masonry — Materials and components, design and workmanship MOAT No 1 : 1974 Directive for the Assessment of Windows
20.4 In granting this Certificate, the BBA makes no representation as to: (a) the presence or absence of any patent or similar rights subsisting in the product or any other product; (b) the right of the Certificate holder to market, supply, install or maintain the product; and (c) the nature of individual installations of the product, including methods and workmanship.
Conditions of Certification 20 Conditions 20.1 This Certificate: (a) relates only to the product that is described, installed, used and maintained as set out in this Certificate; (b) is granted only to the company, firm or person identified on the front cover — no other company, firm or person may hold or claim any entitlement to this Certificate; (c) has to be read, considered and used as a whole document — it may be misleading and will be incomplete to be selective; (d) is copyright of the BBA.
20.5 Any recommendations relating to the use or installation of this product which are contained or referred to in this Certificate are the minimum standards required to be met when the product is used. They do not purport in any way to restate the requirements of the Health & Safety at Work etc Act 1974, or of any other statutory, common law or other duty which may exist at the date of this Certificate or in the future; nor is conformity with such recommendations to be taken as satisfying the requirements of the 1974 Act or of any present or future statutory, common law or other duty of care. In granting this Certificate, the BBA does not accept responsibility to any person or body for any loss or damage, including personal injury, arising as a direct or indirect result of the installation and use of this product.
20.2 References in this Certificate to any Act of Parliament, Regulation made thereunder, Directive or Regulation of the European Union, Statutory Instrument, Code of Practice, British Standard, manufacturers’ instructions or similar publication, shall be construed as references to such publication in the form in which it was current at the date of this Certificate. 20.3 This Certificate will remain valid for an unlimited period provided that the product and the manufacture and/or fabricating process(es) thereof:
In the opinion of the British Board of Agrément, the Cavalok Cavity Closure System is fit for its intended use provided it is installed, used and maintained as set out in this Certificate. Certificate No 00/3673 is accordingly awarded to Ravenscroft Plastics Limited. On behalf of the British Board of Agrément Date of Second issue: 19th December 2003
*Original Certificate issued on 24th March 2000. This amended version includes modified PVC-U closer sections and clip, new statements in relation to Hygrothermal behaviour and Properties in relation to fire, amended national Building Regulations and CDM Regulations and a revised Bibliography.
British Board of Agrément P O Box No 195, Bucknalls Lane Garston, Watford, Herts WD25 9BA Fax: 01923 665301
©2003 e-mail: firstname.lastname@example.org website: www.bbacerts.co.uk
For technical or additional information, contact the Certificate holder (see front page). For information about the Agrément Certificate, including validity and scope, tel: Hotline 01923 665400, or check the BBA website.