Including. Rubershield-Pro. Breather Membrane

Transcription

1 Including RubershieldPro Breather Membrane

2 2 Ruberoid produces a wide range of underslating membranes, primarily to be installed below tiles, slates or metal roofing providing a secondary barrier against wind driven rain, snow and dust. Some like RubershieldPro, also allow the roof to breathe, negating the requirement for traditional ventilation, while other products perform specialist roles like eaves protection or securing overlap joints. This guide will help you choose your underslating materials and understand the other products needed to complete your project. Historically underslatings were hessian reinforced bitumen membranes. These are still available from Ruberoid together with other high performance polyester based bitumen underslatings. Although trusted for many years, they re unsuitable for modern warm roof or unventilated cold roof applications. Breather membranes are very popular and increasingly used on a wide range of projects. Their adaptable, multipurpose use is seen by specifiers, merchants and installers as the optimum solution to underslating requirements, simplifying design, stock control and installation requirements on site. WARM ROOFS Insulation following the rafter line COLD ROOF (VENTILATED VOID) Insulation at ceiling level COLD ROOF (UNVENTILATED VOID) Insulation at ceiling level RubershieldPro (laid over insulation) Vapour control layer Unventilated void space Insulation Underslating or RubershieldPro (laid over open rafters/sarking boards) Ventilated void space RubershieldPro (laid over open rafters) Unventilated void space Vapour control layer Vapour control layer

3 Breather membrane 3 Why RubershieldPro is the breather membrane of choice Today a new generation of underslating is available and most roofers have moved towards breather membranes such as RubershieldPro. A breather membrane allows potentially harmful moisture vapour to escape from within a building to the outside air, while remaining rain and waterresistant. One membrane suitable and approved for all types of roofing construction is a huge benefit, especially when it s also lightweight, easy to handle, strong and durable. RubershieldPro is a secondgeneration breather membrane, which conforms to the highest performance and professional standards. Designed as a fully supported or unsupported breathable underlay for tiled, slated or metal roofing systems, it s equally suitable whether draped unsupported over rafters or laid directly over insulation. The high vapour permeability and waterproof nature of this triplelayer engineered fabric, combined with its excellent tensile/tear strength and high wind uplift resistance, provides a permanent quality underlay for the life of the roof construction, making RubershieldPro the professional s ultimate choice. Additional features and benefits of RubershieldPro RubershieldPro is suitable and certified for use in all category types of pitched roof construction. Highly breathable so allows the escape of harmful moisture vapour Robust with high tensile and tear strength High wind uplift resistance Water and rain resistant Longterm durability Ideal for warm or cold roof applications (ventilated/unventilated) BBA Certification for all roof configurations Environmentally friendly no adhesives or toxic additives 100% recyclable

4 4 Typical warm roof construction Over the next few pages are some typical roof constructions. Detailed specifications and information on the full range of construction options are available from Ruberoid s Technical Services Department. What is a warm roof? Warm roofs are increasingly popular today as we aim to maximise our living space and the available accommodation in any construction. This will be the predominant form of pitched roofing construction in the UK. A breather membrane such as RubershieldPro must be used in a warm roof configuration, to overcome the condensation risk. In a warm roof configuration, the insulation is positioned directly under the external waterproofing (e.g. tiles or slates), following the rafter line. A vapour control layer is usually placed beneath the insulation (on the warm side), to limit the passage of moisture vapour into the insulation. The RubershieldPro breather membrane is placed on top of the insulation, with overlaps, penetrations and perimeters sealed with Rubershield Jointing Tape. Counter battens/tiling battens are used to install the tile or slate finishes. Using RubershieldPro there is no need to ventilate the void space below the breather membrane, as this void space will always be at a similar temperature to the habitable portion of the building, minimising the possibility for condensation. The void space that would have previously been a storage loft, is now a usable space. In addition, a warm roof contributes to increased airtightness, reducing heat loss by uncontrolled air movements, and aiding compliance with the revised Part L Building Regulations (April 2006). Using partial fill insulation between rafters When insulation is positioned between rafters but does not fill the whole rafter depth, an airspace must be maintained between the underside of Rubershield Pro membrane and the top of the insulation to allow a 1015mm drape of the membrane, unless 38mm counterbattens are used. Other requirements are as for when the insulation is laid above or fully filled between the rafters.

5 Typical warm roof construction 5 With rigid insulation boards, RubershieldPro membrane should be laid directly onto the insulation. Counterbattens (minimum 38mm deep) should be fixed according to insulation manufacturer s instructions. If insulation between rafters is full fill, the membrane should be laid directly over the rafters and insulation. Counterbattens (minimum 25mm deep) must be nailed directly into the rafters. A vapour control layer should be installed on the warm side of the insulation as detailed in BS 5250: 2002 Code of Practice for control of condensation in buildings. Using insulation board above and between rafters No ventilation of any void space is required below the RubershieldPro membrane. With clay or concrete tiles or natural slates, air movement is usually sufficient in the space above the membrane (below the tiles/slates) to negate the requirement for additional eaves and ridge ventilation. However, when using close fitting fabricated slates (e.g. fibre cement) additional eaves and ridge ventilation is recommended above the membrane. 50mm air space (ventilation may be required if using convection tight slates or tiles) Tiles Tiling battens Counterbattens RubershieldPro Insulation between rafters Vapour control layer Insulation positioned at rafter level with timber sarking As Scottish practice is for the use of timber sarking, which has a high resistance to the transmission of water vapour, it is advisable to conduct a condensation risk analysis. RubershieldPro fully complies with requirements in BS 5534: 2003 for use with sarking board installations. Where using proper timber sarking planks (usually 150mm wide) laid with a 2mm gap between the boards, there is no need to provide additional ventilation below the membrane. However, where using sarking boards comprising sheets of plywood or OSB, this type of warm unventilated roof configuration is not recommended. In a warm roof where the membrane is supported on a plywood or OSB sarking board, ventilation of the mandatory 50mm airspace below the sarking board is required, in accordance with BS 5534 (BS 5250: 2002). Under these circumstances there is no requirement for further ventilation above the membrane. Use of counterbattens above the membrane (installed on a sarking board) is required where tiles or slates are to be installed on battens. In some instances tiles or slates can be installed by nailing through the membrane directly into the sarking board. However, the tile manufacturer s instructions must be strictly adhered to.

6 6 Typical FIXING warm INSTRUCTIONS roof design details Some typical warm roof detailing examples are given here. Drawings should be used in conjunction with information available in Building Regulations and British Standards. Further advice, regarding the detailing of the RubershieldPro membrane is available from Ruberoid s Technical Services Department Eaves Ensure fascia board is fixed at correct height. Install Ruberoid Eaves Protection Strip.

7 Typical warm roof design details 7 Abutments Ensure ends of tiling battens are adequately supported on last counterbatten, install noggins if required. Turn RubershieldPro up against abutment wall by not less than 100mm and seal to wall with Rubershield Jointing Tape. Fix lead flashing Code 4 or 5, in accordance with current Codes of Practice and manufacturer s recommendations. Lay a continuous length of RubershieldPro, at least 600mm wide, up the valley. Fit valley support boards to a height level with top of counterbattens. Cut main layers of RubershieldPro to a rake down centreline of valley or along sides of valley lining. Valleys (with lead lining) Ridges Lay RubershieldPro over ridge by not less than 150mm.

8 8 Typical What cold is roof a cold design roof? details What is a cold roof? There are two main types of cold roof: A traditionally ventilated void space, where all types of underslating membranes can be used. An unventilated void space where only certain certified breather membranes can be used. A Cold Ventilated Void Roof configuration is the traditional form of pitched roof buildup. The insulation layer is placed horizontally, directly above the ceiling of the upper story of the habitable section of the building, usually positioned between the joists in the loft space. The RubershieldPro breather membrane or any type of proprietary underslating material is placed at rafter level, either draped between the rafters, or supported on a sarking board (usually Scotland). In a traditional cold roof system, any void space below the underslating membrane has to be ventilated. In this roof type, a breather membrane or nonbreathing underslating membrane would be equally suitable. When an underslating membrane is installed in a cold roof configuration draped between open rafters, the use of counterbattens is not required. In a Cold Unventilated Void Roof configuration the insulation layer is also placed horizontally, directly above the ceiling of the upper story of the habitable section of the building, with the vapour control layer placed below the insulation at ceiling level. However, in this situation, only a breather membrane certified for this configuration can be used. RubershieldPro breather membrane is approved for this purpose and should be placed at rafter level, with overlaps, penetrations and perimeters sealed with Rubershield Jointing Tape, draped between the rafters. However, there is no ventilation of any roof void space below the membrane; the only escape route for moisture vapour is through the breather membrane.

9 Typical What roof is a construction cold roof? 9 Use with sarking boards As Scottish practice where using tiling battens, RubershieldPro must be laid beneath counterbattens of a minimum 25mm depth. In some instances tiles or slates can be installed by nailing through the membrane directly into the sarking board. However, the tile manufacturer s instructions must be strictly adhered to. General guidance for cold ventilated roofs Where a roof underlay or breather membrane is to be laid over open rafters, a drape of between 10 to 15mm between the rafters is desirable to guide any rainwater penetrating the main roof finish away from the rafters to the drainage point. Provide for ventilation of the void space in accordance with BS 5534 (BS 5250: 2002), with the inclusion of a proprietary eaves and ridge (high level) vents, fixed in accordance with manufacturer s instructions. RubershieldPro and all Ruberoid underslating membranes fully comply with requirements in BS 5534: 2003, for use with sarking board installations in ventilated cold roof configurations. General guidance for cold unventilated roofs Where a roof underlay or breather membrane is to be laid over open rafters, a drape of between 10 to 15mm between the rafters is desirable to guide any rainwater penetrating the main roof finish away from the rafters to the drainage point. (The membrane must not be pulled tight against the underside of the tiling battens.) Using RubershieldPro in this type of cold roof requires no ventilation of any void space below the membrane. Also, when using clay or concrete tiles or natural slates, air movement is usually sufficient in the void space above the membrane to negate the requirement for additional eaves and ridge ventilation. However, when using manmade slates (or some close fitting interlocking tile systems) additional ventilation above the membrane in accordance with BS 5534: 2003 (BS 5250: 2002) is recommended to avoid potential damage to battens and fixings caused by condensation. It is recommended that guidance be sought from the tile or slate manufacturers concerned. To minimise the risk of condensation in cold unventilated roofs, all penetrations into the roof space must be properly sealed to maintain the integrity of the vapour control layer or external seal, and loft hatches should be made convection tight. All water tanks in the loft space must be covered and pipework lagged. The occupied building below must be ventilated in accordance with Building Regulations, and rooms that experience high humidity levels must have provision for separate air extraction. Use with sarking boards As Scottish practice, where using proper timber sarking planks (usually 150mm wide) laid with a 2mm gap between the boards, there is no need to provide additional ventilation below the membrane. However, where using sarking boards comprising sheets of plywood or OSB, this type of cold unventilated roof configuration is not recommended, and a traditional ventilated void approach should be adopted.

10 10 Typical cold roof design details Some typical cold roof detailing examples are given in this section. Drawings should be used in conjunction with Building Regulations and British Standards. Further advice regarding the detailing of RubershieldPro and underslating membranes in general is available from Ruberoid s Technical Services Department. For cold roofs with ventilated voids, all of the Ruberoid underslating membranes can be used. Eaves (with soffit): Ventilated voids Ensure fascia board is fixed at correct height. Install Ruberoid Eaves Protection Strip. Allow for eaves ventilation in accordance with BS 5250: 2002 Ensure ends of tiling battens are adequately supported on last counterbatten, install noggins if required. Turn Underslating up against abutment wall by not less than 100mm, and seal to wall with Rubershield Jointing Tape. Fix lead flashing Code 4 or 5, in accordance with current Codes of Practice and manufacturer s recommendations. Abutments: Ventilated voids Ridges: Ventilated voids Lay underslating over ridge by not less than 150mm. Allow for high level ventilation in accordance with BS 5250: 2002

11 Typical cold roof design details 11 Valleys (with lead lining): Ventilated voids Lay a continuous length of Underslating, at least 600mm wide, up the valley. Cut main layers of RubershieldPro to a rake down centreline of valley or along sides of valley lining. Cold roofs that are unventilated require the use of a breather membrane such as RubershieldPro. Ridges: Unventilated voids Lay RubershieldPro over ridge by not less than 150mm. If using tightly fitting slates or tiles, then counter battens should be used. Eaves (with soffit): Unventilated voids Ensure fascia board is fixed at correct height. Install Ruberoid Eaves Protection Strip. If using tightly fitting slates or tiles, then counter battens should be used.

12 12 Installation notes Sitework Underslating membranes must be installed in accordance with relevant sections of BS 5534: 2003, BS 8000: Part 6: 1990 and Ruberoid fixing instructions. Underslating materials are designed as a secondary barrier to wind driven rain and snow; it should not be considered a primary waterproofing layer. Good roofing practice dictates that the primary waterproofing finish (e.g. tiles, slates etc.) be applied as soon as practically possible. Whilst providing a degree of protection, underslating membranes should not be considered as a totally weatherproof protection for occupied buildings or where internal fitting out is taking place. With new buildings or buildings that have undergone extensive renovation that have involved wet trades, the additional water within the building during this first heating season, may cause condensation to form in the roof space, which cannot be fully dispersed by the breather membrane. However, when the internal conditions stabilise, this temporary occurrence of condensation will not recur in a properly designed and constructed system. (Additional information available in BS5250. Section 14.1 Owners Manual and NHBC guidance notes). Supporting structure An underslating membrane when installed as a fully supported system is laid over the support and secured with counterbattens. Alternatively, where practical, the membrane can be installed over counterbattens and fixed at 200mm centres using corrosionresistant straps or galvanised clout nails. Tiling battens are fixed to the counterbattens leaving an airspace between the roof sheet underlay and the tiles for drainage and ventilation. Abutments Abutment flashings should be wedged into a mortar joint 25mm deep and at least 150mm above the level of the slates or tiles. Underslating membranes should be turned up behind the flashing at least 100mm, and sealed where appropriate with Rubershield Jointing Tape to prevent rain and snow being blown into the roofspace, and to restrict unwanted air movement. Lap sizes table horizontal and vertical laps Roof pitch Min. horizontal lap partially supported (mm) Min. horizontal lap fully supported (mm) Min. vertical lap (mm) and greater Notes to lap sizes table Reinforcing strips of 600mm minimum should be fixed at hips, ridges and valleys. It is recommended that where underslating is to be dressed into a half round external gutter, Ruberoid Eaves Protection Strip should be utilised in this area. Note as with all breather membranes of this type, contact with solvents or wet timber preservatives can cause localised water penetration to occur prior to the main weatherproofing being installed.

13 RubershieldPro 13 Typical uses of RubershieldPro Breather Membrane RubershieldPro breather membrane is ideal for all types of warm and cold roof constructions. It can be used as: 1. Roofing underlay positioned immediately above the insulation layer in a warm pitched roof below the roof finish, or in a cold pitched roof (ventilated or unventilated). 2. Roofing underlay for use under tiles and sheeted roofs, over open rafters or onto fully boarded substrates. 3. Breather membrane for timber frame wall construction or behind hanging tiles, timber boarding or cladding systems. Other RubershieldPro applications Hanging tiles Masonry cladding Low slope metal roofs

14 14 Ruberoid pitched roof protection range RoofGuardSB Spunbonded polypropylene, high performance nonbituminous underslating. Starex Polyester based, high performance bituminous underslating. Zylex Hessian reinforced, traditional bitumen underslating to BS 747 Type 1F. Ruberoid Eaves Protection Strip In conjunction with the underslating membrane, an eaves protection strip should be used to give lasting protection where the underslating dresses into external gutters. It can be used with any underslating material (including breather membranes), any tile or slate finish and in cold or warm roof configurations. Main uses Used where dressing any roof underlay into an external gutter. Rubershield Jointing Tape When using breather membranes, Rubershield Jointing Tape is also helpful to allow the individual sheets of membrane to be sealed to each other and at detail work, improving waterproofing performance and the airtightness of the installation. A high performance doublesided selfadhesive tape, protected by a silicon release film on both sides. It is applied between the overlap and at perimeter details/roof penetration points in RubershieldPro and other polypropylene membranes to effectively seal the joints. Rubershield Jointing Tape can make a considerable contribution to a roof complying with Part L of Building Regulations by effectively limiting unwanted air movement and improving thermal performance. Main uses Sealing all lap joints in RubershieldPro breather membranes. Attaching RubershieldPro to other surfaces (e.g. brickwork). Sealing the membrane at penetration points (e.g. soil vent pipes). Rubershield Pro RoofGuard SB Starex Zylex Ruberoid Eaves Protection Strip Length and width (m) Warm pitched roof Cold pitched roof (unventilated void) 50 x x x x x x x x 0.33 Cold pitched roof (ventilated void) Eaves protection (dressing into external gutter) Approval/standard BBA Cert. No. 05/4228 BS 747 1F BS 747 5U *Conforms to NHBC Technical Standards * * *

15 RubershieldPro 15 Environmental considerations RubershieldPro is manufactured from 100% polypropylene, bonded together without the use of adhesives. This allows RubershieldPro to be completely recyclable. Health and Safety A Health and Safety data sheet relating to Ruberoid underslating membranes can be downloaded from the Ruberoid web site or alternatively obtained from the Technical Services Department. Compliance with standards RubershieldPro conforms to the following requirements: BS 5250: 2002 (Code of Practice for control of condensation in buildings) Complies with NHBC technical requirements Fully covered for all applications by a current BBA BS 5534: 2003 (Code of Practice for slating and tiling) certificate. BS 5250: 2002 defines a vapour permeable pitched roof underlay as complying with the requirements BS 5534: 2003 and being vapour permeable with a vapour resistance less than 0.25MNs/g. RubershieldPro complies fully with this requirement, and is classified as an LR (low resistance) underlay in accordance with BS 5250: 2002, with a vapour resistance of 0.13MNs/g. Pitched roof buildups usually fall into 3 primary categories: warm roofs, cold roofs (ventilated void), cold roofs (unventilated void), as detailed in British Standards BS 5534 and BS Durability & guarantee RubershieldPro is covered by BBA certificate 05/4228 which identifies that the product will be virtually unaffected by the normal conditions found in a roof space. Correctly installed, RubershieldPro will effectively last the design life of the slate or tiled roof into which it is incorporated. Under these circumstances the effective product guarantee will be the same as for the main tile or slate roof covering utilised. Composition and appearance A triple layer highly breathable weatherproof membrane, made from high tensile spunbonded polypropylene layers around a microporous polypropylene film, bonded together by ultrasonic lamination. The outer layer forms the functional weatherproof surface, the middle layer is the breathable waterproof membrane, and the inner layer protects the membrane from abrasion and damage, also giving additional strength. This enables the fabric to allow moisture vapour to pass through, whilst providing high levels of water protection. RubershieldPro has a green upper surface, printed with the trade name, easy cut grid pattern and head lap lines. The underside is white. Roll width (m) Roll length (m) Roll area (m 2 ) Roll weight (kg) Weight (g/m 2 ) Performance Tensile strength MD 288 (N/50mm) to TD 275 BS EN 12311: 2000 Elongation (%) to MD 78 BS EN 12311: 2000 TD 83 Nail tear strength (N) to MD 168 BS EN 12311: 2000 TD 185 Water vapour transmission (g/m2/24 hrs) to BS 3177 >1500 Resistance to water pressure to moat Pass (6 m/ 24 hours) Mullen burst (kpa) 790 Fire rating to DIN 4102, B2 Pass UV resistance 4 months Wind uplift (at 343mm batten spacing to Appendix 2.25kPa G Standard 90/13286

16 Technical & design enquiries Tel: Fax: Ruberoid Building Products Customer Services Appley Lane North, Appley Bridge, Wigan, Lancashire WN6 9AB Tel: Fax: Whilst every care is taken to see that the information given in this literature is correct and uptodate it is not intended to form part of any contract or give rise to any collateral liability, which is hereby specifically excluded. Intending purchasers of our materials should therefore verify with the company whether any changes in our specification or application details or otherwise have taken place since this literature was issued.