standards rainscreen aesthetics Design considerations

wind resistance thermal performance colour Design Rainscreen cladding principles and benefits Wind resistance Fire safety, acoustics, condensation and ventilation Rainscreen and wall insulation Thermal insulation Thermal design details Recommended design procedure Legislation, guidance and reference Design considerations

Rainscreen cladding Principles and benefits The past The rainscreen principle is not new, nor is the idea of rainscreen applied to wall design. For centuries in Norway, drained and back-ventilated claddings were used with both closed and open joints but without any scientific, systematic foundation. Gradually, on buildings with timber claddings, closed joints were adopted, and openings at both the top and bottom of the cladding allowed for drainage and evaporation of any penetrating rainwater. By the 1980’s, rainscreen was understood and widely used in Canada and Europe. Architects and specifiers...

Rainwater removal • Insulation of up to 240mm thickness can be accommodated • Cladding prevents penetration of most rainwater using a Marley Eternit framing system • All types of insulation can be used – from rigid PUR to mineral wool • Insulation positioned against substrate maximises heat retention • Natural ventilation – stack effect – evaporates penetrating rain • Residual rainwater drains harmlessly and evacuates at base of system • Pressure equalised system naturally inhibits ingress of driven rain and minimises condensation issues • Externally located insulation maximises internal floor...

The aesthetic, remedial and thermal solution Embodied energy for cladding materials One of the key ways in which rainscreen can benefit existing buildings is The table below shows embodied energy for various cladding materials. through overcladding. Lower embodied energy will allow the designer to achieve a higher BREEAM rating. Apartment and office blocks, retail, healthcare and commercial establishments may well require both remedial and aesthetic work to make them suitable for today's environment. On top of this, the thermal inefficiencies inherent in this legacy building stock will almost...

Rainscreen and wall insulation Providing thermal insulation for walls Embodied energy for insulation Rainscreen is a relatively high-benefit, low-cost method of providing The table below shows embodied energy for various insulation products. thermal insulation to external walls for both refurb (overclad) and new Lower embodied energy will allow the designer to achieve a higher projects. It can also help minimise cold-bridging. BREEAM rating. Adding insulation to the external surface of the loadbearing structure has three key benefits: Wood fibre (rigid slab) • Increased thermal efficiency – dependent...

Aesthetics & colour The landscape of colour Awareness of - and therefore care for - the environment is increasing steadily. Far more stress is being given to appropriate colouration of both urban and rural environments in all sectors – domestic, industrial, leisure, public and commercial. Because colours used on buildings are never seen in true isolation, they cannot be considered as absolute and unchanging. They are an integral part of their environment in the most local and most general sense. As part of the language of building they have an important role to play, as do form and material,...

Panel fixings The fixing method chosen can have a The 'visible fixing' systems – screw and rivet fundamental and dramatic effect upon the final fixing – may be seen as providing an appearance of the clad building. appearance somewhere between secret fix Employing a secret fix method, for example, will and edge retention. The smooth facade of result in a sheer, smooth facade unobstructed the cladding will be punctuated by the heads of the rivets or screws, although, in practice, these low profile fixings are virtually unnoticeable. An edge retention system, on the other hand, Visible fixing screw...

Natura, Brunel University, Uxbridge Recommended design procedure Designers are advised to consider the following steps when commencing a design incorporating Marley Eternit products. Reference should also be made to BS 8200 (The following information is provided for ‘Code of Practice for the design of guidance only. Designers should ensure that non-loadbearing external vertical enclosures they make all the necessary calculations and of buildings’, also BS 6093 - ‘Code of Practice take into account all aspects of the specific for the design of joints and jointing in building project design and...

Step 5: Cladding selection Guidance on legislation is given on pages The choice of cladding is a combination 30-31. Planning permission may be necessary of planning, aesthetic and performance criteria. in certain areas and is dependent The key factors are shape, size, colour, texture, on Local Authority policy and control. material and sustainability, see pages 44-89. Step 2: Exposure, wind and rain Step 6: Fixing Method Establish the exposure zone of the site by aesthetic and performance criteria. reference to the map on page 33. This divides The panels may use visible screws or rivets, or the...

Legislation, guidance & reference Before contemplating any cladding project, the designer and contractor must be aware of the current legislation, the design requirements and standards that govern and influence the style, parameters, performance, products and construction of the project. The following section summarises many of the relevant documents, but is by no means exhaustive. England and Wales: Part A ‘Structure’ England and Wales: Part B ‘Fire Safety’ Scotland: Technical handbook, Section 1 ‘Structure’ Scotland: Technical handbook, Section 2 ‘Fire’ England and Wales: Part C ‘Site Preparation...

Building Regulations These are mandatory regulations and, in Copies of the complete set of Handbooks that BS 476-6: 1989 Fire tests on building materials England and Wales, are generated and accompany the Building (Scotland) Regulations and structures – Method of Test for fire approved by the Department for Communities 2004 for Scotland can be downloaded from the and Local Government (DCLG). SBSA web site (www.sbsa.gov.uk). Follow the In Scotland they are generated and approved by the Scottish Executive and in Northern Ireland, by The Office Estates and Building Standards Division (OBD). They...