A structured approach to roof specification and design - SIG Design ...

A structured approach to roof specification and design CPD Handout: January 2014 This document contains the key resources from SIG Design & Technology’s RIBA Certified CPD Seminar, A Structured Approach to Roof Specification and Design, in an easy to use format. The pdf version has links to additional information online. Download it here: http:// bit.ly/SIGDTCPDhandout

Table of Contents Design considerations!.......................................................................................................2 Stage 1 – Establishing the client’s brief!........................................................................2 Stage 2 – Negotiating the Compliance Minefield!..........................................................2 Stage 3 – Finding the solution!.......................................................................................2 Stage 4 - Roofing options!.............................................................................................3 Waterproofing Options: Single Ply!....................................................................................5 Waterproofing Options: Hot Melt!.......................................................................................6 Waterproofing Options: Hard Metals (Zinc and Copper)!...................................................7 Waterproofing Options: Liquid Coatings!...........................................................................8 Green roofing solutions!.....................................................................................................9 Carbon Capture!.............................................................................................................9 Sustainable Urban Drainage!.......................................................................................10 Biodiverse Habitat!.......................................................................................................10 Green Roofs – Built Up or Modular?!...........................................................................10 Built up Green Roof!.....................................................................................................11 Modular Green Roof!....................................................................................................11 What to expect from suppliers!.........................................................................................12 Technical Support!........................................................................................................12 On Site Support!...........................................................................................................12 Guarantees!.................................................................................................................12 Checklist for Essential Manufacturer Support!.............................................................13 Detailing, compatibility & interfaces!................................................................................13 What not to do!.............................................................................................................15 Summary!.........................................................................................................................15 About SIG plc and SIG Design and Technology!............................................................16 SIG plc!.........................................................................................................................16 SIG Design and Technology – The Right Solution, Guaranteed.!................................16 More Information!.............................................................................................................16

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Design considerations Stage 1 – Establishing the client’s brief What does the client need this specific roof to do? Its design and construction must meet a matrix of complex and strategic variables including: •

Planning points

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Performance requirements

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BREEAM points (buildings)

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BRE ratings (product)

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Cost

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Structural requirements

•

Buildability

How do we ensure compliance when there are so many different standards for any one building element?

Stage 2 – Negotiating the Compliance Minefield Once we understand the brief, we can evaluate the options, choose the materials and define the methodology – the job is to waterproof a roof using an engineered solution specific to the project.

Stage 3 – Finding the solution So what are the influencing factors when designing a roof? Here are four different examples where a different roofing solution is selected. © SIG Design & Technology www.singleply.co.uk

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Stage 4 - Roofing options

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Waterproofing Options: Single Ply

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Waterproofing Options: Hot Melt

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Waterproofing Options: Hard Metals (Zinc and Copper)

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Waterproofing Options: Liquid Coatings

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Green roofing solutions Why Specify a Green Roof? •

It makes good use of space, optimising the structural footprint of a building.

•

A green roof captures carbon. It improves air quality by absorbing airborne pollutants through plants removing them from the environment.

•

A green roof substantially increases the life expectancy of the roof’s waterproofing membrane as it protects from UV degradation and extremes of climatic condition.

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It assists urban drainage.

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It provides thermal and acoustic insulation.

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It provides an additional green space for wildlife.

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And of course a green roof is aesthetically pleasing.

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Green roof membranes require FLL certification. There are two levels; for root and rhizome protection.

Carbon Capture

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Page Sustainable Urban Drainage Green roofs are an important component of SUDS – sustainable urban drainage systems. There is often a requirement to attenuate water that has been shed from roofs into the drainage system. A typical green roof absorbs and evaporates 50% of the rainfall that falls on the roof. This rate of absorption reduces the pressure on drains and reduces the likelihood of localised downstream flooding. Biodiverse Habitat Green roofs can make a considerable contribution to conservation of biodiversity. It’s important to include mixtures of drought tolerant native wild flowers plus sedums and grasses. Some London boroughs even stipulate which native plants are to be included by postcode! Specific plants are particularly invaluable to some types of invertebrates e.g. bees. There is also evidence of rare birds using green roofs, e.g. the black redstart. Green Roofs – Built Up or Modular?

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Built up Green Roof

Modular Green Roof

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What to expect from suppliers Technical Support You should receive comprehensive technical support from a manufacturer or supplier and this should comply to all relevant standards. This should include: • • • • • •

Standard Details NBS Specification Clauses Cut to falls insulation design Wind load and thermal calculations Third party accreditation BIM objects and support

Early involvement in a project by a supplier will make the membrane system choice and technical support process simpler in the long run. Suppliers can offer advice, not just on which products to use but more importantly when those products are not suitable and an alternative should be sought. Unlike manufacturers, supplier advice can be ‘brand neutral’. SIG Design & Technology has developed a set of BIM objects with the NBS which are available in the National BIM Library. On Site Support A manufacturer or supplier should offer on-site support to protect the long term integrity of the chosen waterproofing system. This is not just important to ensure the long term performance of the waterproofing system chosen, its also a requirement of British Standards (BS6229:2003) to maintain a roof and guidance on how this should be done can be demonstrated during a site support visit. We provide amongst others: • • • • •

SIG D&T inspection reports SIG D&T Protocol if a problem is suspected Quality Checks Flood, electronic integrity, thermal imaging and air leakage tests Independent electronic testing for Q37 Green Roofs.

Guarantees Guarantees are essential for client peace of mind. The Design & Technology Accredited Contractor Scheme ensures that only accredited contractors can buy and install our materials. Our materials guarantees are backed by SIG plc. Overleaf we’ve prepared a checklist for you to use to ask your supplier if they can provide the same full service.

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Checklist for Essential Manufacturer Support How does your supplier measure up? Essential Requirement

SIG D&T

Project-specific technical support

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Bespoke design

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Wind up-lift calculations

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Cut-To-Falls design

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Drainage calculation support National Building Specification: J42 waterproofing, Q37 green roofs, H71/92 Zinc Registered/trained installer network

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On-site support & assessment

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Guarantees/warranties

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Alternative?

✔ ✔

Detailing, compatibility & interfaces In our experience, problems in situ occur when detailing, compatibility & interfaces have not been properly considered or executed. A modern single ply roofing system is more than just a waterproofing membrane and incorporates a number of key systems accessories. These are the main additional components that should be considered by the specifier to ensure the integrity of the membrane is not compromised:

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Page These two images show where the integrity of the membrane can compromise the NBS specification by puncturing the membrane, ultimately leading to water ingress.

However, by using the correct materials (in the case of this membrane with a FLL certificate) and standard detailing to avoid puncturing the membrane, these roof membrane systems are not punctured at interfaces and do not risk water ingress.

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Page What not to do Poor installation leads to failure and it happens all too often!! In a study by Dutch organisation TNO, it was found that poor workmanship and inexperience were costing the EU some 2 billion euros per year. The key problems are preventable and comprise • • •

punctured membranes, water ingress, and wind and condensation problems.

There is often evidence of • • •

poor preparation, inadequate framework and poor detailing at cable entry.

The picture at the top is a classic on how not to install solar thermal panels. The membrane is punctured. The image underneath shows PV panels that need no penetration of the membrane as they are held in place by their own weight.

Summary Knowledge

 Defining your client's brief  Ensuring compliance with UK British Standards and Code of Practice

 Choosing the best roofing system for the job

 When to specify single ply / hot melt / hard metals / liquid coating

 Green roofing options  Further sources of information / contacts

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Modern roof performance

Manufacturers' responsibilities

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Waterproofing

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Insulation

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Sustainability

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Energy capture

Design bespoke roofing solutions to meet a client's specific brief

 Ensure compliance with UK British Standards and Code of Practice

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Supply, install and guarantee complete roofing solutions

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Ensure performance through effective detailing, compatibility and interfaces

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About SIG plc and SIG Design and Technology SIG plc SIG plc is a FTSE 250 listed company and the UK’s market leading specialist supplier to professionals in the building and construction industry. SIG plc focuses its activities into three business sectors: Insulation & Energy Management, Interiors and Exteriors. Products are distributed through its national supply chain. With over 12,000 employees, SIG trades from over 800 locations across 16 countries. SIG Design and Technology – The Right Solution, Guaranteed. Part of SIG Exteriors, SIG Design & Technology is part of a UK-wide operation which comprises 3 UK partnering manufacturing sites, 140 dedicated roofing depots and our own extensively stocked warehouse in Dudley. SIG Design & Technology’s HQ and training centre is based in Leicestershire at J23 of the M1. It’s here that we train roofing installers to meet the high standards required to meet our Design & Technology Accredited Roofing Contractors scheme – DATAC. SIG Design & Technology works in partnership with you the specifier to deliver full manufacturer support. It’s a complete and impartial design and supply service built around flat roof products (including green roofing systems) sourced from leading product manufacturers. With decades of experience we’re familiar with many of the problems designers and contractors face when looking at getting the most from a roof and have examples of successful projects you can use to satisfy your clients and insurers. Designs are covered by our own PI Insurance. Our roofing systems are installed by DATAC member companies and are backed up by SIG plc’s own guarantee for complete peace of mind.

More Information Website: www.singleply.co.uk Dedicated Zinc and Copper Website: www.sigzincandcopper.co.uk Technical Blog: www.singleply.co.uk/blog Techical Product Downloads: http://www.singleply.co.uk/downloads/ Find your local advisor (Pdf map) http://bit.ly/SIGDTadvisors Meet the team http://bit.ly/SIGDTmeettheteam

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