Flat Roofing Materials – When You Should Use a Mixture of Roof Coverings

This article looks at situations when you might choose a mixture of flat roofing materials on your construction project and how SIG Design and Technology can support you in your vision. Contact us here about your project.

Why To Use a Mixture of Flat Roofing Materials?

There are a number of reasons why you might want to mix flat roofing materials, but they fit into three main areas:

  1. Cost efficiency – using relatively costly materials where they are highly visible, with lower cost (but still appropriate) materials that won’t be seen in low visibility areas.
  2. Performance – choosing the right flat roofing materials for areas of higher foot traffic, plant areas requiring complex detailing or areas of higher exposure.
  3. Aesthetics – using the flat roofing materials which provide contrast between surfaces and functions or to express particular elements of a roof design separately.
Hot Melt Roofing on 5 Broadgate by Make Architects

5 Broadgate in the City of London has a highly performing flat roof with a lot of plant and green roof areas for amenity. The majority of the roof is waterproofed with Permatec Hot Melt, but a cold applied liquid was used in some areas of complex detailing. Click to read case study.

Why Might You Be Avoiding Mixing Flat Roofing Materials?

When we want to design roofs with multiple materials, the challenge arises as to how the interfaces will be designed, executed and guaranteed. Here’s a common scenario that you might find familiar:

  1. Your team has designed a roof with a number of materials and in between them are a number of interfaces – zinc to liquids, slate to membranes, liquids to membranes, for example.
  2. The nature of roof design is such that often the choice of build-up and detail design is carried out in conjunction with a manufacturer of the materials, but many manufacturers only have expertise in one or a small group of products and are only in a position to detail their own products. In some cases, several contractors will be necessary as well.
  3. Because of the inexperience of manufacturers in complex interface design between different materials, detailing can be difficult. The very points of greatest need, the interfaces, become the place where the least care and the least experience is applied. When the project is completed, you end up with beautiful roofs with nasty little details.
  4. Predictably, we find that no one manufacturer or contractor is willing or able to take responsibility for interface design, which increases risk to all parties, and in particular to the design team and their client. If there is a failure, the fall out can descend into a blame game between designer, contractors and manufacturers. Ultimately the client suffers and so does your insurance.

If that sounds familiar, you may be very frustrated with your current method of sourcing roofing materials and professional help. It doesn’t have to be that way.

Do You End Up with Beautiful Roofs with Nasty Little Details?

SIG Design and Technology are not a manufacturer, we are a specialist supplier of a wide range of roofing materials. Our supply chain is backed up by SIG Plc.

Centrepoint - Multi-material roof refurbishment - showing deck

The refurbishment of CentrePoint in London has seen eight separate areas at Centre Point being waterproofed with a variety of flat roofing materials to SIG D&T’s design specification. Click link to view case study.

We are also experienced designers, accreditors and inspectors of roofing design and construction with our own Professional Indemnity Insurance and our own accredited contractors. This means that we can help your team reduce risk on multi material roofs, free of charge to you and of huge value to your clients.

  • 8 Steps to a #PerfectRoof SIG Design & TechnologyWe take a professional approach to roof design.
  • We have technical experts in all sorts of materials who are used to working together to develop solutions to complex roofs (as well as working on simple ones!)
  • We advise you on the best materials for each part of your roof so you can achieve the aesthetic, performance and budget needs for your client.
  • As part of SIG Plc, a critical partner in the UK construction supply chain, you can be confident the materials will be there on time, often supplied via one of our local distribution centres.
  • We work in partnership with you and take responsibility for the interface design.
  • We also provide all the additional bits and bobs you will need from Roof Surveys, U-value calculations and Condensation Risk Analyses to Cut To Falls (Tapered) Insulation Schemes and Wind Uplift Calculations.
  • Our DATAC accredited contractors are experienced in a range of materials and supported throughout the process by our technical team and field technicians on site.
  • We can arrange a full system, one-point warranty if your client requires it, backed up by the confidence of a major supplier in the UK Construction Industry.
  • Our 8-Step approach means we work with you from inception to completion and beyond.

Don’t restrict your imagination based on the lack of availability of specialist support. Talk to us about your roofing project now.

The Importance of Liquids in Multi Material Roofs

Cold applied liquids provide a wide range of benefits for multi material roofing projects. Here are a few:

  1. Because liquids are easy to apply in small spaces, they are often used in areas of complex detailing where single ply membranes would be difficult to execute effectively.
  2. Liquid waterproofing is an ideal material for small areas such as balconies and walkways.
  3. Cold applied liquid waterproofing can be used at low temperatures and can be guaranteed for periods in excess of 20 years.
  4. With fast curing times, single coat seamless application and low VOC options, modern liquid roofing materials are flexible and adaptable to a variety of uses.

Case Study of Multiple Flat Roofing Materials: Imperial Court

Imperial Court Streatham - four different flat roofing materials and systems

Imperial Court in Streatham High Street is a new gated development of apartments and commercial units which uses four different types of flat roofing materials in its construction.

  1. The main roof area is a warm roof with a single ply bonded membrane, rooflights and solar panels for swift completion.
  2. The private balconies are waterproofed with Hydrostop AH+ cold applied liquid waterproofing.
  3. Larger balconies are waterproofed with a felt system over a tapered insulation scheme.
  4. A communal courtyard and play area is waterproofed with Hot Melt direct onto the structural deck with a roof terrace installed over.

SIG Design and Technology worked with DATAC accredited installer AJ Lucas to provide a complete service, including arranging deliveries of materials via their SIG Tunbridge Wells roofing branch to a busy high street smoothly and effectively.

Read the case study here.

Take a Professional Approach

A professional approach to multi-material roof design allows the architect to achieve their design vision with beautiful interfaces, expertly detailed and executed, at no additional cost to that of the materials.

Get in touch if you think we can help on your project.