ROBERT'S TOP 10 ARCHITECTURAL BUILDING MATERIALS - Innovative, sustainable & cost-effective
What is the best type of building material for creating sustainable architectural homes?
I have been asked this question, or something like it hundreds of times over. To which I suggest, “There is no one ‘best’ solution”. The choice of building materials is highly dependant on many factors, including: aesthetic tastes, availability, budget, climate, context, expertise, orientation, and regulatory controls.
Without diving too deeply into each of these factors, this article lists of few of my favourites, and provides some links for your further investigation. Where possible, I have attempted to provide generic materials and systems rather than brand name products, however, this can be difficult in some of these situations due to their relative recency and obscurity.
Robert’s top 10 Architectural building materials
1. Cross Laminated Timber (CLT)
Mass timber construction is one of the newest technologies emerging from the construction industry. Formed from glue-laminated renewable plantation timber, the cross-lamination (like plywood) gives these panels supreme strength and rigidity. They can be fabricated in a factory to any size that's transportable, provide great strength-to-size ratio, and have even been shown to perform well in a fire without failure.
CLT’s recent market emergence will initially see a delay in uptake, and higher costs. However as it becomes more commonplace, competition will drive down prices, and industry expertise will increase. The capturing of carbon (sequestration), coupled with CLT’s mass carbon storage gives the system great sustainability credentials.
It’s factory-based CNC fabrication provides exacting standards for improved design influence when extracted directly from the architect’s detailed BIM file.
Links for further research:
Wood Solutions: Cross Laminated Timber (CLT)
Arch Daily: Cross Laminated Timber: what it is and how to use it.
Architecture & Design Magazine: Cross Laminated Timber (CLT): Australia's rising star and where to get it.
Hyne Timber: CLT and GLT: A perfect combination for many structural building solutions
Cross Lam Timber: Construction Detail - Sections and Performance
Holz Forschung Austria: Guidelines for Construction with Cross-Laminated Timber in Multi-storey buildings.
2. External Insulated Facade Systems (EIFS)
Commonly constituting a rigid insulation board with an external cement or acrylic render finish, EIFS is popular due its low cost, light weight, high insulation, ease of construction, and widely-desired exterior finish as an alternative to rendered brick, block or concrete wall.
Despite receiving recent criticism under national and international industry regulation reform which now limits the use of EIFS and similar combustable material solution in medium and high rise construction, EIFS remains popular in low-rise residential developments.
New developments in the field will hopefully provide more sustainable, non-combustable EIFS solutions in the not too distant future. As sustainability targets increase insulation requirements, and home-owners increasingly value the energy saving benefit of thermal performance, construction systems that promote eternal insulation over internal insulation will likely continue to receive support.
Links for further research:
Whole Building Design Guide - Exterior Insulation and Finish Systems (EIFS)
Walls & Ceilings - The Rise and Fall of the EIFS House
Walls & Ceilings - Prefab wall systems with EIFS
BASIX - External Insulated Facade System
Architecture & Design Magazine - Zego
Bondor - Architectural Facades
Kingspan - Architectural Facade Systems
GreenClad Insulated Facade System - Technical and Installation Manual
Parex - External Insulated Facade Systems
3. Green Roof (Extensive)
If you fancy greenery growing from the eaves, and the ‘hobbit life’ it conjures, an extensive green roof allows for minimal depth soil for growing grasses, succulents, flowering bulbs and ground cover without the expense and structural load-bearing requirements of a suspended concrete slab.
An extensive green roof generally requires a build up of timber or steel rafters or purlins, cladding, waterproof membrane, drainage substrate, filtration fabric, soil and your choice of low maintenance small-rooted plants. Commonly pitched to prevent leaking and excessive water weight, this type of green roof is generally only lightly trafficked to meet maintenance requirements (trimming the verge), and usually drains to the eave (outside of the building’s envelope) like a tiled or steel clad roof. Green roofs and externally insulated by the soil and vegetation, and may not need any other form of internal insulation if designed well. This also means that ceiling lining may be placed above roof framing instead of below.
Links for further research:
Aus Govt - Your Home: Green Roofs and Walls
Archtoolbox: Green Roof Systems- Intensive, Semi-Intensive and Extensive
Bent Architecture: What is the difference between an intensive green tool and an extensive green roof?
Green Roof Plan: Intensive Vs Extensive Green Roofs
Green Roof Technology - Intensive Vs Extensive Green Roofs
4. Green Roof (Intensive)
Intensive green roofs allow for the planting of all forms of vegetation (even trees), and therefore require much deeper soil depth and suitably strong structural support. This is often achieved by forming the roof structure as a suspended reinforced concrete slab.
An intensive green roof will also likely be flat, with minimal grading for drainage which is commonly located internally), and are therefore preferable if intended as a roof terrace for frequent use. The dead and live engineering loads created will therefore also require that the supporting beams, columns or walls are suitably strong, able to transfer the loads (and stormwater) to the site below.
Links for further research:
Green Roof Technology - Intensive Green Roof Systems
Zinco - Intensive Green Roofs
Architecture & Design Magazine - A guide for specifying green roofs in Australia
5. Insulated Concrete Form (ICF)
Like EIFS, IFC currently relies heavily on rigid foam products to provide the desired insulation and strength requirements. As in-situ concrete requires extensive temporary formwork, and high-thermal mass concrete walls also often require external insulation, ICF seeks to replace traditional temporary ply formwork with permanent formwork that also acts as insulation. While this approach has merit, and has seen reasonable industry uptake, its advantages also represent potential disadvantages. Externally insulated thermal mass had great merit. Yet internally insulated thermal mass (aka brick veneer) has poor thermal performance. When you insulate both the exterior & interior of a thermal mass structure, the potential thermal mass is nullified, unable to store or regulate internal cooling and heating.
Alternatively, single sided (externally insulated) permanent formwork, coupled with a temporary or non-insulated internal skin could achieve superior sustainable, cost effective, and aesthetic results.
Links for further research:
Aus Govt - Your Home: Insulating Concrete Forms
PCA: Insulated Concrete Form (ICF)
Architecture & Design Magazine: Going Green with Insulated Concrete Form
6. Permanent Concrete Form (PCF)
While PCF systems and modular concrete forms also encompass most ICF systems, uninsulated Permanent Concrete Forms are commonly more popular, and may offer superior cost and time savings as well as enhanced thermal performance when coupled with an interior insulation solution.
Links for further research:
Architecture & Design Magazine - The Pros and Cons of Permanent Formwork Systems for single dwelling wall construction
7. Rammed Earth
Sometimes also referred to as Stabilised Earth (SE), in its simplest form, Rammed Earth has been around for thousands of years. While its mix and methods vary greatly, this high mass monolithic material is highly appropriate for climates with a large daily temperature shift, and can also be very effective in many other climates when an insulation board is added to its outer face or inner core (Insulated Stabilised Earth).
Popularised in contemporary residential architecture by practitioners such as Rick Joy, modern methods of construction in rammed earth utilise pneumatic rams, skid-steer loaders, conveyor belt loaders, cement binding, decomposed granite shipped from quarries, and can even be prefabricated off-site in factory based construction.
Links for further research:
Aus Govt - Your Home: Rammed Earth
Science Daily: New Research modernises Rammed Earth Construction
Rammed Earth Constructions - Information about Rammed Earth
GreenSpec - Rammed Earth
8. Recycled (re-used) Bricks
Reduce / Re-use / Recycle is a commonly known catch cry of sustainability, and for good reason. Dry-pressed clay bricks are one of the worlds most ‘common’ forms of modular construction. Poor planning, re-zoning, and a culture of replacement commonly results in the demolition of our architectural history far before its building blocks have reached their embodied end. Re-using bricks (with minimal re-manufacturing) allows for the transfer (saving) of embodied energy to new architectural life, and enriches the project with invested history and character.
Popular in industrially-styled architecture, the raw (non-rendered) expression of brick also reduces the costs and additional embodied energy associated with rendering and plasterboard lining.
Furthermore, when exposed internally, and insulated externally or between skins, recycled brick construction can provide high levels of thermal performance, coupling external insulation and internally exposed thermal mass.
Links for further research:
Zero Waste Europe: Rebrick - Reuse bricks to give them a new life
9. Structural Insulated Panel (SIP)
As the name suggests, SIPs can provide an all-in-one structure and insulation system for floors, walls, ceilings & roofs. Most commonly constructed from a core of polystyrene with an outer skin of steel, aluminium, plywood, OSB, or fibre cement, structural insulated panels are extremely versatile, light, and remarkably strong, with a great span capacity (particularly when used in lieu of traditional roofing systems). SIPs are also available in a variety of other core insulation types, to increase their performance in insulation, fire resistance, and strength.
Links for further research:
Wood Solutions: Structural Insulated Panel Systems (SIPS)
Sanctuary Magazine: Composite benefits - when are SIPS the right choice
10. Timber - Renewable, Recycled & Engineered
Available in a wide range of colours and sizes, and useful for structural, exterior cladding, interior lining and detailing applications, timber is certainly not new or unknown as an architectural building material. Yet due to its maintenance requirements and threat from fire, termites, and sunlight, and mould, many people overlook its many benefits and sustainable credentials.
As one of the worlds only renewable materials, timber represents the best choice for long-term sustainable harvesting. While hardwoods taken longer to grow, they also have fantastic durability if ‘treated’ correctly (pun intended). Engineered timber solutions also ensure that nothing goes to waste. Engineered timber panel (such as plywood and OSB orientated strand-board) and beam products (glue-laminated and laminated veneer lumber) offer strong, sustainable, natural, aesthetic solutions for construction.
Links for further research:
Sanctuary Magazine: Recycled Timber material that tells a story
Wood Solutions: Recycling and Wood Waste
Ironwood: Timber recycling process
Wood Solutions: Engineered Wood Products
Timber NSW: Timber: A renewable resource
Forest Learning: Timber: A sustainable and a renewable resource
* * *
The information contained in the article and website are general in nature and are the opinions of the author, through his professional experience and study. This should not be substituted for seeking professional or legal advice in this area. Click here for more details of our content.