We help landowners and homeowners build eco-homes, extend their homes, and create unique holiday homes that gain planning permission and pay them back. RIBA Chartered Architects.
A section of one of our eco-home projects under construction. The curved timber frame uses a thin-profile reflective insulation chosen for the tight geometry, working alongside materials such as oak and cedar, which make up the cladding.
Why Natural Materials Matter
Published August 2024. Updated November 2026.
People looking to build on rural plots, farms and coastal sites want materials that age gracefully and reflect the essence of the surrounding context. Quality natural materials pick up and reflect their surroundings, ageing and often improving over time. Compare that to synthetic materials, which start to look worse as they age and typically, have a much shorter lifespan.
There are also health arguments for natural materials, which have been substantiated by credible institutions, such as the World Health Organisation. Synthetic materials, common in new builds, some insulation, glues and composite products, release chemicals into the home’s interior over time, a process known as off-gassing, which goes on for years.
In this article, we will look at five natural or low-impact materials we regularly specify, and why we use them. Our design philosophy and how we carefully select materials have been key to putting the list together.
1. Timber Framing + Reclaimed Timber
Timber framing has a much lower environmental impact than cement-based materials, commonly used for when constructing the main structure. Responsibly sourced timber absorbs CO2 as it grows and locks it away.
Timber is lightweight as well, making it ideal for transporting to sites. It also makes timber an ideal material to work with for self-build projects.
Insulation can be fitted between the studs of a timber frame; this is ideal as it opens up a wider choice of insulation options to you.
Reclaimed timber is, without question, one of my favourite materials to work with. On a recent eco-home we completed, we used reclaimed scaffold boards internally for the flooring and reclaimed sapele hardwood for the external decking. What is great about reclaimed wood is that it has its own story; you may have seen timber merchants selling old maple floorboards from sports halls that still have the paint markings that divide the space, and scuffs to the floor layered over many years of contact. You cannot manufacture character.
If you're considering reclaimed timber, aim for hardwoods where possible: oak, maple, walnut, sapele. Softwoods can work in the right context; scaffold boards, for example, are a great example of a softwood product. Generally speaking, however, hardwoods age the best and last the longest.
Reclaimed timber offers three key advantages:
Character - Warmth, patina and authenticity that newer materials struggle to replicate.
Proven durability - Reclaimed wood has already lasted for decades, so it will likely last for many more.
Cost - Reclaimed scaffold board flooring typically comes in at £15–22 per square metre of material against £53–135 for tiled flooring. Reclamation yards, salvage suppliers.
The same logic applies to reclaimed brick or stone, particularly in a local context. Reusing stone and brick is an effective way of tying the thread of the structure to the context and surrounding landscape. It ties a new building into the history of its place, avoids the waste of manufacturing new materials, and brings a patina that new products cannot replicate. We are currently using reclaimed wood on our Renewable Container Living project; it remains one of the few materials that genuinely improves with age.
Reclaimed sapele hardwood decking on a recent project. Roughly half the cost of new hardwood, with character that new timber cannot offer.
2. Natural Fibre Insulation (Wool, Hemp, etc.)
Natural fibre insulation, particularly wool and hemp, is one of the most effective and most overlooked materials groups to be using in your eco-home. These materials are renewable, biodegradable and free from the petrochemicals found in many synthetic alternatives.
The reason insulation is easily overlooked is that insulation is specified at RIBA Stage 4, late in the design process, when the budget is already under pressure, and the default becomes the cheapest synthetic board that hits the U-value. PIR boards perform well thermally, but they are petrochemical-derived and non-breathable, and in a timber-frame building that is a condensation-risk decision, not just an environmental one. A breathable wall build-up manages moisture, and this is a big advantage with natural insulations; a sealed one traps it.
Two caveats, because they are the questions I get asked regularly. First, natural fibres need a thicker build-up: wool at a thermal conductivity of around 0.038 W/m·K needs roughly 170mm to match what PIR achieves at 100mm, so the additional space will need to be designed early in the process and cannot be post-rationalised from Stage 4 onwards. Second, cost: expect to pay 20–40% more for natural insulation than the synthetic equivalent. The following are the advantages you may expect:
Healthier indoor environments - No harmful VOCs. Wool, in particular, is excellent at regulating humidity, absorbing and releasing moisture without compromising its thermal performance.
Mould and mildew resistance - Particularly valuable for eco-homes, holiday homes and annexes that sit empty for a long period of time.
Stable temperatures year-round - Natural fibres keep interiors cooler in summer and warmer in winter. With summer temperatures becoming so extreme recently, this matters a great deal.
There’s no single “best” insulation. The right choice depends on the building fabric, and it has to be picked carefully to meet Building Regulations, environmental targets and the needs of the materials around it.
3. Metal Roofing (Zinc and Standing Seam)
Metal roofing is not a natural material. That said, the reason I have included metal is because of reclaimed metal, which is selected for its longevity. We use zinc regularly, including on the Monocoque Cabin, and it remains one of the most reliable and architecturally satisfying roof choices available.
Longevity — A well-detailed zinc roof lasts fifty years or more. Budget: £100–150 per square metre installed
Weather resistance — Essential on exposed rural, upland and coastal sites, where wind and rain break down softer roofing within years rather than decades. Natural slate is the traditional answer here and still an excellent one; but zinc achieves the same lifespan at lower weight, which opens up lighter structures, think timber structures we discussed earlier and longer overhangs.
Passive cooling — Metal reflects solar heat, and paired with a well-designed overhang, it shades glazing through peak summer. As UK summers get less predictable, this is worth more than it used to be.
Aesthetic range — Against timber cladding, cedar shingles or dark-stained boarding, a metal roof reads as contemporary but grounded.
4. Cork
Cork has seen a massive increase in use in recent years. In my view, this can be attributed to a couple of reasons. Firstly, cork is harvested from the bark of the cork oak (Quercus suber), grown mostly in Portugal. The fact that it’s taken from the bark makes it highly regenerative and sustainable to build with.
Secondly, if detailed by your architect correctly, cork can act as an insulating material, whether as external cladding or internal lining.
Key benefits to cork include the following:
Real thermal performance - Cork has a thermal conductivity of around 0.038–0.040 W/m·K, which puts it in the same league as natural fibre insulation and makes it genuinely competitive as an external insulating layer or internal finish. As a result, when used alongside a natural internal insulation, it will reduce the amount of insulation needed, saving you both space and money.
Warm underfoot - Cork flooring is naturally soft and warm to the touch. It might sound like a small detail, but it’s something homeowners notice, particularly in barefoot spaces like bathrooms and bedrooms.
Acoustic comfort - Cork absorbs sound, softening interiors that might otherwise feel hard or echoey. In open-plan spaces, this is the difference between a room that feels calm and one that feels like a canteen.
A finish that ages honestly - Cork develops character rather than deteriorating, which is the pattern with every material on this list worth specifying.
5. Natural Stone
Stone is the oldest answer on this list and still one of the best. It is the material that ties a building to its region more directly than any other; local stone literally is the landscape the building sits in — and in performance terms it does something none of the lighter materials can: thermal mass.
Thermal mass — Thick stone absorbs heat slowly and releases it slowly, flattening the temperature swings that lightweight buildings suffer. Cooler in a heatwave, warmer overnight in winter, with no mechanical help. Paired with a well-insulated envelope, mass is what makes a building feel calm and settled rather than reactive.
Sense of place — Stone sourced from the region picks up the tones and textures of its surroundings, which is why planners in sensitive landscapes respond to it. In National Landscapes and conservation settings, the right stone is frequently the difference between a scheme that reads as belonging and one that reads as imposed — and that is a planning argument, not just an aesthetic one.
Cost, honestly — full load-bearing masonry is the expensive route: budget £200–300 per square metre of finished wall and the structural implications that come with it. Stone cladding and plinth work deliver most of the visual and weathering benefit at £60–120 per square metre, which is where we typically deploy it — grounding a timber building into its site rather than building the whole envelope from it.
Endurance — Stone does not weather so much as improve. On exposed upland and rural sites, it will outlast every other material on this list, and the maintenance schedule is effectively zero.
The Ridge is an example of one of our projects that uses a combination of metal cladding, reclaimed timber, stone, and cork internally
The five natural materials we specify most on UK eco-homes are reclaimed timber (£15–22 per m² for scaffold-board flooring), natural fibre insulation (20–40% more than synthetic), zinc roofing (£100–150 per m² installed), expanded cork (£45–60 per m² for 100mm board) and natural stone (£60–120 per m² as cladding, £200–300 load-bearing). The table below compares cost, lifespan and upkeep, and each material gets its own section further down.
| Material | UK cost per m² | Expected lifespan | Maintenance | Best used for |
|---|---|---|---|---|
| Reclaimed timber | £15–22 (scaffold-board flooring) against £53–92 for new engineered oak | Decades more; it has already lasted decades | Oil or wax every few years | Floors, cladding, decking |
| Natural fibre insulation (wool, hemp) | 20–40% more than synthetic | Life of the building | None once installed | Walls, roofs and floors in breathable build-ups |
| Zinc standing-seam roof | £100–150 installed, against £50–80 for concrete tiles | 50+ years | None; the patina protects itself | Exposed rural, upland and coastal roofs |
| Expanded cork | £45–60 for 100mm board, supply only | 50+ years | None externally; reseal floors occasionally | External insulation, cladding, floors, internal linings |
| Natural stone | £60–120 as cladding and plinths; £200–300 load-bearing | 100+ years | Repointing every few decades | Walls in sensitive landscapes, plinths, thermal mass |
Material costs, UK, 2026. Labour varies by region and by how the material is detailed.
Conclusion: Materials matter
Natural materials look better, feel better and age far better than synthetic ones, but the benefits depend on picking the right material for each job, and that decision needs to come early in the design. For what these choices mean for your overall budget, see our guide to eco-home build costs in the UK. We’re a RIBA Chartered architecture practice based in Birmingham, working across the UK.
If you’d like to talk about how we choose materials, email me at peter@markosdesignworkshop.com or use the link above to book a free call.
