WAYSIDE

Wayside is a low-impact, multi-generational home in Mawgan Porth, Cornwall. Built by ADD Sustainable Construction, it replaces an outdated bungalow with a highly energy-efficient, EPC B-rated dwelling using recycled and locally sourced materials. The design respects the sensitive coastal landscape, with twin timber frames, Warmcel insulation, MVHR systems, and a green roof supporting biodiversity. Achieving airtightness below 1.5 and U-values as low as 0.09 W/m²K, Wayside exceeds Passive House standards. This project showcases sustainable architecture in Cornwall, combining low-carbon construction with long-term comfort, minimal maintenance, and enhanced community integration.

The brief was to provide reasonable provision to support current and future needs for both the client and client’s mother.  The accommodation needed to consist of an open plan living space which includes kitchen, dining and lounge area. 4 bedrooms with lots of natural light and private views, along with an inviting entry sequence and foyer with private amenity space and improved privacy to the rear. Proposals aimed to investigate the efficiency of the site layout and encourage an efficient and visually appealing solution. Proposals explored the potential of first floor views whilst utilising the natural topography to minimise impact to the surrounding properties. Overall, the design should be: homely, convenient and spatially comfortable. The objective was to provide a timeless building that is of its place and harmoniously assimilates with its surroundings. Proposals provided a sustainable improvement over the existing bungalow, encouraging a built environment focused on health and wellbeing with exploration of: breathable construction, ground source heat pump (GSHP), rainwater harvesting, high levels of insulation, triple glazing and a mechanical ventilation heat recovery (MVHR) system. This aimed to provide a future-proof solution in accordance with climate change goals and aspirations.

The design of Wayside has provided a multi-generational living solution, minimising impact to the area and providing a greater age cross-section to Mawgan Porth supporting a greater variety of local public services and businesses. Aligned with paragraph 58 of the National Planning Policy Framework, which encourages design to “reflect the identity of local surroundings and materials, while not preventing or discouraging appropriate innovation”, the design language of Wayside cross references the unique characteristics of the site and Mawgan Porth as a whole, with the client’s brief and schedule of accommodation, to create a carefully considered house of low visual impact and a positive sense of place. The replacement dwelling has been largely sited on the footprint of the existing dwelling minimising impact on the site. Massing has been broken into two to limit the visual impact. The South element recedes from the access road preserving views past the property from the main road. The North element has been reduced in footprint and is further back than the existing bungalow providing a sightline improvement to the site and neighbouring property.

Wayside has been carefully designed to respect the sensitive locality. The scheme’s references to the landscape and built environment of Mawgan Porth to procure a strong, contemporary link with the locale; making a sensitive, positive contribution to the surrounding high quality local landscape and setting. The softness of the local materials promotes a robust Cornish identity. This will be further enhanced by new planting and sensitive landscaping to screen the building. Like ‘Sand Dunes’, an adjacent property designed by ARCO2, these combined strategies engender a recessive, humble and subservient character, which would assimilate sensitively with the topography. For these reasons, it is hoped that Wayside will be seen as enhancing the area.

The building is constructed on an encapsulated cast in-situ concrete raft (locally manufactured using secondary aggregate from the clay industry) sealed under and over with a 100% recycled DPM (Visqueen EcoMembrane®).  The walls consist of two independent timber frames spaced 400mm apart, but not joined.  This allows for maximum recycled newspaper insulation and no cold bridging through the walls.  The roof consists of engineered I joists which use less timber, span further than solid timber and have minimal cold bridging.  Although a timber frame it has lots of thermal mass to create a thermal fly wheel affect and smooth out temperature spikes by incorporating internal stone walls, limestone flooring and 2 layers of plasterboard to the external wall and ceilings.  The entire ground floor has a min. 65mm thick screed with underfloor heating pipes clipped to 200mm high performance rigid insulation (Jabfloor).

The basic principles employed during the design, specification and construction is to ensure that the building has low embodied CO₂ content.   Materials were selected that have not required a large amount of energy in their sourcing, processing or transportation.  The solutions include:

1. Warmcel recycled newspaper insulation: Warmcel is a natureplus® certified product. This is a standard for products that meet the highest standards from raw material sourcing / extraction, to low emissions and clean production methods.  Warmcel is manufactured from recycled newspapers, these are collected from offices, schools, overruns from printing companies and kerbside collections. The manufacturing process uses very little energy, the combination of the cellulose fibre properties and its specific manufacturing process gives Warmcel an extremely low Global Warming Potential of -1.5 Kg Co₂/m².  The CO₂ sequestered within Warmcel is then locked into your building and is actually less than the CO₂ produced in the manufacturing process.  Unlike other insulations, Warmcel is an inert material with no off-gassing of Volatile Organic Compounds, making it the best insulation for a truly healthy home.
2. I-Joists: Engineered timber joists made from small sections of timber and timber by products (see below). They offer many design and performance advantages over conventional structural products including a composition which resists shrinking and warping, an excellent strength to weight ratio straight and uniform dimensions. The joists also have FSC & PEFC Accreditation & Labelling, Life Cycle Assessment and ISO14001:2004 Environment Management System.
3. Timber: recognised as one of the most sustainable building materials, all timber has been specified carefully ensuring that the chain of custody is clear.  This protects against irresponsible sourcing and irreversible damage to delicate ecosystems. Where possible, we advocate the use of European timber (FSC & PEFC) together with locally sourced green timber such as western red cedar which was used for cladding, fascias, barges and soffits.
4. Timber by-products: such as the bitumen impregnated fibreboard to the roof (Bitroc), orientated strand board (OSB), and hardboard (air tightness layer) have also been incorporated in order to utilise further waste products.  Additionally, these products have lower chemical content in terms of adhesives and binders than composite materials such as chipboard and medium density fibreboard, both of which have reported harmful binders which can cause a health hazard when working with the materials.
5. External Joinery: High specification triple glazed windows were specified to help reduce heat loss.  Aluminium windows were chosen to reduce maintenance due to being located close to water and trees.
6. Wood treatments: have been selected which limits the amount of chemicals utilised within the building.  OSMO polyx hardwax-oil rapid for clear internal applications was selected because it incorporates natural wood wax oils which are solvent free. Impra Profilan Opac was used on all timber painted black and is a satin finish waterborne paint which does not contain biocidal components. Awarded the Blue Angel seal award for its environmental friendly aspects
7. Wall membranes: have been eliminated from construction. This serves to provide a breathing shell (vapour permeable) which is not susceptible to condensation build up and significantly reduces the risk of associated respiratory illness.  As it breathes the structural frame is less prone to decay and offers greater longevity
8. Floor membrane: Visqueen Eco Membrane: Manufactured from 100% post-use polyethylene, diverting more waste from landfill.
9. Green roof: consist of varieties of wildflowers that flower throughout the year and promotes a range of wildlife as well as looking spectacular year-round but especially in late spring during the main flowering season. This roof also assists the drainage of the building by slowing down/holding up the run off of water from the roof prior to entering a drainage system.
10. Green roof membrane: EPDM Membrane is the most environmentally friendly roof membrane compared to all other roofing systems and is re-usable.  The membrane is root resistant and exceeds the expected lifespan of the vegetation layer.
11. Rainwater goods: Lindab Rainline polyester coated steel rainwater goods were selected because of quality, durability, minimal maintenance, recyclability and it has the lowest CO₂ footprint of any other system.
12. Natural Stone walling: Quarried locally supporting local economy and minimising transportation/CO₂.
13. Bitroc: naturally emulsified bitumen impregnated fibreboard made from Scandinavian recycled chipped softwood together with waste newsprint to provide a breathable sheathing board to the external walls and roof.
14. OSB: Oriented Strand Board made from thinning’s from managed plantations (FSC); the process utilises 95% of the wood, discarded bark being used for fuel in horticulture.  Used for internal racking walls and first floor sub-deck.
15. Glulam Beams: Small sections of timber from sustainable sources glue laminated to provide a larger structural grade timber.  Used for cantilever, around glass floor and over larger openings as lintels.
16. Jabfloor (over slab insulation):  A+ BRE Green Guide, 100% recyclable, non-toxic and biologically inert, The lightweight nature of the insulation means that less fuel is used when transporting from factory to building site.  BBA accredited, certificate 87/1796
17. Earthwool: insulation to acoustic walls and floors (where breathability is not required).  A+ Generic BRE Green Guide rating.  Made using recycled materials.  Made from rapidly renewable organic materials. No added formaldehyde binder.  No added dyes.  Up to 70% less embodied energy and recyclable.

The green roof consists of varieties of wildflowers that flower throughout the year and promote a range of wildlife as well as looking spectacular year-round but especially in late spring during the main flowering season. This roof also assists the drainage of the building by slowing down/holding up the run off of water from the roof prior to entering a drainage system.

The house exceeds the minimum Passive House U-Values whilst also having a very respectable air pressure test result, maintaining consistent comfort levels throughout the year.

House U-Value Summary – Constructed

Walls

400mm Twin Stud Wall = 0.095

300mm Twin Stud Wall = 0.13

225mm Cavity Wall = 0.14

200mm Cavity Wall = 0.16

Roof

300mm I Joist Zinc Pitched Roof = 0.127

350mm I Joist Wildflower Roof = 0.11

300mm I Joist Wildflower Roof = 0.1127

Floor = 0.114

Rooflight = 0.10

Windows and glazed doors = 1.0 Average

Front Door = 1.0

The following provides a technical breakdown of the building services and performance of the buildings main components:

• MVHR system: 2 no.  high efficiency (90%) Vent Axia Sentinel Kinetic Plus (House) with Summer Bypass and Automatic Humidistat Boost Controller.  Mainly 180mmSpiral Wound Steel duct and PVC 150mm/125mm ducting, ProAir Oval ducting.  Lindab “Safe” Connection system and Zehnder Flat51 low profile ducting system.  Steel painted Adjustable Air Valves, Flexible sound attenuation.  Insulated Externals Ducting U vale of 0.038.  This system provides excellent indoor air quality (moisture, particulates, pollutants are filtered) and the rigid ducting is efficient and reduces noise levels.
• Ground Source Heat Pump: Valliant Gmbh – Flexotherm 8kW.  COP 4.14
• Cylinder: 500l with solar PV compatibility • Buffer cylinder – 400l
• UFH: GF (wet system at 150mm centres) within screed.  Omnie Torfloor Chipboard system to 1st floor and dry sand between battens to 1st floor of pool building.  All with Heatmiser Wireless programmable room thermostats and wiring centre
• Towel rails: Electric towel rails to en-suites with built in programmable thermostats (not used for heating and not required for drying to MVHR maintaining a consistent 40-50% relative humidity in the house, installed as back-up).
• PV & Battery Storage: Awaiting installation
• Lighting: 100% dedicated low energy throughout inside and outside
• Cooking/White Goods: Minimum A rated appliances’ throughout
• Treatment Plant. High performance Klargester package treatment plant provides environmentally safe treated effluent with low running costs (10-14p per day).