Rammed Chalk Paragraph 80 House in a Woodland
September 9, 2022
Drawing courtesy of Roundfield Landscape Architects
Barefoot have been working on a new rammed chalk Paragraph 80 house. The proposed building sits within an existing woodland in a chalk downland landscape, and so we are working closely with the project ecologist (Darwin Ecology), arboriculturist, and Roundfield Landscape Architects to ensure that the building responds to the existing woodland. We intend to do this through extensive green roofs (as shown in the drawing above), a woodland management plan, and detailed coordination with the whole team to bring it all together. This has led to a lot of discussion about the surrounding woodland and its condition, and taking a ‘forest-led’ approach to the development of the house.
We are aiming to reach 10% net gain, which in an existing woodland is a challenging proposition! Natural England advises that any net gain should be fully secured for the lifetime of the development, therefore site management plans will be developed to ensure that the site is enhanced over the lifetime of the house.
“Biodiversity Net Gain Assessments calculate the change in ecological value at a site by comparing the number of ‘biodiversity units’ within the site pre and post construction for both linear habitats, area habitats and demonstrating measurable loss or gains.” (1. Darwin Ecology)
Drawing courtesy of Roundfield Landscape Architects
Unfortunately, the existing woodland has a high prevalence of Ash dieback. This is a disease sweeping through our woodlands to devastating effect. The arboriculturist has been monitoring the trees on the site to observe which ones have more than 50% crown cover dieback; this is a sign that the trees are unlikely to be able to resist the fungal invasion and will therefore be proposed for removal and replacement by other tree species. “Experience in continental Europe, which is now being seen replicated in the UK, indicates that it can kill young and coppiced ash trees quite quickly. However, older trees can resist it for some time”, states Forest Research Institute (2). We hope that some of the more mature trees on the site can be saved and supported to resist the Ash dieback. We intend to use those trees that cannot be retained for interior cladding, flooring and bespoke joinery.
In terms of impact on biodiversity the loss of so many Ash trees is significant, as Ash is the sole food plant for at least 27 species of invertebrate (3). We hope the interventions being made on the site will support and enhance the woodland and wider ecology. Mycorrhizal networks are really important in the health of a woodland, and we are designing the house to be part of the soil network. The science around and interest in the intricate web of connection under our feet is ever-expanding, with books such as ‘Entangled Life’ by Merlin Sheldrake disseminating the wonders of this hidden world.
As far as the link between soil health and Ash dieback goes, there have been studies indicating the beneficial use of natural soil enhancement such as biochar as a preventative measure. Dr Glynn Percival, head plant physiologist at the Bartlett Tree Research Laboratory, has stated that “using enriched biochar could help improve the survival prospects for the UK’s ash trees.” (4). We will also explore the creation of biochar from felled trees in order to feed back into the soil and enhance not only the measurable net gain, but the micro soil-web in turn. Hopefully this will aid in giving the ash on site a healthy longevity. Our design for this exciting building is intended to celebrate the symbiotic relationship between woodland and soil, with the human and forest connections woven together at each level of the plan. In places the woodland is brought directly into the fabric of the building, connecting the human inhabitants with the forest outside via the planted roofs.
We aspire for all our buildings to be carefully situated and connected to their contexts, and this building represents an approach to bridging a home directly to its natural surroundings.
Articles / references:
2: https://www.forestresearch.gov.uk/tools-and-resources/fthr/pest-and-disease-resources/ash-dieback-hymenoscyphus-fraxineus/
3: https://www.britishecologicalsociety.org/assessing-the-impacts-of-ash-dieback/