Have you ever been out, enjoying a glorious weekend walk in the country (or similar) and noticed this?
Then wondered, how exactly it was that grass managed to grow in the most unusual places?
Fascinatingly, the grass you may have witnessed poking up through the tops of stones was intentionally placed there.
Placing soil and grass on the tops of ruined walls, to aid conservation, offers a viable alternative to traditional hard capping.
Eight years of experiments, field trials and monitoring by Historic England and the University of Oxford at multiple historic sites demonstrate how this approach can not only reduce rates of deterioration, but also support biodiversity and reduce costs. Based on this evidence, all of the ruins at Hailes Abbey, Gloucestershire, were soft capped in 2013 and this is proving very successful.
How does it work?
Ruined and free-standing walls are exposed to rain, thermal fluctuations and frost that cause deterioration over time. Hard caps of stone and mortar have traditionally been used to consolidate wall tops and minimise on-going damage, but these often crack / deteriorate, quickly requiring regular maintenance and repair. Using soil and vegetation to cap walls offers an alternative and there is strong evidence that such soft caps are effective at buffering fluctuations in temperature (including frost) and moisture, and thereby protect the tops of walls from further damage. Soft caps also reduce the amount of rainwater running down the face of walls that can increase the harmful weathering of face stones and cause unsightly surface staining.
A 13th Century Cistercian Abbey was the first Scheduled Ancient Monument in England to be entirely soft capped in 2013. Soft caps were applied on all sections of exposed wall, including at ground level and walls up to 5m in height. The cap consisted of locally-cut turf with a thickness of c. 10 cm. In some areas small sedum plants subsequently were added to help prevent edge erosion.
Hailes Abbey suffers from flooding, is situated in a frost hollow and many of the walls were in very poor condition and deteriorating rapidly requiring frequent and costly repairs to the hard capping in the past. Previous soft capping trials at the site had proved effective, supporting the decision to soft cap the entire monument as a more sustainable and cost-effective way of conserving the ruin.
Although costs can vary (see below) the soft capping method has proven to be a cost effective, low maintenance method of conservation that reduces costly maintenance and repair cycles for asset managers. It also provides a degree of ecological enhancement of value in itself; greening ruins provides some aesthetic appeal and limited regulating (e.g. water attenuation) and supporting (e.g. habitat provision) ecosystem services. Results of preliminary trials (in Scotland) show it can be a useful asset management tool that can achieve desired engineering performance outcomes and provide ecosystem services.
Soft capping functions as additional habitat for plants, insects and birds that hard-capped walls do not provide. Plant communities forming soft caps are dynamic and change naturally over time and may support locally similar but distinct species assemblages.
By slowing the deterioration of valued historic assets, soft capping provides a cultural service. Many people also place greater aesthetic value in ‘natural looking’ ruins, and using vegetation to slow deterioration may therefore support broader efforts to engage the public with historic sites.
A detailed visitor perception study at Hailes Abbey found that around 78% of visitors has a positive perception of the capping and 16% had a negative view (the remainder were neutral). Those with a negative view were more accepting once educated about the conservation benefits of a soft cap.
Extending thanks to Historic England, for providing us with this information which was found in “Appendix 1: History – Greening the Grey: a framework for integrated green grey infrastructure.” – A great read.
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Incorporated in 2006, Aura Conservation have existed for over twelve successful years. We have a sound and experienced management team. We can assist you in any of your conservation needs and have a body of long standing and experienced tradesmen we can call on with specialist knowledge of the conservation world. Along with prudent financial management, we have a sound financial foundation that will see us prosper in the coming years.
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