Conservation in Action: Lincoln Medieval Bishops' Palace 

I want both!

Hi Lucinda, you can read more about the conservation technique of soft capping here: historicengland.org.uk/research/results/reports/88-2018

I had the same initial thoughts as you; surely the roots would break apart the stone? But according to that research report, soft capping has many benefits such as it is good at thermal protection, mixed results on how much better it is at dealing with internal moisture than hard capping (hard capping; ’the use of stone and mortar to consolidate the wall head’ according to a google search), definitely better at external moisture reduction though, and in reference to the potential roots problem: ‘… Another concern is that soft capping might lead to the deterioration of underlying stonework by plant roots. This too is unlikely. Grass and sedum do not produce woody roots, and so even if the roots reach through the soil and connect with underlying stonework, they will not cause serious deterioration.’ ‘… Furthermore, it is easy to eliminate the potential for damage any woody plants might pose: simply remove them if they establish themselves in the soft capping.’