INTERPAVE
MEETING NEW PLANNING REQUIREMENTS FOR TREES
Extensive tree planting and retention of existing trees in developments , with provision for long-term maintenance , has just become a priority with new government policies taking effect . Concrete block permeable paving offers an important opportunity to help satisfy these requirements providing irrigation integrated with SuDS , hard surfaces and urban design – as the trade association Interpave explains .
The 2021 ‘ National Planning Policy Framework ’ ( NPPF ) states : ‘ Planning policies and decisions should ensure that new streets are tree-lined and that opportunities are taken to incorporate trees elsewhere in developments ’. However , measures are needed to nurture and allow trees to mature and deliver their real potential – including net carbon storage , urban cooling through shading and evapotranspiration , biodiversity and public wellbeing . So , the NPPF also requires that : ‘ appropriate measures are in place to secure the long-term maintenance of newly-planted trees , and that existing trees are retained wherever possible ’.
PAVING AND TREES IN HARMONY
Urban trees and paving have traditionally been seen as in conflict . But this is not the case with concrete block permeable paving ( CBPP ), a key sustainable drainage ( SuDS ) technique to reduce flood risk and make cities more liveable . CBPP offers unique opportunities to collect , attenuate and treat rainwater runoff , removing pollutants before irrigating green infrastructure . Unlike conventional impermeable hard landscape materials , CBPP allows the same pattern of run-off transfer to the ground as natural vegetation , allowing water to reach tree and shrub roots , despite providing an attractive hard surface above .
Local planning authorities now need to incorporate long-term tree maintenance measures in their planning consents and a straightforward spatial solution , such as permeable paving providing irrigation , offers a holistic multifunctional solution .
BENEFICIAL RELATIONSHIP
The benefits of CBPP for trees while retaining accessibility are recognised by the current Code of Practice for accessibility in the
“ Planning policies and decisions should ensure that new streets are tree-lined … and
appropriate measures are in place to secure the long-term maintenance of newly-planted trees .’
external environment , BS 8300-1:2018 , which states that : ‘ Tree grilles should be avoided . Smooth or paved permeable surfaces should be used wherever practicable ’. Permeable paving can be laid level and still avoids puddles without the need for drainage gulleys . It provides a safe , firm , pot-hole free surface for everyone – including wheelchair users and people pushing prams . Two decades of experience in the UK demonstrate the long-term performance of CBPP with minimal , if any , maintenance .
CBPP generally comprises an upper layer of concrete blocks with permeable jointing and laying course , over a sub-base and other structural layers of permeable material for water storage . Interpave is currently exploring new ways of applying CBPP to optimise gradual supplies of water for tree irrigation at both levels , as well as effective interaction with tree planters and proprietary tree pit systems . Paving layouts are also being considered to maximise the permeable paving catchment area for tree irrigation , particularly outside the protective tree-canopy zone .
Interpave would be pleased to hear from anyone considering integrating permeable paving and trees on projects ( email : chris . hodson @ paving . org . uk )
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