Restoration and retrofit - The Hempcrete Topic: Designing and Building with Hemp-lime - page 454

Traditional buildings were always built from natural,
breathable materials, such as these clay bricks, oak
beams and clay/lime plaster.
However, our architectural heritage in the UK extends further than the 370,000 or so build-
ings that have a listing, and many people in the UK live and work in buildings built before
the First World War. There is growing public awareness of the need to repair, restore and,
where appropriate, improve these buildings using natural, breathable materials. Unfortu-
nately, in the context of the current (very necessary) drive to retrofit insulation to older
properties, there is again a risk of damage being done to the fabric of older buildings and
to the health of their occupants by the use of inappropriate materials.
When asked to upgrade the insulation of older, solid-wall properties, the default response
of the mainstream construction industry is to reach for the highest-spec synthetic insulation
available, which is then either installed between joists or rafters or glued to the inside face
of the external walls using chemical adhesives. Not only do these materials frequently con-
tain harmful chemicals but also they are usually impermeable to moisture vapour, thereby
sealing up the breathable wall of the property and causing the sort of problems just de-
scribed.
In 2012, work undertaken by the Sustainable Traditional Buildings Alliance (STBA), a
collaboration of not-for-profit organizations, including English Heritage and the Society
for the Protection of Ancient Buildings (SPAB), raised awareness of the issues involved
in the retrofitting of insulation to heritage properties and highlighted areas where future