Cob: Grandson's playhouse

[Matthew HALL(SED)]

Melanie
A saying you will no doubt come across time and again is that 'all cob needs is a good hat and a
good pair of boots' to protect it from the rain. This tranlates to a raised masonry plinth wall of
something like stone, fired clay bricks etc, and a good roof with a large overhang if possible to
shed heavy rain away from the wall. If you have string winds and driving rain then you will no
doubt need to protect the wall with a render. It is best to use lime and not cement for this as
lime will allow the wall to 'breathe' whereas cement will not, holding moisture back inside the
wall. This can cause the render to fall offas the mud wall gets damp and can also lead to parts of
the wall collapsing. This summer i visited a recently-built earth house up at a place called
Rowardennan which is along the shores of loch lomond in Scotland (on the bonnie banks no less!). As
you can imagine they get all kinds of weather so this might be a good design to help inspire you.
Have a search on Google.com for "Loch Lomond Visitor
 Centre Rowardennan". It is actually made from adobe (mud bricks & straw) whereas cob is obviously
a monolithic wall, still the design is virtually the same. They built the walls on top of a 2ft
stone wall with a large overhanging purlin-type timber roof. The walls are lime rendered and
whitewashed and look very attractive in my opinion, and would certainly provide the kind of
durability you are looking for.
Hope this helps
Cheers
Matthew


____________________________________________________________________
Matthew Hall BSc (Hons) GradBEng
Centre for the Built Environment
Unit 9 Science Park
Sheffield Hallam University
Pond Street
Sheffield S1 1WB
England

Tel: +44 (0) 114 225 3200
Fax: +44 (0) 114 225 3206
E-mail: M.Hall at shu.ac.uk
Webpage: http://www.shu.ac.uk/schools/sed/earth