I’ll admit I think I’ve driven myself a bit ‘cooling crazy’ after a solid month writing solely about air conditioning. It’s like eating vegetarian for a few weeks and you end up craving a bacon cheeseburger. With steak sauce and a few grilled onions. Ohhh, yeeah. Um, so what am I writing about? Right, wattle and daub.
Why am I writing about wattle and daub? First, the phrase ‘wattle and daub’ is an all-time favorite. I could say wattle and daub all day. This is so strongly true that I’ll have to resist saying wattle and daub over and over … wattle and daub.
The other reason is that it feels like a nice counterpoint to the efficient wall posts I’ve been writing (and have yet to post…basically a look at every wall insulation approach I could think of). After reviewing the next generation of energy efficient building enclosures, why not throw back to one of the oldest.
And wattle and daub represented one of the biggest leaps forward in efficient home construction. Looking at wattle and daub construction (and the roots of energy efficiency) might give some insight into current building.
What is Wattle and Daub
Wattle and daub is an ancient (and I mean 6000+ year old, since the dawn of man ancient) technique for constructing walls in small buildings. Structurally, it is very similar to lathe and plaster construction popular through the 19th and 20th centuries. You would just substitute ‘wattle ‘for ‘lathe’ and ‘daub’ for ‘plaster.’
Wattle ought to be familiar in appearance to fans of BBC, medieval period dramas and Game of Thrones. Wattle is a lattice of vertical thin wood poles with thin reeds or split branches interwoven horizontally. The whole effect is rather like loosely woven rattan. The wattle is used as the application surface for the daub, either between the wall cavities in post and beam construction, or as stand alone walls with stronger vertical supports.
Remember the scene in Monty Python’s ‘Holy Grail’ when the socialist peasants (technically, anarcho-syndicalist communist peasants) were farming mud? It’s entirely possible it was for mixing daub for wall finishing.
Yes, once mud farming was a thing and if you’ve driven anywhere around Florida, you know that sod farming of course still is. If the wattle is our ‘framing’ then the daub is the insulation. Daub is a mixture of mud, clay, various types of lime or stone dust as a binder and hay or horsehair or some similar fiber to give the whole thing strength and flexibility. Basically, it was medieval plaster. Just add a thick layer of exterior lime white wash and you have a 1000-year-old proto-standard wall.
Squint Hard…The Modern Wall is in There
The daub would be fairly vapor permeable, allowing drying in both directions, ideal for the temperate climates in which most early cultures developed. That same layer of hardened daub probably would produce a respectable air barrier as well. In function, it wouldn’t be far remove (OK, far removed in R-value) from a Larsen truss or double stud wall.
A final kicker: suppose the builder erected the building frame, wrapped it in wattle, then applied exterior daub (with some structural supports). No thermal briding. That’s right; a 2000-year-old mud hut could meet aspects of modern energy codes better than houses build in the 80′s or 90′s.
The era of modern heating gives us a lot of leeway with how we construct buildings. We often don’t build houses to maximize solar gain or minimize heat loss as a few hundred dollars more heating fuel covers up any deficiencies. We construct buildings with mammoth glass walls and elaborate architectural details that devour energy. Reflecting back on ancient construction, driven by the need to not freeze to death, can inform our thinking about modern building.