Monday, January 3, 2011
ESSAY; MAMPOSTERIA CONSTRUCTION IN MÉRIDA;
In a natural progression of things that evolve out of necessity and the availability of materials colonial dwellings were built.
With only lime stone rock and wood, mamposteria, (stacked stone) buildings were the only option.
The method is simple;
Lime stone rock abundantly found in Yucatán is stacked; the spaces between the rocks were chinked with smaller stones and then just plastered over. A finishing coat of plaster not always used was optional.
There is no reinforcement in this type of construction. The stone used is soft, absorbent and porous and the plaster-cement consists of lime stone aggregate, “cal”, quicklime, and a stingy amount of cement.
This flimsy cement concoction is never wet cured to enhance its small amount of structural integrity.
The crumbly cement is not cohesive when dry and soft when wet, (from the bottom of the footings to the wall tops all is the same).
If not disturbed these walls could conceivably last for centuries.
The roof, another matter, is a simple procedure;
(Vigas, “rafters” and bovedillas, “filler material”) go to make up the roof and are only plastered over.
Vigas are merely support joists just placed upon the wall-tops and not fastened down in any way. In this case logs were used as the vigas. In more elaborate structures the vigas were actually hewn.
These vigas were placed and spaced at regular intervals parallel on the wall top to be part of the roof. (There are no fastenings.)
Next stones, bovedillas, were placed between these vigas in order to fill the open spaces. Then smaller and smaller stones were placed until a surface that could be plastered was ready.
The roof was plastered inside and out and that was it.
This type of construction when complete can give the appearance of enduring strength.
Make no mistake about it, in time even the best of these mamposteria structures will succumb to the forces of gravity and Mother Nature.
If the wooden vigas, rafters, are allowed to become damp in any way, (a leaking tinaco, roof-top water holding tank or a stopped up scupper) these wooden vigas will quickly decompose into compost. Even the hardest of woods in this tropical climate will not endure when wet.
The result will be an avalanche of deadly rock that will come pouring down.
These buildings do well in the dry season, but the absorptive porosity of lime stone acts like a sponge to draw up and hold moisture.
These structures in downtown Mérida are typical mamposteria construction and as you can see for yourself gravity and Mother Nature have done the inevitable.
This might look like a total loss to you but this mamposteria structure is still a habitation with electric service.
As amazing as it might seem a building like this one may soon have a new roof, plaster and paint job and be put on the market at yuppie-come-lately rip-off prices for the next unsuspecting exuberant and eager discoverer of Mérida.
This is just a natural progression of things that evolve here in the land of buyer-be-ware.
Note; a friend who is an architect bought one of these mamposteria dwellings to restore and discovered that the seller had glued paper over the rotted off vigas and painted them.
© John M. Grimsrud 2011