I was tempted to label this thread "cobtastrophe!" but i restrained myself.
what i'm interested in are lessons learned about natural building techniques that only become apparent after a decade or so of kids, pets, spills etc.
i've pictured a lot of mottled plaster work patching cracks, or erosion by use in cob benches, built in shelves town out by rambunctious young ones.
i've seen alot of photos of beatiful homes with fresh plaster before the family moves in but i think we'd all benifit from hearing about the other side.
i can start by describing the layers of different filling in the stacked stone walls of our basement, some poking out some recessed, some areas totally plastered over, there's even some bright yellow "great stuff" expanding foam caulk installed by a frantic new father (me) on winter day. it's not ideal but it's there and it works til i can figure out a good fix.
There is no problem in naturally built homes there is only a problem that people build homes without sufficient knowledge. That is catastrophic as such, but if you even go further and try new techniques you should have more than an average builders knowledge.
Location: Foothills north of L.A., zone 9ish mediterranean
posted 8 years ago
One of the biggest problems I have noticed in different types of building: (earthsheltered, cob, strabale) is that somewhere along the line water got in, resulting in unliveable mold scenarios. Bottom line, get the roof right, from the beginning, and make sure you have a plan to stay dry during construction.
Take a look at some decade old convenbtional developer-built homes in your area. I see moldy and cracked walls from bad design and poor window and roof installations, cracked floors and walls from bad foundations, and so on - you get the point.
I have also seen really well-built natural homes that are withstanding wear-and-tear There are also some not so old ones that look like shanty's. It seems like design and quality of construction are bigger factors than materials used.
posted 8 years ago
One of the main issues is certainly design, but upkeep is equally important I think. In the book "serious straw bale" they describe a straw bale home build in the '70's for the equivalent of $500 that is not only still standing, but was tested to be in excellent condition with completely dry straw. Neat little place with a good story, here is the link to that section of the book. "serious straw bale" is an excellent read that I would recommend to anyone looking into building a strwbale home
A good friend of mine who is a cob-builder recommends mixing an extra amount of cob during construction and caching it for any eventual repairs. That way, should you need to fix a crack or repair damage, you will have some of the original batch for a color/texture match. The cob can be re-hydrated years later and made pliable again with a hoe and a wheel-barrow. He also recommends sealing it with a natural oil (such as used by timber framers) for added durability.
posted 8 years ago
sol, that's exactly what i was looking for!
i hope i didn't come off as critical of natural construction. it's the choice we've made. i've lived in a load of modernish structure in poor repair so i'm familiar for what to look out for there.
water and cob terrify me, and i'm prone to both over building and porches, so at present our plan calls for an 8 ft wrap around porch and a series of drainage trenches to divert ground water.
On the road from Madrid to my house in the hills I drive through a village in which the houses made of mud bricks and the bottom layers of the walls and the houses in ht evillage are made off the big pebbles that fill the feilds around there so the bottom of the houses which can get wtter from wet ground are made of stone. Water is not only soemthing that comes in through the roof, it also comes up from the floor. I get water welling up through the kitchen floor and i live on top of a ridge, only the ridge is higher on one side of the house than it is on the other. I dug and i mean I myself dug, I dont like to been seen as a wet who can'0t do manual work, a ditch round the wet side of the house and the damp that crept up the walls on that side of the house does not do so any more. I went to Marrocco and was lucky enough to go into a village house in the hills and the passage in the house wa not straight or flat it wound down through the house to a impressive big back room with a terrace all along it length over the valley. It was very nice to go down a passage that sloped with the line of hte hill and was not straight. I have heard that always walknin gon flat floors is not good for ur feet so a sloped floor is healthy harder to tile but healthy. Damp gets into houses were the house has been dug into the hill where the line of the hill is higher than the flloor of your rooms, if you have a marrocan sort of house or my house before i reformed it which also had sloping floors, the trouble which got me to change this i liked the idea of a sloping floor, a s there was not room for a two floors in the house at the back if kept the sloping floor. The house as it was originally had doubled as barn and house so not all the rooms had standing room in them. With a floor that follkowd the slope of hte hill you would have less damp problems. agri rose macaskie.
posted 8 years ago
Mule tree, if you are using cob in a basement exterior as a parge type application let me make a suggestion: add extra hydrated lime to your mix and a little bit of portland as well (unless you are dead set against it) that way if you do get water in your basement (not uncommon even with a good roof) the cob won't dissolve. Also, apply the mix in two stages, the first should fill in all the interstices and make an even surface. (allow to dry thoroughly) The second coat is the finish coat and should be applied in a thin even layer. Make sure to really work the mixture for at least 15 minutes (as long as you want really) to "activate" the clay. (If you are adding portland, wait till the very end of this process) Make sure to "activate" the clay in the cob under coat as well with a spray bottle and a bristle brush. As you apply the finish coat make sure to "spank" the cob with a wooden paddle to assure that it bonds with itself. If you can control the temperature and humidity during the cure, a longer slower drying process is preferable. This approach should minimize cracking.
There are homes from the 1500's still standing, with families in them that are made from cob in England. A great many in fact. I would put a crappy cob constructed home up against a well made stick construction home personally and like to see which does better in 10, 30, 50 & 100 years.
Wow, that would be neat to watch over a lifetime.
posted 8 years ago
An aunt of mine had an old cob house for a while. I remember my fathers enthusiasm over its being made of cobb, all I thought was that i did not like it much, i can't remember why. I remember that my cousin had a box of crysalids hatching in the window. I was too young to understand that now cob is something special, as a child you are not always aware enough of what is normal to understand when something is not so very normal. The modern cob houses have those nice curved walls that are easy to make with cobb, this was a house with squared corners. It certainly did not seem damp and moldy. agri rose macaskie.