Charlie Rendall

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since Oct 28, 2011
Occupy the Forest!
Lake Atitlán, Guatemala
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Recent posts by Charlie Rendall

Hi Eddy,
What made it possible for me to have a successful career in natural building was to live in a place (Lake Atitlán, Guatemala) which has the following advantages:
 (1) a lot of people are moving to this place, and many of them don't speak the language well, are willing to pay a professional for a job well done, and are open to natural building in general (pretty alternative bunch here)
 (2) there are no building codes or inspections - anything goes!
 (3) a tropical environment that's fairly forgiving of rustic natural builds, enabling a lot of trial and error - it also has abundant natural building materials, from volcanic pumice to bamboo to clay to local native hardwoods etc...
 (4) a good source of a moderately skilled local labour force
I also was very careful to cultivate a good reputation as a responsible and high quality builder who respected and took care of his staff.

Local politics is always interesting too and needs careful diplomacy at times!

Good luck!
2 years ago
It's a bit of a rough scan but I found this:

And I have other works of Oscar Hidalgo Lopez with excellent diagrams of joins and trusses that I downloaded ages ago but can't find accessible now. It was called manual de construcción con bambú and the above is a 61-page excerpt from it. I'll try digging it up again later and post it if I get lucky but for now the above is the best I can find for free.

The Gift of the Gods, while expensive, is by far the best single resource that I've ever found on the topic.

Good luck!
I just discovered this trick the other day and worried that the mason jar might break - I did break one the other day by trying to flick the excess chile sauce off a teaspoon inside the mason jar (it was a Ball brand): the teaspoon shattered the jar from the inside out and I was surprised at how easily it broke, and also how thin the glass was.

I've also shattered a plastic Osterizer closed jar that was specifically designed for attachment to a blender knife and base, this time by trying to blend up a small batch of cats claw, which are extremely hard!

Has anyone tried this trick and had the jar break? Or conversely has anyone done this a lot and never had any problems?

Rereading this post I realise I might have discovered a potential new career path for myself in product testing...
6 years ago
Hi All,
Thank you for everyone's contributions on this thread, which I'm finding very useful for consolidating my knowledge of foundations. Foundations used to bother me as a natural builder because most rubble trench foundations I found on the Internet seemed to need a reinforced concrete beam that floats on top of the rubble, and I wanted to make foundations without any cement, and without the ubiquitous underfloor plastic sheeting too! In particular, I wanted to build a couple of small natural cabins on my land here in Guatemala.

We have high rainfall for half the year and I'd seen too many poorly built local houses literally sucking up all the water from the ground around them and causing all sorts of moisture-related problems like black mould, rusted rebar, blistering paint and rotting wood, and indeed health issues for their residents - asthma and chronic respiratory conditions in particular.

So as a largely self-taught builder, I found out about french drains and acquired a simplistic understanding of the basic principle that moisture isn't very well transmitted through air, at least not well enough to be a problem for buildings. Rocks do a pretty good job of stopping moisture transfer too, or at least the non-porous ones do.

I live in a valley that is made up of mostly debris from landslides, which means lots of rocks, gravel and sand of all sizes. "Use what you have" being my first principle for starting designing, I had lots of big rocks and my pet monster: a Milwaukee rotary hammer drill. So I figured I could put each of the four columns on top of a large rock and tie it in with a piece of 3/8" rebar set into the rock with a negligible amount of concrete mix (less than half a soda can of it). I shaped the top of the rebar into a hook that hides inside the bamboo and then drive a long 1/2" bolt through the bamboo and the hook, so as to stop the whole cabin from lifting off in high winds. Many folks fill the first couple of internodes of the bamboo with concrete but I really don't find it necessary or even desirable for such small constructions.

It took a while to dig the holes and get the big foundation stones level (each one weighs around 200-400lbs), and yet longer to dig out all the dirt from around and under the house and then replace it with small rocks covered by a layer of gravel, but once it was done I realised I'd come up with a very low-tech and effective way of insulating my house from the very damp earth beneath it. It didn't take too long - nor a huge leap in humility - to realise that many others before me had probably come up with exactly the same solution.

This was a couple of years ago now, yet I didn't come across some concrete examples (pun definitely intended) of this kind of foundation until reading Jay's first post on this thread, which came as a big vindication of my reinvention. So a big thank you for that Jay, not to mention all the excellent kanji image searches you provide.

Nonetheless, I have some further questions about these foundations, in particular: we have a LOT of hills and mountains here and I'd like to know how to build this kind of natural foundation on a steepish slope. One idea I have is to excavate a large hole, dump a load of gravel followed by a big thick, flat rock, pop the wooden post on top of that and then fill in the rest of the hole with a thick surrounding layer of gravel - is that how it's done? Does anyone have any other ideas? Previously I would just do it with a big concrete footing, but I'm determined to cure myself of this addiction! (Much as I love it…)

Furthermore, how long do these rock and gravel foundations last? Obviously that depends on rainfall and soils, but won't it eventually silt up? Does the soil creep into the gaps, eventually touching the building's other components and compromising their dryness? Is it worth putting geotextile down? I'm broadly against using synthetic materials but accept that sometimes they prolong the life of a building so effectively that its carbon footprint might even be halved.

One more difficulty I have with foundations is that I can find very few pictures and people's descriptions are often ambiguous and confusing. I would love to see more cross-sections of natural foundations, so here for starters is a diagram of the cabin foundations that I built (with the help of several others!), and a photo of what it looked like a few days before we built on top of it. You can just make out the four corners. The big rock in the middle was removed and the dirt replaced with gravel.

Regarding the discussion on modernity, I am at times a wilderness-loving hermit and at others a technology-marvelling geek. I lived the best part of my life in the heart of London in a century-old brick house with lime and rock foundations, which developed problems because of all the concrete applied around and in them in later additions and modifications - a good example of poor application of modern innovations. I've also watched the extraordinary spectacle of whole tower blocks built in the 1950's being dynamited and disappearing into dust in a second (only to make way for yet more tower blocks!) So I like to think we can still build relatively naturally and well in urban settings, and it's more a question of challenging ourselves to do so.

One further line of enquiry that I'm longing to pursue is reinventing Roman cement - their cement was much longer lasting than Portland cement and yet we continue to use Portland cement in vast quantities instead of developing a more stable version of it. This has been posted elsewhere but it seems relevant to post it here again: and

That said, I am looking forward to building lots more concrete-free foundations and learning ever better ways in which to do so. Thanks for your help with this.

With best regards,
6 years ago
You can in Guatemala and other "less developed" nations. I live in a Mayan village on the shores of Lake Atitlán where I estimate around 75-95% of the houses were built by unlicensed builders.

That means that many of them are either unsafe, unlikely to last very long or both, but few complain about this because they're likely responsible for it and moved here precisely for the freedom of building where there are no building codes and licensing. Many of them are also well-built and beautiful, and proof that almost anyone can build their own house.

I got into the building trade here first building my own house then being asked by neighbours to build theirs. I learnt from carpenters, masons, general contractors, architects, engineers, geologists, local natural builders, random crazy inventors and anyone else who had something useful to share - some were local, some from other countries. I also learnt a LOT from books and the Internet, although it has been tricky at times to understand more complex subjects. Fortunately the freedom to make mistakes, and the demand for builders here, has meant that I've also learnt a great from simply having to find a way to do stuff that back in the UK (where I'm from) there's no way I'd have been allowed to go near.

I think if you're conscientious about doing your homework and have a tendency to over-engineer the important parts, that it can be a great education in building and I've now hosted a dozen natural building interns who come here to get the degree of exposure to building that would be a lot harder to find in their own countries. I realise this thread is a little old but if you still feel like a break from all those authorities, inspectors and codes then maybe save a little cash to get you started, and head south to where you can find an abundance of clients and building projects to cut your teeth on.

I started building my own house in 2005, then built my first house for a client in 2009 and if you're interested in what I'm building now then take a peek here:

I should also add that this sort of exposure and learning isn't a substitute for a more thorough education from accomplished masters, but if that's difficult to attain then there are alternatives in places like this. There are also many excellent natural building schools and courses throughout central and south America, not to mention elsewhere in the world.
6 years ago
Hi Thomas, There may be an opening possible, I'll private message you now.
Cheers, Charlie
7 years ago
Hi - yes, it's still open. I just private messaged you. Let me know if you don't get the message! Cheers, Charlie
7 years ago
I’ve recently had the good fortune of being asked to build several new projects in and around the village where I live: San Marcos La Laguna, on the northern shore of Guatemala's beautiful Lake Atitlán, and also of joining forces with a talented carpenter and architect, Steve Selby.

The upshot of which is that I am able to offer an informal internship to people interested in getting hands-on natural building experience.

The internship would be a great way to learn natural building techniques on very original and experimental buildings, with some talented and experienced folk, in a very beautiful place, with a great community of both foreign and local residents. It also provides the opportunity to learn both Spanish and a very transferable trade at a time when natural building is booming, and in a place where building codes are thankfully still a long way off!

I’ll need to flesh out the description a little but in short I’d need someone who could offer their assistance five days a week, for six hours a day. Tasks would include site visits, supervision, documentation, drafting (both hand drawn and computers) and accounting.

You needn’t be a specialist or have a ton of experience but, to make it worthwhile for yourself and our team here, you’d need to be walking fit, independent, flexible, have basic computer skills, and of course be willing to get stuck in and learn whenever possible. Minimum commitment would be six months.

I may be able to offer some kind of accommodation later in the year, although currently our space is limited. A rustic one-bedroom house here rents for about $100 a month, although you can sometimes get free rent for house-sitting, especially during the rainy season (May-October).

If you’d like to know more, please send me a message!

I'm also interested in hearing from any journeymen = the wandering German carpentry apprentices, if anyone knows how to get a hold of them...

Thanks, Charlie
ps. here are a couple of pictures of one of 2012's builds, a bajareque cabin:

And thanks Team Permies - we love you!
7 years ago
is one distance learning possibility, which you could do while you travel the world gaining experience on sites.
8 years ago
I saw a documentary many years ago about how for a long time archaeologists had no idea what cement had been used in the Great Wall of China and they finally discovered they'd been using some form of rice cement! I think they found microscopic bits of rice husks and then a chemical analysis to determine this. I'd love to know if anyone knows what it was or how to make it, since it's clearly very durable. As for its carbon neutrality, well, we can determine that later

p.s. My two cents on the whole Novacem debate above: I think constructive skepticism of new products is a very healthy aspect of permies (and web forums in general), especially with so much greenwashing going on these days - maybe Novacem is a genuine green solution, maybe not, but yes at least it's a step in the right direction in as much as there's an acknowledgement that we should be developing ways of making cement production more sustainable. And I think such debate is also a step in the right direction, we should be asking those questions. Let's hope we find out soon just how green it really is so we can either reject it or start using it!
8 years ago