...well not quite...

We are looking at a project to build some top(ish) end houses in Rwanda and our client very much likes the idea of offsite construction as local skills are very low/unreliable. Water tightness and walls being in the right place are for examples things that are equally essential but not to be relied upon...

...we have suggested that the best thing to import would be some labour rather than the whole house but we need to at least consider the latter, possibly a compromise would be heavy weight low skilled trades local with the lightweight accurate parts imported..

anyone an thoughts, and specifically any companies that are some where between Huff Haus and Portakabin(!)

(as ever, thanks in advance)

J

... we did think that and are continuing to push that option as it works on a number of levels, but need to at least look at the pre-fab option.

J

This might be of interest:

http://www.rammed-earth.org/botswanaproject.htm

Posted By: marktimeDon't underestimate the skill set of local workmen. The real problem lies in holding them to a standard. My experience is that it requires 100% supervision but using local materials and unsophisticated designs you can get a good job done. (Seeing the bubble somewhere in the level is not the same as level!...)

That's exactly the sort of thing our client was describing.

Speaking from direct Rwanda / Central Africa / Developing world experience?

J

100% supervision on health+safety too (experience from Uganda).

Even when it's on, power supply reliability might be an issue (I've measured Ugandan mains - nominally 240v / 50Hz at anything between 80v and 290v and 45Hz to 60Hz in the past). 230v Incandescent bulbs shine really brightly at 290v (they just don't last very long).

Maybe fit voltage stabilisers if this is an issue in Rwanda (with the added benefit that you can use them onsite during the build).

Watch out for the termites they'll eat anything (including the paper plans if they can get near them). If it's going to be air-conditioned, then the high humidity can cause interstitial condensation problems during the hottest+wettest times.

They have similar set of building challenges in the deep south of the U.S. so that might be the place to source some designs (or even just a copy of the local building code).

Oh yeah, design for high lightning strike frequency too (again from Uganda - some parts have experienced thunderstorms on more than 200 days per year before, but I imagine Rwanda is the same) - some of the more intense storms are really amazing to watch (e.g. more than 1 lightning strike per second visible on a really stormy night - like a random frequency strobe, and just watching the clouds growing and changing shape during the day time at 10x the UK rate is impressive).

Rwanda's definitely up-there when it come to strikes, by the look of this:

http://geology.com/articles/lightning-map.shtml

Tim.

I'm with you on upskilling the local guys but won't you be introducing them to a one-off technology? Surely there will be limited demand after you have left or is your client a developer?

A good compromise might be a local construction with imported marble googaws, gold plated brightwork, etc. I imagine you'll have to import fittings and finishes in any case.

BTW, on-site concrete block production will give him his solid feel.

Maybe have a look at the local construction techniques and styles to see what works well and/or those from similar climates.

The cheaper local labour rates, and lower tech+material availability might make some techniques and methods which are more marginal in Europe more viable? I did think of rammed earth for instance, and stuck it in Google, and found this:

http://engeyedesignteam.wordpress.com/2010/09/13/post-review-a-lower-case-spiel/

... which happens to be talking about Uganda. Earth walls are a common local traditional material (at least they are Uganda), and the labour intensive parts of the formwork process become much less of an issue.

If you think European concrete is high embodied energy, then you can bet that Rwandan concrete is worse (lower efficiency plants, less efficient transport infrastructure etc. etc.). I've been told that quality control is poor in East African cements too I believe (maybe you'll need to obtain some samples and get some European analysis?).

In Uganda, Eucalyptus (although a non-native species) is readily available and locally grown plantation species. I don't know if the same thing is true on Rwanda, or how it compares to typical European softwoods etc.

Oh yeah, one more potential issue, the region is quite geologically active isn't it, so perhaps you'll need to consider earthquake resistance too?