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Roofing Alternatives

 
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Hey y'all.

We've just moved out to the middle of nowhere in Sunny South Africa.

The house on the farm we bought has a round-hut attached to it. The roof is a mess, and I'm really not fond of the thatching. We'd like to use it as a pantry area, but since we live in a wildlife hotspot, I'd like to avoid creating a cozy den for rodents and snakes in my pantry.

Bearing in mind that I don't have access to prodigious amounts of lumber, does anyone have some options they'd recommend? I considered tin or corrugated sheeting, but the shape makes that an unlikely solution (video attached for reference).

https://www.kapwing.com/videos/6280cfeb07150900a760e019
 
Rocket Scientist
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Location: Upstate NY, zone 5
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The roof framing looks decent. Is the thatch fastened around sticks on top of the framing? Are those solid, or flimsy/degraded? What is the diameter of the hut, and/or the length of the rafters? Roof slope?

I have no idea what common roofing materials are available in your area. I could see replacing the thatch poles with boards spaced to hold wooden shingles, which are not too hard to fit to a gradually rounded shape like that. If neatness is not critical, I could see adding boards every half meter or so and fitting relatively short pieces of corrugated roofing to those, overlapping at a slight angle. This would look a bit odd but with good overlaps would be raintight. Using shorter pieces would reduce waste from excessive lapping at the top of the pieces. More information on available materials would probably help people advise.
 
pollinator
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Nice looking building!
Here in New Mexico, traditional buildings have heavy flat mud, wood and grass roofs. Bond beams support that weight. Similarly, the round hut probably has just enough structural features to support the traditional roof and protect the building from local phenomena (like typical wind, rain and critter challenges). Exploring local solutions is an important first step: what are your neighbors doing for their retrofits? Also, what resources do you actually have and like? For example, when I think of South Africa, the sailing tradition comes to mind. Are old sails available to you? Would you enjoy working with that lightweight material?
I'm looking forward to seeing how this fascinating project unfolds Johanan.
 
master steward
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I am not familiar with what kinds of materials or plants that might grow in S. Africa.

Though I hope these ideas will help:

Where I live we have people who make use of the stalks of the yucca flower and another plant that I can't think of the name.


source

My suggestion for roofing alternatives would be bamboo. Bamboo roofing would work for a round roof:


source


source


source
 
gardener
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This sounds like a job for: Latex Concrete!

https://velacreations.com/howto/latex-concrete-roof/

There is a great description of how to do it in the link, but basically it's a kind of ferrocement or petrified hessian .
You drape a tarp, secure mesh or burlap over the tarp, mix up your Latex Concrete , which is cement, sand and an acrylic cement bonding agent, and slop it onto the waiting roof.
With enough layers it will support the weight of a human.

They detail the finishing and the layers in the link above
I've seen videos where they use old latex paint instead of the acrylic.
Even if you can't get paint or acrylic,  you will be protecting a waterproof plastic barrier from the biggest enemy, sunlight degradation.
Parging a concrete surface with a strait cement paste is said to water proof it, so that's a possible option.
This technique requires less attention to detail and care than ferrocement, where setting up the armature can take a lot of time.
 
pollinator
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Your thatch breathes and insulates and does evaporative cooling  so it is really good in hot environments, be careful to not ruin that part of the roof. If you do a solid material, add plenty of ventilation at the peak.

I would second the latex concrete as probably easiest to source materials. It is heavy going on so be careful but it makes a pretty strong roof when cured.

 
Johanan Viljoen
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Thank you all so much for the ideas!

Let's do a quick run-through of responses...

Thatch - Aye, I know it has its advantages. Unfortunately, in this case, the disadvantages outweigh them. I adore the local wildlife, but I can't afford to have a colony of bats, tiny rodents, or catastrophic insects living in the roof of this structure. 😅 We have a barn owl and the local paper wasps (think stripe-less yellowjackets with an extra bad attitude problem) that took up residence in our thatched hut.

Sailcloth - Aaah, how I wish. I'd have loved to take on that project. My grandad was a marine engineer so it would have taken on extra significance. Unfortunately, the commercial side of things has long turned away from sailboats, and it would cost me an arm and leg to buy sails privately.

Yucca - This is absolutely new to me, but I love it! I'll have to start growing them on purpose for future roofing projects. They grow like a dream here. I used some chopped down ones as fenceposts once, and every single one of them sprouted. Definitely a sustainable concept in this area.

Bamboo - This... This made my little weirdo heart very happy. Talk about stacking functions. I love the way it doubles as a natural guttering system.. I'll have to do some research as to pricing, but this is a very attractive option to me. In some parts of the country, bamboo is actually an invasive.

Corrugated - I know I can change the structure so that it's more angular, then corrugate... But the room doesn't FEEL angular. It feels like it's happy being round (alas, I now sound like a lune to all but the artists). Plus, it's the most common alternative to thatch here, and I have a slight aversion to doing what everyone else is doing. I want to learn something new, try something different.

Latex Cement - While I can't say that this sets my heart a-flutter visually, it looks like an excellent option financially.

As far as natural resources are concerned... We have access to stacks of red clay, grass, and Acacia trees. 😅
 
master gardener
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Johanan Viljoen wrote:

But the room doesn't FEEL angular. It feels like it's happy being round (alas, I now sound like a lune to all but the artists). Plus, it's the most common alternative to thatch here, and I have a slight aversion to doing what everyone else is doing.

With feelings like those, you will likely feel quite at home here on Permies!  Putting a noticeably angular metal roof on a round, natural material building doesn't work for me either. Also, metal roofs can make some buildings much hotter in the summer and colder if you have a "colder" time of year.

A little bit about your typical weather would be helpful. You identified, "sunny", but are you at all prone to wind-storms or heavy rain periods?

One thing to consider is how long the roof might last with some of the options you're considering. If the material is cheap enough, you may not be bothered by having to do repairs/replace parts every 5 years, but in some ecosystems, that's the reality of bamboo. I love building with it (I have two patches), but I don't have a type that I'd trust for a whole roof. That said, you mentioned that you'd consider the Latex cement option. In a heart-beat, I'd put down latex-cement to make a firm, bug-proof roof and then cover it with bamboo for ascetics and to protect the roof from the sun, and to help with rain-water capture (although I could find a way to do that with just the latex-cement - I'd much prefer to do so with bamboo). All that said, I admit that the wet environment I live in, influences my attitude, particularly this year as we've had several winter months with as much as twice the "average monthly rainfall".

Off-topic: If bamboo is getting out of control in an area, geese will eat the shoots in the spring. I have to protect my P. dulcis patch during "shoot" season, or I'll get none for my own dinner and no new culms! Bamboo is a grass, and my geese are grass eaters - duh!
 
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