Why houses in Bermuda have white stepped roofs (2016) | Hacker News Reader

Why houses in Bermuda have white stepped roofs (2016)

bbc.com

143 pointsthunderbong22 comments

Wife and I did a last minute trip to Bermuda during the middle of the (Canadian) winter some years ago and saw this first hand. In addition to the roofs there was also catchment lots, limestone steps built onto sides of hills to collect and divert water into basins. Very cool though I understand most of the water is now supplied in other ways. Was a nice trip. It was off season there, not beach weather, but cheaper to go and still warmer (low 20s, high teens celcius) than home.

We did a tour of a farm there, cool to see how small farm agriculture works in that climate. The owner did his agriculture degree a half hour away from me at the University of Guelph. Lots of people had personal connections with Canada because of the short flight, shared Commonwealth history, historical Atlantic routes, etc.

It's a great set of islands, and all accessible by bus. Super easy for travel as a Canadian; short ~2.5 hour flight from Toronto, English speaking, Commonwealth country, accepts USD, we had consistently great food.

I don't know if I'd like the tourist scene there in the summer, but I definitely want to go back.

I lived in a house with one of these in Bermuda. Lesson learned that it’s not a good idea to use up your water pressure while the power is out as then your pump doesn’t work. Otherwise seemed to work great.

That's no different than having rural well water, though. Have the same issue here on my property.

I've been to Bermuda and tried this water. It had an odd taste - a bit smokey or 'pan fried' (if you can imagine that). I've been told it's because of the lime-based purification process, plus it sitting in an underground tank for a while. Did anyone else notice the peculiar taste?

Maybe it tastes like a dirty roof?

We do water catchment in a lot of rural Hawaii too, but I've never seen a gutter system that couldn't keep up with tropical storm rains and needed steps to slow it down. We get 200+ inches of rain per year in Hilo so it comes down in buckets quite frequently.

I was quite puzzled by the explanation given for the steps as well. At first I was thinking that perhaps they need a gutter per level due to rain coming in extremely short bursts, but that's clearly ruled out by the pictures. Perhaps it's not about throughput at all, only to limit inertia when the water eventually hits the gutter? Given the steep angles of the roofs that might cause some spillover loss otherwise.

Then why are the roofs so steep? Could be building material: can a small island lacking bodies of water even have clay, for roof tiles? A thatched roof would be impractical for harvesting rainfall. And when you go limestone masonry (apparently the building material available), you'll likely end up with something steep. Steep and stepped, unless you go the extra mile chiseling for smoothness. So the original cause for the stepped nature of the roofs is kind of related to water harvesting (even if the hurricanes mentioned in passing have likely been just as motivational against organic materials), and the steps might actually help by preventing high inertia of water hitting the gutter, but I suspect that's more a convenient coincidence than the accrual reason.

Steep roofs also give you more height for hot air to rise. If they’re vented at the top (not sure but I assume yes) it will also help you get a chimney effect creating airflow through the house.

I seem to remember hearing some explanation like it was about maximizing the amount of time that the rainwater gets exposed to the limestone on the roof? For purification/pH balance purposes?

The same kind of steps were used even for catchment areas that weren't on houses. I remember passing (on the bus) an area that had a whole hill set up with the same kind of stepped/terraced limestone that fed down into some sort of reservoir.

My intuition suggests that rainwater that has spent less time on the roof won't be worse than rainwater that had spent more time there, but this intuition could certainly be wrong.

Regarding the landscape catchment, if it's not in-situ stone that is laid bare and chiseled into shape it might simply be an economy of scale thing, use roofing commodity instead of reinventing the wheel. And if it's in-situ limestone, a major contributor to the decision for stepped/terraced might still be ease of maintenance access. The chemical qualities seem more like a convenient coincidence to me. Perhaps an enabling quality in absence of which they'd have long switched to desalination, but even that would not make it a causal "why". Particularly the part about UV working better with the reflections white making photons pass twice seems doubtful to me, because nighttime rain is probably not entirely unheard of (yeah, I might be wrong about this)

Just stayed at a off the grid cabin outside Volcano and the rain catch system has inspired me put something in for my backyard vegetable garden in Utah.

Wouldn't coarse sandy paint also serve to slow down water in a downpour? But I guess they have been there 400 odd years, so I suppose this has some advantage.

> coarse sandy paint

Sounds like that coarse sand would also leech into the water.

They currently paint the stepped roofs with paint.

The are already surfaces that are painted and have sand mixed in to make surfaces less slippery. The bumps and pits would slow down water as it sought its level toward the gutters.

Not any more then a standard asphalt roof, which is basically what you are describing. Course aggregate mixed with simmering to hold it in place.

The flat parts of each step slow the waters downward momentum much better than a slope would.

tl;dr

> The steps slow down heavy rainfall helping the gutters to collect the water and store it in a tank under the house.

> in the past it was covered in a lime mortar, which had anti-bacterial properties. Now the mortar has been replaced by paint. It's still white, because this reflects ultra-violet light from the sun, which also helps to purify the water.

a tank under the house. interesting. From the pics they look like they bury them

Another interesting trick we do in the tropics: Guppies in the water tank to prevent them from being a source of dengue/zika/chikungunya spreading mosquitoes.

I can't understate how much it sucks to get one of these diseases, never have I felt more run over by a truck than when I got dengue once.

Wow that's a really cool solution I had no idea

What do you do about fish poop and dead fish?

Carbon filtration and checking a couple of time a week with a headlamp and a net for floating things like dead fish and fish poop.

It's mostly used for taking showers and other cleaning. If you want it to be potable it's gotta be boiled or ideally distilled with mineral addition.

Water management is an enormously important thing when mosquitoes carry diseases which can kill you so a few little fish in the water tank hardly phases us

FWIW, it really isn't tl. 3 minute read tops.

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