Saw a video recently looking at houses in Bermuda and rain collection. They claimed that the ridges on the roof increase the surface area in order to increase rain capture.
Surely rainfall is even over a surface regardless of terrain and therefore a ridged roof would collect the same amount as a smooth slopes roof?
In: 16
The idea isn’t that it is going to somehow get more rain to fall on the roof than if it was evenly sloped, which as you rightly guessed would be impossible.
Instead what the steps are intended to do is slow down the flow of the rain as it runs off the roof so that it can be caught by the gutters and stored in a tank under the house. If the roof was just a straight slope then the water would hit the gutter going quickly and some portion of it could splash over. Instead by increasing the surface area while not changing the overall slope the friction of the water flowing is increased and its speed reduced.
The idea isn’t that it is going to somehow get more rain to fall on the roof than if it was evenly sloped, which as you rightly guessed would be impossible.
Instead what the steps are intended to do is slow down the flow of the rain as it runs off the roof so that it can be caught by the gutters and stored in a tank under the house. If the roof was just a straight slope then the water would hit the gutter going quickly and some portion of it could splash over. Instead by increasing the surface area while not changing the overall slope the friction of the water flowing is increased and its speed reduced.
The idea isn’t that it is going to somehow get more rain to fall on the roof than if it was evenly sloped, which as you rightly guessed would be impossible.
Instead what the steps are intended to do is slow down the flow of the rain as it runs off the roof so that it can be caught by the gutters and stored in a tank under the house. If the roof was just a straight slope then the water would hit the gutter going quickly and some portion of it could splash over. Instead by increasing the surface area while not changing the overall slope the friction of the water flowing is increased and its speed reduced.
> Surely rainfall is even over a surface regardless of terrain and therefore a ridged roof would collect the same amount as a smooth slopes roof?
Of course. It’s the cross sectional area of the roof that matters, not the surface area. Imagine that there is no wind, and the rain is falling straight down. It’s not going to make any difference whether the rain falls on a flat roof, a tall A-frame roof, a mansard roof, a hip roof, a roof with ridges, or a smooth roof.
Bermuda is primarily a limestone island. The original roofs on houses were made from limestone slabs quarried on the spot. The pit that the limestone slabs were quarried from became the cistern in which the rainwater was collected. Being somewhat thick, these limestone slabs gave the roof a stepped appearance. Over the years, this stepped appearance became the norm for what roofs were supposed to look like. Modern Bermuda roof systems are made to look like the old limestone tile systems because that’s what people expect.
Long story short, the ridges are aesthetic, not functional.
P.S. Bermuda needs to collect rainwater because there are very few other sources of fresh water on the island. The government mandates that at least 80% of the roof needs to be dedicated to harvesting rainwater.
> Surely rainfall is even over a surface regardless of terrain and therefore a ridged roof would collect the same amount as a smooth slopes roof?
Of course. It’s the cross sectional area of the roof that matters, not the surface area. Imagine that there is no wind, and the rain is falling straight down. It’s not going to make any difference whether the rain falls on a flat roof, a tall A-frame roof, a mansard roof, a hip roof, a roof with ridges, or a smooth roof.
Bermuda is primarily a limestone island. The original roofs on houses were made from limestone slabs quarried on the spot. The pit that the limestone slabs were quarried from became the cistern in which the rainwater was collected. Being somewhat thick, these limestone slabs gave the roof a stepped appearance. Over the years, this stepped appearance became the norm for what roofs were supposed to look like. Modern Bermuda roof systems are made to look like the old limestone tile systems because that’s what people expect.
Long story short, the ridges are aesthetic, not functional.
P.S. Bermuda needs to collect rainwater because there are very few other sources of fresh water on the island. The government mandates that at least 80% of the roof needs to be dedicated to harvesting rainwater.
Bermuda is a rock in the Atlantic Ocean 600 miles east of North Carolina.
The roofs are made of limestone and the ridges channel the water in a pattern across the limestone in an effort to clean it, then it lands in a collection barrel.
Bermuda is a rock in the Atlantic Ocean 600 miles east of North Carolina.
The roofs are made of limestone and the ridges channel the water in a pattern across the limestone in an effort to clean it, then it lands in a collection barrel.
> Surely rainfall is even over a surface regardless of terrain and therefore a ridged roof would collect the same amount as a smooth slopes roof?
Of course. It’s the cross sectional area of the roof that matters, not the surface area. Imagine that there is no wind, and the rain is falling straight down. It’s not going to make any difference whether the rain falls on a flat roof, a tall A-frame roof, a mansard roof, a hip roof, a roof with ridges, or a smooth roof.
Bermuda is primarily a limestone island. The original roofs on houses were made from limestone slabs quarried on the spot. The pit that the limestone slabs were quarried from became the cistern in which the rainwater was collected. Being somewhat thick, these limestone slabs gave the roof a stepped appearance. Over the years, this stepped appearance became the norm for what roofs were supposed to look like. Modern Bermuda roof systems are made to look like the old limestone tile systems because that’s what people expect.
Long story short, the ridges are aesthetic, not functional.
P.S. Bermuda needs to collect rainwater because there are very few other sources of fresh water on the island. The government mandates that at least 80% of the roof needs to be dedicated to harvesting rainwater.
Bermuda is a rock in the Atlantic Ocean 600 miles east of North Carolina.
The roofs are made of limestone and the ridges channel the water in a pattern across the limestone in an effort to clean it, then it lands in a collection barrel.
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