4 ms·

Why are house roofs so dark?

by zx8080 3y ago

leetrout 3y ago
Traditionally metal roofs were not. Tar / pitch is black so roofs were black. A house in my neighborhood has white shingles.
- b112 3y ago
  In many cases, dark both radiates faster, as well as absorbs. So dark makes the house cooler, faster, when the sun isn't shining.
yodon 3y ago
>Why are house roofs so dark? Lightweight, inexpensive, low maintenance, long duration, weather resistant roofing materials were historically few. Neither asphalt shingles nor cedar shakes are perfect (you historically would for example have preferred cedar shakes to be more fire retardant, today cedar shakes are chemically treated with fire retardants but still have other problems), but they were frequently among the best choices. Both are quite dark after aging. Painting asphalt or cedar shake roofs white historically would have significantly increased both installation and maintenance costs. Before the last decade or so few homeowners would have been willing to bear that increased cost. And yes, pottery or stone roofing materials are used in some areas. These are also dark, heavy, and frequently expensive to install, often with a corresponding increase in useful lifespan.
- sandworm101 3y ago
  Cedar actually turns white with age. But most cedar roofs today are treated to maintain the darker "new roof" look rather than age naturally to a ghostly white.
btbuildem 3y ago
Because it's the cheapest solution. Unfortunately they act as heatsinks during the day, and radiate the heat during the night, never letting the surroundings cool. Montreal has made white roofs mandatory for new construction and major repairs/replacement [1]. Large swathes of the city consist of dense residential construction, two- and three-story walkups arranged in rows, all with flat roofs. If you do a flyover, it's easy to tell who'd had their roof redone in the past several years. I imagine with time, this will reduce the "heat island" effect in the urban environment. 1: https://montreal.ca/en/how-to/renovate-flat-roof-or-low-sloped-roof?arrondissement=PMR https://montreal.ca/en/how-to/renovate-flat-roof-or-low-slop...

Why are house roofs so dark?

by zx8080 3y ago

Why are house roofs so dark?

Traditionally metal roofs were not. Tar / pitch is black so roofs were black. A house in my neighborhood has white shingles.

b112 3y ago
In many cases, dark both radiates faster, as well as absorbs. So dark makes the house cooler, faster, when the sun isn't shining.

yodon 3y ago

>Why are house roofs so dark? Lightweight, inexpensive, low maintenance, long duration, weather resistant roofing materials were historically few. Neither asphalt shingles nor cedar shakes are perfect (you historically would for example have preferred cedar shakes to be more fire retardant, today cedar shakes are chemically treated with fire retardants but still have other problems), but they were frequently among the best choices. Both are quite dark after aging. Painting asphalt or cedar shake roofs white historically would have significantly increased both installation and maintenance costs. Before the last decade or so few homeowners would have been willing to bear that increased cost. And yes, pottery or stone roofing materials are used in some areas. These are also dark, heavy, and frequently expensive to install, often with a corresponding increase in useful lifespan.

sandworm101 3y ago
Cedar actually turns white with age. But most cedar roofs today are treated to maintain the darker "new roof" look rather than age naturally to a ghostly white.

btbuildem 3y ago

Because it's the cheapest solution. Unfortunately they act as heatsinks during the day, and radiate the heat during the night, never letting the surroundings cool. Montreal has made white roofs mandatory for new construction and major repairs/replacement [1]. Large swathes of the city consist of dense residential construction, two- and three-story walkups arranged in rows, all with flat roofs. If you do a flyover, it's easy to tell who'd had their roof redone in the past several years. I imagine with time, this will reduce the "heat island" effect in the urban environment. 1: https://montreal.ca/en/how-to/renovate-flat-roof-or-low-sloped-roof?arrondissement=PMR https://montreal.ca/en/how-to/renovate-flat-roof-or-low-slop...