Wetting Your Roof ???

Question

My Friends Mom Just Made Him Go Outside And Wet His Roof Because She Says That It Makes It Cooler In The House ... It Makes No Sense So My Friend Tried To Convince Her That It Was Pointless. So I Was Like "Ill Post It On Yahoo Answers And See what Other People Think" ... So We Could Have Your Input It Would Be Nice.

Answer 1

We do that all the time,  we have a metal roof so it does work for us and cools down the house

all the best

Answer 2

Lot of mixed answers !  It depends on the roof , if it's a flat concrete one it definitely will. A normal house with an attic, decent ceiling insulation and the sun shining on it, I doubt if there would be any difference. Plant some trees and bushes and install a ridge vent.

Answer 3

this has got to be one lame urban legend,people think about it the temp in the attic on even a average day can be sweltering how can wetting the exterior of a roof cool down the extreme heat inside the attic air.Plus you have all the insulation in the attic hence INSULATING you from that heated air in the attic.Roof peak vents,whirly bird vents and solar power ventilation fans on pre set heat settings would do far more.Also how much city processed water are you people spraying on your roofs to so called cool it what a waste of a valuable resource

Answer 4

it might make a small difference, but it's not very practical.  Doing it regularly would use too much water.  An attic fan would make more sense.  I saw a solar-powered one at a home show a few weeks ago.  That seems like an ideal solution to me.  When the sun is shining brightly and you need cooling most, it would have all of the power it needs.

Answer 5

wow, lame much?!

ha.

Answer 6

Oops. You are saving electricity by being one of the few people in the world who doesn't take advantage of fans and A/C. Now you are creating huge amounts of water vapor instead. This will end with the destruction of the earth.

Answer 7

Yes it does work, it will lower the temperature in the house 5 degrees.

however the relief is only temporary.

Answer 8

That is almost as silly as starting every word in a paragraph with a capital letter.  

Answer 9

It will definitely cool the shingles- and damage them by causing premature de-granulation (essentially washing off the ceramic granules that protect the asphalt they are embedded in. But it will not cool the living space of the house. Adding more ventilation in the attic and increasing the R-value of the attic insulation will have a great impact on the temperature- and save energy, but spraying your roof with water will only damage shingles and waste water.  

Answer 10

I've never heard of this, but it might work. It's due to a phenomenon known as latent heat of evaporation. It's similar to sweating. When you sweat, the evaporation takes heat from your body and so you cool down. The same may well happen for a house. If it does, it sounds like a very green way of air conditioning.

Of course, you've heard of Africans storing water in porous pots for cooling the water and porous milk savers work on the same pricipal.

When I lived in Africa, we had a porous pot (called a zir) which worked well. It kept the water quite cool. We used to spray water around the yard to cool down the immediate environment. It was OK. We lived in an area of abundant water! It worked quite well.

Answer 11

It's called evoporative cooling, when water evaporates from the roof it takes heat with it. It's the same principal that swamp coolers use. An attic or gable fan may be a more practical solution. They cost about $50 and are pretty easy to instal.  

Answer 12

you loose latent heat of evaporation from the roof, so yes it does work, but hanging a wet sheet over the door/window is better.