# White plastic sheet on dark roof to reflect summer sun



## smiley bob

Our living room has an open ceiling and so gets very hot in summer. We don't like to use the AC, so we open the windows and use a ceiling fan. But because its hotter this summer than in the past, the open windows and ceiling fan are not enough. So I was thinking of laying down some 6 mil white plastic sheet on the roof over the living room to reflect the summer sun, and then remove it in the Fall. I found that Home Depot has sheeting that is 20' x 100' that will be enough to cover the roof over the living room, but I am not sure how to attach it to the roof so I can remove it in the Fall. We do have some wind here, so I need a method that will hold the sheet in place. The roof is slanted with flat asphalt shingles.


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## ZZZZZ

Where are you located?

The sun will likely eat through that plastic in a matter of days. Even a UV-resistant white tarp will degrade over time in constant summer sunlight every day.

What pitch is the roof? They do make white roofing material that comes in rolls, but that is for use on very gently sloped roofs only, such as 3/12 pitch or less).

(I've always wondered why they don't make white asphalt shingles instead of black or other dark colors.)
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## lenaitch

ZZZZZ said:


> (I've always wondered why they don't make white asphalt shingles instead of black or other dark colors.)


Probably because it would look like he** in about a month.


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## Bud9051

They do make shingles with a high level of solar reflectivity, a good choice if the roof is being replaced.

What is in place for roof ventilation, any attic space or just the sloped roof?

Bud


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## mark sr

I roofed a shed when I lived in fla using 3 different brands of leftover 'white' shingles. Looked uniform when dry but when wet you could see minor color difference ... didn't really matter as within a year or so it was all the same color of mildew.


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## Drachenfire

You could re-roof using tin coated in white sealer.

I have lived in tropical regions where many of the roofs are corrugated galvanize coated in white sealer.

Corrugated galvanize was used because it directed rain water to gutters which drained into cisterns which was the occupants sole source of water. 

The white sealer served two purposes. It sealed the galvanize which kept the rain from washing zinc residue into the cistern and it kept the home cooler.

Electricity in the tropics can be very expensive, as such almost no home has central AC. The owners use other methods of cooling which mainly incorporates the heat reflecting white roofs in conjunction with well placed ceiling fans.

You mentioned using a ceiling fan. Which direction is the set to? Remember, heat rises so if the fan is set in the down draft position, it is blowing the hot air down. The height of the fan and diameter of the blades in relation to the size of the room is also a factor in its ability to provide any measure of cooling.


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## SeniorSitizen

ZZZZZ said:


> (I've always wondered why they don't make white asphalt shingles instead of black or other dark colors.)
> .
> .


They did for about 7 decades and they worked very well. Then the designer people wanted a change, they got it and that surely screwed things up.


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## ZZZZZ

A big problem with galvanized metal roofing is when it rains, it is *LOUD*!
:biggrin2:
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## mark sr

My house has the old style 5v-crimp galvanized roofing on it. It really isn't very loud when it rains, all the insulation in the attic muffles the sound ...... now if you go out in the barn - that's a different story!


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## Oso954

Several shingle companies sell a "white" shingle. They are not as white as we got back in the 60s, some people might say silver colored or light grey.

But, the bottom line is they are a lot cooler than dark shingles.
Here is one example.
http://www.homedepot.com/p/GAF-Royal-Sovereign-White-25-Year-3-Tab-Shingles-33-33-sq-ft-per-Bundle-0201920/100043571
Here is another company's in an architectural style.
https://www.lowes.com/pd/Owens-Corning-Oakridge-32-8-sq-ft-Shasta-white-Laminated-Architectural/3034242


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## Drachenfire

ZZZZZ said:


> A big problem with galvanized metal roofing is when it rains, it is *LOUD*!
> :biggrin2:
> .
> .


The sealant muffles it somewhat. It then has a rather soothing sound when it rains. 

My wife liked the sound of rain on the roof so much that she wants a tin roof when we build our retirement home.


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## ChuckF.

Re the original question about the roof, the better way to go is with trees planted in the right places to shade the roof during Summer mornings and/or evenings. It likely can't be done at high noon, but every hour of shade you can put on the roof will help.


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## ZZZZZ

Drachenfire said:


> The sealant muffles it somewhat. It then has a rather soothing sound when it rains.
> 
> My wife liked the sound of rain on the roof so much that she wants a tin roof when we build our retirement home.


I've never owned a house with a metal roof, but I have been in metal roof houses of friends 3 or 4 times when it rained hard, and it was frightening. 

But that was high in the Colorado Rockies in monsoon season. Maybe it's not so bad in the Midwest or South where the rain is often gentler and steadier.

One time it hailed, and it seemed like we were under some kind of military attack. :biggrin2:
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## user_12345a

a common error is keeping windows open.

keep the windows closed whenever it's warmer outside than in even without ac on.

forget about putting something white on the shingles.

just make sure your attic is properly ventilated and insulated. if you have R30+ not much heat will get in from the attic.


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## Nealtw

I think the question was more about proving a white roof would help before budgeting a few thousand for a new roof.

I would start with the heaviest white plastic you can find lay it over the roof in each corner wrap it around a fair sized rock and tie a rope to it connect the rope to a stack in the ground and tell the neighbors you just camping for the summer.
better would be to have a few 2x4 laying on the roof so there would be an air gap between the roof and the plastic.
A few days will prove whether there is an improvement and cheap to.


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## SeniorSitizen

Old tires hold plastic down on silage pits and they are often inexpensive but you may need to pay some sort of environmental tax on them 1 more time. They would hold the plastic down around any vent stacks very well. Ask the HOA if it'd be ok just for the summer.


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## user_12345a

the uv will ruin the plastic in very short order. 

a roof is a very harsh application for any material.


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## Nealtw

polyethylene membrane fabric 

http://www.cover-tech.com/fabric-buildings?_rdr


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## Drachenfire

ZZZZZ said:


> I've never owned a house with a metal roof, but I have been in metal roof houses of friends 3 or 4 times when it rained hard, and it was frightening.
> 
> But that was high in the Colorado Rockies in monsoon season. Maybe it's not so bad in the Midwest or South where the rain is often gentler and steadier.
> 
> One time it hailed, and it seemed like we were under some kind of military attack. :biggrin2:
> .
> .


Must be the kind of tin. Hail on any roof would be frighting.


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## mark sr

I think it has more to do with the size of the roof and whether or not the space between the tin roof and the living area is insulated well.


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## NotyeruncleBob

Shade or insulation are your only real ways to block that heat.


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## Nik333

How would you balance the idea of trees shading your house with the Fire Dept's suggestion that all foliage be cut back from around the house?


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## mark sr

You have to pick your priorities - can't satisfy everyone.


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## NotyeruncleBob

Nik333 said:


> How would you balance the idea of trees shading your house with the Fire Dept's suggestion that all foliage be cut back from around the house?


Bigger tree further away.


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## anony

Look into solar attic vants on home depot.


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## Drachenfire

mark sr said:


> I think it has more to do with the size of the roof and whether or not the space between the tin roof and the living area is insulated well.


Where we lived, the galvanize roof and 1/2-inch thick ceiling below was separated by 2x8 rafters. There was no kind of insulation between the two. 

However as I said in a previous post the galvanize was coated with a elastomeric sealant which helped muffle the snare drum like sound of exposed tin.


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