Opinion of a cooling idea for my roof...

[omnicat]

My house is a cinderblock cape cod. Traditional shingled roof. No central air. The upstairs gets nearly unusable during the summer, even when I open the windows at both ends (east and west) at night, stick a fan in one to suck in the night air, and then dash up there in the morning to shut the windows and close the blinds...by late afternoon, it's pretty dang hot. And I know it's the roof absorbing heat.

DH has a friend who build a geodesic dome with reflective mylar. Had it set up at a festival, 95 degrees and sunny...and dang if it didn't stay pretty cool inside.

So....What if we made panels of reflective mylar, and mounted them on the roof for the hot months as a way of keep the house from absorbing all that heat?

What do you think?

[Mid Tn Mama]

I don't know about that, but someone here at ht told that they put their laundry to dry hanging in the window. When the breeze came in it acted like a swamp cooler. Do you have a basement? Can you bring in air from the basement that's cooler and have it leave the upstairs?

[Rita]

Sounds like a lot of work, time and money. How would you fasten the mylar so as not to ruin your shingles. Wouldn't it be cheaper, easier more certain to get cooling if you bought a window a.c.?

[wy_white_wolf]

How are you going to protect them from wind, rain, hail?

Do you have an attic. If so line the inside of it with the mylar and get an attic fan to vent the heat out.

I've also heard of reroofing jobs where they tore it off to the decking. Put down a layer of mylar . Then stringer boards and another layer of decking 1 1/2" above the mylar with the new roofing on that. Having that dead airspace vented kept the house from heating up.

[minnikin1]

Mount some wires for climbing plants and train some hops vines up and over your roof on the sunny side.

[Windy in Kansas]

Seems to me that you would be better off spending your money for insulation to keep the heat from penetrating during the summer and preventing heat loss in winter.

[omnicat]

How are you going to protect them from wind, rain, hail?

That's what's concerning me. DH is bent on it. If it actually worked, and didn't tear up or blow away, I'd be all for it.

Wouldn't it be cheaper, easier more certain to get cooling if you bought a window a.c.?

Easier, maybe. Cheaper - not in the long run. Electric price is going bananas.

Mount some wires for climbing plants and train some hops vines up and over your roof on the sunny side.

That's always a good idea. I do that on the west side of the house. I haven't been able to figure out how to get the stuff all the way to the roof. The first floor is three feet up as it is. (I've envisioned some sort of window boxes mounted at gutter-height...but half my probably with potted plants is I forget to water them. Not to mention the logistics difficulties of getting it up there)

Do you have a basement?

Crawl space. And not much below ground level. If it was more of a builder, I might figure a way to pipe some of the somewhat-cooler air up there.

How would you fasten the mylar so as not to ruin your shingles.

Another thing I'm worried about. Good ideas are one thing, but I'm trying to think through the logistics. I tend to be pessimistic about new "projects", and DH is a "go for it" kind of guy.

I know it would work like gangbusters if the attachment and durability of the material issue worked out.

I appreciate all the input.

[omnicat]

Seems to me that you would be better off spending your money for insulation to keep the heat from penetrating during the summer and preventing heat loss in winter.

Oh, don't you know it. Can't afford that fix right now. There's almost no insulation anywhere in the house. And the clearance between the roof and inside ceiling is about an inch or something stupid. We don't have the thousands it will take to deal with that issue.

[SolarGary]

Hi,
I do think it would lower the temperature significantly, but it seems like a difficult thing to do and to maintain.

There are coatings you can paint on the roof that appear to be effective. The coatings are OK for asphalt shingles -- not sure exactly what you have.

There has been a discussion of using this coating on the Yahoo HomeEnergy Group just recently. If you search for "painting the roof to reduce solar heat" or for message number 11189 you should be able to find it. Its quite a long discussion with some good info.

If there was some way you could add roof insulation, this would help both summer and winter.

You can also get a lot of heat gain through windows that the sun shines on, so some form of shading or screening to block solar gain through the windows might help.


Gary

[omnicat]

Thanks, Gary. you're always very helpful.

My current "cooling system" is to run around and open the windows in the evening, and stick fans in a few to suck in the now-cooler air, and then run around in the morning, closing the windows and shutting curtains. Some curtains have solar-reflective material on the outside-facing part...and though seem to work much better than regular curtains. But the heat absorbtion through the roof makes the method short-lived of the upstairs.

We came across the painting the shingles stuff before (we do have asphalt), but DH is rejecting it out of hand because he wants to keep the heat-absorbing properties of the roof in the winter.

I think I'll direct him to the roof-painting discussion (I haven't read it yet), and see if he'll even consider the under-roof application of mylar and surface painting.

And the only reflective mylar we've found is thin stuff for hydroponic gardening - certainly not manufactered with outside weather in mind.

[Wolf mom]

Actually, you need to keep a window cracked open in the attic during the day as the air, if it's hotter than the outside, will excape outside. A circulating fan will also help.

What you are doing now is trapping all the hot air that rises in the attic. That along with the sun baking on the roof isl making it even hotter inside.

Most of the suggestions are long term. This is just a quick fix until something else can be done.

Good luck. Been there, done that.

[tamsam]

First is this a flat roof? you say there is about an inch between it and the ceiling. Is there an attic vent on the ends of the house or a ridge vent at the peak of the roof? If no vents the heat is trapped and will shorten the life of your roof, or so I was told by a roofer. How high is the ceilings in the upstairs? To help insulate the upstairs here and also cut out a lot of work of tearing out the old ceilings, we ran 1 in thick strips on the ceiling leaving the old ceiling in place and put the 4X8 insulation boards up making a dead air space between. Then we painted the ceiling white and presto it stays pretty cool up there and in the winter the only heat is from rising warm air from downstairs. Needless to say we did the same down stairs but the old ceilings had been taken out, but we used the insulation downstairs also. This because we built a fire in the heater before we did the ceilings in the down part and it was way to warm upstairs. Now if one of us is upstairs and the other needs to tell them something we have to go to the foot of the stairs and yell for them as it is so sound proofed. Hope this gives you a little help. Sam

[minnikin1]

Hops are really, really high growers - very unlike ordinary vines. You shouldn't need to raise them above ground level.

Studies done is Florida show that the temps under greenery can be 15 degrees cooler than surrounding areas - you just need a bit of gap between the vines and the roof.

The color of your roof can be significant, too. If you have dark shingles, getting it shaded might make even more of a difference than 15 degrees.

[QUOTE=omnicat;3124899][I]H

Mount some wires for climbing plants and train some hops vines up and over your roof on the sunny side.

That's always a good idea. I do that on the west side of the house. I haven't been able to figure out how to get the stuff all the way to the roof. The first floor is three feet up as it is. (I've envisioned some sort of window boxes mounted at gutter-height...but half my probably with potted plants is I forget to water them. Not to mention the logistics difficulties of getting it up there)

[Alice In TX/MO]

Info about a rediant barrier that it installed on the underside of the roof...

http://www.radiantguard.com/

[omnicat]

Tamsam - it's a cape cod. Peaked roof. ridge vent along the top. Fairly steeply sloped roof - ridge goes east-west orientation. Smack in the middle of the south facing of the roof is a solar-powered attic fan. The attic space was completely unvented when we bought the house. The ridge vent and fan were added when the roof was replaced three years ago.

Inside the upstairs is attic space behind knee-walls that are about 4' high, then the ceiling slopes up following the roof. We can get behind those walls to add insulation (which is on my list), but getting between the ceiling where it's sloped, and the roof, is the tricky part. Very little space there. Ick. Pulling the ceiling down and re-doing it would most likely be eaiser than trying to slide some rigid insulation up between there (or maybe not), but we're short both funds and carpentry experience.

Wolf mom - you're probably right about keeping the window open during the day. It makes a difference downstairs, where we can manage to keep the inside cooler than the outside..but when it's a losing battle upstairs, I may try some different fan/window tactics.

Thanks again for all your input. It's very helpful. Good to get input on all options.

[TedH71]

Try a metal roof? They do reflect heat....

[texican]

Heat rises. The second floor of any home should be hotter than the downstairs, without a/c. I live in a two story, without using my teeny little a/c unit. I leave the windows upstairs open all the time. The ground floor windows and doors are usually shut during the day, and open at night... this way the cool air settles on the ground floor during the night, and stays there during the day. If the downstairs windows and doors stay open during the day, the inside/outside temp equalizes quickly.

Trees really help. I'm thinking of building an artificial tree on my new home... cables and wires and weatherproof netting (like they use to camouflage tanks and whatnot).

[SolarGary]

Hi,
Here is one more idea I did not think of before:

http://www.builditsolar.com/Experime...oofCooling.htm

It basically cools the roof by sprinkling water on it.
I don't like the way it wastes water, but it is effective and simple, and if you get the delivery rate right, it does not use a lot of water.

Gary