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Ed

Jun 17, 2002, 6:43 PM

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Cooling a Concrete Roof

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Hoping someone out there has a suggestion for a low tech solution for insulating an existing concrete roof. The in-law's house has a 10cm concrete slab roof over the bedrooms (with a slight pitch). The cieling is too low to effectively put in a suspended ceiling to help out, and when the sun beats down on the roof all day if gets pretty warm inside.<p>I had a couple of ideas but have doubts about both of them. I'd appreciate any thoughts on the practicality (durability, effectiveness) of either of the two ideas, or any other reasonable suggestions, short of trying to air condition the house.<p>1. Drape a nylon tarp (approx the length x width of the roof) over the roof, with a few lines of block to keep it up off the surface. Figured it might work like the fly on a tent and lend some shade and keep the direct sun off the roof. (Could take it down during Hurricane season!)<p>2. Put a layer (1" - 2") of rigid insulation over the roof (probably in small blocks about 18" square) and then anchor it down by pouring a couple of inches of light weight concrete over the whole roof and insulation (could embed a layer of wire mesh in the mix).<p>Thanks in advance for any advice.<p>Ed

Rolly

Jun 17, 2002, 8:28 PM

Post #2 of 11 (10978 views)

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Cooling a Concrete Roof

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I don't think scheme one will do you much good.<p>#2 will be a help, but you should use insulation as thick as you can afford. 4" would be a lot better. Covering it with a light concrete will be fine.<p>There is a lower cost way -- cover the roof with several inches of common dirt and top with concrete. This is a heaver load on the roof. With only 10cm you can't put too much up there. My house has a 12cm roof with 3 inches of dirt.<p>

Doc

Jun 18, 2002, 12:07 PM

Post #3 of 11 (10977 views)

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Cooling a Concrete Roof

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I ran up on the referrence below at a site related to building a home on Anguilla. Have not used the product but plan to give it a closer look. You would have to cover it with something. Called a radiant barrier.<p>Contact Mike Kerschner <p>Quantum International
11519 Canyon Rd. E.
Payallup, WA 98373-4359
Toll Free USA (888) 854-8543 <p>Manufacturer claims it reduces radiant heat by 80%. Not endorsing it by any means but may be worth a look. Not expensive as I remember.<p>Have also been doing my best to research lightweight concrete. In so doing have learned that in some applications they substitute varying quantities of vermiculite/perlite for aggregate. The site I checked had strength factors for mixes using 4 to 8 parts vermiculite for 1 part cement. This is alleged to possess some insulating properties. The only problem I could come up with is that it is generally applied with a pumper (not always available in the 3rd world) and in some cases a resin of some sort is added to help keep the vermiculite from rising to the top of the pour. Do a google search for light weight concrete for more info in this. Lowest tech way I can think of is to use Kool Coat application like used on mobile homes. Cheap. Don't know how effective as concrete roof makes a fine passive solar heat sink.<p>
: Hoping someone out there has a suggestion for a low tech solution for insulating an existing concrete roof. The in-law's house has a 10cm concrete slab roof over the bedrooms (with a slight pitch). The cieling is too low to effectively put in a suspended ceiling to help out, and when the sun beats down on the roof all day if gets pretty warm inside.<p>: I had a couple of ideas but have doubts about both of them. I'd appreciate any thoughts on the practicality (durability, effectiveness) of either of the two ideas, or any other reasonable suggestions, short of trying to air condition the house.<p>: 1. Drape a nylon tarp (approx the length x width of the roof) over the roof, with a few lines of block to keep it up off the surface. Figured it might work like the fly on a tent and lend some shade and keep the direct sun off the roof. (Could take it down during Hurricane season!)<p>: 2. Put a layer (1" - 2") of rigid insulation over the roof (probably in small blocks about 18" square) and then anchor it down by pouring a couple of inches of light weight concrete over the whole roof and insulation (could embed a layer of wire mesh in the mix).<p>: Thanks in advance for any advice.<p>: Ed<p>

Carl Carlson

Jun 18, 2002, 1:08 PM

Post #4 of 11 (10976 views)

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Cooling a Concrete Roof

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I think the way to go is a combination of reflection and insulation. I'd try 1 inch or greater of foam available in either 2 by 8 or 4 by 8 foot sheets. Isocyanurate (sp?) foam is twice as effective but more expensive than the familiar styrofoam. I'd glue it down. The tricky part is how to protect the foam from the sun and the weather. You might try just a conventional composite roof. On top of that Koolcoat is the way to go.<p>Good Luck
Carl Carlson<p>

Dutch

Jun 19, 2002, 8:12 PM

Post #5 of 11 (10976 views)

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Cooling a Concrete Roof

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: I don't think scheme one will do you much good.<p>: #2 will be a help, but you should use insulation as thick as you can afford. 4" would be a lot better. Covering it with a light concrete will be fine.<p>: There is a lower cost way -- cover the roof with several inches of common dirt and top with concrete. This is a heaver load on the roof. With only 10cm you can't put too much up there. My house has a 12cm roof with 3 inches of dirt.
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Rolly alluded to this, but get some engineering data on the load that roof is capable of carrying. And try to find out whether Hal / lime or other material was used in making up the concrete. Also, when wet, certain materials will weigh a lot more - dirt, as well as non-glazed tiles can soak up a lot of water. Good Luck!

Ed

Jun 24, 2002, 5:49 PM

Post #6 of 11 (10975 views)

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Thanks for the input

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First, thanks to all of you for the input and feedback.<p>Okay, tarp idea is out.<p>May try to pursue foam insulation with lightweight conc on top. Not much engrg data on what the roof will support, not even sure of spacing of the bar or distance from bottom of slab.<p>Local lightweight concrete is made with some lightweight aggregate referred to locally as "Toba" or something like that, it's not vermiculite. Don't expect any strength, just want it to hold together and hold the foam block down (yes, glueing down first is a good idea). <p>May try and find someone in the area who has done this before.<p>Thanks again.<p>Ed

Cynthia Mason

Jun 25, 2002, 7:37 PM

Post #7 of 11 (10976 views)

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Thanks for the input

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: First, thanks to all of you for the input and feedback.<p>: Okay, tarp idea is out.<p>: May try to pursue foam insulation with lightweight conc on top. Not much engrg data on what the roof will support, not even sure of spacing of the bar or distance from bottom of slab.<p>: Local lightweight concrete is made with some lightweight aggregate referred to locally as "Toba" or something like that, it's not vermiculite. Don't expect any strength, just want it to hold together and hold the foam block down (yes, glueing down first is a good idea). <p>: May try and find someone in the area who has done this before.<p>: Thanks again.<p>: Ed<p>In the south when we have a heat wave the chicken farmers spray the roof with water. Not too practical in Mexico with water so scarce but for a temporary fix it would help to put a water sprinkler on the roof.

al lopez

Jun 27, 2002, 11:21 AM

Post #8 of 11 (10975 views)

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Cooling a Concrete Roof

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\In my humble opinion you'll be better off with a double roof construction.
Consisting of overhanging mtl corrugated panels over purlins & frame construction, the idea is to have 2-3 feet in between roofs suported by posts anchored to the exterior masonry walls.
All these materials can be aquired locally anywhere in Mexico at a relatively low cost.
You can contact me if you have additional questions.
Alvar Lopez

John Agnew

Aug 12, 2002, 8:35 AM

Post #9 of 11 (10974 views)

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Cooling a Concrete Roof

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Check out www.kingspanInsulation.com
Thet should help you out.

Kevin Ayling MonierLifetile

Aug 14, 2002, 2:06 PM

Post #10 of 11 (10975 views)

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Cooling a Concrete Roof

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We can offer a cool roof, using white concrete roof tiles to reflect the heat, underspace ventilation, with air inlet to eaves up to ridge line and end ventilation on the ridge.<p>This is used in Thailand, Malaysia, South Africa as part of our Global cool roof project.<p>We manufacture the tiles and components in Guadalajara. Please contact me if we can help further, there are more technical solutions than adding more concrete to the existing deck. <p>Best Regards<p>Kevin

rene

Aug 27, 2002, 4:28 PM

Post #11 of 11 (10978 views)

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Ever heard of Tejas or Roofing Tiles? Very coooool.

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About as low tech as you can get if your roof is strong enough to hold them, they'll cool that concrete straightaway.<p>: Hoping someone out there has a suggestion for a low tech solution for insulating an existing concrete roof. The in-law's house has a 10cm concrete slab roof over the bedrooms (with a slight pitch). The cieling is too low to effectively put in a suspended ceiling to help out, and when the sun beats down on the roof all day if gets pretty warm inside.<p>: I had a couple of ideas but have doubts about both of them. I'd appreciate any thoughts on the practicality (durability, effectiveness) of either of the two ideas, or any other reasonable suggestions, short of trying to air condition the house.<p>: 1. Drape a nylon tarp (approx the length x width of the roof) over the roof, with a few lines of block to keep it up off the surface. Figured it might work like the fly on a tent and lend some shade and keep the direct sun off the roof. (Could take it down during Hurricane season!)<p>: 2. Put a layer (1" - 2") of rigid insulation over the roof (probably in small blocks about 18" square) and then anchor it down by pouring a couple of inches of light weight concrete over the whole roof and insulation (could embed a layer of wire mesh in the mix).<p>: Thanks in advance for any advice.<p>: Ed<p>
 
 
 
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