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You assume this makes sense everywhere. I live in Florida. Air conditioning your attic is akin to burning money. Even filling an attic with loose insulation

You assume this makes sense everywhere. I live in Florida. Air conditioning your attic is akin to burning money. Even filling an attic with loose insulation isn't really enough since there's just that much heat and humidity most of the year. I'm not saying it's a great design but there's absolutely no way to retrofit Florida attics in such a way where air conditioning that space makes sense. The house would need to be designed to have an air conditioned attic for it to make sense but there's probably a really good reason why no house in Florida is like that (probably humidity and mold related).

amluto 3y ago
As far as I can tell, the verdict is very much in. You should not build a vented attic, especially in a climate like Florida. For example: https://buildingscience.com/documents/insights/bsi-015-top-ten-dumb-things-to-do-in-the-south https://buildingscience.com/documents/insights/bsi-015-top-t... (And there are plenty of papers like this.) You have hot, humid air in your attic. You have much cooler air below your ceiling. You have something fluffy in between, which is almost certainly inadequate to keep said hot humid air away from your ceiling. So the hot humid air diffuses and otherwise reaches your ceiling, where it leaks through your ceiling, heats your ceiling, and condenses on your ceiling. And it’s essentially impossible to seal all the gaps. (And you have wood structural members going right through the insulation, and most structural designs make it essentially impossible to insulate them, so you may well have cold structural wood in your hot, humid attic. This is not a good situation.) Oh, Florida also has hurricanes. Attic vents can let wind driven rain in and they can contribute to roof failures during high wind: https://buildingscience.com/documents/insights/bsi-088-venting-vapor https://buildingscience.com/documents/insights/bsi-088-venti... Instead, you can seal and insulate your roof deck, skip the insulation above your ceiling, and treat your attic as conditioned space. The climates where a vented attic is less unreasonable are perhaps places with mild, dry weather and no wildfires. So maybe urban areas in Northern and Central CA? There aren’t too many places like this.

amluto 3y ago

As far as I can tell, the verdict is very much in. You should not build a vented attic, especially in a climate like Florida. For example: https://buildingscience.com/documents/insights/bsi-015-top-ten-dumb-things-to-do-in-the-south https://buildingscience.com/documents/insights/bsi-015-top-t... (And there are plenty of papers like this.) You have hot, humid air in your attic. You have much cooler air below your ceiling. You have something fluffy in between, which is almost certainly inadequate to keep said hot humid air away from your ceiling. So the hot humid air diffuses and otherwise reaches your ceiling, where it leaks through your ceiling, heats your ceiling, and condenses on your ceiling. And it’s essentially impossible to seal all the gaps. (And you have wood structural members going right through the insulation, and most structural designs make it essentially impossible to insulate them, so you may well have cold structural wood in your hot, humid attic. This is not a good situation.) Oh, Florida also has hurricanes. Attic vents can let wind driven rain in and they can contribute to roof failures during high wind: https://buildingscience.com/documents/insights/bsi-088-venting-vapor https://buildingscience.com/documents/insights/bsi-088-venti... Instead, you can seal and insulate your roof deck, skip the insulation above your ceiling, and treat your attic as conditioned space. The climates where a vented attic is less unreasonable are perhaps places with mild, dry weather and no wildfires. So maybe urban areas in Northern and Central CA? There aren’t too many places like this.