Replies to This Discussion

Permalink Reply by Corey Watson on May 17, 2010 at 11:03am

That's a very good-looking and clean installation Pete has there. It's a great use of a radiant barrier with conventional insulation and ventilated attic technology. The fan blowing outside air directly INTO the attic is a very important, and usually overlooked, feature of attics employing powered attic ventilation. Just sucking air OUT of an attic can actually cause mold and/or mildew issues in the living space of Florida homes.

Another approach is to keep the hot, wet, dirty air out of the attic altogether. As little as 3" of spray-foam insulation properly applied to the underside of the roofdeck can keep the whole attic within 15-20*F of the temperature of the living space below (attics typically stay well below 100*F). Spray-foam is a permanent technology, and offers the homeowner cool, dry, usable storage space in the attic, while sealing out humidity, pests (including squirrels!), pollution, and wind. Air conditioning machinery and ducts also benefit significantly from the cooler, dryer space. Average homeowners see air conditioning (and heating) demand reduced by 50%, as well as 25-30% annual electricity bill savings. Sealed-attic spray-foam systems are completely compliant with the Florida State Building Code, and existing home retrofit applications do not require a building permit.

Whether homeowners choose to invest in regular additions of conventional insulation, or a one-time, permanent spray-foam technology, most will see immediate savings and have their investment returned in 3-5 years or sooner.

Permalink Reply by Rob Serenbetz on May 17, 2010 at 8:01pm

Pete,
Well done; thanks for the info.
Not as complete as your job; here's what I did to cool my attic [and house]
1. installed ridge vents and soffit vents for a natural air flow [hot air rises]
2. painted my roof shingles with "Cool Coat" white elastomeric coating. [$50/5 gallon bucket]

Before, I couldn't enter my attic in the summer [an oven]
After, it was cool enough to comfortably work on above ceiling wiring,

My house got cooler and my power bill went down

Rob at earthscoutrob@gmail.com

Permalink Reply by Justin on August 31, 2010 at 10:53pm

These Solar power fans are battery free? It seems a small panel would easily supply a small DC fan enough current on those hot days where they would actually be needed.

Permalink Reply by Andy Karpinski on January 21, 2011 at 12:05am

I've been using a radiant barrier since the 1980's.  They work well and are relatively cheap.  Mine is the foil faced paper and not the reflective bubble wrap type.  The latter is a little more effective but a lot more expensive than foil faced paper.

 

If you are insulating your attic, be sure to also seal any air leaks while you are up there.  This includes the tops of junction boxes for ceiling lights, holes where wires and plumbing goes through the tops of walls, central heat and air duct work, where air conditioning register boxes attach to the ceiling, etc.  I recently sealed all my duct work joints with mastic and sealed the register boxes to my ceiling.  The airflow out of my ceiling vents has at least doubled, indicating how much air was previously leaking from my duct work.

 

Also, be sure to bury all your duct work and register boxes in insulation.  Ideally, the insulation over your duct work should be at least as thick as the insulation on your ceiling.