My company is doing a whole house remodel on a 10 year old Tuscan house, I call this my de-tuscan job as the house was built with an uber-tuscan style and the architects I’m working with have planned a very modern makeover. I think one of my main strengths as a builder is finding ways to greatly increase the efficiency of all the homes I work on. In this case, the house was constructed very traditionally for 1999. It’s a slab on grade 4200 sf single story with a 3 car garage, two by six stick framed, fiberglass batts in the walls, 10″ of blown fiberglass in the attic, two 75 gallon standard gas water heaters, three 80% efficient gas furnaces. All the mechanical equipment is located in the attic with a 6/12 pitch trussed roof. Two of the HVAC systems are original to the house, one was replaced two years ago.
With our Hot/Humid Texas climate and with huge amounts of duct work in the attic my first suggestion is always to goto a conditioned attic by bringing the insulation to the roofline with spray foam. On a typical summer day at 99 outside our attics in Austin can easily reach 130+. The problem with spray foaming this house’s attic is that all the mechanicals are atmospherically vented. They draw in attic air, burn it, then it vents naturally through the B-vent.
If we would spray foam the attic without changing the equipment it would be very dangerous for the occupants. The water heaters were switched to tankless since 10 years is about right to switch out a tank style water heater, but it would have been too costly to replace all the HVAC equipment with 90+ gas units that are sealed combustion. This is the only type of gas unit that can be safely used in a sealed attic system. So, the least cost for the dollar spent was to retrofit a radiant barrier on the roof deck with Sherwin Williams E-Barrier paint. We used 20 gallons to spray this roof and it took two painters 1.5 days to complete the job. Total bill was about $2250. I’m hoping that it will bring out attic temp down 15-20 degrees on those hot summer days which should translate to a savings in our clients AC bills.
-Matt Risinger
