June 2009

Recently as I was inspecting a 1980’s home,  I found the attic temperature was over 150 degrees even though the outside air temperature was only in the mid 80’s.  True this home had a dark asphalt roof which most certainly contributed to the hot attic temperature; but it also had very poor attic ventilation.  The high attic temperature, coupled with the mediocre level of insulation, can only drive the cost of cooling this home into the stratosphere.  Then there’s the additional costs of replacing asphalt shingles every 12-15 years, a lifespan shortened because the extreme attic temperatures literally bake the shingles.  Add to that the cost of replacing an overworked air conditioning system, and we really start to talk money.  (The cost of a replacement AC system can easily run $4000-5000 for a 1500 square foot home).

If you’re feeling smug because your home was built in the last few years and has a tile roof and good insulation, perhaps you should  read on.   Many newer homes in this area have inadequate attic venting, thus experiencing inflated air conditioning costs driven up by the high attic temperatures. Adequate insulation only slows the transfer of heat, it doesn’t stop it.   City inspectors usually give little attention to this concern and many roofers that I deal with don’t understand the Building Code for ventilation (if enough of you start calling them, I’ll bet they learn it real quickly).

Air conditioning systems should last about 15-20 years.  If yours failed prematurely, was it because the attic temperature caused it to cycle off and on too rapidly?

How can you know if your attic is properly vented?  Check your attic temperature on a hot summer day. If you say, “You’ve got to be kidding! I wouldn’t possibly go up there in the summer,” then perhaps you have the perfect attic--perfect that is,  for the air conditioning repairman and your electric utility. 

Ideal attic temperatures shouldn’t be more than 10-20 degrees hotter than outside air on a summer day. 

If yours is higher, then it’s time to think about venting your attic properly.

Attic ventilation-pay once to get it right or continue to pay the electric utility and the air conditioning repairman-it’s your choice.