INSPECT with the
Serving Southeastern PA
& Central/Southern NJ since 1985
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Ventilation and Air Conditioning
This summer can be described in three words; hot, hot, hot! I don't know about
you but my grass is dead, my plants are dying and it seems like a lot of
people's patience are running short. Hopefully one of these days we'll see some
This month's letter is in regard to Ventilation and Air Conditioning. We often
take for granted the space over our heads in the homes we live. Except for us
home inspectors we don't tend to want to get in them too often. In our areas,
the attic temperature can typically reach 150-160 degrees on a summer day.
Below our attic insulation is our ceiling finish and we wonder why it takes so
long for our second floors to cool down. The code calls for 1 sq. ft. of
venting for every 300 sq. ft. of attic space. I can tell you that is
insufficient. In the 70's and 80's we saw the use of gable end vents and attic
fans while in the 1990's and 2000's, vented soffit panels and ridge vents are
common. Most of us have done the right thing by reinsulating our attics to a
cumulative total of 12 inches. In the meantime I am seeing soffits that are
blocked and roofing felt that is installed over the ridge, making the ridge
vents ineffective. With improper ventilation your air conditioning costs will
rise as well as your discomfort level. It will also however, prematurely
deteriorate your shingles and delaminate your plywood even adding the potential
of black mold and mildew to the lumber. Although the attic is not considered a
living area, in many cases we do have to call for mold abatement when the
moisture levels are too high. If you add a bath fan that is only venting to the
attic and not to the exterior, this just accelerates the problem.
|I would ask on one of the next cool days (if one
ever arrives) you visit your attic environment. Please wear at a minimum, a
paper mask. You should have a cumulative total of 12 inches in your attic. If
you don't, any new insulation has to be unfaced or can be blown-in fiberglass.
Any storage that is found in your attic will tend to increase utility costs.
Determine the condition of the soffit vents, the gable end vents, and make sure
that proper airflow is achieved. A cracked gable end vent should be replaced,
as it can allow for insect or potentially bat entry. Attic fans are always
recommended and set the thermostat for 90 degrees. Verify that your bath fans
are venting to the exterior.
To help decrease your air conditioning costs, close the supply vents or adjust
the dampers in the basement that service the first floor rooms which you don't
use so more air can be forced to the second floor. As your thermostat is
generally located on the first floor, this tends to be satisfied more quickly
leaving the second floor hotter. Put the fan switch to the "on"
position instead of the "auto" position. It is amazing how many
people I educate each day about this auto/on switch. Try this and you should
see a difference. Typically with the fan switch in the "on" position
you can raise your home interior temperature by at least another 3 or 4 degrees
above your "comfort level". This will not allow the condensing unit
to operate on a regular basis, just the blower to the furnace. Filter changes
are also critical. Don't forget to change them every 30 days or the 3MFiltrates
every 90 days. Larger filtration systems are now available that need to be
replaced at the end of each heating and/or cooling season. With summers end
rapidly approaching and school around the corner, we can all begin to think of
cooler days, but in the meantime take these considerations to heart and make
your house more efficient.
Jack H. Milne, Jr. President, Tri-County Inspection