The bonus room over your garage is not hot because the air conditioner is undersized. It is hot because the attic above it cannot breathe, and that is the first thing competent roofers mont belvieu tx will look at before anyone quotes you new equipment. Air is supposed to enter low at the soffits and leave high at the ridge or a gable vent, and when either half of that loop is missing, the space above your ceiling becomes a heat battery that radiates down all afternoon. Venting the attic costs less than buying cooling capacity, and it treats the cause instead of the complaint. What follows is the order I should have done things in.
Bigger Cooling Units Treat The Symptom
My first instinct was to throw hardware at it. I priced a mini split for the room, got a number back, and nearly signed the estimate. Then I pushed a logging thermometer through the attic hatch and left it alone for a week, and the answer was sitting in the CSV: 134 degrees at 4:40 on an August afternoon, with the downstairs thermostat holding 74 and the bonus room stuck at 89. The engineering behind that is neither new nor contested. ASHRAE’s published standards work on building ventilation, a library that saw its latest refresh in May 2026, frames attic ventilation as a roof longevity and energy efficiency requirement, and the failure it describes is heat building past 130 degrees in a poorly vented space over a garage until the HVAC system strains and the equipment below it throttles. A second cooling unit does nothing to that 134. It just buys electricity to fight a ceiling that never stops radiating.
Ten years ago this room held a treadmill and a guest bed, so nobody measured it and nobody minded if it ran warm from two until seven. Now it holds a desktop pulling 400 watts under load, a NAS, two monitors and a person who notices when clock speeds sag. The room itself did not change. What we ask of it did, and the roof over it was vented for the old job.
Blocked Soffits Cancel A Ridge Vent
The mistake I hit first, and the one I have watched neighbors repeat, is treating exhaust as the whole job. A ridge vent gets cut in, everyone feels better about it, and nothing measurable happens because there is no intake feeding it. Blown-in insulation gets pushed out over the top plate and buries the soffit openings, and on older houses those soffit vents are painted shut, sometimes twice over. What turns up again and again in these garage-wing attics is a gable vent screened off years ago and never reopened, or a bath fan dumping humid air straight into the same dead pocket. An exhaust opening with no matching intake will still pull air, just not from outside. It pulls from your conditioned house instead, through every ceiling gap and can light it can find, which means you are paying to cool an attic.
One Afternoon Of Attic Heat Math
Run the numbers on the garage wing and it stops being a matter of opinion. That attic floor measures 1,100 square feet, and the 1 to 300 ratio most vent calculators use puts required net free area near 3.7 square feet, split evenly between low and high, so roughly 1.8 square feet on each side. Eight soffit vents at 26 square inches of open area apiece gives 208 square inches, which works out to 1.4 square feet, and two of mine were sealed with paint, so the honest intake number was closer to 1.1. Meanwhile the 22 foot ridge run at 18 square inches per foot delivers 396 square inches, or 2.75 square feet of exhaust. Exhaust roughly doubles intake, which is exactly backwards, and the shortfall gets made up from inside the house.
After baffles went in at the soffits and the gable vent was reopened, my logger showed a 19 degree drop at the attic peak. Call it 19. Honestly, closer to 11 once I averaged a full month instead of the three mild days I wanted to believe. The bonus room itself settled about 6 degrees cooler, the air handler started cycling off again, and the desktop quit throttling around five. The logger does not lie, even when I want it to.
Vent The Attic Before Buying Capacity
If you are searching roofers mont belvieu tx from a hot bonus room at four in the afternoon, ask about intake before you ask about shingles or tonnage. A good crew measures the attic floor, counts the actual open area at the soffits, hunts for the blocked gable, and tells you what balance you have now against what the space needs. Ventilation work is small money next to a second cooling system, and it addresses what the thermometer is actually reporting. Buy the airflow first. Then decide whether you still need the capacity.
