Why Coolers Come Off
Many Albuquerque homeowners convert from evaporative cooling to refrigerated air. The reasons vary: muggy monsoon days when a cooler struggles, the twice-a-year startup and shutdown, maintenance, and water use. The New Mexico Office of the State Engineer's evaporative cooler brochure estimates a typical Albuquerque season at about 7,261 gallons for a 1,500-square-foot home, and 50% or more on top of that with a bleed-off valve. The same brochure notes that an evaporative cooler uses roughly a third of the energy of refrigerated air, so the decision isn't one-sided.
What the HVAC quote often doesn't spell out is what happens to the opening in your roof.
What a Cooler Leaves Behind
A down-draft cooler sits on a curb: a raised box that holds the cooler above the roof surface. Inside the curb is the duct opening, a hole through the deck into the ductwork. Running to the cooler are a water line and an electrical line, each coming through the roof nearby.
When the cooler is lifted off, all of that is still there. The duct opening is now a hole into your house, covered by whatever was set over it at removal.
Two Ways to Handle It
Cap the curb. Leave the curb in place, seal the duct opening from inside, and put a solid cap over the top. It's quick and inexpensive.
The trade-off: a curb is a raised box with corners and a cap seam, on a roof that expands and contracts with temperature. Each joint depends on sealant and flashing, and without a cooler on top, the cap takes direct weather. On a flat roof, a curb can also hold water on its uphill side.
Remove the curb and patch the roof. The curb comes off, the duct opening is closed with new decking fastened to the framing, and the roofing is rebuilt over it. Done well, you can't tell from the roof that a cooler was ever there. It costs more and requires a roofer, but it removes the weak spot instead of covering it.
How the Patch Is Done on a Flat Roof
Many Albuquerque coolers sit on flat roofs, where the patch needs care.
- Curb removal. The curb is cut loose from the deck, and old sealant and flashing tied into the roofing are removed.
- Deck repair. New decking is cut to fill the opening and fastened to blocking. If the deck around the curb is soft from years of cooler overflow, that section is replaced too.
- Insulation and slope. Where the roof has insulation board, the patch gets matching insulation so it doesn't create a low spot.
- Roofing tie-in. It depends on the roof. Our swamp cooler leak guide outlines the method for each:
- TPO or modified bitumen: a patch is welded or torched into the membrane so it's continuous with the field, with no lifting laps.
- Built-up (tar and gravel): new ply sheets and gravel surfacing matched to the existing roof.
- Foam: the foam is cut back, filled, re-foamed and recoated to match the existing coating. See spray foam roofs.
- Water and power line holes. Closed with new decking and sealed into the roofing the same way, or, if a line stays for future use, fitted with proper pipe flashing rather than a dab of sealant.
Check the deck under the cooler every time. Coolers overflow and drip for years, and the wood directly under the curb can be the softest spot on the roof. A patch over rotted decking won't hold fasteners. With the curb off, this is one of the few chances to see the structure without opening anything else up.
How the Patch Is Done on a Pitched Roof
On a shingle roof, the curb comes off and the deck is patched the same way. Then new underlayment is lapped under the existing courses above the patch and over the courses below, and new shingles are woven into the field so the patch sheds water with the rest of the roof. On a metal roof, the panel with the cooler cutout is usually replaced rather than patched.
Shingles fade, so a new patch on an older roof may stand out for a while. That's cosmetic; what matters is that the patch is woven in, not laid on top.
Timing It With the Conversion
The cleanest sequence: the HVAC contractor removes the cooler and installs the new system, and the roof is closed right after. A temporary cover is fine for a short stretch of dry weather, but during monsoon season a covered duct opening is a leak risk.
If your roof is near the end of its life anyway, ask whether to do the removal and the reroof together. Taking out a curb is simple when the whole roof is coming off, and you avoid paying to patch a roof you'll replace soon.
Closing a cooler opening is roof repair, and it's part of our roof repair work. A Free Roof Report before the conversion will tell you what the deck and roofing look like around the curb.