Punta Gorda mold growing on the ceiling in the laundry room
A home owner in your town recently asked me why he cannot just paint over our cut out and throw away a 2X2 foot spot of Punta Gorda mold growing on the ceiling in the laundry room. The mold was caused by an overflow from his A/C condensation pan under the air handler in the attic space.
The answer has several parts but first taking action to prevent a reoccurrence is paramount. The A/C drain pan probably overflowed because the drain line was clogged or obstructed. The A/C condensate pan is like a culture dish in your attic. Punta Gorda Mold spores are present in the air almost all the time. All they need to grow is water and a food material. The A/C condensate pan is wet most of the time. Any biological material that falls into the pan will supply the food and grow a slime Punta Gorda mold. This slime mold clumps up and blocks the drain line and when enough water backs up into the pan it overflows onto the insulation below and eventually onto the back of your drywall which is your ceiling below. There are two important actions you can take to prevent future overflows and subsequent water and mold damage.
1. Ask your A/C service technician to put an antimicrobial tablet into the A/C condensate drain pan. This tablet will discourage Punta Gorda mold growth and help to keep the drain line clear.
2.Attach a wet/dry vacuum to the drain line outside your home where it drains onto the ground. It is a PVC pipe with a “P” trap bend on the end. Do this quarterly and you will most likely never have a blockage again.
First: Why can’t I paint the Punta Gorda mold spot with kilz paint and just cover it over? Kilz does not kill, it just covers. The Punta Gorda mold will continue to grow in and on the back of the drywall, on the studs or roof trusses and on the plywood decking in the attic space and on the paper backing of the insulation. Appling a sealer to drywall will also slow the drying process and the Punta Gorda mold will stay viable longer. Any further wetting or high humidity will jump start the Punta Gorda mold growth and it will spread to adjacent building materials.
Second: The affected drywall must be cut out bagged and thrown away. Not just the visible growth but 2 feet beyond the visible. The wet insulation in the attic should be thrown away. The drywall should be cut inside containment with negative pressure. In plain language, a sheet of 6 mil poly is set up to isolate the growth area from the rest of the home space. Ideally, an air scrubber, a unit that filters the air through a HEPA filter, is attached to the containment. This draws a negative pressure inside the containment and does not allow air from inside to escape. The drywall is carefully cut with a utility knife followed by a hand held HEPA vacuum to prevent Punta Gorda mold spore from becoming airborne. Any affected materials, drywall and insulation, must be bagged inside containment and thrown away outside the home.