What Happens to Fiberglass Batts After a Flood?

Fiberglass insulation works by trapping air in tiny pockets within its fibers. When floodwater saturates the batt, it fills these air pockets with water. Water conducts heat much better than air, so the insulation's thermal resistance plummets. Even after the batts feel dry on the surface, moisture deep inside continues to compromise their performance, leading to higher energy bills.

The batts can also lose their structural integrity. The paper or foil facing often delaminates, and the fiberglass material itself can compress permanently. This sagging creates gaps in your thermal envelope, allowing unconditioned air to move freely. You may notice drafts or uneven temperatures in rooms where the insulation was damaged.

Standard fiberglass batt insulation is generally not salvageable after a flood. The material is very difficult to dry thoroughly inside a wall cavity before mold sets in. Most building science experts and restoration standards consider it a porous material that should be removed and discarded following significant water contact.

Attempting to save them often leads to long-term problems. Homeowners might dry the drywall and flooring, only to have mold proliferate in the unseen insulation later. This can necessitate a second, more invasive repair. The safest course is to plan for removal as part of the overall drying and repair process.

• Batts are considered porous and not cleanable after floodwater contact.
• They trap moisture against wooden studs and sheathing, promoting wood rot.
• Drying in place is extremely slow and often incomplete.
• Any batts with visible mold growth must be removed.
• Batts contaminated by sewage or dirty floodwater are a health hazard.
• Removal allows pros to inspect the wall cavity for hidden damage.

Your first step is to stop the water source and ensure electrical safety. Then, contact local water damage pros for an inspection. They use moisture meters and thermal imaging cameras to detect wet insulation behind walls without needing to open them immediately. This assessment informs the full scope of the needed work.

Discuss the situation with your insurance adjuster early. Document the damage with photos and notes before any removal begins. Policies vary, and your insurer decides what is covered. In many cases, the cost of insulation removal and replacement is covered if the flood cause is a covered peril. The total cost depends on the square footage affected and the type of new insulation chosen.