How to Find Out if There Is Rot Under Aluminum Siding

Examine the aluminum siding and look for pieces that are crooked, loose, falling or bulging. Crooked, loose or bulging siding requires a closer examination.

Look for sections that have a heavy, dark mold growing on them. Press on the aluminum siding at the edges with your hand to determine if it gives under pressure and has soft wood behind it. Mark those pieces for removal and a more in-depth inspection.

Slide a straight siding removal tool under the top edge of the piece of aluminum siding section in question to pull the siding away from the house. Begin at the edge of the house or along a seam. Pull the siding away from the house far enough to insert a flat pry bar.

Place the flat pry bar behind the aluminum siding and pull it, so the nails pop. Do not pull the aluminum siding away from the house so far as to crease or bend the siding. Typically, if the nails hold tight, the wood is in strong condition, indicating no wood rot, and removing the section of siding is not necessary.

Cut the heads off the nails with blacksmith's pliers if the nails release from the wood easily.

Lift the siding and slide it out of place, using care not to bend or twist the aluminum.

Cut the rigid foam insulation with a utility knife to gain access to the wood underneath.

Press on the wood to determine if it is soft and spongy, which indicates wood rot. Tap the wood substrate with the metal end of a screwdriver; if the screwdriver penetrates the wood by 1/4 inch or more, the substrate has rot. Look for crumbling, cracking or deteriorated wood, which are all signs of wood rot. If wood rot exists behind the aluminum siding, remove the siding and affected wood sheathing. Replace the wood sheathing with treated wood and install new siding.

Coat the back of the piece of rigid foam insulation with exterior-grade silicone caulk and put it back in place against the wood sheathing if the wood has no rot.

Coat the back of the piece of siding generously with butyl gutter sealant. Slide the section of aluminum siding back in place, press firmly and hold for three to four minutes to gain adhesion.