Why does New Brunswick paint alligator?

"Alligatoring" is a paint failure pattern where the coating cracks and scales into a pattern resembling alligator skin — and it's one of the more common exterior paint problems seen on older New Brunswick homes.

It happens when paint loses its flexibility and can no longer expand and contract with the surface beneath it. In NB's climate, that's a serious problem, because your siding, trim, and wood surfaces are constantly moving — swelling with moisture in spring, shrinking in summer heat, and being pushed and pulled by 100+ freeze-thaw cycles every winter.

Why It Happens

The most common cause is oil-based paint that has aged past its useful life. Oil-based paints cure hard and become increasingly brittle over time. Once they lose elasticity, the constant movement of NB's freeze-thaw cycles cracks them into that distinctive scaly pattern. Many older homes in Fredericton, Saint John, and Moncton have multiple layers of oil-based paint on their clapboard siding — each layer adding rigidity — until the whole system finally gives way.

The second major cause is applying a hard paint over a softer one. If someone painted an oil-based topcoat over a latex primer or older latex paint, the layers move at different rates and the top coat cracks. The same thing happens when a second coat is applied before the first has fully cured — the layers bond poorly and the top coat eventually separates.

Painting over a glossy surface without proper sanding or deglossing is another culprit. Without mechanical adhesion, the new coat sits on top rather than bonding to the surface, and it cracks and scales as the substrate moves underneath it.

The NB Climate Factor

New Brunswick is particularly hard on exterior paint because of the sheer number of freeze-thaw cycles — many areas of the province see well over 100 per year. Water gets into tiny surface cracks, freezes, expands, and forces the paint apart. Coastal areas near Saint John, Shediac, and the Bay of Fundy add salt air into the mix, which accelerates the breakdown of already-brittle paint films.

Spring is when alligatoring becomes most visible — after a full winter of freeze-thaw stress, the damage shows up clearly once temperatures warm up.

How to Fix It

There's no shortcut here — alligatored paint must be fully removed before repainting. Painting over it just traps the problem underneath and the new coat will fail within a season or two. The fix involves scraping and sanding all loose and cracked paint down to a sound surface (or bare wood if necessary), priming with a high-quality acrylic primer, and finishing with a 100% acrylic latex exterior paint. Acrylic latex is the right choice for NB because it stays flexible through freeze-thaw cycles rather than going brittle like oil-based products.

If your home has multiple layers of old oil-based paint — common on pre-1980 NB homes — test for lead paint before you start scraping. Homes built before 1978 very commonly have lead-based paint on trim and siding. Use a lead test kit from a hardware store, and if it comes back positive, hire a professional with lead-safe work practices. Sanding or scraping lead paint without proper containment creates toxic dust.

This is a job worth hiring out if the alligatoring is widespread across your exterior. A professional painter with the right scrapers, heat tools, and sprayer can strip and reprime a full exterior far faster than a DIY approach — and in NB's short exterior season (mid-May to mid-October), getting it done right and on time matters.

Need help finding a professional painter for an exterior repaint? New Brunswick Painting can match you with local contractors for free — browse the directory at newbrunswickconstructionnetwork.com/directory?trade=painting.