How do I prepare walls for painting in an older Moncton home with plaster walls and cracks?

Plaster walls in older Moncton homes can be beautifully smooth and durable when properly repaired, but they require more thoughtful preparation than modern drywall — especially when hairline cracks and impact damage have built up over decades. The good news is that patient prep work produces a surface that takes paint exceptionally well.

Most older Moncton and Fredericton homes built before 1960 have three-coat plaster over wood lath, while homes from the 1960s and 70s may have two-coat plaster over gypsum board. Understanding what you have matters: wood lath plaster has more flex and movement, which is why you see long diagonal cracks at window and door corners — those are stress cracks, not structural problems, but they will come back if you fill them with a rigid filler.

For hairline cracks, a paintable latex caulk or a flexible spackling compound works better than traditional plaster or rigid joint compound. Apply it into the crack with a putty knife, feather the edges out 2-3 inches on each side, let it dry completely, and sand smooth with 120-grit. For wider cracks (3mm or more), open the crack slightly with a utility knife to give the filler a key — a V-groove holds filler better than a tight crack. Fill in layers no thicker than 3-4mm per coat, letting each coat dry fully, then sand level.

If you have loose or hollow plaster (tap gently — a hollow sound means the plaster has separated from the lath), use plaster washers and screws to re-anchor it before filling. Never paint over loose plaster — it will continue moving and pop your new paint off in sheets.

Pre-1978 homes in Moncton and Saint John frequently have lead paint, often under multiple layers of latex. If you’re sanding plaster walls, do a lead test with a swab kit from your hardware store before generating dust. If lead is present, wet-sand only, contain the work area with plastic sheeting, wear an N100 respirator, and dispose of the dust as hazardous waste.

Once repairs are done and the wall is sanded smooth, prime before painting — this is non-negotiable on repaired plaster. A coat of PVA drywall primer or a quality latex primer-sealer ($40-60/gallon) seals the surface and gives a uniform base.

Expect to pay $400-700 per room for a professional painter to repair and repaint plaster walls in an older NB home, though rooms with significant crack repair or lead paint precautions can run higher.

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