What is the proper sanding grit sequence for refinishing a hardwood deck surface in Calgary?

For refinishing a hardwood deck surface in Calgary, the standard sanding sequence is 60-grit to remove old finish and surface damage, 80-grit to smooth the scratch pattern, and 100-grit for final surface preparation before staining — though the starting grit depends heavily on the condition of the existing finish and wood.

This sequence applies whether you're working with cedar, pressure-treated lumber, or an exotic hardwood like ipe. The goal of each stage is to remove the scratch marks left by the previous grit, progressively refining the surface so stain absorbs evenly and the finish bonds properly. Skipping grits — jumping from 60 to 100, for example — leaves deep scratches that show through the final stain, especially on lighter-coloured finishes.

Starting grit depends on what you're dealing with. If the existing stain or sealer is peeling, flaking, or heavily oxidised (common on Calgary decks after a few chinook cycles), start with 40-grit to cut through the old finish efficiently before moving to 60. If the deck surface is in reasonable shape with just fading and minor weathering, 60-grit is the right starting point. For a relatively new deck that just needs a light scuff before a maintenance coat of stain, 80-grit alone may be sufficient.

Calgary's UV exposure and chinook cycling make proper surface prep more critical here than in most Canadian cities. At 1,045 metres elevation, UV degradation is aggressive — old stain doesn't just fade, it oxidises and forms a grey, chalky layer that prevents new stain from penetrating the wood fibres. If you apply fresh stain over this oxidised layer without proper sanding, the new finish sits on top of dead wood cells and peels within one season. A thorough 60-grit pass removes this layer and opens the wood grain for proper stain absorption.

A Few Calgary-Specific Cautions

Sand with the grain, always. Cross-grain sanding scratches are invisible before staining but show clearly after — particularly on cedar, which has a pronounced grain pattern. Use a belt sander or orbital sander for large flat areas, and hand-sand with a sanding block along edges, around posts, and in tight corners where a machine can't reach.

Time your sanding for dry conditions. Calgary's low humidity is actually an advantage here — wood dries quickly after rain or morning dew, and the dry air helps open the grain for stain absorption. Avoid sanding within 24 hours of rain or heavy dew. The wood surface should feel completely dry to the touch before you start.

Finish with 100-grit, not finer. It's tempting to go to 120 or 150 for a smoother feel, but exterior deck stains — particularly penetrating oil-based stains — need some surface texture to grip. A 100-grit finish provides enough tooth for the stain to penetrate and bond. Going finer can actually reduce stain absorption and lead to premature peeling, especially on dense woods like ipe or cumaru.

After sanding, blow off all dust and wipe down with a tack cloth or damp rag before staining. Dust left in the grain will mix with the stain and create a muddy, uneven finish. Let the surface dry completely after any wet wipe-down — in Calgary's dry climate, this typically takes 30-60 minutes on a warm day.

Staining must happen above 10 degrees Celsius — plan your refinishing project for May through September. Calgary's spring and fall temperature swings mean a warm afternoon can drop below 10 overnight, which prevents proper curing even if application conditions seemed fine. Check the 48-hour forecast before you open a can of stain.

If the deck has significant checking, splitting, or raised grain from years of chinook cycling, professional sanding with a drum sander will produce a more consistent result than a rental orbital. A deck refinishing professional can also assess whether the substructure shows signs of moisture damage before you invest in a new finish coat. Get matched with a local deck professional through the Calgary Construction Network at calgaryconstructionnetwork.com.