Finding what has actually failed
Every deck repair starts with a probe and an awl. Soft wood gives itself away, so I push into the joists, the post bases, the stair stringers and the area under any planter or hot tub. Most decks I see around Toronto are pressure-treated spruce built in the last twenty years, and they fail in predictable places. Rot lives wherever water sits and cannot dry, which is why the top edge of a joist under a gap between boards goes first.
Grey, splintery boards are not the same thing as rotten boards. Pressure-treated lumber weathers to grey on the surface and can still be perfectly sound underneath. That distinction decides whether your deck needs a wash and a stain or a serious amount of new lumber, so it is worth settling before you buy anything.
Boards, fasteners and why the screws matter
Cupped, split and cracked boards get replaced one at a time. A board that has curled into a shallow channel holds water and will keep rotting, and flipping it over is a short-lived trick because the underside has usually been sitting damp for years. New boards go down with two screws into every joist, pre-drilled near the ends so the wood does not split.
Fasteners are where a lot of deck repairs quietly go wrong.
- Modern pressure-treated lumber corrodes plain and electro-galvanized steel, so screws must be hot-dipped galvanized, stainless or coated for treated wood
- Popped nails get pulled and replaced with screws, not hammered back down, because they will lift again next season
- Board gaps depend on moisture: wet lumber goes down close because it shrinks, dry lumber gets a small gap
- Old fastener holes are avoided so the new screw bites fresh wood
- Joist tops that are already chewed up can take a self-adhesive flashing tape to slow the next round of rot
Railings and stairs
A railing you can rock is the most common safety complaint I get, and it is nearly always the post connection rather than the railing. Posts fixed with screws or nails through the rim board work loose within a few seasons. A sound connection uses bolts through the rim with solid blocking behind it, or hardware made for that purpose. Guards have rules as well: once a deck surface sits more than about 600 mm (two feet) above the ground a guard is required, and its openings must be small enough that a child cannot slip through.
Stairs move for two reasons. Either the stringers are not properly hung from the deck, or the bottom of the flight sits on soil or a paver that has sunk. Fixing the top and ignoring the base just relocates the problem. I set the bottom on something solid and level, then secure the stringers with hangers so the flight stops flexing.
Cleaning, sanding and staining
Restoration is the part people underestimate. Stain will not hold on a dirty or damp deck, and it will not hold on a deck that has been pressure washed too hard. High pressure tears the soft grain out of softwood and leaves a fuzzy surface that takes stain unevenly. The order of work keeps that from happening.
- Wash with a proper deck cleaner and a wide fan tip held well back from the boards
- Let the wood dry through several dry days rather than overnight
- Sand the raised grain and rough patches with a coarse grit, then sweep and vacuum
- Check the wood drinks water in rather than beading it before any tin is opened
- Apply penetrating stain out of direct sun, working each board its full length so there are no lap marks
New pressure-treated lumber is a special case. It leaves the yard wet and has to weather and dry before it will accept a finish, so a freshly boarded section is often stained on a later visit. Solid, film-forming stains hide more but peel eventually and then need stripping. Semi-transparent penetrating stains simply wear thin, which makes the next recoat far easier.
Where repair stops and a rebuild starts
Not every deck is worth saving, and pretending otherwise helps nobody. If the ledger board where the deck meets the house is loose or was never flashed, if posts have shifted because the footings have heaved, or if joists are soft along their length, that is structural work for a licensed contractor and it may need a permit. I will show you photos of what I find so you can make the call.
Plenty of decks across the Greater Toronto Area sit in the middle ground: a solid frame carrying tired boards. Those come back beautifully for a fraction of the work of a rebuild, and that is the job I enjoy most.
