Looking after decking in Cornish weather
Updated 23 September 2026
A deck in Cornwall lives a harder life than one in Surrey. It is wetter for longer, the salt air gets into everything near the coast, and shaded decks go green and slippery by November. None of that means decking is a bad idea here; the deck in Benno's photos is proof of that. It means a deck needs an hour or two of attention a year, and it pays back many times over.
The three enemies
Water sitting on the boards, especially where leaves gather or where the deck meets a wall. Algae, which loves shade and damp and turns a deck into an ice rink. And sun on the south side, which greys the timber and opens the grain so water gets in.
Salt, near the coast, speeds all three up and corrodes any fixing that is not galvanised or stainless.
Once a year, in spring
Sweep it, then clean it: a stiff brush and a deck cleaner, or a careful pressure wash on a low setting, working along the boards not across them. Let it dry fully, which in Cornwall means waiting for a dry week rather than a dry day.
Then oil or stain it. Decking oil soaks in and protects from inside; stain sits on top and adds colour. Either is better than nothing, and doing it every year or two is what keeps a deck looking like the day it was built.
Signs it needs a proper look
A board that gives underfoot, a soft spot near a post, fixings lifting proud of the surface, or a whole area that stays dark and damp after the rest has dried. Any of those means water has got where it should not, and it is worth having someone check the joists before it becomes a bigger job.
What Benno can do
A yearly clean and re-treat, board and fixing replacement, joist repairs where the structure has gone, and new decking built with the right timber, fixings and drainage gaps for a Cornish garden. Built-in seating and tables to match, if the space suits them.