Decking needs cleaning regularly throughout the year to prevent moss and algae building up and making it slippery. The secondary aspect of cleaning decking is the safety of the cleaning products you use, both for you and the environment.
Some sources for example, recommend hydrogen peroxide (bleach to you and me) for cleaning and lightening darkened wood but that’s not a very safe cleaner at all, not for nearby wildlife and the water course. There are steps you can take to prevent that algal build up using biodegradable cleaners:
Brushing loose dirt and dust away on a weekly or fortnightly basis will prevent more ingrained dirt and plant debris getting a hold on the decking. Good old-fashioned elbow grease is the safest cleaner and frequent washing down will take off the light layers of dirt and muck that accumulate over time.
Make sure you get into the grooves on the top surface of the decking. Keeping these clear is crucial for drainage, which in turn prevents the decking from becoming slippery. When it was constructed your decking should have had a slight slope (known as the ‘fall’) built into it so that water runs slowly off, without the slope being noticeable.
Getting Rid of Plant Material and Bird Droppings
Depending on where your deck is sited you might also have to remove bird droppings, dust, leaves and other plant debris from overhanging trees or bushes. A stiff brush with water on its own will shift most of it. A biodegradable washing up liquid solution will remove any light stains that won’t come off with water alone.
After a wash down it’s important to sweep the water away to prevent pools settling and seeping into the wood. The fall of the decking should prevent pools forming, but over time movement and warping may create low spots.
Oiling Your Decking
The decking should not need re-oiling or treating as a result of these quick washes. Wash about every four to six weeks, more frequently in the spring and summer when plants, birds and insects are at their most active. This should keep layers of dust and dirt from building up.
Washing your decking is important beacuse small particles of dust and dirt will lodge in the small pores on the surface of the wood. This then provides a basis for the algal growth which will support first fungi and then moss. All of these will hold water and make the decking more slippery.
Hard to Remove Stains
You must re-oil your decking after a hard clean, when stubborn stains require attention. There are proprietary cleaners on the market, some of which will be labelled biodegradable. The key point is to avoid anything with chlorine in it. As well as being a nasty chemical for the environment, chlorine will break down the structure of the wood.
You can also use a weak trisodium phosphate solution. This sounds nasty but it’s better known as ‘sugar soap’, a mild abrasive detergent more normally used for washing down walls before decorating.
A quarter of a cup in a bucket of water will be sufficient, then it’s back to the scrubbing. Sugar soap should not be used if your decking is suspended over a pond though, as it has a detrimental effect on fresh water life (as do all detergents). Again a good rinse and brush off is required and then it’s time to re-oil. Follow the manufacturer’s directions for this part of the operation.
Regular Work Keeps Decking Safe
As with any garden safety related issue it’s regular monitoring and cleaning that keeps your garden safe. It makes economic sense too, decking cleaned and re-oiled regularly should last a lifetime, potentially longer. In addition, if you clean the decking area regularly you will spot any problems, like loose bolts, handrails or cracking timbers, well before they cause a real safety problem.