If you have just built something out of tanalised sleepers then you no doubt want to know how long your marvellous creation is going to last. Well, let’s have a look and find out.
Tanalised sleepers are likely to last between 10-15 years. This can change depending on what conditions they are placed in, usually the wetter they are the quicker they rot.
If your wood is submerged in water then it may last as little as a few years. So it is important to keep the sleepers as dry as possible. You do not want them to be in any sitting water at all.
How to Prolong Your Sleepers Life
There are lots of different ways you can increase the life of your sleepers, I will list a few of the more popular methods below.
Keep Them Dry
While this seems obvious it is not always so simple. But good drainage under the sleepers can help. this will help to stop water pooling under the sleepers which will rot the bottom sleeper very quickly.
Sleepers used in raised beds can also rot quickly due to them being in constant contact with damp soil. One way to help with this is to use a membrane on the backside of the sleepers that would normally be in contact with the soil.
This will help to keep your sleepers much drier and therefore help them last a lot longer. To learn more read my article all about membranes behind sleepers here.
You can also use wood treatments to help preserve the wood. If applied regularly these could double the lifespan of your sleepers.
I don’t recommend using any treatments if you are using the sleepers for raised beds. Any chemicals in the treatments will leech into the soil which isn’t good for the plants or good for you if you are growing veg.
If you drill holes into your sleepers then you are opening a wound where water will get in. This will then be inside the sleeper away from where the tanalised treatment is.
This will speed up the rotting process. But you often need to drill in order to fix the sleepers together, so what do you do.
One good method is to properly countersink the screws or bolts and then fill the hole with dowel. Glue this dowel in generously and make sure it is a tight fit. This should help to create a good seal that will stop any water from getting in.
You could buy a dowel that is a little oversized, say 1mm and then thoroughly hammer it in. This will help to make sure the seal is really tight.
Oak sleepers or any hardwood sleepers, but oak are much more relevant than other woods, tend to last a lot longer. Even without treatment, this can last 20-30 years or even beyond.
Oak rots a lot slower than softwood so doesn’t need any treatment. The downside though is that these sleepers are more expensive and a lot heavier than tanalised softwood sleepers.
Reclaimed railway sleepers are oak sleepers that were used on railways. these tend to be even more expensive than brand new oak sleepers.
These things will last and last though. The railway sleepers have been treated and soaked with all sorts of chemicals, many of which are now illegal due to how dangerous they are.
This is why I would never use reclaimed sleepers if you plan on growing fruit or veg in the raised beds. If you want to use them for steps or just decoration though then they could last 50 years or longer!
If you are thinking of building with sleepers then you might find these posts interesting.