Decking Joists

Decking Joists

It is important to choose timber decking joists with great care. In fact, you should make this a top priority. Regardless of the fact that your deck is raised or flat on the ground, you need to ensure that you end up with the best decking joists as these can either make or break your decking. You must also address the issue of dimensions of your decking joists as well as their quality.

C16 or C20 grade

Normally, the standard for good quality decking joists is anything that is of either grade C20 or C16. The former is the highest grade while the latter is adequate and will suit almost every decking (residential) project including raised and flat decking.

Treat with Tanalith

When a deck is using softwood timber, the timber must be treated with Tanalith. Decking joists are not an exception and so must also be treated with Tanalith. Once the timber has been treated with Tanalith it will last for well over fifteen years. Be careful that you do not end up with decking joists (softwood) that have not been treated as these will not give you good service. Also, never make use of ready notched do-it-yourself joists for a raised deck.

Slight imperfections

It is quite possible that your decking joists may have some tiny splits in them. This is not a reason to be alarmed as it is normal for all kinds of timber to split when they are used in the outdoor environment. With the right treatment, this splitting can be minimized. However, it is important to choose timber decking joists that are as straight as is possible. Some amount of minute curves in the joists is unavoidable and also acceptable. All you need to do to address this curving problem is make a few adjustments to the way that you construct the deck.


It is possible to purchase decking joists packs that include both C20 and C16 qualities in the pack. However, it is possible to order and specify (and pay) for only C20 timbers. At the same time, it is important to understand that when constructing a flat deck you will not be able to use decking joists that measure 6 x 2 and so you will need to look for either 4 x 2 or even 3 x 2 joists. The good news is that even when you have to use the smaller sized joists, you can still make use of certain construction techniques that will help you get desirable results.

There are several different types of decking joists that you can pick and choose from. For example, you can purchase a 45 x 145mm Kiln Dried Treated C16/C24 stress graded decking joists for just 8.50 pounds. This particular product will have been kiln dried and pressure treated and will be made from C16/C24 grade and it has also been planed all round which provides better consistency of size and it also makes handling the joists a lot easier. You can purchase these decking joists in five different lengths that range from 3.0 to 4.8 meters. These joists can be purchased from Silva Timber Products that is a leading supplier in the UK for specialty timber products and more.

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