Last Updated Jun 4, 2010 · Written by Craig Gibson
Water damage is a concern with any deck, especially if the water penetrates the joists, causing rot. However, there are joist protection systems available, specifically designed for use in outdoor areas in order to ensure that joists last as long as possible.
When it comes to outdoor structures such as decking and verandahs, it is assumed that the roof is adequate protection against the weather. This is not true. The outer edges are still exposed and storms and other bad weather can cause the entire deck to become saturated. Not to mention if you decide to clean your deck using water! Joist protection systems are designed to protect and extend the life span of timber floor joists in all outdoor structures.
However, the first thing that you should do to protect your joists is to ensure that the decking boards are laid with the ribbed face down. This will allow water to drain away. Joist protection systems normally consist of a strip of flashing laid over the top edge of the joist. This flashing may be bitumen coated aluminium foil, a plastic product, or rubber-surfaced materials. It comes in rolls of varying lengths, and is simply fastened to the joist using nails or another advised fastening method.
Simply put, the joist protection system acts like an umbrella to deflect water away from the joists and thus keep the timber dry. It also keeps the joists clean. The advantage of a joist protection system over other sealants is that it can reach areas that other sealants would never be able to. The most important purpose of a joist protection system is to eliminate the most common cause of deck failure – the rot migration between the joist and the underside of the deck plank. It completely eliminates wood to wood contact.
In most cases, joist protection systems will at least double the life of your deck or other outdoor area.