That little gap separating your rim joist from your foundation block. Do you really need it? The answer really depends on where you live. Some localities require a termite gap to conform to building code. Other places, don’t. But even if you live in a locale that does not require a termite inspection gap we recommend that you put one in regardless if you are able, and especially if you live in a region in which termites are known to be an issue (which is most places).
But first what is a termite gap used for anyway? Well, to understand this you need to know a bit about termites and how they travel. Termites live and thrive in cold and damp places. They dislike light and avoid it at all costs. This is because, compared to their cousins, the ants, termite’s bodies are soft and fleshy – they lack the tough dark outer covering of chitin that ants typically have that protect them from the suns rays. Termite bodies are often white or translucent and are easily damaged by the sun’s rays. Due to this fact, termites either wait until it’s dark to expose themselves, or they find a way to extend their lair by building tunnels.
Most often the case is that when termites are trying to establish themselves in the wood materials of your home they need to cross the space between the ground of your crawlspace or basement floor, and the wooden materials above such as your floor joists or rim joist. Crossing this expanse for a termite is risky because it leaves their soft vulnerable bodies exposed to light rays and predators. To protect themselves termites will typically try to establish a network of tunnels spanning from their lair below ground and into the wood materials above. They do this by chewing up bits of dirt and mud and other materials and regurgitating it to form a sort of plaster or clay from which they form their tunnels.
These tunnels are the visible signs that tell the inspector that you have a termite problem. And normally without the termite gap you wouldn’t see the tunnels.
Watch this video where we go into greater detail on the concept of a termite gap.