It is a piece of sheet metal—typically galvanized steel, copper or aluminum— that is installed between the stem wall or piers of a home’s foundation and the wood framing members sitting on top, to serve two purposes:

1) Deters termites from reaching the wood structure of the home - Subterranean termites require a moist environment to live, and they build mud tubes from the ground up into a home that are sealed tunnels which protect them from the dry outside air while they search for wood to consume. Because it is difficult for termites to to build their mud tube around the sharp edge of a shield, like the ones shown in the photos above and below, the metal strip slows down their march up into the house. It often forces them, at least for a while, to search for an alternate route upward. But eventually they can get around them. 

2) Makes it easier to spot their mud tubes - Termites are very small creatures and can navigate through cracks as small as 1/32 of an inch to enter a home concealed from view. The metal strip creates a “no-mans-land” that they must cross in plain view to get to the wood structural members of the home. This makes it easier for an inspector to examine a crawl space to find evidence of termite activity.

    Termite shields have been a standard construction detail for homes with elevated wood floors for many years. But they must be carefully installed with no gaps in the coverage of the top of the stem walls or piers in order to be effective. Also, any corrosion pinholes that may develop over time provide a concealed entry point. In the photo below, mortar that was dropped on the termite shield by masons working above it has eliminated the effectiveness of the sharp edge of the shield with a bridge of mortar lumps. 

    So termite shields are not a cure-all, and should be used in conjunction with ground treatments and/or bait traps as part of a termite protection plan. The photo below is an example of termites sending up exploratory mud tubes from the small crack in a different type of location: between a garage floor slab and a laundry platform at the back of the garage. This means that any opening, even a tiny one, can become an entry point. 

   Also, it is worth noting that shields protect a home from subterranean termites; but drywood termites do not need to enter a home from the ground and can get to the wood of a home during swarming season by flying into any opening to establish a colony. Luckily, they do not build their colonies as quickly or eat the wood in your home as aggressively as subterraneans.

    Also, see our blog post How do termites infest a house and remain hidden while doing major damage?

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To learn more about termites, see these other blog posts:

• Should I be worried about termites if my neighbor's house is being tented?

• Is the WDO (termite) inspector allowed to poke holes in my wood siding and trim? 

• Do carpenter ants cause structural damage to houses in Florida?

• How long before closing can you have a WDO (termite) inspection done?

• How long does Bora-Care® last? 

• Why is it a mistake to store lumber in the crawl space under a house?

• Does the presence of carpenter ants in a house indicate that there are probably also termites? 

• Are homes in Florida required to have termite protection? 

• If termite damage appears to be old, does that mean that termites may no longer be present?

• How do I know if my WDO/termite report is "clear"? 

• When do termites swarm in Florida?

• Does a recent termite company inspection sticker mean there are no termites? 

• Can a mobile/manufactured home get termites?

• Do I have to tent the house if I have termites? 

• What is the difference between a subterranean termite and a drywood termite?

• What are the green plastic discs in the ground around the house? 

• How do termites get into a concrete block house? 

• Do termites eat concrete?

• What is a clean WDO?  

• Does wood chip mulch in the yard attract termites?

• I think I have termites. What does a termite look like?

• I'm buying a concrete block house. Do I still need a termite inspection? 

• I saw a little termite damage on the baseboard. Should I be concerned?

   Visit our TERMITES, WOOD ROT AND PESTS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.