How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
What is the difference between a subterranean termite and a drywood termite?
Friday, July 20, 2018
Subterranean termites live in large colonies in the ground and come up into the house to feed on wood. They are dependent on water and a moist environment to survive, and construct narrow mud tubes that run up to reach the wood structure to protect them against dehydration. Subterraneans form their colonies and consume wood much faster than drywood termites.
The range of treatments for subterranean termites includes perimeter chemical barriers, which are either placed in the soil surrounding the house or pumped into the concrete block foundation through drilled holes. Baiting systems that utilize in-ground canisters containing poisoned wood can also be installed encircling the home to reduce or eliminate a termite infestation.
Drywood termites live in nests inside the walls or attic, and do not require a water source in the ground to survive. They establish their colonies and consume the wood slower than subterraneans.
If only one small area of Drywood Termite damage is discovered during a WDO inspection the pest control operator may choose to either remove and replace the affected wood or do a "spot" chemical treatment in the surrounding area only. However if multiple areas or a larger area of damage are noted, tenting would be the appropriate treatment, and the only way to be absolutely sure you have eliminated the infestation is tenting.
The tenting process involves completely covering the structure with tarp panels to create a sealed volume of air, then pumping in a fumigant gas. Vikane, Master Fume and Zythor are a few common brand names, and the active ingredient in all of them is sulfuryl fluoride. The gas kills just about anything living inside the tented area, including roaches, ants, and small lizards, but it provides no residual protection after the tent is removed.
Heat can also be used to kill Drywood Termites within the wall framing and is another option that is occasionally chosen. Tenting and heating the interior of the structure to approximately 140º F will produce a temperature inside the wood framing members of about 120º F that kills both the termites and their eggs.
Also see our blog post Should I be worried about termites if my neighbor's house is being tented?
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To learn more about termites, see these other blog posts:
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