Inside the crawl space you would need to trench around any piers that hold up the home but the outside trench would be all that is required for the actual foundation if you are using Termidor. The Termidor will last for 10 years to protect your home. Please take a moment to look thru our pest control guide for termite treatment.
We would highly suggest trenching and treating instead of only treating inside the cinder block wall. Termidor is meant to bond to soil and be applied into the ground. It will not last very long just treating into the cinder block walls. Cinder blocks are also very porous, so they will soak up a lot of the termidor and you might get a few months of protection instead of 10 years when applying it into the ground.
You should follow the instructions as outlined in our How To Do A Termite Treatment article to treat the exterior and underside of your crawl space.
Yes, in addition to doing the trenching method it is recommended to also treat the crawl space using Termidor SC. Please refer to page 7 of the product label for information on how to treat a crawl space using the product.
Yes, you can use Termidor SC around the perimeter of your home and in the crawl space. If your house is on piers, you will need to treat around each one. It is not necessary to do a treatment in the crawl space if you cannot get to the area.
Termidor SC is a great choice for liquid soil treatment since it has a very long soil residual (10 years or more) and great transfer effect. In preventative applications, you would not be required to treat the inside of a crawl space. However, if there are live termites in the crawl space, then you would still need to spot treat that colony to insure control of them. So just treating the exterior of the house is not considered sufficient if there is already an issue in the crawl space.
If you can treat the termites from elsewhere in the house, then you may be able to spot treat the activity using Termidor Foam instead.
We actually recommend, if possible, to apply Termidor in a trench inside the crawl space. You will use the same method as you do around the entire structure.