Re: Insulation and Termites
If the termite company is a large one, I would go to their office and speak to another representative. That may not be company policy, just one mans opinion. If it is a one man show, then seek another company and question them.
The main thing the termite inspector is looking for is evidence that the termites are getting from the ground to the wood. If your piers are made of rock, brick or blocks, they look for dirt tubes going up the side of the pier. If you have wooden piers, termites will tunnel right up the middle of the pier and are almost impossible to detect.
A common practice in older houses with this type of construction was to use a metal "hat" on top of each pier. If termites found an internal passage up the pier, they would have to build a tunnel to go around the edge of the hat to get to the house. Sometimes these metal hats have to be replaced or at least repaired from time to time. Copper hats would last over a hundred years, but most were galvanized steel.
If you choose any type of insulation, it would have to be installed in a manner that does not interfere with the inspectors ability to detect termite activity. Before insulating, I would address any structural issues with the foundation first. If you have any sagging joists, they will need to be replaced or reinforced. You could sister new joists beside the sagging ones or sandwich 3/4" plywood sisters on each side of the sagging joists.
If the beams are sagging, you may need to add more piers to keep them straight. If the floor boards are the only things sagging, then you might need to add more joists to reduce the spacing between them. If the joists are already up to code, 16" on center, and you don't want to take them up, and you are up for doing a lot of work, then you could rip plywood into 14 3/4" wide strips, put them up to the bottoms of the floorboards. You could screw them in place with 1 5/8" screws and then screw 1x4's to the sides of the joists to further help hold them in place.
That should stabilize the floor and reduce infiltration. For added insulation, you could cut more 3/4" or even 1/2" plywood to 14 3/4" width and attach to the bottoms of the 1x4's. Then use 1" foam to insulate the rim joist all around the edge. This will form a box of trapped air under your floor. Since warm air rises, it will provide a lot more insulation than the materials used would indicate.
Back to the termite problem though. There are new treatments that are very effective. The bait traps work very well and you should be using them. If your termite guy does not offer this, find a new guy. You can also treat your exposed foundation with either Timbor or Boracare. Boracare is very expensive, but you can make your own by mixing Timbor with Antifreeze (ethylene glycol). you can order either ****** and apply them yourself. Boracare has been used on a couple of the TOH projects.
Re: Insulation and Termites
very interesting and informative reply. I learned something from it, and that's good. :cool: