Termite resistant construction practices?
I am relocating into a new area, where I have an entirely new construction challenge to address: termites. Apart from the local practice of soaking the ground with poison, I am wondering if there are any specific construction practices that are used to reduce the damage, or ease the repairs, caused by these little critters. For example, I can readily see where a simple sill plate on a slab would become a termite buffet. What about building on piers, on stem walls? Does height above grade matter, or would a metal flashing make any difference? Incorporating a poison-laden felt gasket? Apart from the obvious fact that termites like to eat wood, what else do they like? Pressure-treated wood? Certain insulation materials? Drywall? Finally, in addition to hearing of your thoughts, I’d like to learn if there are any references out there. Thanks.
Replies
Termites like anything that has cellulose in it, unless it is treated.
Treated sole plates on a slab construction work. Treated sill plates on a stem wall work also.
Termites will find a way through poured concrete walls and slabs. That is the main reason lumber in contact with concrete is generaly a code requirement.
Years ago a termite barrier use to be installed beneath any foundation plate. They were nothing more than lead or galvanized flashing pieces bent to set on the wall or slab edge and under the plates. It was meant to force termites into trying to go around or through it. Forcing them out into an area where the could be seen, or the mud tunnels seen, was the goal.
Building on a crawl space or piers is not always a solution. I have seen mud tunnels built from the ground to the bottom of joist in crawl spaces. Other times I have seen tunnels reach within inches of the joist and just stop. For whatever reason, they just quit and went another direction. No explaining it.
Termites are foraging little beasties. They aren't attracted to wood, but if it is there, the coloney will find it in thier foraging.
Chemical treatment of the soil is the most common method of keeping them at bay. Some of the newer treatments are pretty good, but none of them come close to the old stuuf that was banned by the EPA.
One alternative method I have read about is a sand barrier. IIRC termites do not tunnel in sand. You can do a search on alternative termite controls and get several hits. a lot depends on the area of the country you are going to and the local termite variety.
I use to do warrenty repair work for Terminex as part of my past business. What I learned was the quality of the treatment was more important than all the warrenty hype they push.
You want to jerk thier chain a little, tell each company that bids on treatment that you want a sample of the mixed product taken from the mix they are treating your home with. Send that off to your state agriculture department (division of herbicides and pesticides) for analysis. That is the only way you will ever know that you are getting what you are paying for. Without it, you could be getting shorted on product and end up with little or no protection.
Even with chemical treatments, they are not forever. 10 years is about the max for the current treatment products out there. I try to use a 5 year maintenance schedule just to err on the safe side.
Dave has summed it up fairly well. Termite control falls basically into either a Physical, visual or Chemical barrier. In our area a with typical slab on grade, a monolithic pour is classed as a physical barrier ( in conjuction with penotration protection). Perimeter protection can be either chemical, visual, physical or a combination of all three.
A typical physical barrier may be stainless steel mesh at plate level and penos, chemical impregnated fabric at plate level or plastic sheild.
As Dave has pointed out, the chemicals used these days are not Agent Orange grade anymore so the need to replenish at 5 year or even yearly cycles is required.
One system we use is a reticulated system in which at frame stage our Termite guys come through and run a plastic line through the frame which has very fine holes in. This is terminated at a external box and becaomes a pump in point for future control. ( can also be laid in sand trenches at perimeter)
The other physical method we use in BV situations is Granigaurd which is basically a graded stone that the little critters can't get through.
For slab on grade we can also use visual but this entails being able to see a min of 3 inches of slab at the perimeter.
regards
Mark