Basaltic Termite Barrier
Until now, the only effective barrier against the Formosan was formed by long-lasting chemicals like chlordane. Such Chemicals - Because they represent potential hazards to humans and to the environment - are not now available.
Professor Tamashiro found that particles of a very hard substance with specific size, and shape and weight characteristics could form an effective barrier. Exhaustive tests indicated that Basaltic Barrier has all those characteristics… and is readily available. Further tests were undertaken to determine its effectiveness against the Formosan.
The field tests were spectacularly successful. The Formosan could not penetrate the barrier because the particles were to large and heavy to carry, too small to create gaps through which to penetrate, and too hard to chew.
For the first time in history, a safe, durable, cost-effective barrier against the Formosan Subterranean Termite has been Developed.
HC&D, LLC-through a unique process developed to produce manufactured sand for its concrete products-now supplies the basaltic barrier with the specifically required size, shape and weight.
|Specific Gravity (ASTM C128)||2.7 to 2.8|
|SiO2, %(ASTM C289), min.||45|
|L.A. Abrasion, % loss, max||20|
|Mohrs Hardness Scale||5 to 6|
|No. 4 (4.75mm)||100|
|No. 8 (2.36mm)||95-100|
|No. 10 (2.00mm)||75-95|
|No. 12 (1,70mm)||35-50|
|No. 16 (1.18mm)||0-10|
The Materials and Methods of Termite Control
|Soil Type: The soil beneath floor slabs must be firm and stable. One of the factors affecting this stability is the composition of the soil, particularly the clay content. Clay soils expand when they become wet; that expansion can cause slab "heaving" and foundation cracking that looks very much like settlement cracking. The common "black clay", which is commonly found in valley floors and at the transition between valleys and the adjacent hillsides, is frequently expansive. Where expansive soils are suspected, the advice of a structural or soils engineer should be sought.|
Soil Compaction: A second consideration in assuring the stability of the soil beneath the slab is the compaction of the soil. The soil must be compacted to a density which is permanently stable under the loads imposed. Any movement of the soil beneath the slab will resulting cracking of the slab or in voids beneath the slab. Either condition can allow termite entry. This is particularly a problem where fill soil has been added to raise the grade or a portion of the slab, such as when the uphill portion of a sloping site is excavated and the soil used to build up the lower portion. Standard soils engineering methods require placing the fill material in "lifts" of layers about 12"deep, compacting each layer before adding the next.
Base Course: The purpose of the base course is to provide a firm and even base on which to pour the slab. The material should be crushed rock, S4C of Base Course. In areas of high ground water, use 3B-fine (#67) which is a capillary barrier.
Vapor Barrier: The installation of a vapor barrier will impede the migration of moisture or water vapor from the ground beneath the slab to the floor. In order for the vapor barrier to function it must be unbroken and unpunctured. If the barrier is not tight, blistering of resilient flooring, staining of wood flooring, and damp carpeting can result. 6 mil polyethylene sheet is the most commonly
Sand Course: Placing a 1" to 2" layer of sand on top of the vapor barrier will help to disburse excess water from the bottom side of the slab at approximately the same rate as moisture evaporates form the top surface, during curing. This maintains an even moisture content at the top and bottom of the slab, eliminating curling and reducing cracking. The use of sand in this location, however, may allow access by subterranean termites to cracks or penetrations that might occur in the slab, should any termites get past the primary BTB barrier. Using BTB instead of sand provides the same function for the concrete curing and termite protection as well./p>
Concrete for floor slabs: Use concrete with a minimum strength of 3000psi. good concreting practices in placement, finishing and curing should be employed to minimize cracking.
Footing Drains: Perforated drain pipe should be placed at the lowest part of the excavation and sloped at 1/8" per foot to "daylight". The opening should be protected from blockage.
The Materials and Methods of Termite Control
Reinforcing for floor slabs: Most concrete floor slabs are reinforced with a bar-type reinforcing in the footings and a light-weight welded wire mesh in the "field". Use "chairs" to hold the mesh in the proper position, in the middle 1/3 of the slab. Adding of polypropylene reinforced fibers to the concrete mix will significantly reduce plastic shrinkage cracking.
Control Joints in the floor: To minimize random shrinkage cracks from dying, control joints should be placed 10' to 12' on center in both directions, for a 4" thick slab. A saw-cut ¼ to 1/3 of the slab thickness should be made as soon as the concrete has hardened enough to make the cuts with-out leaving ragged edges.
Curing of the floor slabs: One of the most common causes of cracking of concrete slabs is improper curing, where the concrete loses moisture at a rate faster then the chemical bonding (hydration) occurs. Covering the surface of the slab with a polyethylene sheet after spraying it lightly with water is one of the most effective ways curing methods. The covering should be maintained for at least 3 days. The use of spray-applied curing compounds is the simplest and may also be effective.
Waterproofing Membranes on retaining walls: Where finished spaces are separated from the soil by retaining walls, it is important to provide a good water proofing membrane on the soil side of the retaining wall. Where water penetrates an inadequate membrane, damage to the finished surfaces is likely. In addition, termites can use the wet wall areas as their source of moisture, leading to serious infestation. Cold-applied asphalt compounds, even when reinforced with glass-fiber fabric, are not usually adequate to provide the protection and durability necessary. Some membrane materials which provide good waterproofing also provide space between the waterproofing and the structural wall where the termites can travel unobserved. From a termite protection standpoint, the waterproofing membrane must be both an effective water barrier and tightly adhered to the substrate. Where BTB is installed on the soil side of the retaining wall, no protection board is necessary over the waterproofing membrane as the size and shape of the BTB granules does not present a threat to the integrity of membrane, assuming reasonable care is taken by the installers. Most protection boards are a food source for termites and are, therefore undesirable.
Concrete Vs. CMU for treating and foundation walls: Concrete masonry units (CMU) are commonly used for retaining and foundation walls. Small spaces in the joints between the blocks and the grout used to fill in the hollow cores and surround the reinforcing steel, allow adequate space for termite movement. While the termites cannot damage the concrete blocks, the spaces within the blocks provide concealed pathways from the point of entry to wood, there they can do extensive damage. Well placed poured-in-place concrete does not provide these potential pathways.
Separator Strips: Where one slab abuts another at an expansion joint or where a floor slab abuts a retaining wall, a separator strip should be installed to allow expansion, contraction, and/or differential vertical movement. Asphalt-saturated fiber strips have been used in that condition. Unfortunately, termites can eat the fiber material, leading to concealed infestation of adjacent wood components, occasionally wood, even treated wood, has been used; termites can eat through that as well. While no material is currently acknowledged as ideal for that condition, two materials are promising. One is borate treated EPS foam, cut to a 3/8" to ½" thickness. The second is 60 mil SBS-modified asphaltic sheet (Jiffy Seal, Quaker 701, Bituthane, etc.). BTB should be placed beneath the joint, however, in any case.
Vertical Containment Barrier: When installing BTB against a retaining wall or at the edge of a deep footing, a "dam" can be created to limit the quantity of BTB needed, to control the width of the BTB layer, and to keep soil out of the BTB. Corrugated fiberglass or aluminum roofing sheets are inexpensive, readily available, easy to cut and handle, and will not decay or attract termites while remaining permanently buried next to the building. The sheets should be overlapped a minimum of 4" or 2 corrugations, creating a barrier which will minimize the future penetrations of roots into the BTB. The Corrugated sheets should be placed a minimum of 4" from the face of the wall, the house side filled with BTB and soil back fill on the other. The BTB and the back fill should be placed in 12" lifts, with each lift compacted.
Bio-Barrier: Root penetration into the BTB is a potential by-pass route for termites thru the BTB, as the termites can eat their way along the roots. One way to avoid this, is to install a root barrier at the BTB to soil interface, particularly for the top 12" to 18" of soil. "BioBarrier" is a geotextile fabric impregnated with time-release nodules of a root growth inhibitor.
Wood Treatment for framing lumber: Several chemicals are available for treating wood to resist termite infestation. While the effectiveness of the chemicals and the availability of the treated wood varies, the critical requirements are 1) that the wood is pressure treated, not brushed, dipped or sprayed, and 2) that the treatment is done to an accepted standard. The American Wood Preservers Association (AWPA) publishes the most widely accepted standards.
Problem areas/difficult conditions
Steps you can take to protect your house
Your home is probably the largest single investment you will make. Here are some helpful hints to help reduce your exposure to subterranean termites and the consequent repair costs.