While hurricanes create in-your-face damage, biological threats such as mold, wood rot and termites sneak up on you. Before you are aware of what is happening then can cause thousands of dollars in structural damage and even make you home unlivable. The great trick if dealing with this bio-damage is to stop it before it occurs.
Of course the ultimate way to control termites is to build your house with stuff that termites do not eat. This is the approach used by concrete block homes in Florida.
The traditional approach to termite control has been the use of toxic chemicals. The “Sustainable Sources” website has a great summary of effective non-toxic alternatives for prevention and treatment http://nontoxictermite.sustainablesources.com/#PREVENT.
Borate-treated building products are becoming more widely used for termite control. Borates are naturally occurring mineral salts, which are poisonous to termites but safe for people. Borates are especially useful in preventing dry-wood termites.
Metal shields are one physical barrier to termites. They act as a barrier between subterranean termites and home foundations. Care must be taken to ensure that no cracks form at the joints of the shields, as termites may easily find their way to the foundation from there.
Sand barriers were pioneered in Australia. The concept is quite clever: coarse, sharp sand are used to isolate the house foundation from the surrounding soil. Subterranean termites cannot tunnel through the sand or squeeze between the sand particles.
Sometimes the sand is placed underneath a slab foundation or packed around holes where pipes penetrate the slab. Sand is also effective placed below supporting wood piers.
Stainless steel wire mesh has holes too small for subterranean termites to penetrate. The screen may be used in combination with other deterrents.
The screen is installed under the house to provide a barrier. It can be fitted around pipes, posts, or foundations. It can also be used to for cold joints in concrete and other problem areas.
Desiccating dusts, such as diatomaceous earth, may be used to destroy termites or other pests. Since moisture is a requirement for life, these drying dusts make it impossible for the termites to survive.
Monitoring/bait stations can be an eco-friendly approach to termite control. These stations, containing wood-like termite food, are buried around the perimeter of the house and checked every three months or so for termite activity. When subterranean termite activity is detected, bait tubes, laced with chemicals, are introduced to those stations in which termite activity is detected. Termites feed on the poisonous bait, which is spread through the colony by workers who feed the rest of the colony. As a result the colony is wiped out. Borate-based baits are non-toxic.
Molds need three things to grow: water, food and oxygen. There are molds that can grow on wood, drywall, carpet, and insulation. Mold grows when excessive moisture accumulates in buildings or on building materials.
Molds can cause a variety of health problems: Sensitive people may experience skin rash, running nose, eye irritation, cough, nasal congestion, aggravation of asthma or difficulty breathing. Certain very toxic molds can fatigue, nausea, headaches and weaken the human immune system.
Molds can be prevented by denying them the water and food which they need to grow. Any home weatherization measure which prevents moisture buildup in the home can prevent mold. Air sealing and sealed attics are excellent methods to keep outside humidity from entering the house. Exhaust fans in the bathroom and kitchen also prevent moisture buildup. Prompt fix of plumping leaks will also help.
Molds need food such as paper and wood to grow. In wet places, such as bathrooms, it is advisable to use building materials which molds cannot eat. These include fiberglass covered gypsum wall board, tile, and plastics.
Wood rot is caused by fungi which feast on damp wood via minute threads called “hyphae.” Gradually, the wood is decomposed and its strength is lost. Such damage is often inconspicuous until its final stages, and in a few instances homeowners have suddenly found floors breaking through or doors falling from their hinges due to wood rot.
The key to preventing rot is to control the wood’s exposure to moisture and to employ an effective prevention and treatment program. Wood rot fungi “like” rain leaks, condensation in unventilated crawl spaces, faulty plumbing, leaky downspouts, and contact with soil which provide the moisture they need to grow.
The Ohio University Extension (ref. Fact Sheet on Wood Rot; HYG-3300-96) http://ohioline.osu.edu/hyg-fact/3000/3300.html makes the following suggestions to prevent wood rot.
1. If the wood rot hazard is high, select the heartwood of decay-resistant species or use wood properly treated with a good preservative.
2. Build on a well-drained site. Use proper grading to prevent water from seeping under the house. Install effective drain tile, roof overhang, gutters, and downspouts. Place no untreated wood within 18 inches of the ground.
3. Provide adequate cross ventilation beneath buildings to eliminate dead air pockets. Install two square feet of opening for 25 linear feet of wall. Dense bushes or other plants should not be placed in front of these ventilators.
4. In crawl spaces, install a vapor barrier such as polyethylene sheets on the soil surface to cause soil moisture to condense on the barrier and return to the soil rather than condensing on the floor and above joists.
Another great strategy to prevent wood rot is to only use a minimal amount of wood in hot humid climates such as Florida. For example, concrete block houses with slab foundations have much less wood than traditional frame houses.
A home’s exterior siding , along with soffits, trim and fascia do yeoman’s work in protecting your home from rain, wind, sun, cold, fire and bio-agents like mold. The need for maintenance or replacement is an opportunity to upgrade siding performance.
Siding boundaries along windows, doors, and roof edge need to be well flashed and caulked. This prevents penetration of wind and rain.
Exterior paint should be carefully chosen. White paint can reflect 70 percent of more of solar radiation. If an attractive exterior color is desired, choose a cool-paint pigmented with metal oxides which reflect the infra-red portion of the solar spectrum. These reflect solar radiation better than conventional paints of the same hue. A cooler wall minimizes expansion/ contraction which can produce joint failure. It also prevents heat degradation of the siding material.
Rain Screens: When painting masonry, e.g., stucco or bricks, choose a silicate-based paint which is basically high-performance whitewash. The silicate paint protects the surface, yet is permeable to water vapor. Thus, it allows the masonry to dry out between rains. The alkaline nature of the lime-based paint prevents mold.
It is very important not to paint masonry with a non-permeable paint, e.g., acrylic, which does not breathe. Disastrous stucco wall failure has been traced to stucco formulated to be water-proof, and painted with water-proof paint. When moisture gets behind the stucco either by rain leakage or condensation, it cannot escape. The trapped moisture produces mold and rots the wood behind the stucco leading to wall failure.
A rain screen prevents this problem in masonry and other types of siding. Its four-element design enables the wall to both shed water during a storm, and dry out between storms.
First Layer: the exterior siding, e.g., brick, stucco, vinyl. Sheds rain but is porous or vented so that it does not trap moisture inside.
Second Layer: an air cavity 3/8-inch minimum width. Prevents wicking of water and splashing of water from siding to interior; provides a “drainage plane” for moisture from rain and condensation to flow downwards; and, assists in drying exterior siding.
Third Layer: a weather resistant drainage membrane attached to the support wall, e.g., housewrap, building paper. Protects support wall and directs water downward to a drainage exit hole located on the bottom of wall. Being water repellent, it dries in between storms.
Fourth Layer: Rigid, water resistant air-tight support wall. Protects interior from penetration of moisture and humid air.
A rainscreen need to be custom-designed for a particular climate.
Choice of Siding: A concrete-fiber siding such as Hardie Board is an example of a high performance siding. It is tough and long lasting and resistant to rain, wind, sun, mold, termites, and fire.
Often soffits are made of flimsy aluminum or vinyl. These can be torn off in a hurricane leaving the interior open to wind and rain. Hardie Board is ideal material to upgrade soffits. Hardie board soffits can be fitted with vents. The vents are connected to the attic interior in case of a vented attic. If the attic is sealed, we believe, that the soffits will benefit from small vents to circulate air in soffit-roof-overhang area.
If the siding is to be replaced, consider installing a layer of rigid insulating foam. The foam can either be fused to the siding, or installed as an additional layer beneath. This is especially useful in under- insulated walls to reduce home heating/cooling loads.
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