CASE STUDY – from the files of Integral…………
When confronted with a major loss such as a landslide, you will need someone with the knowledge and experience to quickly assess the situation and, while the work progresses on the restoration of your property, the project manager should have a clear understanding of how to expedite the recovery, in the most cost effective manner.
However, there are three areas that must be addressed in order to accurately assess the damage and make sure that no additional problems arise, due to the delay in repairing the damage.
With losses of this nature, it is customary to obtain a completed engineers report that will advise, and instruct the consulting company and the contractor assigned to provide a Scope of Damage or Work. The engineer assigned to your loss would be able to provide you with a report of his findings and oversee the progress of recovery.
A confined space is an area that:
1. Is large enough, and so configured, that a person can physically enter and perform tasks;
2. Has limited or restricted means for entry or exit; and/or
3. Is not designed for continuous occupancy.
The term “confined space” has a wide application and covers situations:
A) Where there might be a deficiency of oxygen or where an existing safe atmosphere could become deficient;
B) Where toxic or flammable gases, vapors or fumes may be present or could arise;
C) Where disturbance of sludge or deposits could release such vapors; and/or
D) Where an oxygen rich atmosphere might be present or could develop.
Thus, a “confined space” is not necessarily obvious. An enclosed space such as a tank or boiler, entered through a manhole or ducts and shafts, even a closed room or an open ditch, may be considered a “confined space” should any of the listed situations apply. Under normal circumstances, a small, poorly ventilated room would not be considered a confined space. However, when toxic vapors are released, through the application of cleaners or adhesives, the area could quickly meet the requirements of a confined space.
Crawl spaces are typically associated with Perimeter foundations, or Post and Pier foundations. A Perimeter foundation has the appearance of a continuous concrete wall, above grade, with openings to allow air into the crawl space. Post and Pier foundations will involve the use of concrete piers at regular intervals, with posts extending off the pier to a floor system above. A post and pier system will have a skirting, extending to earth, to give the house a finished appearance.
Behind either of these exterior walls lies the transitional zone between the soil and the house. The following will aid in a better understanding of the crawl space, its elements, design, and areas where problems can occur
The Uniform Building Code (UBC) sets out several rules based on generations of experience. These rules apply to all crawl spaces.
All crawl spaces must have an entry 20″ x 24″. In order to move about in a crawl space, the Code requires a minimum of 18” of clearance below the large 2” X 8″, 10″ or 12″ boards, called joists. There must be 12″ below the large beams called girders.
To provide for ventilation and air circulation, the crawl space must have openings or vents, in a ratio of one square foot for each 150 square feet of floor. These openings are covered with a 1/4-inch screen mesh. In addition, the Code requires that the wood and the earth be separated by a 6″ space. And a vapour barrier, consisting of simple plastic sheeting, must cover the soil.
It must be understood that the standards of the Uniform Building Code are the minimum standards. The code makes no effort to establish maximum standards; hence, one must realize that compliance with the Uniform Building Code may not be adequate because of the unique characteristics in each home.
A house constructed on soil which allows for a good migration of water, such as a sandy formation at the top of a hill, may be well served by an 18″ crawl space. However, the amount of water evaporating into the air and being carried out through the vents would be minimal. Conversely, the same house at the bottom of a hill, or a house with a reverse slope (soil sloping toward the house rather than away), may be burdened with substantially more water evaporating from the soil and into the air of the crawl space. In this case, the minimum clearance and vent openings may not keep the crawl space dry.
Similarly, a home built thirty years ago would not have a crawl space with insulation. The addition of insulation would require an increase in air circulation to keep the moisture, held by the insulation, to a safe level.
A vapour barrier is a durable plastic sheeting, placed over the ground, after all the wooden debris has been removed. It functions by causing water rising from the soil to collect in beads on the underside of the plastic and to fall back into the soil. This reduces the relative humidity of the air in the crawl space and, hence the moisture content of the construction lumbers, above. Once moisture has penetrated the vapour barrier or has accumulated on the surface of the sheet, it has been compromised and needs to be replaced to ensure a proper atmosphere.
The code contains an unusual provision on the venting of crawl spaces; code enforcement officials are allowed to deviate from the standards if they believe conditions are such that the ventilation standards is too great. The result of this discretion has been tremendous variation in crawl space ventilation around the community. The critical question is: Does the crawl space ventilation keep the crawl space dry enough to prevent deterioration?
In considering vent screens, the critical concept is net free area. Simply, net free area is calculated by using length times width less the obstruction created by the wire mesh and louver. It is never useful to install louvers over a screen mesh and it is very common to see 1/8-inch screen mesh. The use of 1/8-inch mesh and louvers is never acceptable because the reduction in free area is too great to allow the vent to perform. Vents are located near corners to eliminate inactive air spaces and cross ventilation is essential to positive movement of air by outside breeze or convection.
The minimum clearance between joist and earth has two functions. The first enables a worker to move about in the crawl space and the second and most important is that the clearance between joist and earth limits the cubic volume of air in the crawl space
Many people are allergic to mold and mildew. Poor or not enough ventilation usually causes odors to be generated in crawl spaces. Depending on the amount of growth of mildew and other molds and fungi, the area should be first treated by a specialist. Different soil conditions and compositions can also be the cause of a “bad” smell. In a crawl space, the first line of defense is a plastic cover or vapour barrier.
Ventilation will always help to combat smell and odor. For such crawl spaces humidity sensors, which will find dry fresh air, have been developed. At the same time, humidity levels and wood moisture content are reduced. Wet insulation will dry out and HVAC ducts will sweat less in the summer. The sensor facilitates longer cycles of ventilation without harming the structure. Power fans, not properly controlled, can make matters worse by pulling hot humid air into the crawl space during the summer months. One of the worst offenders is an inside humidistat. You might as well put the fans on a switch. Start them in the spring and stop them in the fall.
The following is a budget to be used for repairs. However, hard numbers cannot be applied until the Scope of Damage/Work has been provided by the engineer assigned by your insurer.
Why this is so important when a landslide occurs that jeopardizes the integrity of the stability of the residence is because the above conditions have to be met in order to re-establish stability. If the residence had a full basement originally then either stability would have held or the entire structure would have to be torn down and rebuilt due to lack of stability. With a partial crawl space or post/pier foundations these areas must be addressed, in this case to the tune of an extra $150,000.