Copy of a report prepared for Taylor Construction and their client.
For several decades, Canadian homes have been built over dirt crawl spaces because it was simple and cheap. Unfortunately, many of these dirt crawl spaces were vented based on the faulty assumption that these vents would allow moisture to escape from the crawl space. We now know that these vents actually increase the relative humidity level. The natural upward air movement draws air from the crawl space vents up into the living space of the home. Did you know that up to 40% of the air you breathe in your home was once in the crawl space?
Vented dirt crawl spaces create a ticking time bomb of potential problems. The bare soil contains high levels of humidity that natural airflow patterns move upwards into your home. This is referred to as the "Stack Effect". This means that not only are mould spores and allergens entering your living space, but that moisture is entering the entire floor framing system under the house, paving the way for damaging wood rot. This can result in expensive structural repairs to girders, floor joists and sill plates.
Benefits of Unvented Crawl spaces
Crawlspace vents effectively become the "determined hole" in a home. In winter, warm air exiting the attic or ceiling creates a negative pressure at the lowest openings in the home. This negative pressure causes cold air to enter through the crawlspace vents and rise through holes in the subfloor to the first floor. This phenomenon creates the "cold floor syndrome" prevalent in cold climatehomeswith vented crawlspaces.
The cold air can also carry unwanted moisture and gases from the soil, and odours from the crawlspace into the home. Typically, the floor above a vented crawlspace is insulated. In unvented crawlspaces, the walls, instead of the floor, should be insulated to limit heat transfer from outside to inside the crawlspace, and vice versa. When properly built, an unvented, insulated crawlspace helps to eliminate problems with comfort, odour, and health associated with mould, mildew, and bacterial growth.
Conditioning the Crawlspace
Once the crawlspace is insulated and unvented, it should be treated the same way as any other space in the house-supplied with a certain amount of heated or cooled air from the mechanical system. Conditioning the crawlspace can help the mechanical components that are housed in the crawlspace (the air handler, ductwork for the first floor zone, and plumbing line, for example) operate more efficiently and last longer because they are not subject to temperature and humidity extremes. Ideally, the crawlspace temperature should be about 55°F to 65°F year-round. All ducts should be well sealed with mastic to prevent unwanted air leakage. This air leakage increases energy consumption because the outside air has to be heated in the winter and cooled in the summer.
CRAWL SPACE/FOUNDATION VENTILATOR 110 CFM
Foundation ventilators also known as crawl space vents play an important part minimizing potential wood decay to your home's foundation caused by excessive moisture intrusion into the crawl space of foundation area. The unfortunate result of less foundation ventilation has been the increase of wood rot in crawl spaces and moisture problems in the living areas of homes. Moist climates require you to provide and maintain adequately ventilated crawl spaces. A crawl space vent system, in addition to venting moisture vapour, serves to vent out other gases, such as those formed from residues in termite treatment, treated wood, and radon gases. The crawl space vent system protects the structure of the house and the health of its occupants. To aid natural crawlspace ventilation, mechanical ventilation should exchange the crawlspace air at least four times an hour or once complete air exchange every 15 minutes. To determine this, multiply the square footage of the crawlspace by the height to calculate the cubic feet of the crawlspace and then divide by 15 to determine the CFM needed to properly ventilate your crawl space.
110 CFM Ventilator Fan
Length x width x height = total cubic feet of crawl space Divide = total cubic feet of crawl space / 15 = CFM needed for proper foundation ventilation.
21' x 18.5' x 2' crawl space = 777 cubic feet of area
divide 777 cubic feet by 15 = 51.8 cubic feet per minute (c.f.m) of air flow needed to ventilate your crawl space
I hereby authorize Air Detectives to perform mould remediation following these guidelines where necessary:
Stage 1: Demolition of all water damaged building material under the following conditions when mould remediation is performed after demolition.
Containment of the affected area is necessary to protect the occupants, remediation workers and the building itself from traveling mould spores. Only containment will offer proper protection to allow for inspection of wall cavities,removal or cleaning of mould. Containment involves plastic sheeting that is sealed with duct tape, Tuck Tape (or similar) to isolate and contain an affected or suspected area containing mould growth from the rest of the building. Full containment (similar to Level IV, NewYork City Guidelines, or Level 3 Canadian Construction Association) should be erected to contain the affected areas before mould removal and remediation activities commence. Complete isolation of CONDITION 3 areas from CONDITION I areas using plastic sheeting sealed with duct tape or similar and properly secured using staples (including ventilation ducts/grills, fixtures, and any other openings)are required.
The use of exhaust fans or negative air machines with HEPAfilters to generate negative pressurization within each containment area is required. Containment should be maintained via negative pressure to a minimum of 0.02 inches of water column. This should be checked periodically before and after any activities inside the contained area as well as periodically during the workday. Containment pressurization should be operated without interruption 24 hours/day until completion and continually logged using a digital differential pressure indicator with data logging capabilities.
Containment area should allow a minimum of 4ACH(air changes) per hour. Make up air into the containment area should be filtered air using a media filter with aMERV8 rating or better. Airlocks and sealed decontamination room for personnel and equipment at entrance/exit of containment is required.
Clean room for personnel dressing area and donning/doffing of Personal Protective Equipment PPE is required. All contained areas should include properly sealed plastic sheeting on the ceilings, walls and floors where possible.
All entry and exit points to the containment system (hot zone, decontamination chambers and clean rooms) must use proper opening and closing mechanisms consisting of either zippers or flaps located on both the positive and negative pressure areas.
Containment should be erected using fireproof plastic sheeting of the following densities:
Walls 6 mil
Floors 10 mil (where possible)
Containment may also be constructed using rip proof poly.
The contractor must secure the containment and no unauthorized or persons not trained in mould inspection or remediation should enter the containment at any time. All areas should be clearly marked as 'Clean Room', 'Equipment and Decontamination Room', 'Load Out Room' Regulated Area etc. Warning signs and restricted area signs should be clearly posted. All surfaces in the contained area including containment barriers and decontamination chambers should be HEPA vacuumed and cleaned with a damp cloth with a detergent solution and visibly clean prior to the post remediation inspection. Contractor must ensure that surfaces that are damp wiped are dried immediately.
A minimum of 3 passes for HEPA vacuuming for final cleaning is recommended. All equipment and tools in the containment areas should be cleaned and decontaminated prior to the removal of isolation barriers.
Cleaning inside the containment area should be conducted from clean working towards dirty areas. Cleaning of walls should be from top to bottom and towards the air filtration device.
All work should be performed using appropriate Personal Protective Equipment (PPE) and should be worn at all times when inside the contained work areas. Proper PPE consists of the following:
* Full face respirators withHEPAfiltration cartridges for chemicals and organic vapours (P 100 cartridge).
* Disposable protective clothing (Tyvek® or similar) covering head and shoes.
* Latex, vinyl, neoprene or nitrile gloves (4 mil thicknesses).
* Work gloves.
All containment procedures must include a sealed decontamination chamber where personal protective equipment is donned and doffed and where sealed bags of contaminated materials as well as contents and personnel are cleaned via HEPAvacuuming before exiting the containment area. All disposable suits, boots, and gloves must be sealed into a plastic bag and disposed of each and every time a person exits the work area into the decontamination chamber regardless of work performed or condition of the suit. Suits are not to be re used.Any building materials showing mould growth will need to be removed. Building materials that cannot be removed will need to have mould cleaned off by sanding, wire brushing or washing with a detergent solution. Several passes of thorough HEPA vacuuming as well as damp wiping of all surfaces in the affected area is required. All building materials which are removable (including but not limited to porous materials such as drywall, wall paper, studs, and carpeting) showing signs of water damage and/or mould growth should be removed in sealed plastic bags (6 mil) or rip proof bags and properly discarded into a secure refuse bin. Double bagging is recommended for added safety. The outside of the bags should be HEPAvacuumed and cleaned with a damp cloth and a detergent solution in the decontamination chamber prior to transport to uncontaminated areas of the building. All building materials and surfaces which are not removable (including but not limited to non porous and semi porous materials such as metals, glass, plastics, concrete, wood) showing water damage and/or mould growth should be thoroughly cleaned and scrubbed with a water and detergent solution, wire brushed, and/or sanded with a HEPA filter attachment to remove the mould. In some cases dry ice blasting of surfaces may be required.
50% of contract price $ _______________ to be paid in the form of a money order, certified cheque
50% of contract price $ _______________ to be paid upon receiving an air sample report fromMBL
in the form of a money order, certified cheque or cash on ______________.
WE RECOMMEND WHEN DEMOLITION AND REPAIRS BEGIN THAT FURTHER BUILDING MATERIAL BE REMOVEDTO LOWER MOULD SPORE COUNT LOWER THAN WHAT THE POST SAMPLING WILL SHOW.
back into carbon dioxide gas. The gas has 800 times greater
volume and expands behind the material speeding up its
removal. Paint, oil, grease, asphalt, tar, decals, soot,
dirt, ink, resins, and adhesives are some of the materials
removed by this procedure. Only the removed material must be
disposed of, as the dry ice sublimes into the
First, dry ice does not erode or wear away the targeted surface as traditional grit media and even wire brushes do. This means that surface integrity and critical tolerances are preserved and equipment will not have to be replaced due to surface erosion common with sand, glass beads, and other abrasive media.
Second, with traditional cleaning methods, equipment is often damaged (bumped, dropped, etc.) while in transit to or from the dedicated cleaning area. Instead most equipment and machinery can be cleaned while in place.
Uses For Dry Ice Blasting for Mould Remediation
Dry ice blasting accomplishes mould remediation faster and more completely than mechanical abrasion. Dry ice blasting does not require toxic chemicals and does not create a toxic dust hazard from remediation operations. Remediation operators have learned that one operator using dry ice blasting can accomplish the same mould removal as three operators using manual scraping and sanding. The range of available nozzles for dry ice blasting equipment enables operators to access tight corners quickly, and in many cases, clear mould from areas inaccessible to hand tools, such as inside corners of wood framing trusses and joists
INDOOR AIR QUALITY TESTING
YOUR CRAWLSPACE GROWS MOULD WHILE THE HOUSE FEELS DRY
How is your crawlspace growing mould while three seasons out of four, your home feels comfortable and dry? Sure, it may feel rather humid on the occaisional summer day, but most the time the house feels fine… So how does your crawlspace trap humidity? Even with your vapour barrier, moisture will condense and breed mould, termites, dust mites and more. Here's the answer. Air in your crawlspace is always more humid than the air in the house. And this is because cool ground temperature keeps the crawlspace colder than the air in your house. Because of this temperature difference, your home's living areas can feel dry, while below, crawlspace humidity runs rampid.
In other words, relative humidity is the percent of water in the air. When R.H. hits 100%, water will condense, rain or snow. Dew Point is the temperature when this happens. Here are a few scenarios to show what happens in your home and crawlspace during typical weather conditions.
NOTE: Crawlspace R.H. (relative humidity) should try be 40% or less in order to keep Dew Point around 10-15 degrees below the crawlspace temperature. EPA recommends 40% - 50% R.H. This will control dust mite and mold populations. A crawlspace dehumidifier should always be used during humid or rainy weather. Humidity in the living area above, can be as high as 50% or 60%, based on comfort.
As the winter air enters, the humidity drops slightly within the crawlspace. Notice relative humidity is 62%, beyond what the EPAconsiders acceptable.As the air migrates upward, it warms greatly and relative humidity drops drastically. The house feels dry, but the crawlspace still requires dehumidification.To control dust mite populations, it is recommended that the crawlspace be kept at 40%R.H. all year long. Unfortunately, most dehumidifiers will not work at a 45° temperature.
Still winter time, but here we have a cold rainy day. It will still feel dry indoors, but notice as the outside air enters the crawlspace, relative humidity only drops to 70%. During this type of weather, your crawlspace dehumidifier should be running.
This is the type of weather where mould really thrives, especially if it were to rain. It's too cold to run the air conditioner, so high humidity goes unchecked. If it were raining, relative humidity outside would be 100%. This would raise the dew point to 55°.With the crawlspace at 58°, humidity would rise to a whopping 89%.All your cold water pipes and exterior walls would be dripping wet.
Here's a nice warm day with comfortable 50% humidity. But because it is so warm, dew point is also going to be warm. Any surfaces below 60° will form condensation. Look how high the relative humidity gets as the air cools to 65° in the crawlspace. At 83% relative humidity, your crawlspace is sure to grow a good amount of mould, as well as make a fine home for spiders, termites, cockroaches and other pests.
The mild summer night is the worse case scenario for allergies.As temperatures near the dew point, dust mites and mould will multiply and run rampid throughout your home. Notice how quickly food goes bad in this weather. Also, if you notice more bugs in your home, these are indications of high humidity.