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Month: October 2015

October 29, 2015

Condensation – An annoying cold weather problem

Condensation is the accumulation of liquid water on relatively cold surfaces. In this article I have attempted to inform the causes and cures of the condensation.
How does it form:
Condensation on window

Almost all air contains water vapor, the gas phase of water composed of tiny water droplets. The molecules in warm air are far apart from one another and allow the containment of a relatively large quantity of water vapor. As air cools, its molecules get closer together and squeeze the tiny vapor droplets closer together, as well. A critical temperature, known as the dew point, exists where these water droplets will be forced so close together that they merge into visible liquid in a process called condensation. This liquid starts forming on the coldest surface of the house, which is the window glass.

Lets briefly talk about a slightly different type of condensation here as well, which forms between two panes of double-pane windows. Double-pane windows have a layer of gas (usually argon or air) trapped between two panes of glass that acts as insulation to reduce heat loss through the window. Other types of gas used in this space have various effects on heat gain or loss through the window. Some windows also have a thin film installed between panes that separates the space between the panes into two spaces, further reducing heat loss and heat gain through the window. If multiple-pane windows appear misty or foggy, it means that the seal protecting the window assembly has failed.

Foggy window

The seal failure is generally caused due to saturation of silica desiccant material absorbing the infiltrating moisture inside the space between two panes.

A double-paned window that appears foggy or that has visible condensation has failed and needs to be repaired or replaced.

What causes it to form:

Condensation causes

Condensation is caused by high humidity which is in turn caused by a number of factors including but not limited to:

  1. People and pets (breathing, sweating, intense activity)
  2. Plants
  3. Shower
  4. Cooking
  5. Clothes washer/dryer
  6. Building material in new construction

What happens if it is neglected:

Condensation damage

Mold and wood-staining fungi can grow on a wetted organic (wood, paint, paper) surface above 15 deg C. and 60 % Relative Humidity. For wood destroying fungi to grow, though, wood fibers must be saturated (about 30% moisture content) and warm. Most building experts consider wood above 18 to 20 % moisture-content to be at risk of rot or mold.

These decay causing fungi grow fast at a warmer temperature, but can grow at lower temperatures, as low as 0 degC. depending on the mold genera and species. Indoor mold is both a rot or building damage hazard and a potential indoor air contaminant that can be a serious problem especially for people who are sensitive such as people who are immune-impaired, allergic, asthmatic, or have other medical or respiratory vulnerability.

Both building rot repair and building mold remediation jobs can be very costly where large areas are involved.

Symptoms of too much or too little humidity

Condensation Control

In the winter, keep the relative humidity low (in the range of 30-45% – lower as it gets colder outside). Purchase an inexpensive hygrometer to monitor humidity. Typical residential hygrometer

Here are some ways to control humidity:

  1. Keep your HRV (or ERV) running if your home has one.
  2. Run kitchen and bathroom exhaust fan every time and keep them on for 5-10 minutes after use.
  3. Make sure your clothes dryer and basement bathroom vents actually exhausts outside of the house
  4. Open the window curtains for at least few hours to allow air to circulate between the curtain and the window
  5. Indoor plants add to humidity. Do not have too many plants.
  6. Check and make sure there is no water leak from outside or plumbing

Thermal Imaging as a Detection Tool

Infra Red images

Under the right conditions, it’s possible to use an infrared (IR) camera to detect failed windows or moisture damage. IR cameras are designed to record differences in temperature. Prism Home Inspections can assist with detecting moisture leaks and resultant damage before it becomes difficult to resolve.

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October 28, 2015

Keep the rainwater out

As GTA is continuing to deal with the record-breaking rainfall, I wanted to suggest you these simple steps that will ensure that the rainwater stays out of your home – where it belongs.

Clean your eavestroughs (roof gutters) of debris. You can do it in few different ways.

Why: Debris in the gutter will block the flow of water towards downspout and eventually to the drain. As a result, it may overflow, damaging fascia board, soffit and/or roof sheathing and end up in the living area through the attic. Lack of proper gutters is also a major factor in the moisture related issues. In order to do their job properly, gutter downspouts should have splash blocks or flexible downspout extensions to prevent ponding, puddling and splash-back near the foundation. You should arrange to clean your gutters twice a year. If the gutters are full of leaf debris, pine needles or shingle grit, rainwater will overflow and cascade over the under-eave structures, possibly causing moisture related damage.

How:

  1. Cheapest but labour intensive method: place an extension ladder at the edge and remove debris by hand or brush. Make sure to wear good quality gloves. Be safe and always work in team when using a ladder.
  2. As an alternative, use a Rain Gutter Cleaning Tool available on Amazonsimilar to this telescopic watering wand attached with a garden hose or pressure washer.            
  3. Get the help of a professional eavestrough cleaning company.

Maintain the grade around the house.

Why: The grade should slope down away from the house on all sides. A general rule of thumb is 1/2″ to 1″ for every foot. The grade sloping toward the house is the leak waiting to happen through the foundation wall. Many basement leaks can be corrected by just improving the grade. Newly built houses are more susceptible to grading issues because of the settlement during first few years. (Photo courtesy: InterNachi)

How: For new house owners, your builder is responsible for final lot grading but you are responsible to maintain that eventually. For older houses, it is strongly recommended to get assistance from a professional unless you are a handy person experienced in lot grading.

Ensure proper exterior caulking around the house

Why: exterior caulk prevents moisture from seeping in through the joints and corners. A good quality, properly done caulking can last as much as 5-8 years at which time it needs to be re-done. Look for caulk around windows, at dissimilar joints and at corners.

ext-caulking-cracking

How: You need to redo the caulking if it is shrunk, has developed cracks and turned brittle. New house owners should ensure that their builder has caulked at all required areas on exterior (and interior). exterior caulking requires more skill than interior because of the height and/or size. In case of larger gaps, you may also need foam backer rod to support the caulk.

It is very important to note that different types of caulk are used in different locations and that some knowledge is required when selecting the correct caulking product.Be aware that some types of sealants are not designed for exterior exposure. If caulking compounds of an improper type are applied where they are exposed to sunlight, heat and weather, relatively early failure of the applied sealant should be anticipated. If interior-type sealants are inadvertently applied to exterior exposure, they should be removed as soon as the first indication of deterioration becomes evident.

So just by following these 3 simple steps, you can minimize any likelihood of rainwater leaking in the house.

If you already suspect a leak but cannot figure out the location or amount of damage, thermal imaging is a very powerful tool that can assist you. For the negligible cost, it can help you determine the location of the issue and suggest a resolution.

Here is an example of moisture that is not visible with naked eye but detected by thermal imaging camera.

For any home inspection needs including Tarion warranty inspections, remember to contact your neighbourhood home inspector at 416.315.5737. Visit www.prismhomeinspections.com for more information.

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