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Renovating Your Basement - Moisture Problems
Remodelling your
basement is one of the easiest and most cost-efficient ways of adding new living
space to your house. Besides the traditional recreation room, more and more
people are using basements for self-contained “granny flats”, rental suites
or home offices. No matter what the renovation purpose, ensuring that the space
is clean, dry and healthy is a critical part of the project — and something
that must be done before anything else.
Common Situations
Moisture is the
most common problem in basements — either entering from outside sources or
being produced inside by the occupants’ activities.
The soil around
the walls can contain a large amount of moisture from surface water that is
seeping down or from a high water table. Water can find its way inside by
gravity or through a crack or flaw in the water protection layer of the
foundation. Water can also be pulled up by a “wicking action” or “pushed
up” by hydrostatic pressure from the soil under the walls or floor. In summer,
warm moist air from outside can enter the house and lead to condensation on the
cool basement walls or floor.
Daily activities
also produce moisture that can be trapped inside the home.
Basement
moisture problems often include:
 | Foundation cracks that leak.
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| Standing water.
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| Efflorescence (white, chalky stains).
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| Wet decaying wood in contact with concrete.
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| Damp or moldy walls or floor.
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| Condensation on windows, pipes and other
fixtures.
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| Wet insulation.
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| Moisture damaged finishes.
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| Musty or damp carpets.
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| High humidity.
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| Stuffy, damp smells.
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Healthy Housing
Renovating is an
ideal time to make your house healthier for you, the community and the
environment. When assessing your renovation project, be sure to consider the
five essentials of Healthy
Housing.
House as a System
A house is much
more than just four walls and a roof—it’s an interactive system made up of
many components including the basic structure, heating, ventilation and air
conditioning (HVAC) equipment, the external environment and the occupants. Each
component influences the performance of the entire system. A renovation provides
an opportunity to improve how your house performs.
Basement
moisture problems can have a huge effect on the durability of the entire house
structure and on the indoor air quality (IAQ) throughout the house.
Avoid Surprises
Moisture
problems are caused by a buildup of a variety of water sources. Whether it comes
from surface or ground water that leaks in, water that wicks up or water vapour
that condenses, it must be controlled.
The easiest way
to control moisture is to stop it from coming in and to exhaust the water vapour
produced in the house to the outside. Here are some of the likely situations
that people encounter. However, every situation is unique. You may need to hire
a qualified professional to do a thorough investigation, find the moisture
problems and suggest the best solutions.
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| Do
the roof, eavestroughs, downspouts and grading direct surface water
away from the house?
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| Repair
or replace a leaky roof. Ensure that eavestroughs and downspouts with
extensions direct water away from the building. Slope the grade away
from the house.
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| A
poor rain drainage system will continue to provide a large volume of
water that can leak in or overwhelm basement drainage systems.
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| Do
window wells drain freely?
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| Install
drainage below window wells.
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| Water
may accumulate in the wells, leading to possible leakage into the
basement through or around the window.
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| Is
there a complete concrete floor?
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| Install
a concrete floor over a sealed polyethylene moisture barrier.
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| Dirt
floors are a huge source of moisture and soil gases.
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| Are
there any white, chalky stains (efflorescence) on the walls or floor?
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| Provide
better drainage and dampproofing to the outside. Efflorescence
indicates water evaporation of moisture that has wicked through the
foundation wall.
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| Continued
efflorescence is a sign of ongoing moisture problems.
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| Are
there any wet or decaying wood windows, sill plates, columns or beam
ends in contact with concrete?
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| Replace
decaying wood. Provide a capillary break between wood and concrete.
Seek professional advice as damage may compromise structural strength.
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| Wood
in contact with concrete will continue to decay and will eventually
result in structural problems.
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| Is
there any wet insulation, framing or moisture damage on finished
walls?
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| Remove
wet insulation or finishes. Fix the moisture source before
refinishing.
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| Materials
that are wet from any source (leaks, capillary action or condensation)
will get moldy and decay, leading to unsightly finishes, durability
problems and hazards to health.
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| Are
there a lot of stored items in the basement?
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| Get
rid of unused items. Store items on shelves. Avoid storing in
cardboard boxes that readily absorb moisture. Allow air to circulate.
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| Too
many stored items, especially on the floor, will allow hidden corners
to get even wetter and encourage mold growth.
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Rewards
| Correcting
foundation moisture problems can improve the durability of your home
and eliminate some dangerous health hazards.
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| A
dry, clean basement space will provide a good starting point for your
other planned renovations.
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Use the Basement Moisture Problems Worksheet to
help you assess problems and set priorities for your basement repairs
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Basement
Moisture Problems Worksheet
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Problem
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Options
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Advantages
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Disadvantages
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Help
Required
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Estimated
Cost
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Costing Your Project
Exterior, below
grade work can be difficult to access and expensive to accomplish. Use the above
checklist to help you assess your options and costs. The cost of essential
repairs will depend on varying conditions, including:
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