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Damp Basements
Most often a Damp Basement is Poor Water Management
A
Guide to Maintenance of your Home provides a quick
method of diagnosing problems within the house. Some of these
problems can be fixed by the home owner and some will need
professional help.
We will update this on a regular basis mainly based on the season of
the year where climate can have adverse effect on a structure.
We hope this will be helpful for you and we will gladly answer any
of your questions.
A Guide to Damp Basement Problems.
MOISTURE ASPECTS TO CONSIDER
High moisture levels can lead to serious structural damage to the construction of the house. Health of the occupants can be at risk and Health Canada has said 38% of all Canadian homes had indications of excessive dampness or mold issues.
What is Basement moisture
Moisture in the basement can be from many forms. This can be water vapour in the air, soil and materials, as a condensed water vapour on cool surfaces, and the usual culprit, leakage through the foundation.
We will deal mainly with leakage as more than 85% of homes inspected in Canada will have some form of leakage or show signs of previous problems of leakage. And, with most of these homes, 90% of them can be rectified just by altering the land grade around the property so water runs away from the foundation.
Search and Diagnose
You will need to be systematic in your investigation if you suspect a dampness problem in your basement. Mainly all the clues will be found inside the basement especially if there is a damp smell or mold is evident.
If the basement is unfinished then your investigation is going to be much easier. Here you will be able to see the foundation walls and see evidence of past flooding or leakage in the sign of efflorescence. Efflorescence is a sign on masonry surfaces in the form of white powdery crystals. These are calcium carbonate crystals which form when drying moisture moves through to the interior of the basement in the form of white powdery deposit.
List of Four Probable Sources and Causes
- Gradient of the land adjacent to the foundation.
- Lack of, or defective, eavestroughs/downspouts.
- Blocked or ineffective drainage system (weeping tile
drain).
- Cracked foundation.
- Ineffective sump pump set up with a high water table.
Gradient of the land adjacent to the foundation.
The gradient of the land adjacent to the property foundation is the number one cause for damp or leaking basements. We can not emphasize the importance on lot grading when it comes to water penetration of basements.
You also need to look at the surface whether it is absorbs the run off or not. Say a driveway of asphalt close to a property needs a recommended run off of one inch per 4 feet would be effective.
Lack of, or defective eavestroughs/downspouts.
NB** (Gutters are also called eaves troughs or troughs. Downspouts are also called rain water leaders, leaders or conductor pipes.)
Gutters and down spouts carry water from the building and project it out from the foundation to allow it to naturally soak into the ground to disperse.
Any property with a basement or crawlspace should have gutters and downspouts to remove water in times of significant rainfall. Gutters may seem to be operating normally in times of gentle rain but when heavy rain is falling it becomes apparent rain is missing the gutter totally. This can be a cause of Excessing Shingle Overhang. This is something to look for as it reduces the gutter opening.
Where the water from the roof ends up is the most important
factor. If the down spout dumps it on the surface adjacent to the
foundation and there is insufficient gradient then the water is
going to end up around the footings of the house.
The best way to
counteract this is to use extensions on the down spouts to take the
water away from the property as shown below
Get the water away from the foundation
As you can see under the down spout the water was originally moved via
an underground pipe which would take it to either a swale or the property line.
These underground pipes get blocked by leaves and debris and also become homes for
Chipmunks!
They usually last for about 10-15 years then become useless.
Blocked or ineffective drainage system (weeping tile drain).
Usually the first indication of a blocked or ineffective weeping
tile drainage system is dampness or actual water ingress into the
basement. Water coming into the sump from the around the outside of
the tile drain pipe coming into the sump. Or standing water forming
on the floor of the basement
caused by water pressure under the slab.
These signs usually mean one thing,
the tile drain is blocked and is not working to remove the water from
around the footing of the property. Now even though this is daunting
to come to terms with, it must be rectified within a limited time
frame. Leaving this will only add to the possibility of permanent
structural damage to the property.
To Rectify the Situation.
Replacing the tile drain is a major job not to be undertaken lightly. We have in the past been involved in this type of work and it is very labour intensive and very disruptive. A 7-8 feet deep trench has to be dug all around the perimeter of the house which destroys gardens and features. The spoil which comes out of the ground means a large mound all the way round the property. A good firm though will replace it all back to how it was and in the long run it will be money well spent.
Get at least three estimates and confirm with the contractor the procedure how they intend to replace the drainage tile, the quality of the product they are using and the length of time the work will take them to complete.
Get references from contractors and verify the references. If there is no phone number with the reference be skeptical. Many companies have been known to write their own references.
Once you have chosen a company ask for a draft contract to go over schedule of events and time frame. Make sure the contract states that the property will be put back how it was found as in back fill of the foundation. Decide with the contractor the initial payment up front and any holdbacks on the final payment. The holdback is a payment you would pay the contractor after a set time after the work is complete. This is usually around 10-15% of the total cost to cover any costs you may incur if the contract does not finish or more work is needed.
In different areas of North America different products and procedures are used. The following is how we fixed the problem and it works.
New weeping tile drain installed alongside the property footing.
Once the trench was dug by mechanical means all the old material is clear out of the working area.
This includes the old contaminated pipe and gravel including the gravel the weeping drain is sitting.
The foundation and footing is pressure washed and let to dry.
This foundation only had a black bitumen coating which was not
protecting the foundation. Once all old material was removed a
new layer of gravel was laid for the weeping tile drain to rest on
and gravel was filled in around once the pipe was pinned down and level.
Three coats of Liquid Blue Skin Aqua-Block 720-38 which seals the foundation/footing joint from the outside and this was continued up the foundation. Then loose stone was swept from the top of the footing to prepare for the foundation membrane.
The foundation Membrane being applied
The Foundation Wrap keeps wet soil away from the foundation wall. Any moisture that may find its way past the membrane is carried to the foundation drain by the air gap drainage path. Platon Foundation Protector is commonly used to waterproof block walls, poured concrete walls, permanent wood, existing foundations and Insulated Concrete Forms (ICF).
Features and Benefits
- Made from tough, durable High Density Polyethylene (HDPE).
- Patented speed clip fastens to all types of foundations in any kind of weather.
- Economical.
- Ease of install.