If you have read my earlier post on crawlspace and basment leakage and waterproofing, and you have taken steps to remove the downspouts discharge from near the home but you still are having moisture manifest in unwanted areas under or in your home what are the some of the next steps that you should consider?
Lets address basements specifically:
We know that the basement is a hole dug into the ground. A ground that we also know becomes saturated.
Lets say that proper steps have been taken to divert the downspouts at least 10 feet away from the home and the grading around the home slopes away for the first 10 feet but moisture is STILL coming in, now what?
There are many different options. The proper solution depends on your budget, and how you want the basement to be used.
-Lets say that the basement is mostly unfinished, concrete floor, mechanical systems, and open framing in the ceiling. This type of basement is the best for some seasonal moisture intrusion however any uncontroled moisture in a home is not ideal. Standing water in basements, even unfinished ones, can contribute to high moisture levels throughout the home. High moisture levels can lead to poor air quality and fungal deterioration all the way up to the attic. Having a dry basement is important no matter to what degree it is “finished.”
The manner in which to remedy this situation depends on where the water is manifesting:
Foundation wall Exterior water proofing: The best corse of action is to collect the moisture that is bubbling up from the ground before it gets to your home. Serious excavation of the exterior of the foundation is ideal. By digging down to the base of the foundation, drainage can be added and waterproofing can be applied to the outside of the wall. This is kind of like water proofing the surface of a pool only backwards. Taking these steps will ensure that the excess water around and under the home is properly collected and prevented from entering the home in the first place. This excavation is serious work and can be dangerous. A trench that is at least 8 feet deep has the real potential of caving in if not properly supported. These steps are usually not for the handy homeowner and should be contracted out to licensed, insured, professionals. (read-$$$)
There are some fantastic pictures and descriptions of the installation of these various water collection techniques here: http://www.finehomebuilding.com/PDF/Free/021140064.pdf
If huge excavation projects are not your idea of a good time you are going to have to take steps to control the moisture just before or just after it penetrates the foundation wall/slab.The best way to collect and control this moisture in a basement would be with the installation of a complete interior perimeter drain.
-Like a exterior foundation drain the interior foundation drain is designed to collect water before it gets a chance to come in contact with your home. As water rises it enters a trench of open pore gravel and a drainage pipe that has holes in the top and sides. The water enters the pipe and flows down grade to a collection point, usually a sump pump.
This system also requires a fair amount of labor for installaion because it involves jack hammering up the slab around the perimeter and digging a sloped trench. All of the busted up concrete and soil that is removed usually has to be carried out one bucket at a time. (read- back breaking and $$) This installation is also best left up to the professionals that have had practice and know the tricks of the trade.
This system is also can have a flashing system added to the wall that allows moisture that comes in through the wall to run down in to the drainage system under the slab. There is a picture of this system on page 6 of the previous link.
-If jack hammers and mud and buckets do not sound fun you are now looking at the least invasive and most inexpensive alternative: the surface gutter system. This system is very similar to roof gutters where water is collected at the edge and diverted to a collection system. Depending on the amount of water and where it is coming from this may be a great, relatively low cost solution.
This is a great site with some step-by-step procedures for how to install this basement “guttering system”: http://www.waterproof.com/DIY-installation/squidgee-installation-all.html
I worked on a basement waterproofing crew when I first moved to the Salem, Oregon area. We installed quite a few of these systems. They are relatively inexpensive and do not involve a whole lot of back breaking labor.
The gutter system has downsides in that the water is in the home. The standing water can still lead to high humidity and mold issues on the back side of the wall.
If you still have questions about which system would be best you can always give me a call. Your friendly local Salem, Oregon Home Inspector who also has expirence installing all of these systems.