Drainage time…

With a ridiculous amount of rain falling this time of year the phone starts to ring off the hook with a variety of water penetration issues. Gutters are overflowing, water is creeping and basements are flooding. So here are the basics. If you have water coming in your house, through windows, doors, ceilings or your basement you need to make sure of a few basics.
  1. Keep your gutters clean. This is still the number one reason for water penetrating your home during heavy down pours.
  2. Make sure your grade around your house is sloped away for at least 10 feet where possible. Also it needs to fall at least 1 inch every 4 feet.
  3. Don't plant trees or any significant foliage against your foundation.
  4. Make sure your downspouts empty out at least 4 feet from the foundation.
  5. Get your roof inspected every few years to determine its wear and how much life it has left in it.

Damaged roof tiles and a gutter full of debris can lead to serious water penetration

Now my suggestions are a little more in-depth. If you have regular gutter issues:
  1. Add some kind of gutter protector to keep leaves out of your gutters, plastic or metal will do the trick. Downspout strainers are a cheap and inferior substitute, your gutters will still block up with debris and overflow during heavy rain. This is not a substitute for gutter cleaning, but a compliment that will mean less work at cleaning time. A composite roof will steadily fill the gutters with sediment, also sludge from smaller leaf litter will buildup over time.

    Good quality gutter guards will prevent most debris from making into the downspouts and clogging up the system.

  2. If you need to run downspouts away from the house try to make sure they will not get damaged by being stepped on, driven over or mowed. Bury them if you must but try to make the end empty in the open or into a shallow system of well filtered french drain style pipes.

This drainage works, but it could easily be damaged and is inconvenient

If you have a leaking basement: Try to establish exactly where and how the water is entering the basement. This will determine what repair is required. For basic foundation wall water penetration I recommend adherence to IRC 2003 section R406.2 Concrete and masonry foundation waterproofing. To paraphrase: waterproof using a membrane from the top of the footing to the finished grade (dirt level near the foundation) with a membrane consisting of one of the following:
  • 2-ply hot-mopped felts
  • 55 lb roll roofing
  • 6-mil PVC
  • 6-mil polyethylene or
  • 40-mil polymer-modified asphalt
  • The joints in the membrane shall be lapped and sealed with an adhesive compatible with the relevant waterproofing membrane.
Added to this I would follow Bob Villa's advice and consider sealing the basement by digging out the footing, scraping & brushing the basement wall, filling any cracks or openings with hydraulic cement followed by a thick layer of tar and 6 mil Visqueen on the wall. Finishing this by back-filling the whole excavation with 100% pea stone. (1 ) A french drain or trench drain running along and then away from the foundation will assist in directing water around from the house. If the basement is leaking through the cold joint or percolating through the basement floor through a crack or porous location then the best fix is a combination of exterior excavation and coatings along with interior excavation, foundation waterproofing and the installation of a sump pump. I would recommend this repair be performed only by a professional outfit. Finally, an extra step I like to do to protect a basement from water penetration is pour a 2-3 inch thick concrete pad around the foundation at ground level sloping away from the basement for about 30 inches. Just off the edge of this I like to bury a french style drain directing water away from the foundation and dissipating it at least 30 feet from the house.  
This entry was posted in Best practice, Project Tips.

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