drainage under deck

[Anonymous]

We live in a geodesic dome. We currently have front and back decks that we are connecting. The land slopes @ 3 feet over the 40 ft distance. The joists on the lower area do not touch the ground. the joists on the upper area do. What would be the best drainage method to insure no water back-up next to house and prolong the life of our wood joists?

We have purchased 4″ corrugated piping and had started to bury it, but now we wonder if this is sufficient. Would perforated sock pipe with gravel under and over be a better choice, or would the natural grade of the land insure adequate water drainage through an unperforated corrugated pipe?

Thanks so much,

Carol

[John Aldrich1Participant]

Carol, I hope that your wood floor joists are placed on a concrete, treated timber, or rock foundation, or piers of some sort. There is no drainage system that will prevent the disintegration of untreated wood joists that are set on soil.

As far as an adequate drainage system around your Dome house is concerned, it really depends upon the volume of precipitaion that you receive in your specific locality. Do you live in Phoenix, Arizona, in Portland, Oregon, a rain forest area in Australia, or in the desert outback? My recommendation is to install a “code approved system” for your specific jurisdiction. Check with the local building code authority in your area as to the requirements of a foundation drainage system.

If you would like to investigate the state-of-the-art materials used in foundation drainage systems, go to the following web pages:
http://www.ads-pipe.com

Click on Products, and then go to the “Advan-Edge” product.

and
http://www.invisiblestructures.com

Click on the “DrainCore2” product.

The slope of the land from one side of the dome to the other is 11.5 percent. This is an excellent grade for efficient drainage. JWA

[Author]

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