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Does the Underground/Wofati house solve or create a drainage problem

 
Ronen Hirsch
Posts: 18
Location: Romania
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I've been reading, rereading and contemplating Paul's Wofati http://www.richsoil.com/wofati.jsp article and there's something that i can't make sense of.

The drawings all isolate the behavior of rainfall and water at the house ... and the Wofati design does improve the diversion of roof rainwater ... but it seems to ignore everything that is happening uphill.

There is an entire hill above the house with water draining down it ... much of which is flowing to the front opening of the house only to be diverted by ditches around the house! How is that not a bigger problem (surface area of an entire hill) then the water from the roof (a MUCH smaller surface area)?

It seems to me that the key element is downhill sloping roof ... but why is that coupled with an uphill facing house? Depending on the slope of the roof, it seems to me that you can still have a downhill facing house. Am I missing something?
 
Fiona Dunne
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I was also confused by the hill. Why have a hill on the uphill side at all? Does it help with insulation or windbreak or something? Why not just make this on flat land?
 
Brian Knight
Posts: 554
Location: Asheville NC
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Fionna, I think its best meant for a naturally sloping site. I have seen buildings that berm the earth on otherwise flat sites and they were indeed in very high wind areas. Perhaps detection is another good reason but I think the insulation benefits are tougher to justify.

Ronen, I saw the same discrepancies as you. You cant control what ground and storm water is doing in real life with blue arrows under the house. I wouldnt read too much into the water drainage aspect of the design as every site is going to be different.

I just completed a house that was dry when we cleared the land but when we started to excavate for the foundation, right after a period of heavy rain, water was welling up from the middle of the building pad. We installed some good drainage techniques and so far so dry. By using evil PVC drain pipe (protected by clean gravel encapsulated in silt fabric) the drains to daylight will be able to snaked should they become clogged in the distant future. The up hill swale is best practice for all sloping site's storm water management.

The best thing I like about the wofati method is it makes better use of North facing slopes for building sites. If someone was trying to keep their home hidden, this would be a great technique. Personally, I would prefer the South side of the Mtn any day.
 
Ronen Hirsch
Posts: 18
Location: Romania
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Thank you for that injection of common-sense Springtime.

What worries (not really ... only when I apply my mind to it) is that another "eco-building philosophy" is being suggested around this supposed problem of drainage ... as if that were the main design feature of a house. Yes, drainage is an issue that needs to be addressed (and is way more complicated then "water flows down a hill" and associated with many other building aspects)... but at the expense of something as basic as south-facing passive-solar when you HAVE a slightly sloped hill facing the south?
 
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