Comments on: Frost Protected Shallow Foundations (FPSF)

By: Terry

Terry — Wed, 17 Jun 2009 23:38:48 +0000

I have an existing home in Taberbash, Colorado (outside Winter Park)and i am going to build a new one in the near future. i want to use FPSF because of water table issues during the seasonal runoff time. The question i have is: What about moles? My current house has a standard foundation/crawl space and has moles digging around the yard and definitely along the foundation. It is difficult to keep them in check. Will they dig through the foam? How deep do moles go?

By: lavardera

lavardera — Thu, 23 Apr 2009 19:40:20 +0000

The horizontal extension would depend on your location and how deep the frost line extends. Well, thats if if it is similar to a conditioned house’s configuration.

By: mike

mike — Thu, 23 Apr 2009 18:43:39 +0000

IE…Unheated structure
Unheated garages and other outbuildings require a different approach. A shallow foundation for one of these structures relies on heat from the earth. Ground temperature remains fairly constant around the local average annual temperature, which is between 40 and 50 degrees in the U.S. The footing bears directly on a layer of foam. The foam must extend beneath the entire structure, and it must bear on 6 to 12 inches of gravel.

By: mike

mike — Thu, 23 Apr 2009 18:37:40 +0000

That’s what i initially thought, but I see a detail invloving the insulating material that is specific to un-heated buildings also, whereby it utilizes the geothermal heat from the earth below to keep the footing from freezing. Unfortunately the detail fails to show how far horizontally from the footing wall the insulating material needs to run outward from the wall to function properly… on a simple seating wall situation it would not be practical to have to excavate more than a few feet on each side.

By: lavardera

lavardera — Thu, 23 Apr 2009 17:56:55 +0000

dont think this works without a heated interior space to prevent the earth below the footer from freezing

By: mike

mike — Thu, 23 Apr 2009 15:34:31 +0000

I’m a homeowner who is in the process of planning an outdoor bluestone patio to contain a curving circular low profile sitting wall (27″ +/- tall) enclosing the outer area of the patio. Since I will have natural stone veneer faced piers (42 ” tall+/-) with manufactured columns above constructed within this same patio space to hold up a deck above, I naturally would like to use the same veneer stone for the construction of the sitting wall.
I do not want to go through the labor and expense of constructing a full depth (below frost level – assumingly 42″ in the hudson river valley of NY) concrete wall to support the “wet set wall”, and i do not want to construct a dry laid wall either, since i want it to match the stone pier look. I’ve explored using the rubble footing concept utilized by Frank Lloyd Wright in some of his Chicago homes of the 50′s, but I still would need to excavate down to the frost depth, and then after filling the cavatity with clean crushed stone, would still need to add perforated pipe within and drain to daylight, which would be about 200 ft away. (a drywell will not work with my siol type either).
I’ve reviewed many segmental block wall types, but these just do not cut it in terms of trying to match the real stone appearance.
My question: Is there a possible mechanism in utilizing this insulating technology to construct a shallow foundation “wet set stone veneer” sitting wall, that will not be subjected to frost heave and consequent damage?

By: Kevin D

Kevin D — Mon, 15 Dec 2008 08:27:52 +0000

There are some possibilities for a through the wall heat pump for hot water (HPWH), but all of them are semi-custom. One-off solutions should to be avoided when trying to keep costs down, but OK if they are truly simple.

One possibility is to put the HPWH in its own vented room and duct the cold air straight outside. Freezing the pipes is the big fear for that scenario, but avoidable. The other big drawback is that now it’s hard to use it for summer cooling. There would have to be a damper to direct the cold air from the heat pump into the dwelling instead of outside.

But that would require a biannual task to be performed by the occupants, and that’s is a no-no. That’s one of the nice things about boilers, you never even have to change a filter.

So, there is some needed technological development in this field. That is, a self contained HPWH that gets air from outside or inside, depending on the need for cooling. Another feature they could easily add would be to preheat the hot water with ambient air during the summer.

By: goran

goran — Fri, 12 Dec 2008 20:56:30 +0000

I’ve just started reading some of the archive info, and its amazing how many options you’ve looked into for HVAC, and how much info is here.

By: tlynch

tlynch — Fri, 12 Dec 2008 14:37:28 +0000

Great article on heating a well / super insulated home:

http://www.buildinggreen.com/auth/article.cfm?fileName=110101a.xml

By: chad

chad — Fri, 12 Dec 2008 13:54:14 +0000

Wise words Kevin. You’re on the money here. We are actually looking at eliminating the radiant floor in the next home and moving to all electric for the reasons you stated.

As far as the thru-wall heat pump for water heating, I’ve looked and not found. Could you point us in the right direction? The only heat pump water heaters I’ve found are completely internal. During the winter they will suck heat out of the house to heat our radiant floor, which is heating the house. You can see how this could become a vicious cycle…