footing insulation
footing insulation
(OP)
In general, the depth of foundation or footings should be below the frost depth penetration. However, if this is not practical, there are methods to raise the foundation above the frost depth. But it has to be compensated by placing insulation layer (styrofoam). Any guideline in terms of thickness, type of styrofoam , and location of this insulation ?
Thanks
Thanks





RE: footing insulation
There are some useful publications about Styrofoam........if I dig them up I will pass info along.......for starters try Dow Corning.......perhaps web site.......
RE: footing insulation
RE: footing insulation
RE: footing insulation
Regarding the column design, How can I design columns with wedth of 20 cm, knowing that when i try to do this it says that "column depth less than 10 inch, design ignored"
Though if i did the design manually, i will get a result, so why cant staad do it???????
How can i go around this
RE: footing insulation
You might also refer to the "Building Insulation Design Handbook" from the Oak Ridge National Labroraty (Publication DE88-013350)
You might also search the net for the foam insulation societies.
Karl D. Henry, Architect
RE: footing insulation
RE: footing insulation
The insulation is installed either just below the topsoil or above the footing. The former so that the grass isn't 'burned' due to the reduced, impermeable surface.
RE: footing insulation
As dik mentioned, the earth provides heat, a constant temp of 50 deg F - always. For an area such as here, this can mean a differential temp as much as 100 deg F compared to the outside temp. It is therefore important to provide a means of stopping frost penetration into the foundation area. Keep in mind, frost mainly travels downward - not horizontally.
Generally, I use 2-3 inch thick(2-3 layers 1 inch thick, lapped) type 4 extruded polyethylene (R9-13.5, blue board or pink board depending on brand) along the vertical sides of the thickened slab and 4 feet out from the slab around the perimeter. This is conservative but utilizes the full sheet of insulation board-usually in sizes of 4ftx8ft.
Some items to remember:
Make sure the structure is heated and insulated BEFORE freezing temps have ocurred.
Provide drainage as dik also mentioned. This is important since heat is conducted thru moisture much faster and can subsequently freeze.
If the vertical insulation above grade remains exposed, it must be covered with a protective coating against UV damage.
I have also used this concept in designing "frost-free" footings for columns ,piers, and walls by pouring directly on the insulation under the footing.
A good guide to use is in the 2000 IBC for residential construction. (Starting at R403.3). There is also a free energy program called MNcheck.
http://www.commerce.state.mn.us/pages/Energy/Builders/ECodeMain.htm#Software
RE: footing insulation
polyethylene or polystyrene?
Have used insulation for horizontally as well as vertical frost movement (some foundations with slightly over a foot of cover. and have never left it exposed to the elements (uv deterioration). Also for protecting pipes and culverts against frost jacking have used the DOW Hi-40 and Hi-60 load resisting insulation.
RE: footing insulation
Most homeowners do some landscaping around thier house- shrubs, bushes etc. If the insulation covers 4 ft. of perimeter away from the slab, then..no planting in that area?
RE: footing insulation
The soil conditions for growing will be different than with no insulation. Because the insulation is rather shallow, the soil may dry out faster. Also, I'm not sure what problems one may have with roots damaging the insulation board (which of course you don't want), depending on the plant. My two cents....Choose plants that tolerate drier conditions and have shallow growing roots and I don't think there would be a problem.
I have, by design, used less of a distance out from the foundation for the perimeter insulation when the characteristics of the soil (well draining, compacted gravel or sand) and the topography of the building site(ex. near other structures) have allowed it. As I said before, 4 ft. is conservative. I have used as little as 2 ft. For protection of the insulation board where digging may occur, place cement board or treated plywood on top of the insulation.
dik,
My mistake (I should proof-read better). It is polystyrene, not polyethylene. Thank you.
I also want to remind everyone when building a slab on grade, it is important to slope the existing soil away from the bottom of the perimter of the slab so that a "bathtub" effect is not created by the excavation for the slab/foundation.
RE: footing insulation
http://www.muni.org/services/departments/public/bsdhandouts/97ubcpublic.htm