Frost depth
Frost depth
(OP)
What happen if you cannot achieve frost depth on retaining wall. Can you put helical piers underneath the wall to counteract lifting from the frost? How do I know how much I need?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
Download nowINTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Frost depth
RE: Frost depth
RE: Frost depth
RE: Frost depth
RE: Frost depth
RE: Frost depth
DBM
RE: Frost depth
Also, bear in mind that when specifying insulation it must be a bearing type insulation, AND that you must insulate in order to acheive a "thermal path" not less than the depth of the frost line. And a good rule of thumb for the thickness of insulation required is 1" = 1' of soil cover. Thus, since in your case you have a frost depth of 4', with your footing having 1' of soil cover, you need to provide min 3" of SM rigid structural load bearing insulation that extends out 3' from the face of your footing. Also remember than your retaining wall should not be considered capable of protecting the founding soii from heave. That means that you need to extend the insulation back into the soil being retained or up the inside face (which is more typical) of the retaining wall in order to ensure a 4' thermal path.
Two products come to mind immediately: DOW Chemical's Styrofoam Highload series and Owens Corning's Celfort series (I believe this is the Canadian trade name, and that OC has another trade name for the product in the US). Remember that all of these products must be protected from any medium and long term exposure to sunlight, since UV rays degrade them considerably. Typical details of how to go about using them are available both from DOW and Owens Corning.
I can draw a sketch and post it if you like, as I have done designs like this numerous times.
Hope that helps,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: Frost depth
RE: Frost depth
Don't underestimate the effects of frost. I have seen the framing of a 2 story building raise about 3" when the basement area collected water during winter construction.
RE: Frost depth
RE: Frost depth
RE: Frost depth
I can understand the COEngineer's client not wanting to approach the neightbour. Not everyone has people adjacent to them that you can approach, unfortunate as that may be. I've seen one (admittedly extreeme) situation where approaching the neighbour caused unbelievable head-aches. The neighbours employed a surveyor to monitor and guarentee that no "transgretions" (sp?) occured... Unbelievably difficult people.
I agree with CarlB regarding placing the foam above the footing... That typically saved you from having to use one of the higher load bearing grades. I would, however, point out that the need to insulate the back end is very sensitive in this case, as you need to ensure that there is a sufficiently long thermal path. All while bearing in mind that you can't assume the concrete to be providing any protection. What I'm getting at is that penetration around your insulation and through the footing to wall interface is an issue.
Regards,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...