Walkout basement and Footing Protection
user-223434
| Posted in Construction Techniques on
I am currently looking at a basement completion project that that Iwill need to remove a 5 foot wide window and install a 5 foot garden door
The properties landscape lends itself nicely for such a walkout however I will be needing to remove 40″ of soil to meet with basement floor level and I am concerned about frost protection at the footing
I am not sure of how to insulate the footing from frost
Inclemently I will be able to provide natural drainage to rear of property and have sufficient fall
Any Ideas Folks
Replies
I don't know what part of the country you're in but here in the midwest, frost line is 42" below finish grade. Removing 40" of grade removes 40" of frost protection in the midwest. Are you removing this just infront of the "new garden door" or for a good length on both sides of the door? Do you have to add some perpendicular retaining walls to hold the adjacen grade you are leaving?
Here in the midwest, you'd be exposing more to the freeze thaw cycle and you might expect the garden door to not open and close properly year round. A sharp plan reviewer should catch this and require you to excavate and make a foundation and footing at this area reach down to frost. Remember, the grade at the new door sill is the new finish grade at this point.
I hope you're not in the midwest.
Google "Frost protected shallow footing". Essentially, this is a code recognized method of insulating the ground outside of a footing to prevent it from freezing. Unless you're in the Yukon, you'll likely be able to address the problem in this way.
Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
Thanks Andy
Yes there wiil be two perpendicular retaining walls one foot or so on either side of garden door
I have done some research on shallow footing insulation but I am not sure to place the insulation, do I place directly under the door and two feet or so out from the wall, and how far past and beyond the retaining wall
I am located in Niagara Falls Ont.area
Maybe Piffin will step in here - I think he's actually done these. My knowledge is theoretical.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
Don't forget that there may also be a draintile outside of that wall that may be just above your new door sill height.
Yes I have considered that, I would hope that the top of the draintile would be at the same level as the top of the footing footing or just a few inches below surrounded in gravel
1/ Any ideas as to how far the insulation should extend from the foundation wall and out into the excavation ?
2/ How far either side of the door opening should it extend ?
How much insulation and where it goes is detailed in the pdf file I linked to earlier.
Beer was created so carpenters wouldn't rule the world.
Piece of cake. Essentially a frost protected foundation uses ridgid foam to keep the cold from penetrating the soils as easily and effectivly raising the frost level.
It's common in european countries and is just getting more popular in the colder US states. In SE Wyoming our frost lines were from 48" to closer to 60" in some windy/rocky areas. With a frost protected foundation we could use 24" walls, saving a bunch on excavation, forming and concrete.
A few houses we built were on dead flat country so all we needed to do was scrape the topsoil off and start building. Backfill was brought in to raise the yard slightly and provide the typical 18" of coverage. We'd always install foundation drains since the footer is so close to the surface.
It's an easy concept and the following link will give you everything you need to know. It's essentially the design guide that is available from many other links, but this seems to be good quality.
http://www.cs.arizona.edu/people/jcropper/desguide.pdf
Beer was created so carpenters wouldn't rule the world.
In Ottawa, where the frost depth is 5'-0", we went 3'-0" both ways.