"Rat Walls" 2

[kjkeiser]

OK, I have read everything on thickness of a slab for a light load driveway/garage.

And I apologize for the terminology; my Midwestern family calls it a "Rat Wall". Or a spade depth "footer" dug around the perimeter of a slab.

What I would like to know is the effectiveness of a "Rat Wall". If it is required how deep should I make it and is a spade width sufficient?

 

[Tryan]

A "Rat Wall" is exactly that,it stops rodents burrowing under a slab from the edges. They are effective if that's a problem in your area.The rodents burrow under and excavate big areas of fill from under your slab to make a "home", effectively leaving it partially suspended!If it is subjected to a heavy load in that area, then it may collapse!I would suggest about 18inches deep might be enough and dig it with your narrowest shovel {3 or 4 inch} and fill it with a weak mix of concrete as it is only a deterrent! Also make sure the top of the rat wall touches the edge of the slab and is continuous right around!

 

[kjkeiser]

Thanks for the reply;

I'm not so sure that it is a problem with rodents, I was looking at it more as a structural item.

While yes it is called a "Rat Wall" does it not add stability to the slab?

My father had a pad poured for a shop and they dug the "rat wall" and poured it and the slab at the same time.

Is there a problem with a continuous pour for this? Do I need it?

Thanks

 

[DTGT2002]

This would actually be more like a "turned down footing". It helps to confine the soil beneath the slab, as well as thicken the edge of the slab were the continuity is lost and the slab is subject to cracking due to the loading of the edge. it shoudl be a continuous pour.

As far as sizing the turndown slab/footing, it is not my place to design it for you. See if someone local can give you a size appropriate for your area and climate.

Good luck,

Daniel