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Expansive Soils & Floating Basement Wall

kkjim's picture

Upon moving to the Denver Metro area, from the East, I was confronted with some new (to me) framing techniques. Specifically, floating framing in the basement. This is to mitigate the effects of expansive soils (bentonite) Floating walls are regular stud walls about 6 inches shorter than usual, bolted to the floor joists of the story above, so the walls hang about 6 inches off the floor.  A 2 x 4 base plate is anchored to the floor. 8-10 inch spikes pass through holes in the bottom framing member and anchor into the base plate, keeping the wall plumb.  This allows the slab to rise and fall approx 4" without affecting the framed walls.  While this is common for this area, I have not been able to find any standards, guidelines, or methods of construction in print.

My job requires me to conduct on-site service calls for a specialty cabinet retailer.  Because of this, I am involved in the planning (& aftermath) of many basement remodels.

Of particular interest is the (apparant) lack of consideration for the mounting of cabinetry on these floating walls.  In many instances, I have witnessed the same carpenters who installed the framing, mount base cabinets resting directly on the floor, and screw as usual to the floating framing.  The framing must float to mitigate the vertical movement of the soil.  Imagine the impact to the base cabinets when the floor rises 3-4 inches, and the cabinets are mounted securely to the walls.

I have only happened upon 1 contractor who had a solution for this.  Usually I am met with blank stares.

I would welcome any input, from any source, of where I might find some type of "official" information on this topic.

(post #91770, reply #1 of 10)

You won't find your answer in my reply.  I am familiar with this type of construction as a friend owns a house 20 mi north of Denver and it is framed as you described.  Press on to find the answer so you avoid the inevitable wreck.  Seems like hanging the base cabs and letting the toe kicks float is the best way, but what a pain and how is it accomplished at a reasonable cost?  Maybe visit a large builder and see if you can get access to their engineering dept. for a discussion. 

You could set the cabs on the floor, attach to the wall via a slot in the back of the cabinet, don't caulk the countertop to the wall.

I wonder what the homeowners have experienced as far as the anticipated movement goes.  I heard they had some very bad experiences (replace foundations) in the Highlands Ranch area.

Gotta go plow 8"


(post #91770, reply #2 of 10)

accordian toe kicks? 


(post #91770, reply #3 of 10)

No problem. The cabinets are attached to the wall with sheetrock screws. When the floor moves up or down, the screws break off. Instant floating cabinet.

(post #91770, reply #5 of 10)

What happens if your floor is expanded at time of instalation and then shrinks?

(post #91770, reply #6 of 10)

It was a joke. The very idea of attaching cabinets to the wall with sheetrock screws gets some people here all riled up.

Sudden Linguistic Insight: I just realized that riled is a dialect pronunciation of roiled, just like the characters in the old westerns who pronounced poison as pizen.

(post #91770, reply #4 of 10)

Some places around my area my probles with expansive soils, but I don't think that they are near as bad.

Anyway I have heard that people that work in those places fix the wall to the floor and float the top to the joists.

Don't know if it will work out there or not or if you can get in early enough to have them change there practices.

. William the Geezer, the sequel to Billy the Kid - Shoe

(post #91770, reply #7 of 10)

No experience with this myself but if you work with a Log Home mentality, building a home that is designed to shrink then it would seem that slip joints would be the answer.  Doors, windows, walls, and cabinets are all built with slip joints… why not in a basement in Colorado???


(post #91770, reply #8 of 10)

Do you guys drive pilings under your slab for support? Because of the ground movement here thats what we do. 30' wood pilings for homes are the norm around here and we either can them for commerical or us concrete pilings on larger buildings.

busta :0)

(post #91770, reply #9 of 10)

So far the slot in the back is the way I recommend, although, as I mentioned ...I have only seen one contractor even give it thought.  The framing attached to floor joists is now a code issue in many municipalities in the Denver Metro area. 

Soil movement is quite serious...there have been many developments closed down, houses condemned, etc. here. 

I appreciate all the input from each of the respondents.

(And I must confess to the following...I too get riled at the thought of cabinets hung with drywall screws!)

Although drywall screws are the least of the "What were they thinking?" moments I have seen with local contractors.  There is very little regulation here in CO, and while this has many positives, I am involved in situations weekly with "fly by nights" and "jack of all trades" that leave me questioning what plane of existence some of these "professionals" came from.

While in line at Home Depot recently, I heard the best example of the rampant ignorance of which I speak...

A young tradesman in line caught site of the Taunton Press' kiosk of Pro Books with the slogan "For the Pros, By the Pros" prominently displayed.  He turned to his companion and said, (no joke/no exaggeration) "If that ain't the stupidest thing I ever seen...if your a pro like us, you don't need no dang book!"

That about sums it up. 

(post #91770, reply #10 of 10)

Try this:

Colorado Geological Survey, Department of Natural Resources, 1313 Sherman Street, Room 715, Denver, Colorado  80103     303-866-2611

Ask for:   Special Publication #43, A Guide to Swelling Soils for Colorado Homebuyers and Homeowners    by David Noe, Candace Jochim and William Rogers

I believe it was first published in 1997.  I don't know if there has been an updated version.

It gives details for walls as you describe and much more!

I'm about to build on swelling soils.  Wish me luck!

Average Joe:

I'll wait here while YOU go wrestle the wild alligator.

"Doubt is not a pleasant condition, but certainty is absurd."

~ Voltaire