Thread: FLOATING FRAME REQUIRED OR NOT

hey all
this is a wood sub floor----with crawl space below----cant find anything in code check to tell me if this finished basement frames should be floating--both pictures are the same flooring--ones painted fancy---it's sunday so cant call code department--thanks
charlie

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I'm not sure what you mean by "floating". Can you elaborate more on that? Why do you consider it a basement if there is a crawl space below it?

jim
i have a lower level---basement sub floor----wood =with access to a crawl space--access panel with humidifier-thermostat controlled fan below----my finished basement walls are framed to wood floor and are not floating {walls or framing} for adjustment for settling movement----should they be floating ----on concrete i know yes--but what about wood sub floors

Scratching my head with the same questions Jim has.

Charlie, most of the ones I see up here are not floating. The ones I see down in Colorado Springs, most are floating due to the more expansive soil there. I think it most likely depends on the soils report from that lot.


Floating walls are used here because of the expansive soil and the slabs heaving in differant weather conditions. The first one I saw it was like what the he88 is that. Sorry I dont have a pic, but basically there is a plate on the basement floor fastened, and another plate about 4"-6" higher secured with a long spike. The drywall is not attached to the bottom plate, it is attached to the higher plate. A wide molding is typically used, attached to the bottom plate so the wall can "float up and down" Weird, but it works without destroying the drywall, door frames etc.

Charlie, didnt notice the part about the wood floor. If anything needed to float I assume it would be at the foundation, and Ive never seen that. Only seen floating walls with a slab.

hey paul

thanks----most of the time with poured slabs--they are floating because of the settling threat---but was wondering about the wood sub floor---over the crawl space---dont know how to report it--yeah our soil sucks here---cant remember seeing it before---maybe will wait to call the permit code folks tomorrow----thanks for knowing what i was talking about
thanks
charlie

Those of you that think we are nuts here it is or google floating walls.

thats what i thought too----floating slab walls but not on wood---i'll see what the code folks say
thanks

thanks paul i was looking for that on google---sometimes the southern guys dont deal with basements or crawl spaces---but thats what this web is for---sharing our region conditions---life is learning everyday
charlie

Paul, Charlie,

???????

I'm looking at that drawing Paul posted and I don't see what is "floating"?

The walls are attached to the "foundation wall" (at least that is what it says) and that foundation wall extends down to the top of the "concrete floor slab" (which runs *under* the "foundation wall" ...

Okay, there is 3" of space to allow for movement of the slab, but ... ????

How to heck is the slab to move upward when the foundation wall is resting on the slab???

Now, I could see the need for that *IF* the concrete floor slab was floating "within" (not under) the foundation walls.

jerry
that photo is alittle misleading---there really is a spike that goes from the upper 2x4 into the lower 2x4---which gives the upper wall a little floating so when the slab heaves or moves--the upper wall doesn't rise and crack everything above it---i will look for a better photo---but it works around here---stay tuned---but i'm taking the rest of the day off
charlie

Jerry you are right, that picture is misleading. In order for that to work the slab would have to end at the foundation wall.

Normally what I see is the slab, and the exterior wall is wood frame. The other thing not in that picture is the spikes I referred to. Picture about a 6" spike driven into the bottom plate, the gap, about 4" and the top of the spike not being driven all the way into the upper plate. The spike head is a couple inches above that second plate. Thus the slab can heave up and down and the wall doesnt move because the bottom plate is sliding up and down on the spikes. Next one I see I will post a picture.

Originally Posted by Paul Kondzich

Next one I see I will post a picture.

Thanks.

That's wild. I'm not that far away from you, and I've never heard of that before. Our soil doesn't move much, so I guess that's why. It reminds me of some log houses that I've seen and the special things they had to do to prepare for the logs settling in after construction. At least that was all in one direction. That must create a few issues for the builders.

Still trying to get my head around it. So even if you have a basement slab, it would move up and down that much? I can kind of picture it on a slab on grade setup, but with a whole house sitting on a foundation wall six feet below grade, it still moves a few inches each year? That seems crazy. Glad I don't have to deal with that.

jim
thats why we are all on the web--it's great isn't it----even old marines like me learn something everyday----either paul or i will post a better picture at our next inspection--chow
charlie

What I'm still trying to figure out is why would you also need to "float it" at the top plate too?

If the framing is attached to the foundation wall, the wall should not be floating in relation to the framing above, which is setting on, or otherwise attached to, the foundation wall.

The slab, "floating within" the foundation walls, on expansive soils, yeah, there will be some movement ... but ... 3"-4" of movement? WOW!

jerry

welcome to the rocky mountains---either the earth below our 14,000 ft peaks sunk--or their arising--go rockies
charlie

Boy I wish I had a picture, all the ones on the web are not like we are talking about. Jerry disregard it being attached to an exterior foundation wall. Also Jerry when I said top plate I am referring to the plate 4" above the slab plate, not THE upper top plate at the top of the wall. Jim the footer, and foundation dont really move (here it could be block, or most likely a poured wall.) It is more the interior footprint of the basement. I suppose the reason for that is with a large slab, a little bit of soil movement is going to be transferred to a large piece of concrete. Also if their is a post in the basement, it is on its own pier foundation so if the floor heaves it does not move the post. There is also issues with gas piping, and solid copper plumbing because they dont like to move. When you see a picture you will say oh ok I get it now.

jerry-jim-paul

heres some photos of floating frame or walls----the last two are the better product----the drywall is nailed to the top 2x4 and not the bottom one---then molding can be added but again only attached to top 2x4---thus the wall can shift with movement---if nailed to base 2x4---wall cracks will show up all over the place---i have seen that---hope this clears up floating frames or walls
charlie

From what I know, and that ain't much! Colorado is the only place that does the floating wall trick.

Originally Posted by CHARLIE VAN FLEET

jerry-jim-paul

heres some photos of floating frame or walls----the last two are the better product----the drywall is nailed to the top 2x4 and not the bottom one---then molding can be added but again only attached to top 2x4---thus the wall can shift with movement---if nailed to base 2x4---wall cracks will show up all over the place---i have seen that---hope this clears up floating frames or walls
charlie

Is it really floating with those nails connecting the plates?

Yes David they do. Actually if you ask me it should be called a floating floor because that is what is actually moving. The walls are just built that way so they dont get damaged, also we should have said earlier, these are non-load bearing walls. But nobody asked me so they are floating walls.

Why don't they forget about those long spikes and just support the roof and wall framing with sky hooks? Colorado has great sking, but I'd rather live in stable California.

Let me get this straight ...

The only things holding that wall from falling forward due to the weight of the drywall are those spikes???

Yes Jerry. The spikes are at the bottom of the wall, the top is attached and constructed in a conventional fashion.

Originally Posted by Paul Kondzich

Yes Jerry. The spikes are at the bottom of the wall, the top is attached and constructed in a conventional fashion.

Paul,

Unless I read Charlie's post wrong, he said the top was also floating.

Which is why he said the framing was not attached to the foundation wall.

*IF* the top is attached in the normal fashion, then the framing could also be (should also be) attached to the wall as shown in that drawing.

jerry

no the drywall is installed as usual-- nailed at the upper 2x4 where the spike head is--but not at the bottom 2x4---so if there is movement the lower 2x 4 will move up into the spike and not cause wall damage---thats why they say floating----still looking for a photo about what i'm saying-----is that a better view

After going back and re-reading the posts, my understanding is this:

- The top plate of the framed wall is securely attached in place.

- The framing of the framed wall is securely attached to the foundation wall.

- The framed wall is framed with two bottom plates:
- - one attached to the framing in the framed wall
- - another attached to the slab
- - the space between the two bottom plates allows for up and down slab movement
- - a trim piece (baseboard) is nailed to the bottom plate which is attached to the slab and moves up and down over the wall above it, concealing the space between the two bottom plates

Which means the only problem with the drawing Paul posted is that the slab continues under the foundation wall and it should stop within the confines of the foundation wall.

How's that?

jerry

yes --paul photo was not exactly what we are talking about----the moving spikes were missing----my third and fourth phots is the real thing--hope that makes it a little clearer----the buildong world sure is interesting isn't it---i will try hard to find a web site to help understand the moutain moving states---to jerry mccarthy---are u saying things are solid in the golden state----gotta love those fires and mud slides and lets not forget EARTHQUAKES---give me 300 days plus of sunshine and golf and great skiing

Hi Charlie,

Just got back from Breckenridge and came across your question here. Interesting discussion.

Just in case you still need it, to answer your original question: NO, floating wall construction is not required on top of the plywood basement floor you were looking at.

For all you guys who live on stable ground, this is referred to as a structural basement floor. Due to the expansive soils located in various pockets throughout our Colorado Front Range, these floors are built with wood joists in an I-beam system attached to the foundation, and a liberal space between the soil and the floor joists. It is usually not fully accessible as a crawl space. The foundation itself is usually supported on piers down to bedrock or 0 resistance, whichever comes first, as provided for by the engineer.

The humidistat you saw, Charlie, is there to control a ventilation fan that is supposed to keep the "crawl space" dry and the wooden floor and joists from rotting. These underfloor areas are highly prone to moisture damage due to "wood destroying organisms". Always check the humidity down there and look underneath, even if you've got to use a mirror or your camera to do it. Many of these fans have failed or were never installed in the first place. Richmond Homes has replaced quite a few of these floors (foundations too) under warranty in a huge subdivision called Rock Creek, all built, largely improperly, on expansive soils.

Re the walls: I think you guys now all have the hang of the floating walls that are necessary when a basement slab is used. These slabs are always poured in-board of the foundation walls and can move up AND down, up to 6" depending on moisture content of the soil; Another reason that proper grading & drainage is so important. The base trim is attached to the BOTTOM plate only. And yes, all posts are separately supported along with the use of flexible connections at all plumbing & gas lines. These slabs can only be used where the soil test shows the coefficient of expansion is minimal. Otherwise the foundations are supported on piers & bond beams, etc. as above, depending on the engineered design.

The primarily bentonite clay in the soil is actually mined & packaged as pellets for use in sealing around well casings. Just pour it in the outer cavity and it expands and seals when it gets wet. Just like freezing your engine block tho, when it works on a foundation. Improperly framed basement walls on slabs can crack the house all the way to the roof. Beware of remodels or owner-finished basements!

Oh, by the way, the improved method of floor construction is concrete supported throughout by its own piers and LOTs of rebar. Lots of $ too, but no more rot. Also makes for easy built-in passive radon ventilation.

Hope this helped a little,

Ross
Morgan Inspection Service
Niwot CO

ross
hope u didnt break a leg---i'm well aware of those humistat fans--have crawl around many crawl spaces in rock crack--i mean creek----funny how we here in colorado have invented the floater--was surprised to here about they being unknown in other areas----have had many realtors claim they dont need radon tested because they have a mitigation fan---the humistat---sometimes its hard convincing them of the difference---the are blind
charlie

Ross' post confuses me even more.

First, there is this structural basement floor which is attached to the foundation walls with clearance to the moving-up-and-down-soil below it, thus it is 'fastened in place and not floating'.

Originally Posted by Ross Morgan

For all you guys who live on stable ground, this is referred to as a structural basement floor. Due to the expansive soils located in various pockets throughout our Colorado Front Range, these floors are built with wood joists in an I-beam system attached to the foundation, and a liberal space between the soil and the floor joists.

Then Ross continues with a floating slab ...

Re the walls: I think you guys now all have the hang of the floating walls that are necessary when a basement slab is used. These slabs are always poured in-board of the foundation walls and can move up AND down, up to 6" depending on moisture content of the soil; Another reason that proper grading & drainage is so important. The base trim is attached to the BOTTOM plate only. And yes, all posts are separately supported along with the use of flexible connections at all plumbing & gas lines. These slabs can only be used where the soil test shows the coefficient of expansion is minimal.

Or ...

Is Ross saying both types are used depending on whatever factors come into play? Such as: cost; soil expansion; etc.?

If that is the case I understand:

- Wood floor system used for basement floor to allow for soil movement below without affecting the floor above.

- Slab on expansive soil will move up and down, so the walls are not floating, just the bottom bottom plate and the trim (base) floats with the slab. Those spike are not going to keep anything aligned, so you might as well just let the trim cover the bottom of the wall above without bothering with those spikes.

Sounds like it would be better (at least easier for me to understand the concept) for the house to just run piers down to bed rock and support the whole place-- or use sky hooks as Jerry said

Hi guys,

Charlie, I did make it back with both knees intact, thanks, but the slush at the bottom nearly got me! Spring skiing's always fun.
Figured you must know about the problems at Rock Creek. Misread, tho, & thought you were asking about the humidistat too.
And yeah, I've had realtors mistake (?) those fans for mitigation systems. Some will pretend anything to avoid part of an inspection. Besides that, I always recommend testing even if a radon system IS in place. Found one just the other day that was running but not functioning due to a blockage under the vapor barrier in a dirt crawl space. 14.0 pCi/L in the finished basement.

Jerry,
Didn't mean to confuse you...I guess my post was pretty long. Sorry. But it sounds like you talked your way through it in your last paragraph. You got it now: 2 different systems.
Except that the spikes do need to be in place to keep the bottom of the wall from kicking out. They're pretty sturdy & need to be installed plumb to the world. The tall base just covers the gap but won't cover horizontal displacement...could even get torn off.

Brandon,
Til we perfect the skyhook, yuk yuk, that's exactly what they're doing in the homes with the structural floor: The whole foundation sits on piers. The ones with the floating slab will just have a conventional footer. And sometimes they get cracked.

Last but not least, I'm remiss in not acknowledging in my first post that Paul had it right all along on the floating slabs & walls. He knows what he's talking about. Just didn't seem like it was clear to some of you.

Cheers, Over & out for tonight,
Ross

Ross I thank you for your opinion of me, I have only been inspecting in Colorado for a couple years, before that I was in S.W. Florida where the inspections were a piece of cake compared to here. I see you only have a couple of posts so I feel that you will find this site invaluable. As you go along here you will find that the time that Jerry Peck puts in here that helps so many people is priceless. I have never posted a question that Jerry has not had some input on. When this question came up about our strange little piece of the world, I found it refreshing that I was trying to explain something to Jerry for a change. I suppose I didnt go into enough detail etc. Anyway Ross welcome aboard and if you are ever in the Colorado Springs area I would be happy to let you buy me a beer...

Originally Posted by Ross Morgan

Didn't mean to confuse you...

Not to worry, Ross, I'm easily confused.

Except that the spikes do need to be in place to keep the bottom of the wall from kicking out. They're pretty sturdy & need to be installed plumb to the world. The tall base just covers the gap but won't cover horizontal displacement...could even get torn off.

But ...

*IF* (and they should be) the bottom bottom plates are secured to the slab, how can those bottom bottom plates be displaced? Unless the slab moves horizontally, which can't happen as the slab is confined within the foundation walls??

The only way I see the spikes being necessary is if the bottom bottom plate is not attached to the slab, in which case the bottom bottom plate would have nothing to 'pull it down' once it had been pushed up.

Even with those spikes, if the bottom bottom plate comes loose (which seems to be the only what that the spikes would be needed), then the bottom bottom plate would float free from the slab and remain at the highest level the slab pushed it up to.

You guys are not through explaining yet, you've got more to do to get it through this dense head of mine why those spikes are needed.

Thanks Paul. I've enjoyed seeing all the posts from folks all over the country. If I get down to the Springs I'll give you a call. And yes, I've noticed that Jerry is everywhere!

OK Jerry, I'll give this one last try. Take a look at this photo: Floating Wall Detail.jpg

Imagine an interior wall hanging only from the ceiling structure, except for its "floating" attachment to the bottom plate by the spikes.
The "bottom bottom" plate is nailed & glued to the slab and will always stay with the slab.

Without the spikes, the top plate and stud attachments to it would act like a hinge.

The spikes are all that keeps the wall from kicking out at the bottom, above the "bottom bottom" plate.

If they weren't installed plumb, then as the floor moved up it could cause horizontal displacement as the "upper bottom plate" has the spikes driven through it. It has to follow the direction of the spikes!
It would probably be minor, but possibly enough to crack the drywall finish at the joints or cause a gap where the base trim covers the drywall.
Remember that the extra-tall base trim is attached only to the "bottom bottom" plate.
It slips up and down on the drywall.

Whew! Gotta take a break & go hang out in a crawl space...something easier. I'm agonizing too much over editing these posts. Its hard to know how they'll come across. Took me 20 minutes just to download & figure out the dang spell checker!

Cheers,
Ross

Morgan Inspection Service
Niwot CO

Ross,

That's an interior wall, which is different than that shown in the drawing which was posted (which was of a framed wall attached to the foundation wall).

Which is why I asked and made reference to (several times) about it being attached to the foundation wall.

'Free standing' (er, 'free hanging') interior walls, yes, I understand that, but my question (which should have been clarified by me, but we were discussing framed walls attached to the foundation wall, so I understand it in my mind) was regarding those walls framed and attached to the foundation walls ... as in the drawing which was posted.

OK, Jerry,

Sorry I forgot the part where you were asking about "attached to the foundation wall". Seems like so long ago. We've been talking about several systems here and I guess I lost track of your original question, in my effort to address Charlie's first original question (which confused this and the other system), and then explain the rest and the reasons for em.

That drawing was out of whack so I'd kinda discounted it. In that case the wall itself is stable and I guess the spikes would be optional, but most guys use them throughout anyway. The double bottom plates are still always used to allow for a base trim that will float with the floor. If its a floating floor.
Just like Paul's first post.

Ross

Morgan Inspection Service
Niwot CO

Jerry,

P.S. I guess I must've thought that you were missing the point about most of the consideration for the spikes actually being for interior walls & had gotten hung up on the wall attached to the foundation because of that illustration. Sorry I didn't answer that part more directly in the first place.

Ross

Originally Posted by Ross Morgan

had gotten hung up on the wall attached to the foundation because of that illustration.

I missed the part where we stepped away from the foundation walls and into the middle of the room. No wonder you were so far away and I could barely see you.

Hello everyone.

Does anyone know how much of a gap should be between your baseplate and the bottom of the frame? I've heard 3in, 4in, 6in?!?!?! Does anyone know what is required by code in Highlands Ranch, CO?

Thanks

Originally Posted by Jeff Siebert

Does anyone know how much of a gap should be between your baseplate and the bottom of the frame?

I would think that the only answer to that is: "Depends on where the ground is at the time."

Would you want 4"-6" when the ground was in the up position?

Or when the ground is in the down position?