When you first heard of a floating wall, you went “whaaat”, right? That’s how I felt, and I couldn’t comprehend what a floating basement or a floating wall really meant, let alone why someone would need one.
Floating wall is, as the name suggests, floating, but not wobbly. Its frame is essentially nailed to the joist and the bottom plate is nailed to the floor. The frame and the bottom plate have a minimum of an inch or 2 inches in between. To secure and stop the frame swinging a pin is used to secure the bottom.
The reason why you are here makes me think you are in an area with expanding soil. You are likely from Colorado. Or you became so curious to know all about the floating wall.
You have a lot of questions running in your mind, I guess.
Why someone would need a floating wall?
How to build a floating wall? How to secure the drywall to a suspended frame?
How will the bottom plate be secured in place?
How to put a door or window if you have a floating wall…
…and on and on…
I get it.
Here’s a detailed guide that will answer all, if not most of your questions.
I was as curious as you are, if not more, in knowing about floating basement walls.
However, I am being honest here. I didn’t do one myself, and where I live its clay soil that doesn’t expand.
So, I didn’t have a need for one, so I haven’t done it myself.
All I am trying here is to talk to a couple of carpenters who have done it.
Then compile and give you the information needed to tackle if you are in that situation.
What is a Floating Wall?
No, I am in no way talking about building a wall like one in the above picture.
But in the grand scheme of things the idea is the same.
Curious to know where this was shot – It’s an abandoned building in Japan.
Floating walls are designed so that the basement floor or the concrete floor can move a little bit without moving the wall. Up and down and still not have an impact on the walls.
If you are in a high moisture area and a type of clay soil it happens. You can allow the floor to move a little bit up and down without damaging the rest of the house.
Without pushing the walls and buckling the drywall, pushing up on floors and that sort of a thing.
Basic idea is that you frame your wall – as usual. The difference is this.
It might be tight to the ceiling and have at least an inch of gap between the floor and the bottom of the framing. It varies between 1″ to 3″ inches.
First, you attach a plate to the bottom of the floor – a pressure treated one, as per the code.
Then you build your wall frame as usual, but an inch or 2 inches shorter than it needs to be.
After that, you attach the wall to the ceiling so that the frame is floating. So, there is a space between the two plates.
The bottom plate (pressure treated on the floor) and the bottom plate of the frame (that’s suspended in the air). Then we use a nail to secure both the plates. Usually, a #60 D or larger nail is used as the pin to secure.
That nail keeps the wall from wobbling back and forth. Otherwise, it will be swinging around and moving around at the bottom.
Once you get that nail, it is going to be super solid. You must have one nail every 16 inches apart.
That’s the basic concept. We see this a lot in the expansive soil areas such as Colorado.
Floating walls are usually your interior walls.
Your exterior walls will be usually a normal wall, from ceiling to floor (concrete blocks or poured in concrete).
If the exterior walls are moving up and down, then you might have other issues.
Why Do I Need Floating Walls in My Basement?
But that begs to ask an even bigger yet important question.
What kind of soil do you have in your area? And do you see any movement on the floors?
Usually, the answer is an expansive soil and a dripping bedrock.
It might not be sudden but over time you will notice the movement. If you have a normal construction on these kinds of soil, you will also witness cracked drywall.
Sometimes, the drywall bows, bend and crack. You might also have your window and such sticking up and out of shape due to the movement.
And for all you know, it might be Code to install a floating wall.
Why are floating walls framed in Colorado?
Because the Colorado soil is known to have a lot of Bentonite in the soil. Bentonite swells with moisture.
So, all the dirt under the house will swell when it’s frozen or when it sucks moisture. That, in turn, lifts the floor up a little bit. Up to an inch of floatation is not unreasonable.
Engineers will be involved when the soil test reveals Bentonite in the soil. If that is the case a floating floor and a pier-based foundation will be suggested and constructed.
If your house has this issue (if you are in this area) and is built like any other normal house, then you might have other structural issues too.
In any case, you should try to get a floating wall for all interior walls from worsening the problem.
Do not use the wall that you build as a load bearing wall. It should technically hold the drywall doors and trims in place, and that’s about it.
What is a Floating Basement?
Floating basement is a loose term used around.
The pier foundation is built first, and the house is constructed on the pier in an expansive soil. If the soil moves, the whole house will move with the pier.
Which is totally fine – that is what is expected.
However, the basement floor is a slab that might be independent of the house.
It’s not a bad idea to hide the floating wall with shelvings like the above.
How do I frame a floating wall?
What you do is build the frame on the floor and then try to secure it in place.
Then following it by pinning the frame to the floor plate so it doesn’t swing.
That’s the 50,000 feet view of the process. So, that’s the quick gist, but let’s see the construction process in detail.
Step 1. Measure and mark the wall position
First, snap a line on the floor and then another line on the ceiling – joist area (exactly on top).
Make sure that the walls will be plumb once you put it in place.
Step 2. Fix the bottom plate to the floor
Then get the bottom plate set and nailed to the floor.
Make sure to nail and secure the bottom plate where you made the chalk line.
Since you are building the rest of the frame, you will have to use the chalk line to be absolutely straight, level and plumb.
Step 3. Build the wall frame and drill holes
Now build the wall frame in section. Frame the wall on the floor and get it to the rough desired location where you want to erect.
Then you need to drill holes between the studs go. Make sure the holes are straight up and down.
Step 4: Get the spacers cut (for ease)
Then what I do is this. Get a few pieces of lumber that match the size of the gap (a little small) that I am allowing.
Let’s say I am aiming for a 1 ½ inches gap floating wall, then I will measure and cut a few pieces of 1 ¼ lumber to use as a spacer (think wedge or shims) at the bottom.
This helps to lift the frame and the top plate comes pretty close to the ceiling.
The ¼ inch gap is so you can lift and swing it in at an angle, if needed, and still not tight when working.
Step 5. Align the frame and nail it to the joist
Now align the top plate of the frame with the chalk line you snapped earlier.
From one corner of the wall, try to nail it using your nail gun. While nailing, hold the studs and give a push to the ceiling and nail them.
This is to ensure you have a tight connection between top place and joists.
After this, you can remove all the 1 ¼ inch shims or wedges you used at the bottom.
Step 6. Drive the pin between frame and bottom plate
Now if you have the holes drilled correctly and the same size as the diameter of the nails you are using, your job will be easy.
You want the nails to be sitting straight to allow and accommodate the up and down movement.
Insert the nails in the predrilled holes and hammer it into the bottom plate sitting on the floor.
You want the nail to be loose on the frame and tight on the bottom pressure treated plate.
And get the nail a few inches taller than the top of the frame so it allows the movement and still keeps the wall secure.
Remember to fire block or firestop. This is important as it is per code in several jurisdictions and you will fail the inspection if you don’t have fire blocking in place.
Sprayform is probably your only options because you need the movement and can’t have a solid structural product.
Step 7. Drywall, baseboard, and finish.
Now when your drywall this wall, you need to drywall the frame and leave an inch off the floor and not secure it to the bottom plate that is sitting on the floor.
That is what we are trying to prevent from building a floating wall – buckling.
And use a tall enough baseboard to hide the gap between the two bottom plates.
Make sure to nail the basement board to the bottom plate and not to the drywall or the wall frame in any way.
Prehung Door in Floating Wall
This is tricky and needs a sound understanding to pull this perfectly.
Let’s see how.
The main idea is to let the door and the frame float.
To do that, you need to nail the door frame to the bottom pressure treated plate.
So, the wall will be floating, and the door will not be nailed to the frame.
Technically It will be nailed but that should allow for the vertical movement.
What you do is this.
Leave a gap between the frame and the wall stud (2 inches gap) and then use a long nail to secure the frame from falling.
This gap will be enough to flex the nail and have a vertical movement.
You are only nailing to the studs just enough so it’s not falling out.
You are thinking how is this going to keep the whole door from not falling right?
It wouldn’t be super solid, but you need to friction fit the frame to the studs.
Don’t nail the king and jack studs.
This is very important.
Make sure to leave the same gap above the door frame. Between the cripple stud and the door header.
This will allow the same amount of space for movement without any issues.
There are a few methods you can use. Here are some
Keep the door frame tight. Nail it to the bottom plate.
Provide a 2-inch wide gap between the door frame and the wall stud and nail the frame on the side to keep it from falling.
This allows for vertical movement as the nail is not fastened tight.
King stud and jack stud.
Do not nail the king and jack stud. Keep it tight or have a gasket in between them.
Nail the jack stud to the bottom plate. Jack stud header must be treated as the bottom plate.
Leave a 2-inch gap between the bottom stud (below cripple on the frame) above the door and the header jack stud.
Now drill a hole in the bottom stud of the frame above the door and drive a pin into the header jack stud. (this implementation is exactly as the frame and bottom plate is nailed)
Make slots in studs
That will get everything out of square and crunch the frame, break the wall etc.
Now to get away with it, door frame will have slots cut and bolts used instead of nails.
We can make slots in the frame. Vertical slots for the same thickness of the screw diameter.
The vertical slot height should mimic the gap left between the wall and bottom plate.
Make holes in the jack stud and leave it into the slot on the king stud and bolt it. Tight enough that it can move the whole frame up and down, but not wobbly.
This is by the best solution I can think of.
How to Build a Floating Wall with Metal Studs
In fact, in Canada wood studs are outdated and simply laughable to be used in basement framing.
Metal studs are the norm, however in the US wood studs are still used for the basement.
Basement is a moisture ridden place and a metal stud is much better for several reasons.
This is a special case and not many have done a floating wall using metal studs.
Slip track is probably your solution.
There are deep leg tracks built for this reason.
First, get the regular track at the bottom and a deep leg on the top.
Then you fasten the metal studs to the bottom plate. Make sure to drywall on the studs and leave the top plate as is. Do NOT screw on the top plate.
This will allow for any movement as the studs slide up and down.
There you have the exact method used by professionals to build a floating wall.
The frame and the wall as a whole technically are hanging, suspended in the air.
Reason for this, as we saw earlier, is to accommodate any movement in the floor (soil) below.
Soil with Bentonite tends to soak up moisture and expand. So, when you have an expansive soil, the floor moves with it.
That will break, bend, curl the wall and frame and crack the drywall.
Hanging frame allows for the expansion without disturbing the wall. In any case, you should not have a load bearing interior wall to achieve this.
If you are curious like me, you learned something new today.
But, if you are in an area with this issue, you just saved yourself a big headache. Now you know how to fix it once and forever.