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Wow, leveling a subfloor is not very hard!

This blog post has consistently been one of our most popular, because we talk about how we tried to avoid leveling a subfloor and the moral of the story is:

We should have leveled the concrete subfloor at the outset - it was so easy and the results were great!

2024 Update: 5 years Wiser; We added words of wisdom to the bottom of this post! Scroll for more.

In the past, why did folks avoid subfloor prep?

With traditional flooring options - like solid hardwoods and engineered flooring - materials are permanently installed using nails & glue and preparing the subfloor for these installations can be a nightmare. 

Take for for example a flooring renovation where a house has settled on one end so that one side of the flooring project is several inches higher than the other. In this case, if you need to nail or glue down your flooring materials - you probably have a long road ahead of you.

Permanently installed materials require complex certifications because installers must be trained to lay planks evenly on a perfectly flat surface with known expansion joints. Skipping the subfloor prep step can have disastrous consequences.

In this case, you would and should -- at minimum -- consult an engineer or a contractor; you might need to creatively shim your plywood; and you might even need to jack up the beams that support your floor. If your subfloor is concrete, it is even more complicated... See why folks avoid it?

Property OwnersAnd, Steller Floors are fundamentally different

Steller Floors are not permanently installed. Our patented assembly system attaches plank to plank to form a continuous sheet instead of plank to subfloor - which means that our flooring can float above most continuous flat subfloors. We simply require no deviations greater than 1/8" over 8-10' including compliance.

Our Steller Floors flooring planks are also produced with exceptionally high quality so that they self-straighten as you install them. So, while a traditional, permanently nailed or glued down assembly might accidentally start forming a curve during installation across the subfloor, a Steller Floor will tend to correct itself. 

With no nails or glue to worry about, and no sleepers required - plus no need to be concerned with perfectly level subfloors -  our high-quality, real-wood Steller Floating Floors can be installed over subfloors remediated with simple liquid leveler - which is easy. 

Read our own subfloor prep story from summer 2019 below!


Our Steller Subfloor Leveling Story

I'd like to start by admitting that everyone makes mistakes, and our team is no different.

So, here comes the confession: when we installed demo floor in Summer 2019 at Penn State's Innovation Park, we figured that the subfloor was a professional pour, and it would probably be fairly flat. In retrospect, we obviously should have checked! In reality, the subfloor was DEFINITELY not flat.

Instead, the subfloor was crowned in the middle, and had dips as big as a 1/2". We learned that our very flat flooring boards can bridge some subfloor imperfections, but over a 1/4" and you'll get some bouncing and light creaking noises. Lesson learned: follow your own subfloor specs, Steller Team!

One piece of good news was that since our floors don't require glue or nails, fixing it wasn't going to be expensive or time-consuming.

Since the space is used as a conference room during the week, we had to quickly fix the problem over the span of a weekend, and we wanted to cause as little disruption as possible.

So, on a Friday evening, two of us took 45 minutes to remove the whole floor from the room (275 sqft) and we arranged the boards in the hall according to their original location in the room.

Figuring out how bad the subfloor was

We had an idea of where the problem areas were based on how the floor behaved, but we wanted to know exactly how bad the subfloor was.

To measure the dips in the subfloor we rolled a straight, 5' long 1/2" metal pipe on the floor to find the peak (which was in the middle of the room). Then, we laid the pipe out with a level, and measured how many 1/16" washers we could fit under the pipe.

Areas that needed more than 1 washer needed to get leveled - so we marked those areas with permanent marker on the floor.

How to level a subfloor—what we found

That evening, we did a quick crash course in liquid floor leveling (because we are not contractors, we are wood products nerds). Evan had worked with concrete during his time in AmericCorps, but we wanted the floor to turn out well, and not need to be ground flat (which would create a ton of dust).

So, we studied up here:

Using liquid levelling compound - Our experience

On Saturday morning, we gathered our materials and followed the directions on the bag to maximize the amount of water in the mix. For us, the first pour was probably not mixed well enough (maybe 30 seconds more mixing with the drill would have made it better), so that first pour accidentally created a slight, 1/16" crown where there used to be a dip.

We figured out that the mix should seem very much the consistency of pancake batter, and you will need to physically push it around to get it level. We dragged our 5' long pipe across it, but it would have been nicer to have an 8' long pipe on hand. Luckily, the second two pours went much better than the first. The leveler did cure pretty quickly, and within 15 minutes was at the point where you wouldn't want to mess with it, because at that point you could create more problems than you can solve.

We rolled in a dehumidifier to make sure any water from the mix that ended up in the air was removed, and we let the concrete set up overnight. On Sunday, we came back to find a nice level subfloor that deviated no more than 1/16" over a 5' span (approx 1/8" over 10'), and we reinstalled the moisture barrier (6 mil poly) the 275 sqft floor in about two hours.

After the subfloor was repaired, the Steller Hardwood Floor doesn't move underfoot, and as the floor settles into its new position we expect a light snap-crackle pop for a week or two, but with use and weight on the floor, it will settle in. As we continue monitoring the floor, we will keep an eye on the humidity in the room to make sure it isn't too wet or too dry. Plus, at some point soon, we also expect to get some neat removable baseboards (made by the James Wood Company) installed to complement the floor!


2024 Update - 5 Years Older & Wiser

Now many moons older and wiser, Britta & Evan have now been through many more Steller Floors installations over both plywood and concrete subfloors than we can count. Here are some pieces of wisdom we have learned about subfloor prep over that time that we can officially share!

Liquid Leveler is still the best option

As Steller Floors have grown in popularity, we have heard of many, many ways to level subfloors but by far, the best way is by using liquid floor levelling compound. It is the fastest, easiest, most cost-effective solution in the bunch. 

DIY is very easy, but its cheap to have done

If you are brave or a capable home renovation expert, liquid floor levelling compound should be no problem whatsoever. However, because it is so easy, it is also very, very low cost to have done by a carpet or flooring supplier in your area. 

Get it Done - You'll be happier!

You should always remediate your subfloor. Folks always worry that remediating their subfloor will be difficult because of the horror stories they hear. Especially if you are getting a Steller Floor, please, please, please remediate your subfloor.

It is easy, cost-effective and fun to use subfloor levelling compound if you need it - and you will be much happier with the outcome in the end.