Solid wood floor curving

[Christian Tag]

Hi everyone,

This is a chalet recently built in 2010 around Montreal. The concrete slab is poored on the ground (no basement). We have no idea what kind of insulation is put there between the slab and the floor. I've noticed as I was inspecting the house that the floor boards are curving (like a U shape). Its noticeable mostly if you look at the light reflection on the floor ... like a stair effect. The problem was present only on the main floor, not on the upper level. The electric baseboard were set at 19.5 C and I could feel the floor cold under my feet.

Do you know what could cause the floor boards to curve like this ?

Thanks for your help

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[Rick Cantrell]

Several conditions could make the floor buckle or warp, also depends on the type of flooring.
But my first thought would be lack of or improper moisture barrier between the slab and the flooring.
Next I would think that the floor was not given time to acclimate to the house before it was laid down.

[Garry Sorrells]

MOISTURE.
Is it an engineered floating floor? Click Lock flooring?
If not floating, could you tell if the flooring was glued down?
The type of flooring would lead to the exact cause as it is related to the installation.

The flooring material should have been a below grade use design to start with then it is about the installation. Also, how the slab was designed would have a large effect on the flooring installation and present problem.

[Scott Patterson]

That is called "cupping" and has only one cause, MOISTURE!

Several conditions can cause this and they range from an improper install (most common) to the home being vacant with no HVAC running in the home. This is a major problem with seasonal or weekend homes; folks cut everything off to save money and end up with problems like this.

Wet mopping can even cause it.

[Christian Tag]

I assumed its engineered foating floor since its laid on concrete. The seller doesnt know what kinda floor he has, is there a way to know just by looking at it if its solid wood vs engineered, or if its glued, nailed or click lock ?

[Scott Patterson]

I assumed its engineered foating floor since its laid on concrete. The seller doesnt know what kinda floor he has, is there a way to know just by looking at it if its solid wood vs engineered, or if its glued, nailed or click lock ?

You can tell, you just have to look close and know what you are looking at. Also floating systems sound and feel a little different when you walk on them.

[Jerry Peck]

This is a chalet recently built in 2010 around Montreal.

Curious as to what makes that a "chalet" and not a two-story house?

As the others have said: moisture.

Unless you are in permafrost land, I find it strange that they built a slab on grade because the frost depth must be quite deep there.

[Garry Sorrells]

Jerry,
A Realtor description makes it a "chalet".

Christian,
Usually determination of material and installation is by experience.
Finding an exposed edge can get you started as to what it is and how installed.
As Scott said a floating floor has a feel and sound to them due to movement. Springy with a soft clip-clop tone.

From pictures I would bet it is an engineered floor system. Some can handle moisture and others can not. The age of the house would suggest that the flooring can not be subjected to moisture.

There is only one real solution and that is to replace the flooring and determining the moisture source and how to best deal with it.

[Christian Tag]

Thank you everyone for your time and support !

Really appreciated !

[Jerry Peck]

A Realtor description makes it a "chalet".

Garry,

That was what I was thinking.

[Kristi Silber]

Looks like an engineered wood floating floor to me. The planks are wider than typically found in solid wood these days, and the edges are rounded. If it were solid hardwood it would have to be installed over sleepers to nail it down.

This is from a site about hardwood flooring:

"The most common condition causing cupping is the sub-floor having a higher moisture content than the wood itself. The moisture moves from the sub-floor into the drier wood flooring, leaving the bottom higher in moisture content than the top of the board, causing the bottom to swell more than the top of the board. The top is not swelling at the same rate as the bottom, leaving the top smaller and cupped.

An example of this condition would be a new construction home without heat or air conditioning when the floor is installed. The condition of new construction buildings are generally wet after with the sub-floor high in moisture content. The installers arrive to install wood that is drier than the sub-floor. The heat, or air conditioning, is turned on after the installation, drawing the moisture from the sub-floor into the drier hardwood flooring resulting in the cupped condition."

[Scott Patterson]

Looks like an engineered wood floating floor to me. The planks are wider than typically found in solid wood these days, and the edges are rounded. If it were solid hardwood it would have to be installed over sleepers to nail it down.

This is from a site about hardwood flooring:

"The most common condition causing cupping is the sub-floor having a higher moisture content than the wood itself. The moisture moves from the sub-floor into the drier wood flooring, leaving the bottom higher in moisture content than the top of the board, causing the bottom to swell more than the top of the board. The top is not swelling at the same rate as the bottom, leaving the top smaller and cupped.

An example of this condition would be a new construction home without heat or air conditioning when the floor is installed. The condition of new construction buildings are generally wet after with the sub-floor high in moisture content. The installers arrive to install wood that is drier than the sub-floor. The heat, or air conditioning, is turned on after the installation, drawing the moisture from the sub-floor into the drier hardwood flooring resulting in the cupped condition."

Kristi, what your wrote is kind of true.

The moisture barrier is what is suppose to stop the transmission of vapor from the slab/subfloor. You can have a good barrier in place and still have cupping.

Also you have to realize that only the top of the flooring planks are sealed and the underside is raw or unsealed. The wood sucks in moisture from the air in the room, if the room has a fairly high RH then you will also see cupping.

You do not need sleepers, they could also install a plywood subfloor/base and then nail into that. This is a very common install with slab construction. The plywood is actually nailed or ramset into the slab.

[Kristi Silber]

Scott, I didn't write that, it was a quote.

You do not need sleepers, they could also install a plywood subfloor/base and then nail into that. This is a very common install with slab construction. The plywood is actually nailed or ramset into the slab.

Yes, I thought about that after posting. You don't see a lot of slab construction around here. At any rate, you'd need something to nail into. I would think in Quebec it would be better to nail into sleepers to minimize conductive heat loss, but the point is moot.

[Paul Phillips]

Curious as to what makes that a "chalet" and not a two-story house?

As the others have said: moisture.

Unless you are in permafrost land, I find it strange that they built a slab on grade because the frost depth must be quite deep there.

Here in MN, slab on grade with frost footings is pretty common.
Some may say we live in permafrost land. But we do not.

[Kristi Silber]

Paul, where in MN are you? I see very few homes without basements in the Minneapolis area.

[Paul Phillips]

Paul, where in MN are you? I see very few homes without basements in the Minneapolis area.

New construction within last ten years in Hutchinson,litchfield, wilmar. How about all of the commercial properties.