The Importance of Humidity and Your New Floors

Everyone that has lived in Michigan for any period of time knows that there is a LOT of humidity here. When it comes to hardwood floors, humidity is a big issue.

When you hire us to install and/or sand and refinish your hardwood floors, you will notice that we put a lot of effort into getting the humidity and moisture content in your home just right, before we start working. This allows us to create the best environment possible so we can do a professional job of restoring your floors.

But… one of the first things we notice people do right after we finish restoring their floors is to turn off the air conditioning or dehumidifier in the summer or crank up the heat without using a humidifier in the winter.

We would like to explain why this isn’t a good idea.

First – Why Humidity is an Issue

During the humid summer months, your floors draw in moisture from the outside air causing them to expand. When they expand excessively it causes major problems like buckling and crowning.

In the winter the opposite is true. As cold outside winter air enters your home and you warm it up, which dries it out, the relative humidity of that air will drop considerably. This will draw the moisture out your hardwood floors and they will shrink. This can cause large unsightly gaps, loose boards and sometimes annoying squeaks.

Neither option is good for the aesthetics or health of your floor.

The solution in preventing both issues is to balance the range of humidity in your home throughout the year.

In Detroit, a range of 35 to 50 percent relative humidity in your home is ideal.

How to Maintain Proper Humidity Levels

Below are four suggestions to help you maintain balanced humidity levels in your home so you can avoid these issues…

1. Suggestion 1: Buy a Hygrometer

A hygrometer is a device that measures the amount of relative humidity (RH) in the atmosphere. We strongly suggest investing in one. You should be able to pick one up on Amazon.com for under $25.00. It will make looking after your floors so much easier as you will always know the exact RH level in your home just by looking at the reading.

Suggestion 2: Control Ventilation

For an older house with lots of drafts, the inside air is replaced by outside air in roughly 1 to 2 hours. Newer houses are usually much more efficient and take about 5 hours to replace the air.

The technical term for this is ACH – or air changes per hour.

The higher your ACH level the harder it is and the more expensive it is to keep control of the RH level inside your home.

The biggest ventilation culprits in an old house are leaky drafty windows and doors. Recessed lights and holes and gaps in ceilings and floors are also big perpetrators. It makes sense that if you can close up these drafty areas effectively, then you can get your home’s ACH down to more normal levels.

This can be as simple and affordable as using insulation strips and some caulking, or as complicated and expensive as replacing all your doors and windows and re-insulating the entire house.

Suggestion 3: In the Winter ADD Moisture

In the winter months, outside air that makes its way into your home and is dried by your heaters, requires added moisture in order to bring the humidity in the air up to our balanced levels (between 35 – 50%). By adding moisture to the air it will stop your floors from excessively drying out and shrinking.

The easiest way to do this is with a humidifier. There are two kinds of humidifiers. You can use either a free standing unit or a permanent installed one that is attached to a central forced air furnace. Both work well and the one you choose will depend on the size of your house and area of wood flooring.

Suggestion 4: In the Summer REMOVE Moisture

In the summer the problem is too much humidity. So in order to stop your floors from taking on too much moisture you will need to reduce the moisture in the air. This means using either an air conditioner or dehumidifier.

Which one is better?

An air conditioner is very similar to a dehumidifier. The BIG difference is that with a dehumidifier, the evaporator coil and condenser coil are both in the same room. So while it does remove moisture from the air, the unit also acts as a heater by releasing the warm dry air back into the room.

With an air conditioner, the evaporator coil is in the room and the condenser coil is on the outside of the house. So like the dehumidifier, it removes moisture from the air to bring the humidity down, but it also removes heat from the room which is much better in the summer.

Below is a chart to help you see the difference between humidifiers, air conditioners and dehumidifiers and when to use each one…

Air Conditioner Dehumidifier Humidifier
Function To reduce the moisture content in the surrounding area and to cool air. To reduce the moisture content in the surrounding area. To increase the moisture content in the surrounding area.
When to Use During warm and humid months where humidity is greater than 50%. During warm and humid months where humidity is greater than 50%. During cold and dry months when humidity is less than 35%.
Differences Cools room as it lowers humidity. Heats up room as it lowers humidity.

The Bottom Line on Humidity 

In the end, wood is wood, and physics are physics. But… there are certain things that can be done to try and control them so your floor has a fighting chance of looking good and staying healthy throughout the year. That’s why we are passionate about educating people on how to properly maintain a balanced RH level in their home.

So after we leave, please, don’t forget to keep using your air conditioners or dehumidifiers in the hot humid summer months. And when the weather turns cold and you crank up that heater, please also turn on your humidifier.

If you do you will be rewarded with a beautiful looking floor year round!

Oh and don’t forget to invest in a hygrometer.


Seasonal Expansion and Contraction – Why Does My Hardwood Floor Have Gaps?

Posted by Victor Mulbauer, January 19th 2014

Over the summer you’ve invested a significant amount of money to have either your hardwood floors refinished, or have new wood floors installed. Now, just a few months later, it’s winter and you’re starting to see gaps throughout your floor.

Gaps are visibly present throughout the floor. They can be seen running along the length of the picture.

Gaps are visibly present throughout the floor. They can be seen running along the length of the picture.

What on earth is going on? Is there something wrong?

Thankfully, in most situations the answer is no.

What you’re experiencing is perfectly normal for all things made of wood in your home, including your hardwood floors. There is a simple explanation for why you sometimes see gaps in your floor and other times in the year you don’t.

The reason is that wood is hygroscopic. Hygro what??? Let me explain…

When something is hygroscopic it has the ability to attract and hold water molecules from the environment it’s surrounded by. For example… have you ever been to a restaurant and had a salt shaker that won’t let any salt out because it’s all clumped together? This happens because the high humidity levels int he surrounding air have caused the salt crystals to absorb moisture. Now the salt has expanded and clumped together to the point that it can’t come out of the small shaker holes… so you either eat your fries without salt or search for a dry salt shaker on another table.

Exactly the same type of thing happens with wood.

The moisture content of your hardwood floor is going to change depending on the relative humidity of the surrounding air in your home. As the humidity level increases, the moisture content increases too. This makes wood expand. Likewise, when the humidity levels drop, the wood’s moisture content decreases and it contracts or shrinks.

The technical term for this is Equilibrium Moisture Content (EMC).

You may have noticed that wood doors in older homes get tighter in the summer months and are harder to open, but in the winter they’re back to opening and closing normally. Those solid wood doors are dealing with the same EMC issue.

Like doors, this movement in floors is almost noticeable in the seasonal changes between winter and summer. In the summer your house is open, there is lots of humidity in the air and the wood in your floor is fully expanded as it absorbs moisture. Then winter rolls around, it gets cold, you shut up your home and turn the heat on. In turn the humidity levels drop and the wood in your floor releases that moisture it’s been holding and it begins to shrink.

That’s when you start to see gaps forming.

It gets especially bad when we have freezing cold days like we have experienced the last few weeks here in Detroit and everyone’s furnaces are cranked right up and all the moisture is sucked out of the wood. Thankfully these unsightly gaps will disappear when spring rolls around with its increased humidity levels and the heat gets turned off.

But what if you don’t want to wait for summer?

Is there anything that can be done to close the gaps a bit now and keep the floor tight throughout the year?

What Can Be Done to Control the Gaps?

One of the best things you can do to control the gaps in your hardwood floors is try to keep the humidity levels in your home stable throughout the year. In order to do that you will need to add moisture to the air during the drier months.

The easiest way to add moisture during the months you have your heat on is to invest in a humidifier and set it at a level of 45 – 55 percent. (Gaps start to appear when the humidity level creeps below 40 percent). That way the relative humidity in your home will stay stable and your floors won’t contract or expand as much during the year – which means far fewer gaps.

There are two types of humidifiers to choose between. One is a permanent installation that’s connected to your furnace and works throughout the whole house. It gets integrated with the blower system and draws water directly from the main water supply.

Thoughts for Preventing Gaps in New Installations:

There are a few things that can be done before a hardwood floor is installed that will greatly help with preventing gaps down the road…

  • Make sure the wood flooring gets acclimated properly before installation. Once the flooring is delivered we recommend placing it in the room it will be isntalled in for as long as possible. Stack it well spaced out so all the planks are able to acclimate evenly. Two weeks is ideal. Make sure the room is at the temperature and humidity level you normally have it at, or will have it at, for living in.
  • Make sure your installer uses a moisture meter and knows how to calculate EMC. The flooring must be checked for moisture content when it’s delivered to see if it’s within acceptable levels. this will also allow the installer to anticipate future movement. The subfloor should also be checked.
  • When you choose wood flooring, realize that the wider the board is the more seasonal movement will occur within each plank. A 2 1/4 inch wide board will expand and contract far less than a 6 inch or 12 inch wide plank. If you want wide plank floors you really need to put a humidifier on your shopping list as well.
  • Plain sawn flooring will expand and contract roughly twice as much as quarter sawn (or vertical grain) flooring. Quarter sawn is much more stable but it is also much more expensive.
  • Don’t deliver or install hardwood flooring until all wet trades (drywalling, painting, etc.) are finished and the high humidity levels have settled back to normal. If you must have the flooring there while wet trades are working, keep it wrapped in plastic to keep the humidity out and then give it ample time for the moisture content to stabilize before installing it.


In Conclusion…

So as you can see there is nothing wrong with your hardwood floor if you have some gaps in it. Wood is a natural product that predictably reacts to the environment it’s placed in. How much it expands and contracts all depends on the weather and humidity levels you keep in your home. If you’re installing new hardwood, it will also come down to how well your installer understands EMC and prepares the flooring before it is installed.

With a little foresight, being sure to follow the tips above, and investing in the right humidifier, you can greatly limit the amount and size of gaps you will see in your floors until summer rolls around once again.