When converting shipping containers into a home, one of the easiest ways to save money is to keep the container’s original flooring.
But is this safe?
It’s a question I get asked through email at least several times a week.
“Should I remove the floor in my shipping containers?”
The main concern with the floor is safety. Typically the floors in shipping containers are made from tropical hardwoods which have been treated with crude pesticides.
These harsh chemicals are also dangerous to humans.
In this article we are going to look at whether you should remove the original plywood floors in your containers.
Shipping Container Flooring
To understand shipping container flooring we must look back to the original purpose of shipping containers.
Shipping containers have been designed to withstand the punishment of ocean travel and to protect the goods inside of them during transportation.
Typically shipping container floors are 1″ marine plywood made from tropical hardwood such as Keruing or Apitong.
Such hardwood unfortunately attracts pests.
To stop insects and other critters from damaging the produce inside the containers, the wooden floors are treated with pesticides to kill off the insects.
Whilst this is good when using containers for transportation, it isn’t good when using containers to build a home- these pesticides are also harmful to humans.
The good news is that many of the extremely harmful pesticides such as Aldrin and Dieldrin have now banned or highly restricted since the 1980s, however other pesticides are still used on nearly all container flooring.
According to the Container Owners Association around 70% of shipping container floors are still made using tropical hardwood.
So, whilst many shipping container manufactures are looking at alternative forms of flooring such as Bamboo or Steel, the chances are that your shipping container flooring will have been treated with pesticides.
How to Check Your Shipping Container Floors
If you’re fortunate enough to be purchasing your containers brand new, then you can specify that either: a) they don’t treat the plywood with pesticides or b) you use an alternative form of flooring such as steel or bamboo.
However, the majority of people build with used shipping containers, so what should they do!?
Well, a certain amount of detective work will be required.
To establish which chemicals have been used to treat your floor you need to look at the consolidated data plate, also known as the container safe convention plate. This plate is generally attached to the container’s front door.
On the plate you will find a section named “timber component treatment”. This section has three parts:
- Part 1: IM (immunity)
- Part 2: Treatment chemical
- Part 3: Treatment date
Once you’ve established the chemicals used you can determine whether or not you need to remove the floors. Take a look at World Health Organization’s classification of pesticides to determine the harshness of the chemicals used.
However, the data plate won’t tell you everything. For instance, if the container’s floor was damaged at some point and replaced, then the plate won’t show this. Also the data plate won’t enlighten you as to what was shipped inside the container or if any harsh chemicals were spilt inside the container during its life on the seas.
If you’re looking for further information on container markings, I found this document very helpful.
Should You Remove The Plywood Floor?
You should now have identified your container flooring and the chemicals that have been used to treat the floor.
In my experience I’d say most of the time people completely remove the original plywood flooring and replace it with new flooring.
Ultimately though, the decision is up to you and your budget.
It goes without saying that the safest route is to remove the original flooring and fit new flooring. This will give you peace of mind.
However, the cheapest option is to keep the original flooring and treat it.
First then, let’s look at how to remove the floor. We will then discuss how to treat the floor if you decided to keep the original floor.
How to Remove the Plywood Floor
If you’ve decided to play safe and remove your floor this section is for you.
To remove the plywood you need to cut the floor bolts out first- you can use a still saw for this. The bolts are fixed along the cross members and are normally space every 12 inches.
Once all the floor bolts have been cut out you can use a pry bar or similar to lever the floor panels up and out of the container.
Whilst it’s a relatively straight forward job it can take a surprising amount of time!
Once the plywood has been removed, you are free to fit your new flooring.
One of the benefits of removing the original flooring is that once the floor is removed you can insulate underneath the container.
Normally it can be tricky to insulate underneath the container- you generally have to hire a Hiab/Crane and use spray foam whilst your containers are being lifted up.
However, when you’re removing the floor you can easily access the floor’s cross members and you can apply spray foam or panel insulation with ease!
How to Treat the Original Plywood Floor
If you’ve decided to keep and treat your original plywood floor this section is for you.
The main concern with keeping the original plywood flooring is hazardous fumes oozing from the pesticides used to treat the plywood.
Whilst these chemicals potency is greatly reduced after a few years, there is still a risk and it needs treating.
The most popular route is to apply epoxy to the flooring- this will act as a sealant and limit the vapors oozing from the pesticides.
When choosing your epoxy you want to make sure that it is solvent free and most importantly that it is recommended for use on wood.
Before you apply the epoxy you will want to clean the plywood with isopropyl alcohol.
Make sure when you are applying the isopropyl alcohol and epoxy that there is plenty of ventilation as the fumes can be very strong!
If you don’t want to use epoxy then another route is to use a non-breathable flooring underlayment. Larry from Sea Container Cabin converted his used shipping containers back in 2010 and decided to use a non-breathable flooring underlayment.
The flooring underlayment was fitted straight over the original plywood container floors. Then tiles were laid on top of the underlayment.
The other option I’ve seen used a few times is concrete. Again, just like the underlayment discussed above, the concrete is used to ‘seal’ the plywood flooring.
Before the concrete is laid a polyethylene plastic is placed on top of the original plywood and then the concrete is laid.
The majority of shipping containers are fitted with a plywood floor made from tropical hardwood. This hardwood is treated with potentially harmful pesticides before it’s fitted into the shipping containers.
Whilst this makes the containers perfect for transportation, it means the containers aren’t ideal to live in because the pesticides used to treat the wooden floor can also harm humans.
Deciding whether to remove your container’s original flooring or not is a personal decision.
Really it depends on the history of your shipping container, your budget and personal preference.
Without a doubt the safest option is to remove the plywood flooring and replace it with new flooring. This way you know exactly what chemicals have been used on the floor.
However, for those of you who have containers that haven’t been treated with pesticides, replacing the floor can be a waste of money.
Instead you can use a sealer such as epoxy to seal the container’s floor and then continue to convert your shipping container home.