Shipping Container Flooring And Pesticides Blog Cover

Should You Remove The Plywood Floors In Your Shipping Containers?

Posted By: October 4, 2016 In How To

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One of the most often asked questions that we receive is “Should I remove the floor in my shipping container?”

When converting shipping containers into a home or office, one of the easiest ways to save money is to keep the container’s original flooring. However, the main concern with using the existing 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 dangerous to humans and so it is not recommended to use the existing plywood flooring.

Shipping Container Flooring

To understand shipping container flooring consider the original purpose of shipping containers. They have been designed to withstand the punishment of long distance ocean travel and to protect the goods inside of them during transport.

Most often, shipping container floors are one inch marine plywood made from tropical hardwood such as Keruing or Apitong. These types of hardwoods unfortunately attract pests of all sorts.

To prevent damage to the goods by the insects and other critters, the wooden floors are treated with pesticides.

This is an understandable process for transporting goods, but is not safe when using containers to build a home or office. These harsh pesticides are harmful to humans, especially children and the elderly, and should be avoided in shipping container buildings.

The good news is that many of the extremely harmful pesticides such as Aldrin and Dieldrin are now banned or highly restricted. However, other pesticides are still used on almost all container flooring.

According to the Container Owners Association, a large percentage of shipping container floors are still made using tropical hardwood.

So, while many shipping container manufacturers are looking at alternative forms of flooring such as bamboo and steel, the chances are that your shipping container flooring will have been treated with pesticides.

How to Check Your Shipping Container Floors

If you are fortunate enough to be purchasing your containers brand new, then you can make some specific requests. You can request that the plywood floors are not treated with pesticides. Alternatively, you can request an alternative type of flooring be used instead of the plywood, such as steel or bamboo.

However, realistically, the majority of people do not buy new shipping containers but build with used containers. What should be done if this is the case?

When building with used shipping containers with treated plywood floors, a certain amount of detective work will be required to decide if the floors are safe to keep.

To confirm which chemicals have been used to treat your floor, locate the consolidated data plate, also known as the container safe convention plate. This plate is generally attached to the container’s front door.

Shipping Container Consolidated Data Plate

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 discovered the information about the chemicals used on your container, determine whether or not the floors will need to be removed and replaced. Review the World Health Organization’s classification of pesticides to further understand the harshness of the chemicals used.

Note that 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 inform you what was shipped inside the container or if any harsh chemicals were spilled inside the container during its life on the seas.

If you are looking for further information on container markings, this document may be helpful.

Should You Remove The Plywood Floor?

Generally speaking, most people completely remove the original plywood flooring and replace it with new flooring to be prudent. 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 install new flooring. This will give you peace of mind and the confidence that you have made the best choice for your family and friends.

Next, let’s look at how to remove the floor. Then we will discuss how to treat the floor if you decide to keep the original floor.

How to Remove the Plywood Floor

To remove the plywood, you need to cut the floor bolts out first using a hand saw or reciprocating saw. The bolts are fixed along the cross members and are normally spaced every twelve inches.

Once all the floor bolts have been cut out, use a pry bar to force the floor panels up and out of the container. This is a relatively straight forward job, but it can take a surprising amount of time! Once the plywood has been removed, you are free to lay your new flooring.

Another of the benefits of removing the original flooring is that once the floor is removed you can insulate underneath the container. With the flooring removed, you can easily access the floor’s cross members and you can apply spray foam or panel insulation with ease!

Without removing the flooring, it can be tricky to insulate underneath the container. You generally have to hire a HIAB/crane and use spray foam while your containers are being lifted up.

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 eliminate the pests. Even though the chemical potency will dissipate after a few years, there is still a risk. The floors need to be treated to be safe.

The most popular solution 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, ensure that it is solvent-free and most importantly that it is recommended for use on wood.

Before you apply the epoxy, clean the plywood with isopropyl alcohol.

As a safeguard when applying the isopropyl alcohol and epoxy, make certain that there is plenty of ventilation. These fumes can be very strong and are toxic.

If you don’t want to use epoxy, an alternative is to use a non-breathable flooring underlayment. Larry, from Sea Container Cabin, converted his used shipping containers years ago and decided to use a non-breathable flooring underlayment.

Shipping Container Home Flooring

© seacontainercabin.blogspot.co.uk

The flooring underlayment was placed straight over the original plywood container floors. Then tiles were laid on top of the underlayment.

Another option we’ve seen used 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. The concrete is then laid on top of the plastic.

Summary

The majority of shipping containers have plywood flooring made from tropical hardwood. This hardwood is treated with potentially harmful pesticides before it’s placed into the shipping containers.

This makes the containers perfect for transportation, but means the containers aren’t ideal to live in since the pesticides used to treat the wooden floors can also harm humans.

Deciding whether to remove the original flooring in your container or not is a personal decision. It depends on the history of your shipping container, your budget, and personal preference.

 


If you have further questions or comments regarding flooring, please enter them in the comments section.

Comments
  1. Adam

    Yellow tongue flooring is treated with pyrethrum to protect it from termites, I suppose this isn’t as harsh as the pesticides used on the original flooring but what flooring is best, cement sheet?

    • Tom

      It really depends on what aesthetic you’re going for. Almost any flooring type used in traditional construction could be used in a container. The import point is that if your flooring is made from a permeable/breathable material, that you coat the old plywood underlayment with epoxy or plastic to prevent toxic vapor migration.

  2. SamMcPhersonNZ

    As someone who lives in a 20 foot reefer I wouldn’t recommend it.
    Cutting the stainless interior is difficult to do. The insulation on my container was extremely flammable…. But didn’t catch fire while cutting the stainless.
    Stainless is extremely hard. A reciprocating saw wouldn’t cut it. A angle grinder would. But beware! As the grinder cuts into through the stainless steel interior the stainless heats up and expands… Pinching the disc of the grinder causing kick back.
    About 3 months ago I was cutting my first window into my home cutting above my head (with no guard or handle on the grinder which ofcourse in hindsight was a terribly stupid idea but may have not prevented the accident)… The grinder kicked back violently enough for me to lose grip and made its way full running down my body…
    When it was finished I could see my carotid artery in the open wound in my neck. It also got me in the arm and hand doing nerve damage…
    So yeah…. Don’t plunge cut with a angle grinder cutting stainless. There is also condensation issues with the inside of the outer walls with reefer containers. If your interested I’ll explain the problems and how I’m going to fix it with my next container build which will be non reefer and start in 6 months.
    Cheers
    Sam McPherson

    • Tom

      Hi Sam,

      Thank you for sharing and I’m sorry about your experience with reefer containers. So next time I presume you will be using standard containers?

      Tom

  3. Wendy

    Russ,

    Please reply to Tom’s question! We need your experience!

    Wendy

  4. Russ

    Good on you for your work in housing made of shipping containers.

    My main comment, and this relates to flooring as well, is that normal steel shipping containers are (in my view) a cheaper way of finding “a box” to live in but again, in my own personal view, has on going costs that make them far more problematic, than if folks chose an insulated reefer / shipping container, as opposed to a steal shipping container.
    2) All of the Reefers that I have had or been inside of, have nothing that can absorb toxins which then need to be dealt with, to make them safe, & to enable a relaxed, safe habitat.
    They also don’t need insulating and the sweating, i.e. condensation problems, that steel shipping containers have, are totally done away with also.

    3) If a Reefer is chosen correctly, it is possible to ensure that even the outside sheathing of the container/Reefer is virtually all stainless steel and rust problems that are a fairly certainly normally on going, are hugely reduced.
    I can generally get 40 ft High cube Reefer for between Kiwi $5000 & $7500 (late 2016) The steel containers of the same dimensions are generally about $3000 to $4500 so the extra cost is in my view far more worthy of serious consideration.

    4) The flooring I put in them, is generally treated 19mm (3/4″) ply. These I rivet to the aluminum extruded floor. The floor is made up of many closely placed, aluminum, semi “I ” beams all made into a very strong surface. Because of the extra height of the roof/ceiling, a raised floor can be made to enable any types of wiring and plumbing needed pipes & drains. This can be done without making for a lowered ceiling from what “normal ” types of houses have and generally require by building standards, Consents etc etc (if one goes along with all that c….)

    Happy, secure relaxed living and good on yee all who are like me who choose not to run along to a Bank & ask for a noose to be placed around our necks for decades to come and therefore become bonded to the Banks.

    Cheers

    • Tom

      Hi Russ,

      Thank you for getting in touch and sharing your experiences of building with reefers.

      I have previously looked into building with reefers but was discouraged when I heard about the problems of cutting through the containers (damaging the insulation etc.). How have you found this in your experience?

      Tom

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