How to Build a Tiny House Subfloor On A Trailer

Many people want to build tiny houses on solid skids or foundations. When you want to build anything in a tiny house, you should make a proper plan. In the case of building a tiny house subfloor, everything should be perfect. Subfloor on a trailer is very crucial for your tiny house. It is more than the underlayer of the flooring. Subfloor protects your house from moisture, pests, and debris. Moreover, it is a barrier that separates your house from the outer world and keeps your house secure and safe. You may think about how to build a tiny house subfloor on a trailer?

In today’s article, we will discuss with you everything about constructing the tiny house subfloor on the trailer. We will also include all the instructions related to the topic. Let’s have a great look into this matter!

Why Subflooring: Is It Important?

While you construct a tiny house, you will get enough flexibility. The subfloor is the cover of protection between the house and the outer world. It may have different makeups in case of construction and materials, but it is a structural or thermal sandwich between the finished floor and the trailer. Indeed, you can build a subfloor on your own. 

A subfloor not only stabilizes the flooring but also gives you some other benefits. Firstly, it will protect you from unwanted insects.

Besides, it has great accuracy in insulating the floor. Again, the subfloor will help in managing the moisture. We will focus on all these points.

• Protects Against Insects And Pests: Insects and bugs can invade the tiny house easily through the trailer. Without good flashing material, insects and small animals can enter your tiny house. But, subflooring will retain your tiny house safe once you build it. So, insects can not enter the house.

• Accurate Floor Insulation: Subflooring will need some materials to build it. For example, metal will provide good thermal bridging. With more metal used in your tiny house, the insulation will protect the floors from losing heat in the winter season. So, subflooring will give your floor insulation accuracy.

• Proper Moisture Management: The subfloor will accumulate moisture with low exposure to the outer world. The inside will degrade and rust while keeping it unprotected. Adding the vapor barrier and installing flashing are two necessary steps you need to take for protecting the trailer and tiny house. 

What Are The Parts Of The Subfloor Framing:

• Flashing: For flashing, materials like galvanized steel or aluminum are most commonly used. The flashing is the first layer of the subfloor which protects against moisture, debris, and pests. If you want an alternative, plywood can be a cheap option. Although the plywood is water-resistant and stronger, galvanized steel and aluminum are the best for heavy protection. So, when you want to attach the flashing with your tiny house, it will take a few days to weeks to build it. Moreover, in case you have extra space, then you can use extra layers of flashing for the tiny house. But most people use one layer only.

• Framing: Framing of the tiny house is similar to installing the wall framing. Wood types material is most commonly used for framing. You need to measure the width of the trailer to build the framing. Along with the separate cutting pieces for setting the frame. Again, you have to lock the frame on the margin of the trailer.It ensures your house connection with the outside of the trailer. You can also create cross beams with wood. It will attach with the heavy wood glue which will make the insulation material strong. Therefore, you can build framing.

• Insulation: Insulating the tiny house subfloor is a very vital point of this build. The trailer’s metal framing is very conductive. You can apply spray foam for insulating the cavities of the trailer. It is a very easy and rapid way. However, when you consult a professional for doing this, it will cost you around 200 to 400 dollars. But it may depend on the size of your trailer as well as the service provider company.An excellent option is utilizing the firm foam board for filling in the cavities. You have to measure the depth, height, and width for better accuracy. Fill the gaps with good quality canister spray foam for sealing all the gaps. XPS, Polyiso, and EPS are the best choices for insulating the rigid foam board. 

• Vapor Barrier: The last thing you have to install before the main subfloor adding is the vapor barrier. Although most of the rigid foam boards may provide a vapor barrier. But, putting it gives an extra layer of protection from the moisture. A vapor barrier is a thick sheet of plastic, usually made of polyethylene. It does not need to be sealed like the air barrier. You can simply place it on the top of other layers and then install it. Once you use glue for installing the vapor barrier, it has to suit the material. Polyethylene will melt when it comes in contact with the sealants. Therefore, most builders like to use an alternative, commonly named acoustical sealant for installing the vapor barrier.

• Subfloor Sheathing: The last portion of the subfloor is the sheathing. It is commonly made of plywood or sometimes OSB. Choosing the material for subfloor sheathing can depend on the layer of the floor you will put on the top of it. Plywood has less tendency of swelling and also stiffer too. So, these features make it the perfect flooring layer for the tiles to avoid cracking.On the other hand, OSB is comparatively smooth on each side. It is used as the layer for linoleum and vinyl flooring. We will not suggest using concrete such as subfloor materials. That’s are traditionally used by many people. But, in reality, concrete is very heavy to use. Similarly, the plank will loosen after a long time. It can also deteriorate rapidly in the moving tiny house. So, these are not suitable for use in the roving tiny house. 

Ways Of Building The Subfloor:

For building the tiny house subfloor on a trailer, you can follow two ways:

• Build directly on the top of the trailer.

• Build the separate framing on the top of the trailer. 

Build directly on the top of the trailer:

All trailer designs will not allow for building the subfloor directly on the top of the trailer. Only trailers featured with spaced crossed members will allow you to do this. By doing it, you can save some vertical spaces. For this reason, people like to build directly on the top of the trailer. More space can make a significant difference in a little house. 

Build separately on the top of the trailer: Building the subfloor on the top of the trailer is a perfect way to increase the trailer’s width. Because you will build it some inches outside of the framing of the trailer, it can extend the width of the tiny house. With the proper design, you don’t need to worry about anything. Therefore, it is the most common method taken by builders. 

Building a Tiny House Subfloor On a Trailer:

There are different layers in the floor of a tiny house. You can easily build the subfloor when

you plan properly about tools and materials. While you prepare for this phase of construction, it will be easy for you to divide your tasks. This will ensure the accuracy of every step. Once you start doing, you can finish the subfloor around four days to one week. So, the steps for constructing are as follows:

• Right Trailer: The first step is leveling and parking the trailer into the building site before the start of construction. You can use different tools such as the level, jack pads and scissor jacks. Each corner has to adjust properly at a time. After that, you need to double-check it with a level. The hand crank can work properly when you make small adjustments. The scissor jack plug needs to attach to the electric drill for raising and lowering the scissor jacks quickly. To this point, the scissor jacks will not be attached permanently with the trailer. Moreover, the intention is to screw the jacks with the trailer.

• Flashing: Flashing is the thin strip or sheet of material that is water-resistant. It is usually installed at the windows, roof intersections, doors, and exterior of foundation walls. Flashing is the first part of the tiny house subfloor. If you have an old trailer, it will have a flashing. You can order or build it by yourself. You will need duct tape and tapping screws for securing the flashing into the trailer. You can use the tapping screw for attaching the flashing with the trailer frame. Likewise, use duct tape for securing the loose gaps on the cross beam’s every side. The flashing will keep the water out of the bottom of the trailer in the tiny house. Flashing with two boxes will lay across the overall trailer length. Each layer is overlapping the other layer. Water can not reach the insulation when it penetrates the seam.

• Underlayment: Adding the underlayment of the subflooring surface will offer many things. Some can offer moisture control, sound control, anti-fungal, and anti-bacterial properties. Generally, the underlayment can be found between the finish floor and the subfloor. However, it can be attached by the finish floor. In this situation, the underlayment will exist between the floor framing and flashing. That provides the level of surface proper insulation. Five sheets of plywood are used for making the underlayment layer.

• Floor Framing: The frame is settled together with the corners. It attaches to the deck screws. The frame is assembled for ensuring an accurate fitting for the joist. As the frame has completed, the next step is drilling into the frame.It will secure the frame with the trailer. This trailer installation will provide extra space inside your tiny house.

• Insulation & Vapor Barrier: Installation of the insulation into the subfloor is the same as installing this on the wall. If you use firm foam boards for insulation, you have to use spray for sealing any gaps. Fibrous insulation like Rockwool mas works properly on the subfloor. Measurement of the depth of every cross member cavity needs to be taken for getting the perfect fitting for the insulation. Further, mitigate thermal bridging with the application of the sill plate gasket into the angles of the trailer. You have to cover wherever the cross beams will touch the wood. It will work to prevent thermal bridging. The sill plate gasket has to be attached with glue. You can add an extra vapor barrier after the installation of the insulation.This will keep the moisture from attaining to the subfloor. Simply fix the vapor barrier with the nail gun for keeping it pinned to the floor. We suggest poking a small hole when the vapor condensates from the outside. It will let the moisture out from the condensation.

• Place The Subfloor: Lastly, attach the subfloor to the trailer by tightening the subfloor into it. Take a look at the “type” of plywood based on the size of crossbeams. It ensures the right size and amount of materials for the tiny house. Place the subfloor as opposed to the cross beams that add strength. Measure properly every space to avoid any waste of the materials. 

Placing the first subfloor is the beginning of your tiny house project. Do it properly, therefore you will get a rigid foundation to support your house.

Conclusion:

A well-built subfloor will protect you from animals and the environment. It will assure your safety as well as security. All of these are possible when you can build it properly.

Accordingly, the best solution is our outlined steps. This is all about how to build a tiny house subfloor on a trailer. We hope this article will help you to find the right way of building the subfloor. Happy building!