How to Finish the Inside of a Cabin Shell

small cabin sheds interior
  1. Sample Floor Plans for a Two Story Cabin
  2. Finishing Cabin Interior: Electricity and Plumbing; Part One
  3. Finish Cabin Interior: Electricity and Plumbing; Part Two

If you’ve recently purchased a cabin shell you may be getting ready to finish the inside. With some skilled labor, the right materials, and the right tools, a prefab cabin shell can easily be turned into a cozy living space. This guide is intended to give advice specifically for finishing the inside of a small “shed-type” portable cabin (pictured below) that is installed on a gravel or concrete pad. However, this information may also apply to other types of cabins. (Not what you’re looking for? See our Cabin Design Ideas)

small prefab cabins

When compared to a building with a brick and mortar foundation, a portable cabin is a cost-effective way to expand your living space. It is not considered to be a permanent structure because it can be moved to a new location if necessary. This makes it ideal for a variety of situations including campgrounds, hunting cabins, rental properties, an extra room in the backyard, etc.

Although some builders may offer to finish the inside for you, there’s a good chance you purchased your pre-built cabin as a shell that still needs to be finished on the inside. If you haven’t purchased your cabin yet ask the builder to insulate the floor for you since it is almost impossible to do it later without removing the floor plywood. Also, ask the builder for house-type windows and doors. The windows should be large enough for a window air-conditioner unit (unless you have other plans for cooling in the summertime).

small prefab cabins

Now we’ll take you through the different phases of finishing the inside and give a few pointers as we move along.


The first step is to set up any 2×4 divider walls if you plan to divide the cabin into different rooms. Begin by creating a floor plan for your cabin that’s drawn to scale. This can be easily done using graph paper. Drawing a floor plan will help you visualize the layout of the cabin interior and make adjustments before you begin.

You may also choose not to install interior divider walls if your cabin is very small (a 10×12 shed for instance) or if you prefer an open floor plan. A cabin with a loft can provide great sleeping quarters that are out of the way of the main living area (which can eliminate the need for a separate bedroom).

Depending on how your cabin was built you may need to install ceiling joists (unless you want to leave the ceiling open). You may be able to skip this step if your cabin shell was built using engineered trusses, however, if the trusses are spaced at 48″ apart you’ll need to install 2×4 cross members on the underside of the trusses before installing drywall or paneling.

small prefab cabin interior 1
small prefab cabin edited 1

Finishing Cabin Interior: Electricity and Plumbing; Part One

The next step is to run wiring for electricity and install a water supply and drain lines if you plan to have running water in your shed cabin interior. This can be a highly technical procedure with a lot of variables. If you are not comfortable with this step, contact a licensed plumber and an electrician. However, if you have a bit of experience here are a few things you’ll want to do.

Make a copy of your floor plan.

Get out the floor plan of the inside of your cabin and make a copy of it if you want. Then mark all the possible places for light switches, receptacles, light fixtures, and any other electrical source or outlet. Also, mark where you are going to mount your breaker panel. A breaker panel is the main distribution point for electrical circuits in your cabin.

Next, you should go to the inside of the cabin and visually check each location you have marked for an outlet, switch, or other light fixture. Make sure there is nothing in the wall studs that will prevent an easy install.

Electrical – How to finish a cabin shell with electricity.

Unless otherwise noted, all measurements for outlets and switches are recommendations.


Using a tape measure and pen or carpenter’s pencil mark the wall studs where you want your outlet. Most outlets will be 16 to 18 inches from the center of the outlet to the floor. Make sure this will work with the rest of your plans. For example, it might make sense to install one higher for your fridge, if you are planning to have a refrigerator in your cabin. Marking off outlets will make installation easier later.

For this example, we’ll reference the standard 4-inch electrical box as pictured below. Nail this box to your wall stud at each location you have marked. Use the tabs on the side opposite the nail (against the stud) to install it at the correct depth.

Light Switches

Do the same for all the light switches throughout the cabin as well. The most common position for light switches is 48 inches from the center of the switch to the floor. To get this height, measure 46 inches from the floor and make a mark with your pencil. If you are using the standard 4-inch electrical box this will put the center at exactly 48 inches from the floor.

The National Electric Code specifies that there must be one switch in every room to operate any light that is in that room. Not only is it code, but it’s also good practice so be sure to have at least one light switch per room.

Porch Light

If your cabin has a porch, don’t forget to install a porch light and a light switch inside for that light. Having a porch light will help make your cabin even more attractive, not to mention easier to find in the dark!

small prefab cabin parts

Image Credits: Home Depot and Wikipedia

Let’s run the wire!


The wire we’ll use for this project will be the yellow-sheathed 12-gauge wire that you can find at almost any department store. In each room, you can run the wire through the wall studs (#5 in the picture above on right) by drilling a small hole in each stud at the same height, usually a foot or two above your outlet height. Building code says the hole drilled in the wall stud may not be more than 1/3 the width of the stud. Use a 3/4 or 7/8-inch drill bit for a wire hole. This is within Code and provides ample room for your wire.

If you are using one breaker for all the outlets in each room, run your feed wire from your breaker panel through the top plate (#3 above). If you do not have a second floor in your cabin, running the wire on top of rafters is the quickest and easiest method. If you do have a second floor, use the same drill bit to drill holes in the floor joists to bring your wire to the room you are wiring. Don’t drill multiple holes in the same floor joist close together. Spread them out so you won’t weaken the structural integrity. String the wire to the room you are wiring and drill a hole in the top plate to bring the wire down inside the wall to the first outlet.

Bring the wire down to the box you have nailed to the stud and leave any extra wire there. 12 inches of extra wire isn’t too much. Cut the wire and start a new run to the next outlet stringing it through the holes you drilled in your wall studs. Leave extra wire at that outlet, cut it, and start a new run to the next outlet. Repeat this process in each room.

Light Fixtures and Switches

Run the wire from the breaker panel directly to the first switch. Drill a hole in the top plate of your wall (#3) and drop the wire down to the switch box. Leave extra wire there, cut it, and run a new section from the switch box up through the hole you drilled in the top plate and over to where you will hang your light fixture. Do the same for each room. If you have multiple lights running off the same switch, run a wire from the first light fixture to the next light, and so on.

Before calling it perfect…

Before calling the job finished, it is not a terrible idea to call an electrician and have him look over the wiring to make sure it is okay. You don’t want to take a chance with a loose wire, or something not hooked up correctly. An experienced electrician can help you make sure your cabin shell is wired correctly.

Plumbing – Get Running Water in Your cabin shell

Just like the electrical wiring, plumbing will require a bit of work. All the plumbing is usually done under the floor rather than on the wall. If your floor is finished, doing the plumbing now will be a lot more in-depth. If this is your case, you may want to call a plumber to assist you.

Before you even begin with the plumbing you need to make a plan for everything related to the plumbing. This plan should include the water supply system, drainage, and vent system. At this point, you should also decide what size piping you are going to use for each of these systems.

Make sure you plan for all the fixtures and appliances you will be installing. Will you be installing a toilet, a shower, sinks, or washbasins? What about washing machines and dishwashers? Your plan should list out everything you are planning to install now, as well as anything you may be installing in the future.

small prefab cabin 2 plumbing basics finishing small cabin
Plumbing Basics

Water Supply

If you plan to have water in your cabin shell, you will need to make sure to have a water supply. The main water supply pipe should generally be a 3/4″ or 1” pipe. This pipe is usually under pressure from your main water shut-off and pressure tank. If you plan to have hot water, split your main supply into two separate lines, one for cold and one for hot water. Your hot water supply line should run directly to your hot water tank. From here, smaller pipes, usually per or PVC, carry the water to each individual fixture and appliance.

Drainage, Waste, and Vent System

This system is designed to get rid of any water used by fixtures and appliances. The drains in your sinks, shower and toilet all run to the main drainage pipe called the waste stack. If you have a two-story cabin with plumbing on the upper level, make sure you run a waste drain from that floor, down to the main waste stack. The main stack is usually a 3” or 4” pipe that collects all the wastewater from the drain lines coming from fixtures and applies. The drainage pipes are usually 2” PVC.


To complete the drainage system, you will need a vent. This vent serves a very important role in keeping your cabin free of nasty odors. Also, the vent will allow the waste stack to work by supplying it with air to keep the wastewater flowing. Each waste pipe or drain in your finished cabin shell will be connected to a vent pipe that is connected to a series of fresh air inlets running up through your roof. The vent system creates multiple ways to block sewer gases from entering your cabin living space.

We recommend contacting a licensed plumber.

Because of the extent of the work that is needed for plumbing, we recommend contacting a professional plumber to assist you in plumbing your cabin shell. You don’t want a water leak ruining the integrity of your cabin, so asking a plumber to help you is a choice you will not regret.


Insulating your cabin shell can be thought of as one of the most important steps to finishing the interior of any small shed. Insulating your walls and ceiling will help keep the heat inside in the winter, and the cool air in during the summer.

If you haven’t ordered your cabin shell yet and you are planning to insulate it when you do have it, ask your builder to insulate the floor. It is easiest to insulate the floor before installing the floorboard.

There are two main ways to insulate any wall or ceiling: spray foam and batt insulation. We are going to cover both in this article.

Windows and Doors

Since you will have windows and doors in the cabin, you will want to insulate around each one. At any hardware store or lumber yard, pick up a can of Window and Door Insulation like the one pictured here. This is an important step: make sure to use Window and Door Insulation around windows and doors. Regular expanding foam insulation would expand to the point that it would put so much pressure against the sides of windows so that you couldn’t open them.

Window and Door insulation doesn’t expand too far and therefore it is the perfect thing to use around doors and windows.

Spray Foam Insulation

Spray foam is an easy and sure-fire way to make sure your cabin shell is insulated properly. Spray foam insulating for finishing out the interior of your cabin is a great way to make sure you insulate all the little cracks and corners that batt insulation can’t.

If you are planning to use spray foam insulation in your cabin shell, you can do it yourself with a kit purchased from a store or even online! You can get a two-part mixture (which comes in two metal cylinders) with a supplied application hose and nozzle and do it yourself. Most smaller kits will cover an area of 650 sq. ft. which will cover four 8’x20’ walls at R-12 value.

It is very important to prepare properly before you begin applying spray foam insulation to your cabin shell walls. Make sure you’ve sealed off all electrical outlets and switches. Make sure the walls are free of dust and dirt or anything that would hinder the insulation from adhering to the wall.

When you are ready to begin, make sure to read and follow all directions supplied with the product you are using. Use proper safety measures including eye protection, a nose mask, and gloves. Also, wear old clothing or disposable coveralls.

Apply the spray foam insulation in layers or as directed. Once it has had sufficient time to cure, make sure there are no bumps protruding past the stud walls. Any insulation sticking past that point will not allow the wallboard to seat properly against the wall.

Check with a local contractor or carpenter about using a vapor barrier. A vapor barrier will stop water and condensation from forming against the insulation and allowing for mold growth.

Fiberglass Batt Insulation

Fiberglass batts are installed very easily. Batt insulation usually comes in 8- or 10-foot-long batts. Starting at the top of your wall or roof, tuck it in the corners and work toward the bottom pushing in the edges for a nice firm fit. Do not push in the center or in any way pack the insulation together, make sure the insulation stays fluffed. Cut around outlets and light switch boxes.

If you decide to use fiberglass insulation, we recommend installing gutters on the cabin to catch the water that runs off the roof. This will help to eliminate any moisture that might enter the walls from water splashing against the bottom of the cabin. (It’s a good idea to install rain gutters anyway to protect your cabin).

Just remember that moisture plus fiberglass insulation equals the potential for mold, which is something you’ll want to avoid. Installing gutters will go a long way when it comes to keeping the bottom edge of your cabin or wood storage sheds dry. (Building a shed base also helps to keep your cabin dry).

Wall Board

Now that you have your walls insulated, it’s time to cover them up for an attractive appearance inside. Step one is to pick out your wallboard.

The most common option for permanent residential type homes is drywall, but it is not recommended for a cabin shell unless the cabin is set on a solid concrete foundation.

Tongue & Groove Boards

The most common choice for finishing prefab cabin walls is tongue-&-groove boards. Tongue-&-groove boards (T&G) are a very popular pick for cabin interiors. Most manufacturers of finished cabins will use this as a default for their cabins. Because of how T&G boards are installed, they won’t show cracks between them if/as they dry out. Also, if your cabin is not on a solid concrete foundation, T&G boards allow for the foundation to settle and the cabin to shift without causing the boards to crack. T&G boards can also be used on prefab cabin ceilings very easily.

Tongue-&-groove boards are also easier to handle during installation. Rather than a large 4×8 sheet of drywall, T&G boards are generally 6 inches wide and come in whatever length you need. To hang T&G boards, all you need is a tape measure, pencil, speed square, saw, and a drill/screw-gun/nailer.

As you install the wall paneling, make sure you cut out spots for your outlets and switches!


This step is pretty self-explanatory, so we won’t go into much detail. Choose any color of interior paint you prefer. If you like the look of natural wood, choose a stain or varnish to protect the wall paneling while still highlighting its grain and texture.


Install your flooring after you have finished with the wallboard, plumbing, electricity, and painting and before you finish your trim work. cabin shells come with a sub-floor already installed.

Carpet Install

Installing carpet isn’t the easiest project to take on, but it will definitely be easier in a cabin shell. The steps and process will be different based on the type of carpet that you choose. To make the job easier, make sure you have all the tools you need.

Here is a list of carpet installation tools you should have.

  • Carpet Knife
  • Duckbill Napping Shears
  • Knee Kicker
  • Power Stretcher
  • Carpet Row Cutter
  • Seam Roller
  • Seaming Iron
  • Stair Tool/Carpet Tucker
  • Stapler (Electric Staple Gun)
  • Wall Trimmer / Stair Tucker

This is a partial list of all the tools some professionals might have, however for a small project like finishing out the interior of a cabin, this list should be all you need. Since you will only be using these products for one time, consider renting them. Most carpet stores will have tools for you to rent. The carpet store may be able to offer installation services as well if you’d rather not tackle the project yourself.

Here is a list of carpet supplies you will need

  • Tack Strip
  • Padding
  • Carpet

To begin installing carpet, collect all your supplies and tools. Making absolutely sure you have all the tools you need before you start makes the project go much easier.

Step #1: Check for any squeaks in your subflooring. If you do find any squeaks, screw the subfloor down to the floor joist as near to the squeak as possible using a drywall or deck screw. (As a side note, if you purchase a cabin shell from Gold Star Buildings, you shouldn’t have any trouble with the floor squeaking! ;D)

Step #2: Nail your tack strip down along the perimeter of the room, leaving a 3/8” gap between the baseboard and tack strip. Make sure the arrows on the strip are pointed towards the wall. Nail tack strips down around any obstructions in your room including air vents, doorways, etc. Always make sure every tack strip has at least two nails.

Step #3: Install the padding (if applicable). Padding protects a quality carpet and makes the carpet feel softer under your feet. You may pre-cut the padding or cut as you install. Roll out the padding starting in any corner of your room. Make sure to trim excess padding but be sure to have the padding as close to the tack strip as possible. Staple down the padding just to keep it from moving. One staple every couple of feet is perfect.

Step #4: Install the carpet. Roll out the carpet in your room and position it where it will be installed. (You could also precut your carpet outside the room. This option may save some time, but it’s important to make sure your cuts are accurate!) Leave excess along the walls to trim off later. Nail the carpet along the wall every 5” or so and use the carpet tucker or plastic paddle and tack the carpet down in the gap along the wall. Don’t hammer the carpet directly onto the tack strip.

Step #5: Using the power stretcher, stretch your carpet in increments. Lock the power stretcher head and tack the carpet into the tack strip.

Step #6: Trim your carpet along each wall and tuck it into the gap.

Congratulations! You’ve just completed the carpet install! You may now trim out the room. Make sure to run a sweeper over the newly installed carpet to pick up any dirt or debris that accumulated there before and during the install.

How to install linoleum plank or tile flooring.

If you’ve chosen linoleum flooring to finish out a kitchen, dining area, or living room in your small cabin, we’ll look over this project with you.

Preparing. You’re going to need to properly prepare for this project. Any nails, staples, large pieces of dirt, and other debris could potentially ruin your linoleum after it has been installed. Since you’re installing the linoleum in a new prefab cabin, you shouldn’t have to worry about your subfloor being rough or uneven. However, if your project involves an older building and your subfloor is rough or uneven, cover it with 1/4-inch sheeting otherwise known as, underlayment.

When you are purchasing your supplies make sure to get 10% extra so that if you run into any damaged pieces now or further down the road, you have enough to fix it.

Step #1: Finding the center of your room. Before you apply adhesive and start laying down linoleum, find the center of your room and lay linoleum from there to each wall to determine a final layout pattern. Layout all your tile and cut around any obstructions. Cut your tiles to fit along the walls.

Step #2: Begin applying adhesive and laying tile in small 5’ square areas after you have decided on your layout. Use a circular motion with your trowel to apply the adhesive to each tile one at a time. Repeat the process until the floor has been installed.

Step #3: Roll the tile with a 100-lb roller. To ensure that your tile has been installed firmly against the subfloor, roll the entire floor with a 100-lb roller. (You should be able to rent a roller from most tool rental stores.)

When you have all the tile glued down and rolled, this project is about completed. To finish your cabin shell interior flooring, install the baseboard and trim.

finished shed cabin interior in pa 5 1
Finished Linoleum

Basics of Interior Trim

Trim work is a huge topic in its own right, so we won’t be able to go into extensive detail. However, here are a few tips to help with trimming the interior of your cabin shell.

#1: There are no minimum requirements for trim. Trim and baseboard simply make your finished cabin interior look a lot better.

#2: You can find the trim board at any local department store or lumber yard.

How to trim out a cabin shell door with straight cuts.

The fastest way to trim around a cabin door is to select your trim board and measure the height of your doorway. Measuring from the top of the flooring to the top of your door, mark and cut your trim board to the right length. While fastening the board around the door, make sure to leave a 3/16-inch gap around the entire door. Follow the same on the top of the door. Feel free to personalize with decorative trim or use your own style to trim.

How to trim out a window (with straight cuts).

Follow the same pattern you did for the door trim. In this case, copy the top of the window trim underneath your windowsill.

how to trim out windows cabin interior finish

Another way to trim around windows and doors is with angled cuts.

The whole trimming process is the same, except for the board along the top of your window or door. Leave the top piece of your trim board long. To make it look great, the overhang should be 2X the width of the trim board. (If you are using a 1×3 trim board, each end should overhang 3 inches (6 inches total.)) Set your circular or chop saw to cut at a 45-degree angle and cut both sides of the trim. When the board is at your desired length, nail it in place.

How to install baseboard trim.

The floor trim or baseboard is to cover all the gaps between the bottom of the wallboards and the flooring. Install the baseboard tight against the flooring if the flooring has been installed already or leave a gap between the subfloor and the baseboard. This gap will vary based on the flooring type you choose, so check that first.

Finishing The cabin shell Interior: Electricity and Plumbing; Part Two

Plumbing – Finishing the plumbing in your cabin.

If you hired a plumber to help you, he should have wrapped up everything and made it easy for you to finish out when you install a sink, spigot, shower, and any other plumbing fixtures. You may even want your plumber to come to finish hooking everything up to ensure there will be no leaks in the future.

Electrical – Finishing the electrical work in your cabin.

If you ran all the wires yourself and had an electrician look over everything or hired him to help you with the whole project, you are ready to finish it up now. Test the lights and receptacles and install covers on all the outlets and light switch boxes. Make sure there are no exposed wires and you should be finished with the electrical.

All finished?

Once you have completed all the install details and finished out your cabin, it’s time to move in! Whether you place it in the backyard, on your vacation property, or at a campground, a quality prefab cabin is an excellent addition to your property that will add value and serve you for many years to come.

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