Shipping containers are versatile, especially when it comes to re-purposing them into living spaces – or using them to extend an existing dwelling. This page has been designed to cover the details about how to plan for and build a container extension onto your home.
Don’t forget the building permits – before you begin planning, make sure you know if the local building codes allow you to use a container as an addition to your home. Once you know that you can use a container, you will need to get your building permits. Be sure to include any permits that may be needed for electrical and plumbing.
Careful planning is required when planning to use a container as an addition to your home. There will be significant demolition work involved, along with special considerations unique to using a container to extend your home’s living space.
Living Space Type and Placement?
It is important to determine what type of living space the extension will be. This will also help determine electrical and plumbing needs, which may affect where the extension is located. Once you have determined how the space will be used and where it will be located, you will need to decide how it will be attached to the rest of the house.
When planning for building directly onto your home, you will need to consider some critical factors beforehand. Before any demolition work begins, it is best to consult with a structural engineer. A structural engineer will come out and look at your home, evaluating its structure and what you will need to do in order to safely add onto it. You may also want to consult with an architect to help you design a way to integrate the addition with style. The critically important thing here is to make sure the wall you open up can still support the weight of the house. If structural integrity is an issue, you may want to look at other options.
Building a room and connecting it to the house via a small breezeway is an alternative that can ultimately save you both money and time. If you are looking at a high cost for building on an addition, this may be a better alternative.
Building the Extension
Regardless of whether you build the extension as an addition on your home or as a standalone structure, it will have to be built like any other dwelling. This will involve all of the elements of a major remodel, minus the demolition.
Door and Windows
You may want to have at least on window, and you will definitely need at least one door for your extension. When planning, be sure to include the placement of these elements. You will need to cut them out before placing the container where you will want it. Also, for the door, you may want to remove the doors that came on the container, removing all hinge hardware. This will leave you with an open area you can frame in and make into a wall, much like you would an interior wall in a house.
Framing the Walls
After the vapor barrier (if you’re using one) is installed, you can frame in the container similar to to way you would a room in a house.
Electrical and Plumbing
After the walls are framed in, it’s time to plumb and wire your extension.
If you plan to use fiberglass batt insulation, you will need to figure out an effective vapor barrier system. If you have no intention of siding the exterior, you can install a vapor barrier on the inside of the container. Be clear, however, that this is problematic from the start. The money you save now may cost you more later. Shipping containers, being made out of steel, tend to produce a lot of condensation. This can collect in the vapor barrier, causing the steel to rust. Even though containers are made out of weathering steel, prolonged exposure to moisture will eventually cause rust to eat through, albeit several years down the line.
There are three issues which make fiberglass insulation a poor choice for a container room:
- Moisture Absorption–Fiberglass absorbs and holds moisture which, in turn, destroys its insulating value.
- Convection Currents–Fiberglass insulation allows convection currents of air to travel through it, virtually eliminating any insulating quality it may otherwise have. The fast heating and cooling cycles of the steel walls can amplify these convection currents.
- Mold and Mildew Growth–When fiberglass gets saturated with moisture, mold and mildew tends to form. This poses a health hazard for whoever uses the room.
- Mineral Wool
When it comes to containers as dwellings, this may be the best insulation for the dollar. It serves as a vapor barrier, actually drying out damp spaces where it’s installed. Its insulating quality never degrades, and it cannot grow mold or mildew. Furthermore, it’s fireproof. While substantially more expensive than fiberglass, it won’t develop any of the problems fiberglass has. Finally, it can be installed like fiberglass batt panels, with no need for a separate vapor barrier.
- Closed-Cell Spray Foam
This insulation is also an ideal match for container dwellings. It is also applied after the walls are framed in. It possesses qualities similar to mineral wool insulation, such as consistent insulating quality that doesn’t degrade over time, and it functions as a vapor barrier. Its closed-cell structure prevent convection currents from forming, and mold and mildew won’t grow in it. The only real drawback here is the cost–it can be up to 3x the cost of fiberglass insulation. However, it’s a ‘do it once and forget about it’ solution. If you elect to go this route, leave it to the professionals–they have the experience, expertise, and equipment to do this right the first time.
- Drywall Installation
This is something that’s a little harder to do than it may look. Cutting and hanging drywall involves a fair amount of brute work. Once the drywall is hung, you will need to tape and mud all screws, nails, and seams. After about three rounds of that, the wall should be ready to prime for your finish coats of paint.
This is probably the easiest part of the whole project. Block in the corners, windows, and doors, then roll the rest.
And You’re Done!
After you have completed all your hard work, you can kick back in your new extension, pleased with how it looks.