DIY Metal Stud Framing
1. Why Metal Framing?
2. The Tools
3. Basic Assembly
4. Design Strategies
1. Why Metal Framing?
The reason we went with metal framing on our tiny house is because we reclaimed an RV trailer with a 7,000 lb weight limit and wood framed tiny houses are generally over 10,000 lbs. Metal studs are generally 70% lighter depending on the gauge steel that is used. Some newer tiny houses are framing with heavy duty metal studs but we went with lighter, widely available metal studs that we got from our local big box store. We used a mix of 20 and 25 gauge studs with the thicker (20 gauge since lower gauge is thicker) where we wanted more strength like the overhang and the bottom piece of track that connects the wall to the floor.
Steel studs can be a little daunting if you are only familiar with wood or not familiar with framing at all. When we were first trying to make metal studs happen we were fascinated by every screw and connection on the rare detailed images we could find on the internet. There was not much before our video. Now that our house is almost entirely complete we can say that we have no regrets going with metal and think it’s a great option for those trying to save a little weight for their trailer or to save on gas.
2. The Tools
The tools above are the most important with the exception of a utility knife since most people probably already have one. As shown in the videos below, the knife is used with the square to score the cut in the metal stud and the snips are used to cut the sides. The 3″ metal hand seamer is a tool we use all the time for things we never knew we needed it for. It is used to safely bend a cut line til the stud snaps loose and also to bend and manipulate the sizes of the C channel studs.
3. Basic Assembly
Our Metal Stud Videos
While there are several ways to go about framing a tiny house the first choice is 16″ or 24″ on center (on center means center of one stud to the next stud). We chose 24″ on center since we were relying largely on the exterior sheeting for wall strength and wanted to minimize material use, detail work, and weight but the house would be stronger if it was framed 16″ on center. It is important to note that metal studs aren’t like normal studs in that they have a C channel stud and a U channel referred to as track. This C channel acts as a classic stud but the U channel goes horizontally as an end cap and you bottom and top or brace halfway up your wall. For our house we simply framed the two side walls first and connected them with the end walls. Then we framed the overhang and finally added the roof beams.
a. Setting the Stage
The first step in framing your tiny house with metal studs is making sure that you have a level subfloor or border around the edge of your trailer which may consist of your trailer itself if you have one of the newer trailers with an anchor flange. In addition to a smooth based you also need an open space in which you can build your wall on the ground. This make everything safer and easier but like wood framing building vertically is an option too. In our video you can see a time lapse of us assembling our main walls (26 feet long at the overhang) which almost resulted in us getting poison ivy.
b. Cutting Technique
This part is simple once you get the hang of it but we suggest a good pair of gloves as an additional item to help keep things safe. Once you have figure out the length of the stud you need to cut you can simply mark it with a sharpie and line up the square with your mark and score it once or twice with an utility knife. After the score is complete you can follow the emboss lines with your tin snips to cut the edge. Once the side snips are complete you can bend the metal back and forst until it snaps. VOILA! However, for those horizontal track supports halfway up the wall you will need to cut out a more difficult hole which can be done by drilling a hole (1/4″ or more) and using tin snips to work your way around. In addition, cutting any diagonal supports can be a bit of a challenge but just involve a diagonal cut on the side of the C channel instead of a straight one.
The part that took some of the most trial and error for us was finding the right screw technique. No matter what we always knew that pancake head (AKA truss head) screws were the best because they didn’t create a weakend divot due to the flat underside of their head and have a wide surface area. However, at first we tried self tapping screws which have a little drill bit built into the end of them since they are considered standard metal stud screws. However, those were a pain to penetrate the metal with especially when erecting the walls up on a ladder and kept sliding off before they did. They also made a hole that was a little too large for the screw threads to get a really strong, tight grip with. We eventually realized that a normal Tek screw was very sharp and with some pressure can penetrate multiple layers of metal studs easily. They also had enough friction on the point to stay in place without sliding or flying away off to the side.
Standard Self-Tapping Screw
Click on image for 100 pack. These are a pain and don’t create as strong of a bond. Maybe there is a brand out there that doesn’t over-drill and create too big of a hole.
4. Design Strategies
There are a few thing that can be done to ensure a stronger build with metal studs. Some of these are absolutely necessary and some aren’t. Anchoring the walls to the roof and the trailer are a must but extra diagonal supports might not make or break the build. That being said, the more triangulation the better for strength but it also takes longer to build and uses more material. Keep in mind that the outer sheathing acts to triangulate the walls and support shifting. We also went a step further beyond that and added strapping when we added sheathing which you can see in our outer sheathing video.
a. Bracing All Wall Segments
The wall must be braced to the trailer and the wall must be braced to the roof. This can be done with metal straps that are thicker than typical strapping used to support pipes. Driving conditions are similar to hurricane winds so why not use hurricane straps?
Hurricane Tie Strap 50 Pack
These hurricane straps can be used on the outer side of the metal stud to connect the roof to the walls and the walls to the trailer depending on the type of trailer you have.
Hurricane Tie Bracket 4 Pack
If your trailer doesn’t have a flush outer surface against the wall something like this might work well but many are required, not just on the corners. This is a good design for metal studs because you can spread out the force with many screws on the stud and use a larger screw to anchor downwards.
The metal stud system creates a unique opportunity for triangulation and extra strength. Think of water towers, cranes, and other steel structures that rely on triangulation to be strong and lightweight. While wood framing doubles or triples itself up over doors and windows on the headers, steel framing can utilize triangulated trusses (think bridges) as headers. Below is a picture that showcases some of the triangulation when we were part way done with the framing. After his point more triangulation was added to the sides of the wheel well trusses. The trusses are generally 12″ tall which allows for two roughly 45 degree angled pieces within each 24″ gap These pieces are normal stud C channel and not made of U channel track. In addition, triangulation can be added to account for fast braking like you can see in the picture below on the bottom left corner. That diagonal beam is designed to bring horizontal force downward into the trailer. On the top left we also triangulated to the upper corner in case someone were to walk on the overhang edge. We added x’s where we felt the most strain on the overhang would be.
c. Be Aware of Odd True Dimensions
The one thing we were not told anywhere is that metal stud walls don’t follow a normal 3.5″ thickness like wood studs do. The total thickness of the wall for calculations like total trailer width are important but when the track and screws are all in it is closer to a true 4″ wall. Because of this detail our house is actually 8′ 6 1/4″ which is over the regulated amount by 1/4″ so let’s hope we don’t get a stickler who wants to ticket us. In addition, these studs are not actually 1 1/2″ thick like wood studs, they are closer to 1 1/4″ but I’m sure it depends on the brand. This is important to know because it might make things fit a little poorly at the ends of a wall if you thought they were 1 1/2″. This is the advantage of going with a precut steel framing company because they indent the screw hole for you so the screw heads aren’t proud.
d. Inner Wall Reinforcement
This is something we hadn’t seen specified, ways to reinforce the wall internally where you might be hanging a heavy item or connecting a loft beam. You can see on our overhang that we used a doubled up bottom track and this was using the thicker 20 gauge pieces. As far as interior reinforcement for hanging or anchoring, if you know where this is going to occur you can cut and insert wood blocks to anchor into. For example, where we hung our TV we added 24″ in wood block into the stud because we wanted a swivel mount that would put a lot of force on the wall. For the the loft beams we added wood blocking horizontally under some mid-wall track pieces we added. So it is a bit of a metal-capped wood beam and has held up quite nicely and doesn’t give when weight is applied.
e. Metal Roof Beams?
Another area completely lacking in information was how to do the horizontal roof beams with metal framing. These are generally interior commercial wall materials and besides tiny house metal framing companies we didn’t see anyone use metal anywhere for the roof. So we sat down with an architect and did load calculations and eventually decided on simply doubling up every other beam to make an I-beam. While it wasn’t necessary, we also welded a metal girder using 1/8″ angle iron welded to rebar for the center of the butterfly roof. This was some extra work it cost almost nothing and acted as a great anchor for our ceiling fan. This was mainly to create a peak to drain water away from the center but also made the roof give a lot less when walked on. This could have been achieved with a single wood beam as well.
f. Electrical Considerations
This can largely be worked out when building but if you want to be particular you can design electrical channels to fit the precut pipe holes in the panel. However, it simply isn’t the case that these will be everywhere and you will want a 1.5″ metal hole saw. In the precut holes or your own holes you always want to use a plastic collar to prevent from cutting wires as well.
1.5″ Carbide Tipped Metal Hole Saw
I don’t care how well you think you have designed your electrical layout, you will need one of these at some point.
One of the favorite aspects of our tiny house is that we decided to be a little brave and go the metal stud route. It took a bit of pioneering and we are sure there are many improvements to be made upon the building process but we are happy to be able to share some of what we learned with the DIY community. This building method will certainly improve the mpg of a tiny house, doesn’t cost any more, and uses less dangerous power tools than wood framing. Lastly, with our weight limit and trailer length we sort of had to do this so we are extra pleased that it worked out.