How to Build a 12x20 Cabin on a Budget





Introduction: How to Build a 12x20 Cabin on a Budget

Fix & Improve It Contest

Finalist in the
Fix & Improve It Contest

Building a cabin yourself is much more economical than buying a prefab storage shed. The cost of materials for this build, including doors and windows, was around $2,200, which was about the same price as the install would have been on one of this large size if I’d purchased it from a hardware store. I know this for a fact because six years ago I bought a 12x16 shed from a well-known company close to where I live and it cost $2,000 for them to build it and drop it off. Today that same building would cost $4,200. With such a big price increase I decided that if I wanted to add a cabin to my property I had to build it myself.

If you decide to do the same, remember to check with your local authorities to make sure you don’t need a permit. It’s not likely that it’s required for a building of this size, but you never know.

If you would like to see the finished inside of the cabin please click here:

If you would like to see the matching modern outhouse please check this out:

Step 1: Floor Illustration

Here is the 12x20 floor plan showing where the 4x4s and the floor joists would be located.

Step 2: Drilling and Planting the Posts

1st picture: shows my ford tractor and my neighbors post hole digger he let me borrow.

2nd picture: shows the posts planted and the bottom 2x10 stringers.

3rd & 4th pictures: show the upper 2x10x12 and the 2x10x16 upper stringers being nailed in at 7 feet 8 inches.

Step 3: Setting the Center Rafter Board

This picture shows the center rafter board. I measured over 6 feet to the center. The roof is going to be a 5/12 pitch roof so the rafter board had to be 30 inches to the top of the board.

Step 4: Making the Angles for the Top and Bottom of the Rafters

1st picture: shows using a quick square. Put the pivot point at the top of the board and turn the square until the 5 on the * COMMON TOP CUT* line graph lines up with the outside of the board. Then draw the line to make the angle.

2nd picture: Once you cut your first angle then you have to measure from the tip of your cut down the length of the rafter to get your measurement for the seat cut. Once you have that measurement then you put the pivot point on that mark and turn the square until you get your 5/12 angle again. Then measure up that angle 2 1/2 inches and draw that line.

3rd picture: shows taking the edge of the square and lining it up with the 2 1/2 in line and turn the square until the tip is lined up with the edge of the board. Then draw that line.

4th picture: shows the angle seat that I just drew cut out.

Step 5: Setting the Rafters

1st picture: shows the rafters being set next.

2nd picture: shows the rafters on and the starting of the purlins being put on the top of the rafters for roof support. This is what the metal roofing is screwed to.

3rd picture: shows the tails all cut to 9 inches long and shows the steel roofing over hanging the roof by 2 inches to support the facia boards.

4th and 5th pictures: show the roofing installed.

Step 6: Adding on a 4 Foot Porch

Here is where it started to get complicated for me. I was looking for a 12x16 cabin, but once i looked at it I decided I wanted the whole 12x16 for floor space so i added a 4 foot porch to the 12x16 to make it a 12x20 total building instead of a 12x12 inside living space.

Step 7: Side Wall and Purlin Illustration

Step 8: Lag Bolting the Outer Joist to the 4x4 Poles

I had to screw (36) 3x3/8 inch lag bolts to all the outer joists into the 4x4s for stability.

Step 9: Hurricane Studs

1st picture: shows the (20) 13 inch hurricane studs with the 5/12 pitch angle cuts.

2nd picture: shows them installed.

Step 10: Floor Joists and Insulation and Floor

1st & 2nd pictures: show the (14) 2x10x12 floor joist installed

3rd & 4th pictures: show the 1x2 furring strips nailed to the inside of the floor joist 1 inch below the top of all the joists.

5th picture: shows the 1 inch insulation board between each joist before gluing and nailing the floor to the joist.

6th picture: shows my Dad lending a hand nailing down the floor.

Step 11: Rough Sawn Lumber for 8 Inch Board and Batten Siding

1st - 3rd pictures: show my dad cutting the siding boards to 8 foot long.

4th - 6th pictures: show the boards up on the wall and the soffit and the facia boards being put on.

Step 12: Studding in the Porch Ceiling

This picture shows the studding in for the porch ceiling, 16 inch centers and 4 foot long studs.

Step 13: Studding in the Front Wall and Door Frame

Studding in the front wall and front door frame, it was a hot day!! Here's my dooraggin' Dad! Just had to take a picture of this! He-he-he...

2nd picture: my friend Josh came over for a day to lend a hand on the mitre saw.

Step 14: Gable Ends

Here are the gable ends finished with the batten strips attached. All that's left for them are the two vents.

Step 15: Finished Cabin Structure



    • Science of Cooking

      Science of Cooking
    • Pro Tips Challenge

      Pro Tips Challenge
    • Epilog Challenge 9

      Epilog Challenge 9

    We have a be nice policy.
    Please be positive and constructive.




    Was this in US dollars? When you finished, is it just framed or finished inside? Not talking furnished. Thanks.


    Without any vertical support for the ridge beam ... you put 1 foot of snow on that roof ... and you will be wearing that roof.

    Absolutely Correct "djkulp!" There are no joist spans, also called collar ties. No vertical supports for the rafters of the ridge also called ridge beams. See pic everyone. This or different design is required to meet code. This coolbean design here does not meet code anywhere that I am familiar. Hurricane ties are not meant to replace joist spans. Hurricane ties are to prevent aspirating air of high winds from pulling roof up and off...not support. He needs plywood triangles and/or joist spans. Plywood triangles are at apex and both sides of ceiling joists or collar ties. (see photo for triangles, diagram for collar ties) His roof load capacity is ????? below all specs for this type of structure.

    ceiling-joist-span-i11.jpgshow_image_in_imgtag (1).jpg

    I am planning to build a similar size structure soon and I appreciate your comments on this a lot MassSpec, not to be 'critical' of this build so much as to educate people about the things you have mentioned which can be serious safety issues or at the very least code violations. I'm sure many people might build a similar design as a 'shed', but as a living/working space, it's good reason for caution.

    Thank You KipA2! Sometimes I really feel that leaving comments and such is just a waste of time. You make me feel otherwise here as I like to share and help. Your comment "not to be critical of this build so much as to educate people" is right on target. I made a mistake in my analysis that must have also been confusing. I said "no vertical supports for the rafters of the Ridge also called a Ridge Beam." Well he does have a ridge beam. And a ridge beam with extra vertical supports directly below it at the two ends of the ridge beam. His ridge beam is also about twice as thick as it needs to be because the ridge beam only deals with push and pull forces along the length of it, there are no perpendicular forces to the length of the ridge beam like bending so most ridge beams are only 1 inch thick... although they are 10 or more inches in width. They have to be to be able to touch the entire end of the rafter when cut at an angle, which is longer than the rafter board width. He also has good support at the bottom of the rafters, where they touch the wall. He used a lot of extra wood to support the ends of the rafters. This is really my observation: Instead of using better DESIGN for strength, support, stability....he uses a LOT of extra wood to compensate for the lack of a better design. Along those lines I have some more design considerations that are very helpful. Now understanding WHY they work is essential so all those who don't care to know why will not appreciate the following so no comments please. (Logically you shouldn't be on this website if this includes you....just saying nicely.)

    So I have a couple more considerations with explanation that I would like to share because understanding the reason for these structures was critical to my ability to build a solid home. First how we framed the roof of our home:

    >Our roof framing, by code, required us to have a rafter design that is an exact triangle to start. With a ridge board and collar ties across every other rafter triangle. So a right triangle, 90 degrees at the apex, equal sides for the rafters and attached to the rafters at the bottom are boards that are also serving as our ceiling joists for the top floor. These ceiling joists or the only horizontal boards at the bottom of the triange are all attached at the ends of the rafters and these bottom boards (ceiling joist boards). The bottom corners of the triangle roof framing go out far enough past the masonry walls to form substantial eaves on opposing sides of the house. The corner of this framing at the end of the eaves has gutter boards attached, large enough to slope the gutters to the downspout(s). So this "bottom board" of the triangle extends on both sides of our house about 3 feet out so that we can open windows at the front and rear of our home during a rainstorm. OK..Now in addition to these triangles, for support structure of snow for example are collar tie boards on EVERY OTHER triangle of roof framing. They are similar if not the same in dimension to the ridge board, 1" thick and 10 or 12" wide because again this is a pulling force that keeps the rafter boards from deforming, like the roof flattening out with weight on it. The weight of all these triangles rests on top of cinderblock and brick (you can only see brick on the outside of the house). The collar tie boards are closer to the bottom within the height of this triangle (height meaning straight up from bottom to the apex parallel to gravity). I imagine these collar ties are necessary because the framing triangles are resting on the masonry walls and not nailed or lag bolted or bolted as would be true if the walls were framed wood. I believe we have some very large timbers within the masonry at the top for attachment, as we also do for installing entry doors.... but you get the point because attachment of wood within the masonry can not handle too much stress or the mortar can crack. The bottom boards (ceiling joists) are 2 x 8, the rafter boards are 2 x "larger than 8" and the ridge board and collar tie boards are 1 x "larger than the rafter boards." The collar tie boards are parallel to the bottom boards, for clarity.

    I'd have to say you're not wasting your time as I'm wanting to build a 20x16, 1 1/2 stories high, with an open to below loft, and a upper deck covering half of the roof, overlooking a gorgeous beaver pond in Northern Ontario. Please never stop sharing your ideas or opinions. :)

    I wrote the reply below this one first. So please read from lower reply first. Now the promised design strengthening and load spreading techniques:

    >See diagram of "Mid Span Stringers." They are twin 2 x 4's. One is on edge and the other is against the first but on side. What is their purpose?

    The board on edge is the more important board. Try to bend a board parallel to the 4 inch (3.5) side. Impossible without a huge amount of force. In our house we have 2 sets of these at both "mid span" locations. {I forgot to mention below that the triangle roof framing also rests on a load bearing wall at the midpoint of the bottom or ceiling joist boards. And due to their length the ceiling joist board across the bottom of one triangle frame is 2 boards. They overlap directly above the load bearing wall. (In building a shed, the bottom board or the collar tie, will always be a single board.) The overlapping bottom boards (ceiling joists) are fastened with appropriate Simpson Strong Tie fastening system or Timberlok Engineered lag screws or bolts. To each other and also to the top of the load bearing top board; so they are really no different than a single bottom board. But if you did this in a shed you would need rather large posts and support boards across the length of the shed. Which is fine if you like many posts and are building a very large work room/ man cave/woman cave/shed. (And the extra work involved.)} ...So because of the middle support, we have 2 "mid points" and use 2 stringer assemblies. The board on end is extremely unyielding in the vertical direction. When screwed or nailed to the top of the bottom joists it provides for a rigid and flat ceiling surface below (reduces drywall cracks). The stringer board laying flat only has one purpose; to help attach the on end board to the ceiling joists. Screw or nail the bottom of the on edge board right thru the center of the side of the flat lying board and screw or nail the flat board to the ceiling joists is the idea. The corner formed by the two stringer boards also give rigidity in both the vertical and horizontal directions. This was a VERY common practice in homes built about the time of my birth in the 1950's. Now here is a really cool added benefit which I will call spreading the load across many joists instead of a load being supported only by the joist below it. This is great stuff! After installing a stringer(s), imagine standing directly on top of a ceiling joist while upstairs making a storage space or putting in batt insulation. With the stringer in place your weight will be distributed across many joists like a flattened out bell curve. Instead of all the weight setting atop a single joist, the weight is now supported by 7 or 9 joists! (How cool is that.) Now view the second picture. There are other methods for achieving this same result. Two more are shown: solid bridging and diagonal bridging. Sorry about the res of the pic below, the top is the diagonal bridging. Diagonal bridging comes in metal form already with nailing holes and at the proper length for the size of the joist.

    On our upstairs ceiling joists we used stringers, so we could run insulation batts under the bridging without as much heat transfer or cutting of the lengths of R-21 Owens Corning batts. R-21 is the best for 5.5 inches thick. You have to special order the high density insulation, not in stores. OOPS! I told you our ceiling joists are 2 x 8 ? They are not, they are 2 x 6. (true 1.5 x 5.5). And we ran standard less expensive R-30 rolls perpendicular to the insulation between the joists to cover the joist heat transfer and make the majority of the surface R-51.

    Now in our basement ceiling, also our upstairs floor, we used block bridging between the joists. It was perfect for this application. There are many ways to install these including a Kreg Jig HD. Or nailing them through the joist into the end of the block bridge, which is why the picture shows them staggered. Using a Kreg Jig HD you can line them up if you want. I imagine strait block briding is about 5% or less stronger so don't be a perfectionist about this. It's the incredible advantage of weight distribution that is so cool! Underneath the upstairs bath tub, for example, we "sistered" joists and also used block bridging to distribute the water weight across as many joists as possible. Tubs can hold from 80 to 110 gallons, so at 8.34 pounds per gallon that totals around 800 pounds!

    The third picture is our upstairs ceiling. My real first name is Leonardo. neck kinda hurts now so I should go. God Bless and safe building to everyone! Final hint. Get an impact driver. Best is Makita in my opinion. Check out TimberLok and "engineered lag screws" that require no predrilling and can even cut out their own bevel for a flathead screw. Also use torx drive or square drive or similar. Phillips is last resort, if you do use phillips make sure your bit fits your screws perfectly or it will be frustrating to keep the bit in the screw when you drive them. See last picture for Phillips vs. JIS, which look the same. You can not mix the two or you will strip the screws and mess up the bits.



    ...or near sand dunes...(Rujberg-Knude Lighthouse Station in Zeeland, Denmark)

    Abandoned, Rujberg-Knude Lighthouse, DK-3.jpg

    Thanks for your hint, but this project is not for the "First day DIYer". Anybody tackling anything of this magnitude will realise what Rules of Static will have to be applied in their area.

    well i live in upstate ny 6 foot and no problems yet been 6 years now.andthere is truss supports tied into the ceiling ..