DIY-Prefab

My little 12′ x 12′ woodshed is pretty much done now. I had a friend of mine who needed a little work come over and paint it for me. I also built the sliding barn style door and got it mounted to the track. I still have a couple of minor details to finish like installing some kind of latch on the door and adding the roller on the bottom edge to keep it from swinging in and out.

One neat little detail that I was able to incorporate in the door was to reuse a wood frame window that I removed from our main house a while back when we updated to double pane vinyl windows. It was originally installed tall and narrow but it was just the right size to put in the top of the door turned on its side.

See what you think…

So what did it end up costing to build this little building? I will still have to go back and total up all of the receipts but I can tell you that the total for the materials was definitely less that $1500 total. The majority of the lumber, siding and foundation materials was just a little over $800 and two pickup truck loads from Home Depot. The roofing materials came from Lowes for right around $300. The sliding door track and hardware was just over $100 from a local specialty hardware store here in Portland called W.C. Winks. I had a few odds and ends of materials on hand already but not that much overall. The window was the main special thing I had on hand. The 1×3 trim was a real deal from our local Habitat for Humanity Restore. I think I paid about $12 for most all of what I needed. I borrowed the framing nail gun from my son-in-law which was a big help. I rented the siding nail gun from Home Depot and ending up keeping it longer than I had intended and had to pay something like $97 for it. I could have bought a new one from Harbor Freight for that amount or less. I already have an air compressor and the other tools that I need. I did pay for some of the labor since my youngest son is not fully employed at the moment and my painting friend needed the work too.

How long did it take to build? I spent about 4 hours shopping for the first big pile of building materials the day before we started in earnest. I think I built the framing table top on that first partial day too. The nearest Home Depot is only about 1 mile away so making two trips was not too big of a deal. I also have a pickup truck so that helps. It would have saved some time to have ordered the stuff from a local lumber yard and have had it delivered. With my son’s help we got to the top of the floor on the first full day. We had to do a little more digging than we had anticipated for that part. Also the woodshed is maybe 75′ from where we unloaded the building materials so we had a lot of carrying to do. Day two we had built the walls all the way to the top. Day 3 we had framed the roof and installed the roofing. On day 4 I had to get back to my day job while my son installed and fully caulked all of the exterior trim. The painting took about 1 day total spread out over two partial days. I also built the door over a few hours. The total construction time to get the little building to where it is now appears to have been about 9 total man days of effort. I will have to spend an hour or two to finish up the minor details I mentioned above and to clean out the sawdust and wood scraps out of the building. The interior is completely unfinished with nothing painted so it would take more time to finish the inside more if someone wanted to do that.

As explained in post number 29 I decided to prefabricate the wall panels of a 12′ x 12′ storage building that I built recently. This post continues where the previous post left off. As I said before I did not strictly speaking need to use the prefab techniques that I used since I was not going to be transporting the panels to a different place for assembly. These panels were in fact installed around the edges of the floor immediately after each one was built. The prefabrication table was sitting right in the middle of the new building. I think you can see what I mean by referring to the following photo.

When the 4′ wide wall panels are attached to each other a double stud (vertical member) is created. In my design of this shed my rafters fall at 4′ on center so this means that they will always sit on top of a double stud. This also helps explain why I do not need a double top plate (the horizontal member at the top of the wall). By the way you will notice in the above photo that there is no top plate on the top of the walls. This is because I added a 12′ long top plate at the top of the wall panels when they were all in place. This next photo show pretty clearly how each of the homemade trusses sits on top of the single top plate directly above a pair of studs. It also shows how we attached 2×4 purlins (the horizontal cross members laying on top of the trusses). Flat 2×4 purlins are capable of supporting the type of roof sheathing that I chose to use which needs to have purlins rather than rafters that are closer together.

The type of roofing I used was a product that I found at Lowes called Ondura roofing. It is a composite material in a corrugated form. The sheets are 48″ x 79″. I designed my rafters very carefully so that I could use full sheets at 79″ long. This meant that my roof overhang had to be a little smaller than I might have liked but it works out OK. This next photo shows a view of the completed roof.

Over this last weekend and a little into this week my youngest son and I built a back yard wood shed. While we did not strictly speaking need to apply very much in the way of prefab techniques I decided that I wanted to use it as a small practical example of how prefab techniques could be applied to a simple project even if the prefabrication was not being done in a location remote to the construction site. The building is 12′ x 12′ in size. It has a simple roof line with a roof pitch of about 4/12. If you have been following my other posts here in this blog you will recognize that I used a ladder style of wall panel design rather than the more conventional version where all of the studs are vertical. I used Hardiboard 4′x8′ sheet siding. All of the wall panels use a full sheet. The floor system sits on concrete piers. We dug relatively shallow holes for each of the piers, poured in a bag of dry ready-mixed concrete and set the pier on top. In my experience the dry mix will eventually absorb enough moisture from the ground to become solid. In the mean time it provides a sufficient base for the building even if it is still in dry form.

I wanted the floor system to be relatively low profile so as to keep the overall height of the building low. Rather than placing beams on the pier pads and then laying joists across them I took a somewhat more complicated approach where I used 4×6 beams, attached 2×4 ledgers to the bottom of each beam and then added 2×4 joists between them. The drawing below shows the arrangement. I could have used only 3 beams and used 2×6 joists. I would not have had enough height on the beams to have used the ledger approach but metal joist hangers would have been fine. The following photograph shows a part of the actual floor frame.

Each of the wall panels were sized such that the bottom of the 4′x8′ Hardiboard sheet would overlap down over the floor frame. This meant that each of the vertical members had to be cut to size. There were 3 different types of panels. One panel was a full width panel. The other two were designed so that the 4′x8′ Hardiboard sheet would overlap another wall panel at the corner. This meant that I had both a left hand and right hand version of the panels. The main thing that I would like to point out in this post is how I prefabricated the wall panels.

I build a very simple framing table out of a sheet of 7/16″ thick OSB with a frame of 2×3 lumber around the edges. I supported the table with two standard folding plastic saw horses. I used a black Sharpie marking pen to draw lines on the table to indicate where framing members should be placed. I also drew a pattern for my rafter on the table. I screwed down a few short pieces of 2×4 block at strategic locations to help make it easier to quickly position the framing members when building a panel. It was then a pretty simple matter of placing all the framing pieces, nailing them together and then adding the siding sheet on top. In this case I was fortunate to be able to borrow a framing nail gun from my son-in-law that was very helpful for nailing the 2×4 lumber together. I also rented a siding nail gun for nailing the Hardiboard siding in place. If I did not have access to a framing nailer I probably would have used decking screws to assemble the frame. I find that it is easier to hold things in place if you can quickly attach members with a nail gun or a screw gun. Manually nailing the members would certainly be possible but harder to do on a table at the height of mine. If I were to manually nail the panels I would probably have set the table much lower – maybe directly on the floor. You will have to look closely in the photos below to see some of my lines. Hopefully the idea will be obvious enough. The second photo shows the frame members on the table just after they have been nailed together. Notice the nail gun.