Re-roofing our Gambrel Roof Barn

It has officially been one year since I finished re-roofing our century old barn. Before I started the project, I had a hard time finding information on re-roofing a large barn roof. So, with that in mind, I decided I would lay out the process I went through. This is by no means a full authoritative post on re-roofing a barn roof, but rather a journal of sorts, covering the process I took to re-roof our barn.

WHY

Why re-roof this old barn myself? Here are just a few reasons I decided to re-roof the barn:

• Hiring someone else to re-roof our barn was cost prohibitive. Doing it myself would save me $15,000-20,000.
• Finding someone willing to re-roof our barn was a challenge in and of itself. Most contractors did not want to touch it, let alone even come out and look at it.
• Re-roofing was a skill set I lacked. This project could resolve that.
• If I didn’t get a roof on the barn soon, it would share the same fate that most turn-of-the-century barns are succumbing to, that inevitable and inescapable collapse due to neglect. There are at least a dozen collapsed barns within a 5 mile radius of our house.
• In Minnesota, a proper shelter for animals to escape the harsh winter weather is a must. This is our primary poor weather shelter for our animals.

Before taking on this project, I had never taken part in re-roofing anything. Growing up, I had watched my father roof and re-roof buildings, but being just a child, my attention normally shifted to projects of my own, like building that fort in the woods.

Not only had I not re-roofed a building before, but going into this project, I was uncomfortable with heights. Considering the unsure surface that was our barn roof, those heights were even more intimidating.

RESEARCH PHASE

Alright, the decision to re-roof the barn was made. Time to move onto the planning/research phase. Lets start with some dimensions. With dimensions, a material list can be formed. With a material list in hand, the material can be ordered and the project can move to the implementation phase.

For dimensions, I utilized the free 2D CAD software Draftsight. I have since discovered SketchUp, which would now be my preferred software of choice for building layout and design.

I drew up the roof in Draftsight, laid out flat, so I could determine the amount of steel roofing I needed to order. Each rectangle illustrates a single sheet of steel roofing. The white portions of the drawing represent the existing metal roofing installed on all of the additions on the barn. The red portion represents the portion of the roof that was in need of replacement.

As you can see, I needed 62 sheets of steel metal roofing. It came out to:

(15) 8′ Sheets

(32) 10′ Sheets

(15) 12′ Sheets

I used off-the-shelf lengths (2′ even increments) as they were easier to obtain. As the barn was no longer square, each piece would need to be trimmed anyway, so there was no need ordering custom lengths.

In addition to the steel roofing, I would need screws and trim.

So, some basics on metal roofing. The peak or top most point of the roof requires “ridge cap”. This sheds water to either side of the roof at the top most point of the roof. I ordered 50′ of this. They came in 10′ sections.

The “hip” part of the roof, the part of the roof where the slope changes, required flashing. You can buy preformed roof flashing or flashing rolled up in bulk rolls (cheaper). I opted for the preformed flashing, as I didn’t know about the rolls of flashing at that time.

Along the front and rear of the barn, along the edge of the roof, I purchased “rake trim”. This trim provides a clean transition along the edge of the roof line. It also serves as another protective measure to keep water from gaining access to the buildings wooden frame underneath the steel roofing.

Finally, I installed metal fascia over the wooden trim along the edges of the roof.

The wildcard in materials list for me was the lumber requirements. Before installing a metal roof, you need to run “purlins” every 2′, horizontally. Typically, one will use a 2×4 for this “purlin”. This is the board that the metal roofing gets fastened to.

In my case, as you will see later on, the roof had been exposed to the elements for several years and had begun to sag significantly. My plan was to use lumber of various sizes as spacers, to give the finished roof a mostly square appearance.

HUMBLE BEGINNINGS

With materials on-site, a tarp on the ground, and a pitchfork in hand, I was able to fairly easily remove the shingles from the roof, a section at a time. The roof had the original wooden shake shingles installed, with two layers of asphalt shingles installed over them. Obviously, some places just plain had no shingles left at all!

As I would clear a section, I would then affix my purlins onto the cleared off roof at 2′ intervals. These purlins acted as a ladder of sorts to allow me to increase my reach and access to further portions of the roof. I worked my way horizontally across the roof. Working horizontally allowed me to have access to the portion of the roof directly above the portion I just cleared. This became important as I reached very, lets say, “un-square” portions of the roof.

NEVER SQUARE

As I cleared portions of the roof in the ever more sagging regions of the roof, it became necessary to run a string line from one side of the roof to the other. This allowed me to shim up the purlins so the roof would come out looking square.

The further towards the middle of the roof I got, the worse it got. As you can see here, I literally had to build a short knee wall on the roof to compensate for the sag in the roof. Additional reinforcement and support on the interior will be completed at a later date.

FINALLY! METAL!

Once the purlins were in place, I started to measure, trim, and install the metal roofing, sheet by sheet.

After the metal was on the roof, I used scaffolding to traverse the perimeter of the barn to install fascia and rake trim.

In my opinion, the overall roof turned out well. No where near perfect, but it has breathed new life into a barn that would have otherwise continued to rot and decay.

Some pointers worth noting that I either discovered during the project or received from others along the way.

• Do not skip the purlins. Do not install metal directly over asphalt shingles. Asphalt shingles and metal roofing contract and expand at different rates during temperature fluctuations. This will cause the shingles to rub against the metal like sandpaper, eventually leading to a rusted out roof.
• Invest in a safety harness. I have wife and children and couldn’t imagine having left them husband/fatherless because of my own ignorance and preference of avoiding the use of an in-expensive safety harness. $100 for the harness + a little inconvenience of dealing with the rope every time I wanted to move was a small price to pay to avoid a life changing fall.
• Buy twice the amount of screw you expect to use.
• Take a minute or two while you are up there to just enjoy the view of your homestead/farmstead. Besides our silo, the barn roof is the highest point on our property. It won’t be that often that I will get to take in a view like that.
• After a few weekends and many evenings on the barn roof, my fear of heights is nearly non-existent now.
• Use shoes with a good amount of traction. Don’t expect those shoes to look great when the project is complete. I wore holes on the outside of both shoes from their constant contact with the roof and constantly relying on them to hold me in place while in many tight spots up there.
• Once you remove that first shingle, expect the rain to come. We received over 10 inches of rain during the few weeks it took me to finish up this project!

Hopefully that gives you a fairly full glimpse into re-roofing that old barn. Are you thinking of taking on a barn roof? I am still by no means a roofing expert, but I would love to try to point you in the right direction if you have any questions!

-Jeremy (http://mnhomesteader.com/blog/)