Buiding the Roof

This turned out to be the most difficult and time consuming part of the construction so far. An arched roof is really cool looking and it is good at shedding rain. But it is not so easy to construct. This section goes into great detail about how I built the roof and why I did it this way.

The Framework

Here I am test fitting the arch to see how well it matches the cut radius of the front wall. It fit well enough that I didn't have to do something over.

First I had to calculate the measurements to lay out 10 arches on equal centers from fron to back. I wrote a small program to subdivide the length, taking into account the width of the arches as well as the distance between the inside front and back walls.

I marked off and cut notches in the top to receive the arches.

This is the arch tail.

Here I use a long stick to keep the arches straight and in place as I fasten them in with screws and epoxy.

Of course it rained a lot. The installed arches went a good ways toward supporting tarps and keeping most of the water out.

I needed 13 foot long strips to fasten onto the tails of the arches to make a foundation for the plywood and a nice soffit. But I had only 8 foot long pieces. Thus I needed to fasten two pieces together. A butt joint would not do here. So I created scarf joints. Here is a scarfing jig for cutting precise dihedral angles in two pieces of wood so that they match when glued together.

Here I make the scarf cut for one piece.

A closer view of the scarf cutting process.

The finished scarf cut.

The sides are installed to complete the eaves.

In addition to the 10 inside arches there is an arch for the front and back. These brackets support the arch that extends out the front.

Here the front arch has been fastened on. it is satisfying to see progress like this.

Here is a close up of an arch support bracket.

The arches are in place and held to the correct spacing on the centerline.

I used an aluminum straight edge to check the fit of the arches.

I sighted through the lenght of the aluminum channel to make sure it was straight. This faintly resembles the tesseract in the movie Intersteller. It is also a good sign that I have not yet bent this aluminum out of shape as a straight edge.

The frames make a nice pattern of sunlight on the inside. But this wasn't for long.

The aft part of the roof frame brackes mounted.

The aft frame arch is mounted.

Here I installed the framework to support the mollycroft.

I had to do a bit of planing to get the frames even.

The Sheathing

If I thought the arches took long enough to fabricate wait until I applied the roof sheathing.

First I thought I would be able to install the sheating in large sections at a time.

I ran into this problem. The plywood likes to expand and contract with levels of humidity and rain. I considered removing the entire sheet and starting over. But I ended up adding more epoxy and nailing the lifted sections down. This fix was satisfactory.

I went to the back and installed the first of smaller sections that span two arches each. I still had some problems with the plywood lifting up in places. Sometimes it would lift up, the epoxy cure, and then contract. For that I cut the plywood a bit and glued it down again.

I kept going section by section. In a couple of places I did do things over. But fortunately not enough to need to order more plywood.

At last the first layer is on.

Today was a slight bit of snowfall. I got good at keeping the roof dry.

For the second layer I started with a 10" strip. I used string weighted down with bricks to apply even pressure and hold it down while the epoxy cured. After it cured I ran my hand over it and listened. There were some voids. Not real good but nothing I could do about it.

I went to 5 inch strips. These would take a lot longer to install but the glue up was more manageable.

Here I have glued up a bunch of 5" strips, gradually working my way forward. There is some unevenness but I did a lot of sanding to fix that.

As I worked forward I evolved the method of holding the stirp down. I finally settled on using two ratchet straps and tightening them down as much as I could. I also figured out the optimum amount of epoxy to apply.

Here I am near completion of strip installation. After sanding I applied more epoxy to seal it up.

It is now sanded and ready.

I laid down fiberglass and wetted it out with epoxy. I worked 5 hours straight to wet out the entire roof. I ended up using more epoxy than I planned and I had problems with bubbles.

After the epoxy cured I started sanding. Here is a job best done in the rain! The fiberglass and epoxy dust is not nearly as nasty as when it is dry. I sanded out and patched up bubbles. Beyond a point I left it a bit rough. First, I don't see people staring at the top of the roof so much, and secondly if I am up on top it is less likely that I will slip.

Here I put on the primer coat. I mixed Interlux one part Boat Coat gray and white to make a light shade of gray.

More priming.

Aft Support Brackets

I drew these brackets up in Inkscape to get the proportions right.

Two brackets being made.

The brackets are mounted in place.

Another view of the brackets in place.


I installed a rain gutter.

Soon enough the rains came. Gotta love smart phone camera focusing!

The Finished Roof

Finally done! Along the way I though of many ways that seemed easier than what I ended up doing.