I have been looking or a paper to represent tarpaper and I found this pastel paper at an art store. It is made by Canson.
My initial venture was to apply the paper like tarpaper in real life. The problem was the paper is about .010 inches thick. That is about 3/4 of an inch in my OO scale world. The first photo is of that technique. This is the technique I developed to disguise the thickness. That is the second photo. I found that butting the segments against each other they could give the illusion of being the thickness of real tarpaper.
This paper has a grainy texture and is not absolute black. It has a brown tar hint. One side has a criss-cross texture. Regular construction paper lacks texture and isn't the right color.
Cut a piece of paper large than the roof. This is an Atlas Trackside Shanty.
This is after the overlapping roofing was removed.
Scribe a line down the center of the sheet at the ridgeline. This will make a sharper bend. It will look like the tarpaper is thinner.
Bend the sheet at the scribed line.
Figure where the sheet ends would be if they over lapped. I am figuring on a scale three foot sheet. My roof is almost a scale 6 foot. From the top I will figure a folded whole sheet. I measure up from the bottom a distance less the overhang thickness of the roof and the overlap of the next sheet. Mine figures to be 2'-6". If I had a larger roof I would make the next mark at 2'-9", the sheet width minus 3" overlap.
Transfer that to the paper.
Using a NEW single edge razor blade cut the ridge piece. Initially I though that the glue placed along the line marked by the sheet would raise the adjoining sheets enough to indicate the tarpaper thickness.
I continued gluing the next sheets. Butt them up against each other.
Notch the corner with your NEW single edge razor blade. Scribe along the red line against the roof. Apply glue to the blue area. I am using Quick Grip.
Roll the flap around the roof. Trim the excess off with a NEW single edge razor blade.
Don't use a hard instrument to press the paper down. Use a piece of wood. A hard object will crush the paper fibers.
Do the sides first and then the long side.
Originally thought that the bead of glue would raise the paper enough. The control of just the glue was not controllable enough. The next idea was running a razor blade under the edge and rolling it up slightly. Be careful not to cut the paper. Use an OLD razor blade.
The edge definition with the slight roll improves the appearance.
Take sharp pencil and lightly place "nail heads" along the ridge line piece. Nail heads should be placed along the overhang.
This makes very realistic tarpaper. The pastel paper has the right color and texture. It easy to apply and economical.