Applying felt and flashing for installing roof shingles

Applying roofing felt and installing roof shingles is important because the roof is the first line of defense against the elements. It has to be done right and with the right materials. The basic idea is that a roof will let water or snow run down to the ground with no stops on the way. If water forms pools on the roof, it has a more likely chance of getting in than water that runs straight off.

The type of roofing material depends mostly on the local climate. I will cover only two types of roofing materials because of our purpose in creating a nice home on a tight budget, there are many other choices that don’t make sense.

I live in an area where there is a fair amount of snow and ice, but rainfall is minimal. In these conditions, a person could do well by installing roof shingles or metal panels and stay in budget.

roof flashing


Asphalt shingles are much less expensive than metal and they are of much better quality than they used to be. If I travel 30 miles north, most roofs are made of metal because of the heavy snowfall. Just 15 miles south of my home, most roofs are made with asphalt shingles and metal roofs are considered overkill.

I opted for a metal roof because of some of the problems I have seen locally with asphalt shingles. If you can get away with using shingles then do it because it’s a lot cheaper.

Metal is a little harder to work with because it’s difficult to cut. The roof goes on faster with metal because so much area is being covered at one time. The cost difference is substantial though. The house will appraise for more with metal because it is more durable.

Now to start with, we will need to have a protective barrier to put directly over the sheathing or the wood on the roof. This moisture-resistant barrier is called roofing felt or tar paper.

It’s important that the roof is dry before this goes on or it will hold the moisture in and cause the roof to start rotting.

roofing felt

Roofing felt comes in different lengths, widths, and thicknesses. 15-pound felt is the most common thickness. You just roll it out starting at the bottom of the roof from one end to the other end. If you have to put two pieces together while going across, then you should overlap them at least 4 inches.

You can secure it with galvanized nails, but only put in as much as is needed to prevent the wind from blowing it away. The second row will need to overlap the first row by at least 2 inches. That’s why you start at the bottom and work your way up.

tar paper

Once you have finished with all the roofing felt you will need to consider the areas that need flashing. The flashing material is important and can be found wherever roofing materials can be found.

The illustration below gives us a good idea how the flashing is applied and shows its purpose in diverting moisture downward in vulnerable areas such as valleys, hips, chimneys, vents, or any other attachments.

roof flashing

This shows how the flashing is installed and where it is placed above the shingles or beneath them.

The flashing for metal roofs is applied in exactly the same manner as installing-roof-shingles. The only important difference when doing a metal roof is that the flashing and the fasteners be the same type of metal as the roofing material to prevent electrolytic action which causes deterioration. You can usually find the same color of flashing as the metal you buy at the same place.

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