A roof drip cap or drip edge is used to direct water away that would otherwise run behind your gutters. If the roof edge is too short to direct all rain water into the gutters this creates the problems of rotting of the fascia and roof, stains, flooding and erosion. Fortunately this problem is easily corrected by installing roof drip caps.
Drip caps extend from under the first row of shingles and into the gutters. They are the first step in the preparation of a roof for finishing. Nail the drip cap along the entire perimeter of the roof. Follow with an ice and water barrier that overlaps the drip cap. Next comes asphalt roofing paper, followed by metal flashing and finally the shingles.
Replacing Roof Drip Caps
If the existing drip cap is rusting, staining or needs replaced for any other reason this is a relatively easy task. You should be able to do it yourself. You must first remove the old drip cap.
To do this you must carefully pry the first row of shingles up with a thin, flat tool. Do not pry them up to far or else you could crack them or the shingles in the row above them. Then insert the tool under the drip cap at the nails. Gently lift up and pull the drip cap out from under the shingles.
Slip the flat, wide rim of the drip cap underneath the first course of shingles. Be sure to make the outer edge extend over the gutter. Secure the ends of the drip cap with small roofing nails. Make sure that the nails are up under the shingles.
Apply a continuous layer of roofing cement along the top of the drip cap. Then press down on the shingles to fasten it all together. Reseal all the shingles with a layer of roofing caulk.
Drip caps can be purchased at any home improvement store or lumberyard. They typically come in eight foot strips. Use tin snips to cut to the proper length.
There are two sizes of drip caps. Six inch or long and three inch or short. The six inch size is for the length of your roof. The three inch size is used on the side of your roof.
Drip Cap Materials
Aluminum drip caps are probably the most popular. They should last fifty years. It is the best deal for the money. It is easy to work with.
Stainless Steel will last a lifetime. It is somewhat expensive. It comes in a polished or a satin finish. They are the most attractive type and worth the extra investment if your budget allows for it.
Copper is cheaper than stainless steel but the runoff will discolor stucco and stone.
Lead is the easiest to install. It is also expensive and it is considered an environmental hazard.
Drip caps are usually the first thing to go when negotiating a roofing contract. Some roofers will even claim that they are unnecessary. These contractors claim that if the shingles extend over the gutters then it is fine to omit the drip cap. This is false.
When the shingles alone extend over the gutter they can become bent. Drip caps began to be added to asphalt roofs in order to prevent this sagging. This sagging will lead to cracking along the edge of the roof.
Broken shingles along the line of the roof deck creates a greater chance of water seeping into the substrate. If water gets under the shingles it can lead to staining and deterioration of the edge of the roof deck and the top of the fascia. Long term exposure to this can have a detrimental affect on the trusses and roof joists. The absence of a drip cap may not cause visible damage in the short term but over time it can lead to preventable damage and costly repairs.
If you have a slate roof you do not need a drip edge. Slate does not sag. You may choose to have a drip edge anyway. A copper drip cap under slate is very attractive.
There is a difference in drip caps made for asphalt and slate shingles. A slate drip cap’s primary purpose is not to support the shingles but to protect the edge of the roof. For this reason they do not need the horizontal flange. You may use drip caps with this flange on a slate roof but you must not use drip caps without this lip on asphalt roofs.
If you are trying to decide if you need a drip cap on your roof consider that for an inexpensive option it’s benefits far exceed it’s cost, especially in the long run.