Roof Installation Process

All About the Roof Installation Process

Whether you’ve hired a professional or plan to install a roof yourself, understanding the steps involved will help you ensure your new roof is properly installed. Here’s an overview of the installation steps for two different types of roofs on your home.

Removing the Old Roofing

The old roofing will probably have to be removed before the new is put in place. Many people will install multiple layers of roofing over top one another to save time; but adding too many layers (i.e., asphalt shingles) can lead to premature failure in the roof. The old roof should be stopped down to the sheathing, and rebuilt.

Evaluating the Roof

After removing the old roof, evaluate the sheathing. Roof sheathing is made up of flat panels that provide structural support and a base on which roofing materials, like shingles, are attached. Look for any moist areas or trouble spots that will have to be replaced.

Protecting Against Ice

If you live in an area that’s prone to ice for even part of the year, install an ice and water barrier around your roof. This product goes on around the edges of the roof, but especially at the very bottom edge that is most prone to the buildup of ice. This sticky underlayment adheres to the roof sheathing, then nailed down for added strength and stability.

Putting on the Drip Edge

The drip edge for the roofing goes down in two different parts of the installation. For the lower part of the roof it goes on before the underlayment, for the sides of the roof it goes on after. First, install the metal drip edge along the bottom edge of your home over top of the ice and water barrier. Nail it into place flat against the roof.

After you get the underlayment installed on your home you have to go over that with drip edge on the sides the same way that you did at the bottom. This prevents water from running over the edge of the siding and then back underneath it.

Putting Down the Underlayment

Underlayment, whether felt paper or synthetic, is saturated in water resistant materials and comes in two thicknesses, 15# and 30#. The 30# underlayment is twice as durable as the 15#, but the synthetic products are much more durable than either felt paper option. If you are looking for the most effective way to protect your roof besides for the roofing itself, invest in the more expensive synthetic underlayment, it’s the most convenient and durable option.

Roll the underlayment along the edge of the roof and secure it in place using cap nails every four inches along the outside edges and around eight inches in the center. These cap nails should not go through the drip edge, but instead just above it.

Roll out one row of underlayment after another securing it all down with cap nails making sure to overlap the lower row by at least six inches with the next row. Overlap the underlayment sections up to the peak of the roof and then install a row straddling the peak so that the underlayment caps off both sides of the roof at the same time.

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Getting the Roofing on

The technique that you use to install the roofing of your home depends on the type of roofing you choose. Shingle roofing, corrugated metal roofing, and clay tile roofing require different approaches. This article discuss the installation process for the two most common types of roofing: asphalt shingle roofing and panel metal roofing.

Installing Asphalt Shingles

Asphalt shingles are known for being one of the simplest types of roofing materials to install. First, lay a run of starter shingles along the bottom of the roof and nail them firmly into place using roofing nails a couple inches up from the edge of the roof. Lay a row of starter shingles down both sides of the roof as well and secure those in place using roofing nails an inch or two away from the edge as well.

Lay out the first full shingle near the bottom corner of the roof and lock it into place using six nails all just below the tar line of the shingle. Lay the next shingle down and nail it the exact same way. Continue this process until you’ve gone across the roof from one side to the other. For each new row, stagger the roofing. Shingles have broken sections at the bottom and square sections. Line the square section of your next row up with the broken section of the previous row so the break is right in the middle of the square. This gives water something to flow over so it isn’t leaking down behind your shingles. Lay out all the remaining shingles with the new staggered pattern, but use four nails per shingle this time. On the next row of the shingles go back to the original position so that your shingles are lined up with the edge of the roof once again. This maintains the stagger and makes the roof stronger overall. Repeat this process up to the cap of the roof on both sides until you are within five inches of the top.

To cap the roof you need a set of ridge cap shingles. Lay the first shingle on the left side of the roof so it’s overhanging the edge slightly and nail it down on the right side of the shingle to lock it in place. Lay another piece down so it’s overlapping that right edge and covering the nail, and nail it in the same way. Continue this trend until you cover the ridge entirely. Put tar or roofing cement over the exposed nail on the end to finish your installation.

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Installing Metal Roofing

Start your metal roofing project by installing a string line at the base of the roof peak at the level that you want your overhang. You put the string line in place to help keep your overhangs even around the edge of the roof. Most homes aren’t perfectly square and you’ll have to make minor adjustments to the roofing as you go to try to keep the overhang even. With the string line in place it will be easy to figure out how to adjust the piece.

Take care to get your first piece on the roof square so that either the side or the bottom edge is running square with the roof. You may not be able to get both sections of the roof square so pick the one that you care about the most and take your time getting it just right. Lay the roofing down so that the side with the taller ridge is facing to the right, this is the side that you want to lap over with the next piece. Now screw the panel down to your roof using screws with rubber washers to help keep water out. Put screws up one ridge at a time and spread them out into two-foot rows vertically. After you finish screwing one ridge move to the next and add the same number of screws in the same rows. Do this all along the panel until you get to the last ridge. Slip the next panel over top of the first covering the last ridge. Line the next panel up with the roof so it’s square and screw down into the overlapped ridge following that same screw pattern. Continue doing this along the entire roof until it’s covered with the metal roofing.

Once you have all the roofing panels in place it is time to cap off the ridge of the roof. Start by installing a ridge vent and insulating under it with a waterproof sealant. Lock the ridge cap down over top of the vent and you’ve completed your roofing installation.

Sealing Vents and Pipes

Throughout the installation of the roofing, there will be pipes and vents that need to be sealed. These are usually sealed with a special rubber boot that simply slips over the protrusion. In order to protect these vulnerable sections of the roof, protective rubber boots are slipped over top of the pipes and installed underneath the higher row of roofing when installing around shingles. When installing on metal roofing, you seal under the flashing using a roofing cement and then fasten the flashing right over top of the metal roofing using rubber washer roofing screws just as you did with the roofing itself.

Now that you know what goes into installing a basic asphalt shingle or metal roof, you can decide if you want to do the work yourself or to pay an expert to take care of it for you instead.

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