Replacing Composition (Asphalt) Shingles
The shingles on your roof are an important component of your home. However, most of us do not think about them until something goes wrong. Composition shingles are made with a combination of materials, including a core of felt or fiberglass matting impregnated with asphalt and then covered with mineral particles. These types of shingles are designed to last 15 to 25 years (sometimes 30 years), after which they need to be replaced. Typically, a new layer of composition shingles may be applied over the existing layer – so saving you the time of removing the old roofing.
Before you decide to install new shingles over your existing shingles, you should take into consideration the following:
How steep or complicated is your roof? Shingling a simple gable roof on a one-story house is pretty straightforward. However, if the roof is steep, has multiple planes, needs valley work and complicated flashings, consider the job carefully before you make a commitment to begin.
Is the roof sheathing in good condition? Check out the attic and look for voids, separating plywood, and broken boards. You may also want to inspect the rafters. Check for rot by poking with a screwdriver. All rotten or damaged boards under the old roof must be replaced. If this is the case, hire a professional to do this work.
How many layers of shingles already exist? Most building codes allow a maximum of three layers of asphalt shingle (the original layer plus two reproofing layers). Check the number of layers on your roof by examining the rake (sloped) edge of the roof.
What is the condition of the old (existing) shingles? Bumps or dips in the old layer of shingles can not be hidden by new roofing. If the old surface is not uniformly flat, it should then be removed.
As you're getting ready to reroof your home, you need to look at the following:
Eaves and rakes. Look for rot along the edges. Make sure the fascia boards are sound and solidly connected to the rafter tails.
Valleys. It's always a good idea to check the condition of the metal valley flashing.
Flashing. Take a look at the flashing around chimneys, vent stacks, and skylights.
One of the toughest jobs is getting the new shingles onto the roof. For an extra fee, many suppliers can "load" the roof for you, using a crane or conveyor belt. Otherwise, you will need to carry the shingles with you up a ladder. Entire bundles typically weigh about 75 pounds. Of course, you can open the bundles and carry smaller loads.
While up on the roof, make sure to form a level base for stacking the shingles. After all, the last thing you want is to have to retrieve shingles sliding off your roof back to the ground. A good strategy is to set a bundle on either side of the ridge. This allows you to set up an open work area.
Cutting Curves in Wood
Much of the finish carpentry in a home contains curves – pretty tricky work for the do-it-yourself weekend carpenter. Some of the curved cuts are for necessity. For example, holes through walls, doors, floors, and roof (for pipes or ducts). Others, however, are a bit more decorative – an archway, or a curve of a circular window.
Whatever the curve's purpose, it requires tools and techniques different from those used for straight cuts. For most curves the best tool is an electric saber saw, ideally one with variable-speed control. Blades inch inch wide with 8 to 10 points per inch are suitable for most jobs, but other blades are available for special uses: a hollow-ground blade, for example, will make splinter-free cuts in plywood; a blade with 12 or 14 points per inch is advisable for scrollwork.
When power is not available, or when work space is too cramped for a saber saw, you can turn to any of several handsaws specifically designed for cutting curves. A coping saw has a delicate blade and a limited cutting range; it is best suited to finish joints in woodwork and to fine, intricate scrollwork. The keyhole saw can tackle heavier tasks, while the compass saw serves for still rougher work. Both come with an assortment of blades designed for different materials. The blades are tapered, with narrow tips for turns and for cutouts started from small drilled holes; and because the blades can be reversed, compass and keyhole saws are ideal for use in jobs with tight clearances and awkward undercuts.
Since you must guide the aforementioned saws by freehand, it is very important to mark a guide-line before cutting any curve. More often than not, you can simply hold an object to be duplicated – a section of decorative trim, for example – in place and trace its outline. However, some situations require more complex calculations and marking techniques. For instance, to mark an elliptical hole for a round pipe passing through the roof, you must plot the pitch of the roof and the size of the pipe on cardboard, then cut out the marked cardboard, then cut out the marked cardboard as a template to transfer the ellipse to the roof.
In other situations you must resort to scribing – a marking technique for fitting material to an existing curve. Generally, it consist of setting the wood – the floor boards in a semicircular alcove, for instance – against the curve and running a simple school compass around the curve to duplicate, or scribe, the arc on the boards.
When you cut a curve, be especially careful of the pressure you apply; under excess pressure, a handsaw blade will buckle and a saber-saw blade may shoot out of the cut or snap in two. Mark the guidelines for a saber saw on the unfinished side of the board if possible, because the upstroke cut of the blade splinters the wood; if you must work on the finished side, cover the guidelines with transparent tape to minimize the damage. Steady the board by
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