A well-constructed roof should last from ten to twenty years, depending on weather conditions and the materials used in its construction; however, no roof is expected to continue forever. Most roofs will require a certain amount of maintenance and repair on an annual basis. It is to your advantage to have an understanding of basic roofing fundamentals, even if you do not intend to do the work yourself because such knowledge can save you money when you deal with professional roofers. You will be able to appraise the work better as it is being done. If you feel that laying a new roof or repairing a roof will be too complicated for you to handle, then contact a reputable roofing firm. Many are listed in the Yellow Pages, but you should check with the local Better Business Bureau about your choice before signing any contracts or making any commitments. The Better Business Bureau may have a file of complaints against the firm you choose (being in the Yellow Pages are only a listing, not a seal of approval). Never allow a door-to-door salesman to talk you into a “cut-rate” job. Very few reputable roofing firms do business this way.


Most people would instead not work on a roof, because of the dangers involved. The height and pitch of most roofs are specific factors that should not be taken lightly. Falling from a roof can result in severe injury and even death. Never go on a roof if you are afraid of heights. It is no way to cure this type of fear. Don’t try to prove something to yourself or others. Risking your life is just not worth it. If heights do not bother you, you should still carefully plan the job and follow a definite safety procedure. All professional roofers plan the post before they ever get on the roof. The job planning should include how the ladders and scaffolds are to be set up, how the materials are to be transferred to the roof, and where the safety rope and safety harness are to be positioned. The clothing you wear should be loose enough to enable you to move freely. Never wear shoes with leather or composition soles even on the driest roofs. Tennis shoes offer the best footing. Bare feet will also give sound footing, but there is always the possibility of stepping on a rusty nail or picking up a splinter. Many roofing materials are brittle particularly asbestos shingles, tile, and slate and can be broken when stepped on. This problem can be avoided by distributing your weight more evenly over the surface of the roof. When working on a tile roof, for example, try to distribute the weight of each foot over two tiles at a time. Professional workers lay a 1 x 6 board on flat roofs and work from it. On pitched roofs, a ladder should be used. A rope and safety harness is recommended on pitched roofs for additional safety. Both should be made from %-inch nylon rope because this type of cable offers the most exceptional tensile strength. The amount of line you will need depends on the particular job. It should be long enough so that one end can be tied to a nearby tree, window, or door frame, or some other objects that will hold your weight without slipping. It should also be long enough to enable you freedom of movement over the surface of the roof. The rope should be inserted through a three-foot length of garden hose which should be positioned at the point where the line crosses the roof ridge. This will protect the roof covering materials along the hill from the pressure caused by your weight. A safety harness can be purchased from a mail-order house, or through a local building supply outlet. If you make your safety harness, use %-inch nylon rope and construct a safety harness. Never work on a roof unless it is entirely dry. Even dew moisture can make the roof slippery. Every precaution must be taken to ensure that you have secure footing. Don’t get up on a roof if it appears that a storm is approaching. Chances are you won’t be able to finish the job before it starts to rain anyway, and it will probably cause you to work faster than necessary and with less caution. There is also the danger of lightning. When a thunderstorm is nearby, the air will be charged with electricity. Flash can be a threat without the clouds being directly overhead. If there is a TV antenna on the roof, disconnect it. If you can’t do it, have a professional come out and do it for you. Don’t handle or go near power lines, TV antennas (even when disconnected), or other types of electrical devices or wiring.


No roof repairs should be attempted without suitable ladders or scaffolds. Furthermore, they should be carefully inspected for possible broken rungs or other defects and used correctly.

A scaffold can be used not only for getting up and down from a roof, but also for holding the materials nearby while you are working. This saves a lot of steps because you do not have to climb down from the roof as often to get more supplies. The principal advantage of using a scaffold is that it does not lean against the gutter or eave, and therefore cannot cause any damage to these parts of the roof. A scaffold can be purchased, built, or rented. Most towns of any size have Rent-All stores that will have one or more buildings on hand. Renting a scaffold is recommended over purchasing one because the amount of time spent in roofing structure is relatively short and any extensive reroofing should not be necessary for some years. Don’t attempt to build a scaffold unless you are a good carpenter. A poorly constructed framework is worse than no scaffold at all. The cross bracing is particularly crucial for safety. All handmade buildings should have cross braces. Any ladder you use for access to the roof should extend far enough above the eave to allow you to step directly onto the roof. Never use a ladder so short that you must climb to the top of it. This can be dangerous. Check the ladder over first for broken or loose rungs, or splits in the rails. If the ladder is defective, do not use it. Never use a painted ladder, because the paint could be concealing a cracked rung. A ladder should be raised to the roof by “walking” it. Place the bottom end of the ladder against the wall, and increase it until it is in a vertical position. Lift the bottom of the ladder and move it away from the wall a distance approximately one fourth its length. The ladder should be positioned so that it is straight (i.e., not leaning to one side or the other). The bottom of the ladder should be firmly placed so that the bottom of both rails rest solidly and evenly on the ground. If the ladder wobbles when you climb it, get down immediately and reposition it until it is stable. When raising a ladder, do not slam it against a gutter. It is straightforward to damage a channel in this way. Never learn from a ladder, because unevenly placed weight may cause it to fall. Try to keep your hips between the two rails as you climb the ladder. A one-board or ‘‘chicken ladder” is recommended for use on roofs of tile, slate, or other types of brittle and easily breakable roofing materials, because it spreads your weight more effectively. These are homemade ladders consisting of 1 x 10 or 1 x 12 board to which 1 x 2 pieces of wood are nailed. A “chicken ladder” should also be hooked over the roof ridge. Metal brackets for supporting a 2 x 4 can be purchased through most local building supply houses. The brackets are nailed to the roof, and the 2 x 4 board provides footing on roofs with a steep pitch.  

Roof Construction Details

Familiarize yourself with these details, because you will be confronted with the terminology involved here throughout the book. The ridge is usually stock about one inch thick inserted between the rafters at the top of the roof; the peak should be broad enough to receive the whole depth of each beam. Rafters are used to support the roof surface. A common beam extends all the way from the ridge to wall plate and is not connected to any other timber. Each rafter also extends a short distance beyond the wall plate. This is referred to as projection or overhang. A jack rafter is quicker than a standard timber because it is connected at the upper end of either a hip rafter or valley rafter. A cripple rafter, on the other hand, is attached at both ends to a hip or valley rafter. A hip or hip roof is one which has a sloping surface from each wall of the structure to the ridge. A minor roof is any roof extending out from the main roof. It is connected to the main roof by a valley rafter. A valley is the portion of the roof formed by the meeting of a minor roof and the main roof. The rafters are covered with sheathing which provides a surface for the roofing materials. Sheathing consists of 1 x 6 boards or 5/s-inch ply’s cord. Other thicknesses of ply’s cord sheathing are also used. The sheathing is covered with a base layer of roofing felt which is overlapped several inches. The amount of overlap and exposure is usually recommended by the manufacturer. The run is a horizontal line extending from the fascia line at the outer edge of the rafter to a plumb line extending down from the center of the ridge. The fascia or fascia line is the inside of the fascia forming the cornice. A gable is the triangular area of wall at the end of a gable roof. Those portions of the roof that overhang the walls of a structure are the eaves. The pitch of a roof is the slant of the rafters expressed in inches to the foot. Angles are referred to as 1/4, V3, or V2 pitch. A V a pitch roof is one which will rise 6 inches for each foot of run. A V3 pitch rises 8 inches for each foot of run, and a V2 pitch rises 12 inches for each foot of run. The pitch of a roof should be taken into consideration when laying a new roof, because it will determine the type of roof covering material used in many cases. For example, asphalt shingles can be used on roofs with a pitch of 4inches or more, but require special application when the pitch is less than 4 inches. The special application usually requires the cementing down of each shingle with roofing cement. A salesman at the local building supply house should be consulted and his recommendations followed. The roofing materials should be properly stored when not being used. Containers of asphalt roofing cement should be stored on end and level. Roll roofing should also be stored on end. Keep all materials in a heated and dry area, but far enough away from any heat sources to avoid a fire. Roofing materials are highly flammable. Weather extremes can result in poor working conditions. The best temperature range is between 50°F and 80°F If the temperature is below 50°F., keep the roofing materials particularly asphalt shingles and asphalt roofing cement in a dry, warm place before using them. The roof sheathing provides the base for the roof covering materials. Two or more layers of a special asphalt impregnated roofing paper are laid over the sheathing to produce a waterproof cover. Finish roofing materials, such as shingles, tiles, or slate, are laid over the roofing paper. The roofing materials are laid in courses beginning at the eaves and working toward the ride on pitched roofs, or from one end of a flat roof to the opposite one. Each course overlaps the course laid before it. This overlapping of the courses enables the roof to shed water more easily without leaking through the sheathing, but it can complicate repairs. Minor repairs will necessarily constitute interruptions in this over lapping; therefore, you should examine how these materials are overlapped before you begin work.


Roofs are subject to all kinds of weather conditions and will sooner or later develop one or more leaks. The most common types of leaks in a roof are traced to one or more of the following causes: 1.  Warped, corroded, or cracked flashing around chimneys, vents, and other structural interruptions in the roof surface. 2.  Broken, loose, or missing shingles, tiles, or other types of roof covering materials. 3.  Rusty, loose, or missing nails used to secure the covering materials to the roof. 4.  Dried out and cracked roofing compound used to seal seams in roof covering materials. 5.  Blocked or damaged gutters and downspouts. 6.  Rotted or cracked roof sheathing board. 7.  Ice dams forming along roof eaves.

Tracing Roof Leaks

Most roof leaks are difficult to trace because the water almost never collects directly under the point at which it enters. It will frequently run a considerable distance down a joist (rafter) or some other part of the structure before dropping and forming a puddle. The best time to trace a leak is during the day when there is sufficient light. Find the point at which the water has been collecting and then look for water stains along the joints above it. These stains will usually lead you to the point at which the water has been entering. Sometimes you will be able to see a small pinhole of light. If you can locate the leak, shove a straight piece of wire through the hole to indicate its position from the outside. If you cannot find the point where the water is entering, calculate its approximate location by measuring the distance from the end of the joist to the point at which the stains end. Add to this measurement the length of the roof overhang, and this will be the approximate distance of the leak from the edge of the roof. If it is raining, trace the flow of water up along the joist to its approximate entry point. Repairs are impossible until the rain stops, but you can mark the point at which the water enters and place a pail where the puddle is forming. To ensure that the dripping water does not change its position on the joist, run a string or wire from the joist down to the pail. After you have located the leak from the inside (or at least determined its approximate location), go onto the roof and try to find the cause of the leak.    

Temporary Repairs

A temporary repair is any kind of repair that will stop or effectively contain the water leaking through the roof on a temporary basis until permanent repairs can be made. Repairing a leak is not recommended when the weather is bad. A wet roof offers very slippery footing and could be dangerous; therefore, you should spend as little time up there as necessary. The leak should be stopped with a temporary repair until it is possible to get up on the roof and make a permanent one. Once you have located the leak, you can cover it from the outside with a large piece of waterproof material (canvas, plastic, etc.). Temporary repairs from the inside depend on where the leak is found. If it is a small one in the roof sheathing located away from a joist (rafter), ridge board or wall plate, a square of plywood and a 2 x 4 can be used. Dry off the area and coat it with roofing cement. Coat one side of the piece of plywood with roofing cement and press it down over the area. The 2×4 should be precut so that it forms a tight fit between the plywood and the floor. Small leaks around the edges of rafters, the ridge board, and wall plate can be stopped with roofing cement or putty, but this will not last very long. Buckets and pails are necessary to catch the water for larger leaks, although the waterproof cover on the outside of the roof will, in most cases, reduce the amount of leaking water to a minimum.


Flashing is a material used in roofing to produce a water tight joint. It is frequently used where the roof joins a chimney, vent pipe, skylight, or some other vertical surface. It is also used in valleys and along ridges, and less frequently along an eave or gable end. Flashing is available in rolls of aluminum, copper, and galvanized iron, ranging in widths from 12 to 18 inches. Aluminum and copper are the more commonly used types of metal flashing. Aluminum flashing is becoming more popular, because it is less expensive than copper. Neither aluminum nor copper flashing require a special finish to protect the metal against corrosion. This is not the case with galvanized iron. Unless it is covered with a protective finish, it will rust and corrode. Even with the protective finish, a scratch or damage to the flashing can cause the metal to deteriorate. Do not use ordinary nails to fasten the metal flashing to the roof. These will rust. Aluminum nails should be used with aluminum flashing; copper nails with copper flashing. Follow the manufacturer’s recommendations for the type and size nail to use. Both plastic and mineral-surfaced roll roofing are also used as flashing materials. Their principal advantage is that they are cheaper than metal flashing.

Flashing Around Chimneys and Vents

The joint between a chimney and the roof should always be protected with flashing, because this is probably the most common source of roof leaks. Consequently, great care must be taken when applying the flashing to these areas to ensure a tight and long lasting fit. The flashing around a chimney is sometimes built up from a number of different sections. The base section is applied first and laid along the base or bottom of the chimney. It is frequently laid over the shingles. The flashing laid up the slope of the roof along the sides of the chimney is cut to the size of each course. This is sometimes referred to as step flashing. Step flashing is also applied to the back of the chimney, but the upper sections of this flashing (i.e. the section laid against the chimney) is cut long enough to extend several inches above the chimney cricket (see Chimney Cricket). After the base and step flashing are applied, a cap or counter flashing is laid over them. This is a one piece section of flashing cut to size for each side of the chimney. The top edge of the counter flashing is bent (usually about 1/2 inch) and inserted in a mortar joint in the chimney and sealed with brick mortar. 1.  After the last course of shingles has reached the base of the chimney, take the measurements for the base flashing. 2.  Cut out a rectangular piece of flashing material. Its length should equal the width of the chimney plus 12 inches. Its width will equal the combined distances from the base line of the chimney to a point equal to the exposure allowed for the shingles, and from the base line to 1/4 inch above the mortar joint of the first or second course of chimney bricks. 3.  Bend the piece of flashing so that the bottom half lies flat against the roof and extends out to the middle of the last course of shingles, and the top half lies flat against the chimney. Position the flashing against the chimney so that exactly 6 inches of flashing extends on either side. 4.  Cut 6 inches in from each side of the flashing along the bend. Make two additional 1A inch cuts in from the top of the flashing where it will bend around the chimney. 5.  Bend the top half of the base flashing to fit the contours of the chimney, and cut each side to fit the slope of the roof. Bend back 1A inch of the top of this section to form a lip to be inserted in the mortar joint. Remove 1 A inch of mortar from the joint. 6.  Cover the bottom of the base flashing with asphalt roofing cement and nail it to the roof. Insert the VA inch lip in the mortar joint and seal it with brick mortar. 7.  Cut and apply a separate section of step flashing for each course of shingles laid up the roof slope. Each section of step flashing is coated with asphalt roofing cement and nailed to the roof. 8.  The cap or counter flashing is designed to cover both the base and step flashing. It is cut to size in one section for each side of the chimney. It is bonded to the other flashing, and the top edge is bent to fit into a mortar joint. 9.  The base flashing is not covered with shingles. The step flashing is covered with shingles up to the edge of the chimney. Another method of applying flashing to a chimney involves applying it directly to the roofing felt and chimney before the shingles are laid. In this method, the step flashing is cut much wider than those described in Step 7 above. The shingles are laid up to the edge of the chimney and bonded to the flashing with asphalt roofing cement. Cap or counter flashing is not always used on chimneys. Some roofers will create a lip on the upper edge of each step flashing and insert the lip in a mortar joint.

Insert in a Mortar Groove and Seal with Brick Mortar J Nail to Roof Sheathing

Many roofers will further waterproof the flashing by applying asphalt roofing cement to all joints and along all edges. The flashing around vents and soil stacks is relatively uncomplicated to apply. Manufacturers often provide flared skirts and flanges (or shields) that function as flashing. When these are provided, follow the manufacturer’s instructions for attaching them to the roof.

Chimney Crickets

A chimney cricket (or saddle) is a built up area on pitched roofs behind the chimney. It is designed in the shape of a small false roof to throw off water that would otherwise collect behind the chimney and possibly cause leaks. It also prevents the buildup of snow which can result in the same problem. The top of the cricket is commonly located at a height equal to one half the width of the chimney. For example, if the chimney is 30 inches wide, the top of the cricket will be located 15 inches up from the point at which the chimney meets the roof. Cut a piece of flashing to cover the cricket and allow an overlap of 4 or 5 inches on the chimney and roof. Nail the flashing to the roof and cricket sheathing. Cover the nail heads with a dab of asphalt roofing cement. If the cricket is a large one, you may have to construct the flashing from two or more sections soldered together.

Dormer Flashing

Step flashing should be applied up the slope of the roof against the sides of a dormer. The procedure is the same as the one described for applying step flashing to chimneys.

Valley Flashing

Valleys are formed when two roof sections, or a wall and a roof section, come together at an angle. These valleys will frequently extend from a roof ridge to the eave. Because of this, many builders substitute mineral-surfaced roll roofing as a flashing material rather than use the more expensive metal flashing. The major disadvantage of using roll roofing for flashing is its tendency to expand or contract during temperature extremes. The expansion or contraction of the flashing can cause the roofing cement along the edges of the flashing to crack and possibly leak. 1.  Measure off enough material from the roll to cover the entire length of the valley. 2.  Strike a chalk line down the middle of this strip and cut it in half. 3.  Trim the top of the strip to fit the angle of the roof ridge, and trim the bottom to fit the angle of the eave. 4.  Take this half section and nail it in the valley with the mineral surface facing down. Use large head roofing nails spaced 6 inches apart and 1 inch in from the outer edges of the strip. 5.  Cut off another strip of material from the roll the same length as the first one, but do not cut it down the middle. Trim the top and bottom of the second strip to fit the roof angles. 6.  Nail the second length of roll roofing down over the first one, but with the mineral-surfaced side facing up. Use the same nailing pattern described in Step 4 above. 7.  For additional protection from leaks, seal the edge of the flashing with roofing cement. Metal flashing (copper, aluminum, etc.) is also available in rolls, ranging up to 18 inches wide. Only one strip of metal flashing is used in a valley. The nails should not be positioned closer than 6 inches apart. Some metal flashing is available ready- made with an inverted via running down to middle of its length to facilitate drainage.