All gutters need to be kept clean. They should slope uniformly, without sags, to downspouts. Gutter and downspout materials are usually galvanized steel, aluminum, copper, or plastic. Buildings with sloped roofs can have a variety of drainage systems, including Rainwater Harvesting options. With a sufficient overhang, water can drain directly to the ground without being collected at the roof edge, thanks to proper Gutter Slope and Pitch. Drainage of low-slope roofs is accomplished in one of three ways: without gutters or downspouts; with gutters and downspouts; or by downspouts that go down through a building’s interior. The illustration below is of a low-sloped roof with interior pipe drainage, showcasing Downspout Placement. Drainage without gutters and downspouts can damage the exterior wall with overflow. If the roof has no gutters and downspouts or interior downspouts, the inspector should carefully check the exterior walls for signs of water damage, emphasizing the Importance of Proper Guttering. Most functional gutters have a minimum ratio of gutter depth to gutter width of 3:4. The front edge is typically ½-inch lower than the back edge, and Seamless Gutters are preferred. Four inches is considered the minimum width except on the roofs of canopies and small porches. If there is a screen or similar device to prevent anything but water from flowing into the gutter, its performance during a rainstorm should be checked to be sure water can actually enter the gutter, and Gutter Guards can help with this. Gutters without screens or similar devices should have basket strainers installed at each downspout, ensuring proper Gutter System Maintenance. The inspection image is of a screen covering the gutter, highlighting the need for Gutter Inspection Checklist before cleaning. Cleaning the gutters is a dangerous home maintenance job. Be careful.

A roof that is nearly level or slightly sloped is called a low-slope roof. No roof should be actually level and flat. It must have at least a slight slope to properly drain. Low-slope roofs can be expensive to repair, so care should be taken in their maintenance. Regular maintenance and periodic inspections for low-slope roofs are necessary. Problems with low-slope roofs are common and more difficult to diagnose than sloped roof problems because the path of water leakage through flat roofs is often quite hard to find and trace back to the source. Home inspectors should check for indications of ponding water (or puddle formation) on the surface due to either improper drainage or sagging of the roof deck structure. If the cause is a sagging deck, it should be structurally corrected. Flashing   Home inspectors should inspect the flashing and joints around all roof penetrations, including drains, stack pipes, chimneys, skylights, hatchways, antenna mountings, and other roof-mounted elements. The inspection image is of an inspector checking the poorly installed flashing around the chimney stack that penetrates through the flat roof. The black roof tar sealant is not reliable. Check to see if metal flashing needs to be tightened or fastened, and if asphalt or rubber flashings are brittle or cracked. Parapet wall caps and flashing may develop damage due to wall movement or moisture. There are a few categories of low-slope roof-covering materials, and they should be checked and inspected as follows: Built-Up Roofing The first common type of low-sloped roof covering material is built-up roofing, sometimes called roll roofing. Built-up roofs are composed of several layers of roofing felt material that is lapped, cemented together with bituminous material, and protected by a thin layer of gravel or crushed stone. Built-up roofs vary greatly in life span, but those used in residential buildings usually last about 20 years, depending on their quality, exposure, number of plies, and the adequacy of the drainage. Because built-up roofs are composed of several layers, they can hold moisture in the form of water or water vapor between layers. Moisture not only accelerates deterioration, but it can also leak into a building. Regular maintenance and periodic inspections are necessary. Home inspectors should look for cracking, blistering, alligatoring, and wrinkling, all of which may indicate the need for roof replacement or repair. The homeowner should consult an experienced roofer or their local neighborhood home inspector for further evaluation if they have doubts about the roof’s apparent condition. Single-ply Membrane Roofing A single-ply membrane roof consists of plastic, modified bitumen, and synthetic rubber sheeting that is laid over the roof deck, usually in a single ply, and often with a top coating to protect it from ultraviolet light degradation. Single-ply roofs are installed in three basic ways: fully adhered; mechanically attached; and loose-laid with ballast. If properly installed and maintained, a single-ply roof should last 20 years. Roof penetrations and seams are the most vulnerable parts of single-ply membrane roofing and should be carefully inspected. The material is also susceptible to ultraviolet light deterioration. A protective coating can be applied, but it will need to be reapplied periodically. Check carefully for surface degradation on an unprotected roof and fading of the coating on a protected roof. Check also for signs of water puddling and poor drainage. Roll Roofing Roll roofing should be inspected before and after the winter season in cold climates. Roll roofing consists of asphalt-saturated, granule-covered roofing felt that is laid over the roof deck. Inspect roll roofing for cracking, blistering, surface erosion, and torn sections. Seams are the most vulnerable part of roll roofing and should be carefully checked for separation and lifting. Also, check for signs of water ponding and poor drainage.

According to the InterNACHI® Home Inspection Standards of Practice ( www.nachi.org/sop ), the inspector shall inspect the roof-covering materials from the ground level or eaves. Home inspectors should report on the "roof-covering" or the "roof-covering materials" that were observed during the home inspection. Inspectors should not  report upon the "roof system", "roofing", or "roof assembly," the components of which are not readily observable. Components of a roof system or roof assembly are not readily visible during a visual-only inspection. The components of a roof system or assembly may include the roof deck, load-bearing components, trusses, underlayment, substrate, fasteners, thermal barrier, vapor retarder, insulation, ventilation, and roof covering. Can home inspectors see underlayment? No. Roof fasteners? No. Decking? No. "Roof covering" is a term specifically used and defined in the International Residential Code (IRC) and building standards. Roof covering is the covering applied to the roof deck for weather resistance, fire classification, or appearance. And since the covering is layered, not all of the covering material is visible during a home inspection. The other terms, such as roofing or roof system, reference a combination of components used together to form a complete assembly. A system is made of its parts. An assembly is made of smaller components. And most of the smaller parts and components of systems are not readily visible during a home inspection. They are beyond the scope of a home inspection. The focus for the home inspector should be on the roof-covering material. A variety of roof-covering materials may be installed on a house or building to be inspected, such as asphalt shingles, clay, and concrete tile, metal roof shingles, wood shingles and shakes, and metal roof panels. For example, built-up roof covering is a type of roof covering and is defined in the International Residential Code as a common roof covering for houses and buildings with relatively flat roofs and made up of two or more layers of felt cemented together and surfaced with a cap sheet, mineral aggregate, smooth coating, or similar surfacing material. Homeowners should not expect their home inspector too see everything during a home inspection. Why? Just about everything (every component and system of a house) is limited and restricted in some way for the home inspector during a visual-only home inspection.