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EXTERIORS of buildings

ADHESIVES, EXTERIOR CONSTRUCTION
AGE of a BUILDING - how to determine
ALGAE, FUNGUS, LICHENS, MOSS
ANIMAL ENTRY POINTS in buildings
ANIMAL ODORS IN buildings
ARCHITECTURE & BUILDING COMPONENT ID
ASBESTOS IDENTIFICATION IN buildings
ASBESTOS ROOFING / SIDING DUST
ATTIC CONDENSATION CAUSE & CURE

BARK SIDE DOWN on DECKS, TRIM, STEPS
BASEMENT WATERPROOFING
BEST CONSTRUCTION PRACTICES GUIDE
BRICK VENEER WALL Loose, Bulged
BRICK WALL DRAINAGE WEEP HOLES
BOOKSTORE - EXTERIORS

CAULK GUN TYPES, CHOICES
CAULKS & SEALANTS, EXTERIOR
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CATCH BASINS

DECK & PORCH CONSTRUCTION
Deck Construction Best Practices
DECK COLLAPSE Case Study
DECK FINISHES COATINGS PRESERVATIVES
DECK FLASHING LEAKS, ROT Case Study
DEFINITIONS of ENGINEERED WOOD OSB LVL etc
DRYWELLS, FRENCH DRAINS for FLAT SITES

EARTHQUAKE DAMAGED FOUNDATIONS
ENERGY SAVINGS in buildings
ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
EXTERIOR WALL SIDING TRIM & FINISHES

FLASHING MEMBRANES PEEL & STICK
FLASHING for METAL ROOFS
FLASHING ROOF WALL DETAILS
FLASHING ROOF-WALL SNAFU
FLASHING SIDING DETAILS
FLASHING WALL DETAILS
FLASHING WOOD ROOF DETAILS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FOOTING & FOUNDATION DRAINS
FOUNDATION CRACKS & DAMAGE GUIDE
FOUNDATION WATERPROOFING
FRENCH DRAINS

GALVANIC SCALE & METAL CORROSION
GLUES ADHESIVES, EXTERIOR CONSTRUCTION
GRADING & SITE WORK, EXTERIOR

GUTTERS & DOWNSPOUTS
    ARE GUTTERS NECESSARY?
    BASEMENT de-WATER vs GUTTERS
  FLAT ROOF DRAINAGE SYSTEMS
  FLAT ROOF INTERIOR DRAINS
    FLAT ROOF DRAIN CLOGS
    FLAT ROOF DRAIN ADDITIONS
  GUTTER CAPS
  GUTTER DEFECTS LIST
    CLOGGED GUTTERS
    LOOSE GUTTERS
    OVERFLOWING GUTTERS?
    OVERSHOOTING GUTTERS
    SLOPE INADEQUATE, GUTTER
  GUTTER DEFECTS, MORE
    BACKFLOWING GUTTERS
    GUTTER INSTALL ERRORS
    SAGGING GUTTERS
    DRIP LINES INDICATE OVERFLOW
    GUTTER END CAPS
    GUTTERS On NO-EAVE buildings
  GUTTER HANGERS
  GUTTER REPAIR, LEAKY JOINT
  GUTTER SCREENS
  GUTTER SIZES
  GUTTER TYPES
    GUTTER PROFILES
    ALUMINUM K GUTTERS
    COPPER GUTTERS
    EAVES TROUGH, INTEGRAL GUTTERS
    GALVANIZED GUTTERS
    PLASTIC GUTTERS
    WOOD GUTTERS
    YANKEE GUTTERS
  NO-GUTTER SYSTEMS
  SNOW & ICE DAMAGE to GUTTERS
  DOWNSPOUT / LEADER DEFECTS
  DOWNSPOUTS BURIED / BELOW GRADE
    ABANDON BURIED DOWNSPOUTS
    CLOGGED BURIED DOWNSPOUTS
    CONNECT DOWNSPOUTS to BUILDING DRAINS?
    PERFORATED PIPE DOWNSPOUT DRAINS
    BURIED ALUMINUM DOWNSPOUTS
    UNDER-SIZED DOWNSPOUT DRAINS
    SHARED DOWNSPOUT DRAINS
  DOWNSPOUT EXTENSIONS
    DOWNSPOUT ONTO BACKFILL
    DOWNSPOUT ONTO IN-SLOPE GRADE
  DOWNSPOUT LEAKS
    DOWNSPOUTS SPLIT
    DOWNSPOUT LEAKS at CONNECTIONS
    DOWNSPOUT EXTENSIONS TOO FLAT
    DOWNSPOUTS UNDER DECKS
  DOWNSPOUT DEFECTS, MORE
    MISSING GUTTER, DOWNSPOUT
    DOWNSPOUTS, NUMBER NEEDED
    DOWNSPOUT / GUTTER STRAINERS
    DOWNSPOUT ANIMAL DAMAGE
  DOWNSPOUTS, OTHER USES: A/C
  DRYWELLS, FRENCH DRAINS for FLAT SITES
  FRENCH DRAINS for DOWNSPOUTS
  SURFACE CONTOURING for DRAINAGE
    SWALE for DRAINAGE CONTROL
    SLOPE RECOMMENDED at buildings
  CATCH BASINS

HEAT TAPES & CABLES on Roofs for Ice Dams
HOUSE PARTS, DEFINITIONS
HOUSEWRAP INSTALLATION DETAILS
HUMIDITY LEVEL TARGET

ICE DAM PREVENTION
INDOOR AIR QUALITY & HOUSE TIGHTNESS

KIT HOMES, Aladdin, Sears, Wards, Others

LEAD POISONING HAZARDS GUIDE
LEAD TEST KIT for HOME USE
LEED GREEN BUILDING CERTIFICATION
LOG HOME GUIDE
LIGHTNING PROTECTION

METAL LATH, PLASTER & STUCCO
MOISTURE CONTROL in BUILDINGS
MOISTURE CALCULATIONS
MOISTURE PROBLEMS: CAUSE & CURE
MOLD DETECTION & INSPECTION GUIDE
MVOCs & MOLDY MUSTY ODORS

ODORS & SMELLS DIAGNOSIS & CURE

PAINT ANALYSIS, DIAGNOSTIC USES
PAINT & STAIN GUIDE, EXTERIOR
PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
PORCHES & Sunrooms
PORCH CONSTRUCTION & SCREENING

RAILINGS, DECK & PORCH
RAILINGS, STAIRWAY
RETAINING WALL DESIGNS, TYPES, DAMAGE
RETAINING WALL GUARD RAILINGS
ROOF ARCHITECTURAL STYLES - PHOTO GUIDE
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF DORMER TYPES - PHOTO GUIDE
ROOFING DIAGNOSIS INSPECTION & REPAIR
ROT, FUNGUS, TERMITES
ROT, TIMBER FRAME

SEARS KIT HOUSES
SEPTIC & CESSPOOL SAFETY
SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
SHEATHING, Gypsum board
SHEATHING Homasote & Other Board
SHEATHING, OSB
SHEATHING, Plywood
SHEATHING, FOIL FACED - VENTS
SIDING, Sheathing Identification - Photo Guide
SIDING, ALUMINUM
SIDING, ASBESTOS FIBER CEMENT
SIDING ASPHALT ROOF SHINGLES on WALLS
SIDING ASPHALT SHINGLE or SHEET
SIDING DAMAGE by SPLASHBACK
SIDING EIFS & STUCCO
SIDING, FIBER CEMENT
SIDING HARDBOARD
SIDING STEEL
SIDING VINYL
SIDING, WOOD PRODUCT CHOICES
SIDING, WOOD INSTALLATION
SIDING WOOD, FAILURES OVER FOAM BOARD
SIDING WOOD, FLASHING DETAILS
SIDING WOOD SHINGLE INSTALLATION

SINKHOLES, WARNING SIGNS
SOUND CONTROL in buildings
STAIN & BIODETERIORATION AGENT CATALOG
STAINS on buildings - QUICK GUIDE
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
STAINS on/near CHIMNEYS
STAINS & FINISHES, INTERIOR
STAINS on INDOOR SURFACES: PHOTO GUIDE
STAINS & Thermal Tracking
STAIN DIAGNOSIS on ROOFS
STAIN DIAGNOSIS on STONE
STAIRS, RAILINGS, LANDINGS, RAMPS
STONE CLEANING METHODS
STONE VENEER WALLS
STUCCO WAll FAILURES DUE TO WEATHER
STUCCO WALL METHODS & INSTALLATION
STUCCO OVER FOAM INSULATION
STUCCO PAINT FAILURES

SURFACE GRADING, SITE DRAINAGE

TERMITES, ROT
THERMAL EXPANSION of MATERIALS
TREES & SHRUBS, TRIM OFF BUILDING
TRIM, EXTERIOR CHOICES, INSTALLATION

VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in buildings
VINYL Siding or PLASTIC Window ODORS in buildings
VINYL CHLORIDE HEALTH INFO

WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in buildings
WIND ENERGY SYSTEMS
WIND TURBINES & LIGHTNING
WINTERIZE A BUILDING

More Information

Gutters & Downspouts, common leak points (C) Carson Dunlop Assoc Roof Gutters & Downspouts Home Page
InspectAPedia®  -      

  • Types & photos of roof drainage systems: gutters, downspouts
  • Definition of eaves trough or integral roof gutter; Definition of yankee gutter
  • Comparison of aluminum gutters, copper gutters, plastic gutters, wood gutters
  • Gutter & downspout defects, clogging, overflowing, holes corrosion, leaks that cause wet basements or crawl areas
  • Gutter screens, types, uses, maintenance
  • How to avoid Snow & ice damage to roof gutters
  • Roof gutter installation & repair details: drip edge, slope, capacity, leak sealants, support, length & placement of leader & downspout extensions
  • Proper installation of buried downspout extensions
  • Proper installation of French drains & seepage pits at flat sites
  • Gutter & downspout defects cause wet basements & crawl areas
  • Questions & answers about roof gutters, downspouts & other roof drainage control systems

Building gutters, leaders, roof drainage systems: in this article series we describe good gutter and downspout installation details, the need for roof gutters and drainage systems, and we describe the types of roof gutters used on buildings. This article series discusses how to choose, install, diagnose & maintain roof gutters & downspouts, & roof drainage systems to prevent building leaks and water entry.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.

© Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

Guide to Roof Gutter & Downspout Systems

No gutter installed (C) Daniel FriedmanOur page top sketch of common roof gutter leak causes is provided courtesy of Carson Dunlop Associates.

See GUTTERS & DOWNSPOUTS for a guide to types of roof gutter systems. See GUTTER DEFECTS LIST and DOWNSPOUT / LEADER DEFECTS for examples of common mistakes in handling roof runoff. Also see EAVES TROUGH, INTEGRAL GUTTERS and YANKEE GUTTERS that are discussed in separate articles. And see TREES & SHRUBS, TRIM OFF BUILDING for another step in avoiding clogged gutters and downspouts.

Quoting from Carson Dunlop Associates' Home Reference Book:

Gutters and downspouts have two major functions. Firstly, they protect the walls of a building from water that would ordinarily run off the roof. This water can damage the wall surfaces and cause localized erosion at ground level.

The most important function of gutters and downspouts in homes with basements or crawlspaces, however, is helping to ensure a dry basement.

Regardless of the foundation type, there is always the risk of water penetration. The less water there is in the soil near the foundation wall, the lower the risk of water penetration into the basement.

Gutters should collect all water run off, and downspouts should discharge the water into proper drains or onto the ground well away from the foundation walls

[Click any image or drawing to see an enlarged, detailed version.]

Are Gutters Really Necessary?

Raccoon outdoors on a downspout (C) Daniel FriedmanIf your building is located where it rains or where there is snow-melt, your building probably needs a roof drainage system to carry water away from the building in order to prevent leaks into the building, especially if the building includes below-ground areas such as a basement or crawl area.

A very large percentage of basement or crawl space water entry, moisture, leaks, rot, and mold problems all begin at the building roof, with the failure to adequately capture roof runoff and to direct it away from the building.

We have met a few architects who never include gutters in their building design, arguing that "Gutters are ugly, and besides we've never had a water entry problem in our homes." Yet every home we inspected of that design had a wet basement within a short time of construction, sometimes even during construction, [excepting in arid climates of little rainfall, homes built on slabs with no basement or crawl area, or homes whose surrounding soils incorporate special subsurface drainage systems].

Even where a roof drainage system such as simple gutters and downspouts are installed, errors in their installation or failure to maintain (and clean out) clogged gutters remains a most common source of wet basements and crawl spaces.

Fix the Gutters Before Installing a Basement de-Watering System

Watch out: While on occasion we find a home that was built over a spring or stream bed, or was unfortunately located at the bottom of a hillside, even then, mis-handling of water coming off of the building roof is very often a major source of chronic basement leakage. Before installing a costly basement de-watering system to cure "rising damp" or "high water table flooding" at your building, making an expert inspection of the condition of the gutter and downspout system is worthwhile.

In some climates some roofs and buildings make it difficult to install and keep gutters on the roof. For example a standing seam metal roofed building in a climate subject to heavy snowfall or ice formation may keep losing its gutters to sliding snow and ice. Proper gutter installation details and snow guards can solve this problem on some buildings. See Snow & Ice Damage to Building Gutters for details.

Where those steps don't work, a more costly and extensive surface and subsurface installation of geotextiles and waterproof drainage mats below the soil surface (or below gravel) at the building eaves can be constructed to keep water away from the building foundation, draining it to a distant catch basin or lower site area. See BASEMENT WATERPROOFING.

Types of Gutter & Roof Drainage Systems

Gutter Types by Profile or Shape

By examining the shape or "profile" of a gutter from the ground we can often determine whether it is made of aluminum (below), galvanized steel, or plastic. It's also usually easy to identify copper gutters even from ground-level inspection, as we illustrate below.

Gutter and Downspout Details (C) Carson Dunlop Assoc

The sketch at left shows a traditional "K" profile aluminum gutter at left, and a more-rounded galvanized steel gutter at right.

Sketch courtesy of Carson Dunlop Associates.

Gutter Size & Capacity: the gutter size needed at a building depends on the total roof area being drained and the length of gutter available to collect that water. The most common gutter sizes are 4-inch and 5-inch widths. Details are at GUTTER SIZES

Types of Gutter Hangers or Supports: are discussed at Types of Gutter Hangers

Aluminum K-Gutter Shape & Profile photos

The aluminum gutter shown below is commonly referred to as a "K" gutter because of its gutter profile, as shown in the gutter profile sketch above. Aluminum gutters are widely used in North America as they are light, easy to install, and corrosion resistant. The outer gutter surface is a baked enamel finish available in white, brown, green, and black. The interior surface may be a silver or bronze color depending on plating.

Aluminum K Gutter (C) Daniel FriedmanAluminum K Gutter (C) Daniel Friedman

Aluminum gutters are easily bent such as by an inspector's ladder or by careless chopping of ice at the roof edge. Connections among gutter sections are made using a combination of slip-joint connectors and sealant, often butyl caulk. See Types of Gutter Hangers for a discussion of how aluminum gutters are secured to the roof edge.

Copper Gutter Shape & Profile photos

Copper gutters are readily identifiable by their characteristic colors (red, brown, or marked with a green patina). Copper gutters are provided in a variety of profiles including the "K" shape (shown below), a rectangular or "box" shape that may be custom fabricated for the building, and traditional half-round design. The copper gutter shown at below right was custom fabricated to fit at the wall top of the building. You will notice the brown oxidized copper interior of the gutter and the green copper patina on the gutter's exterior and upper edge.

Copper Gutter (C) Daniel FriedmanCopper Gutter (C) Daniel Friedman

New half-round copper gutters and rectangular copper downspout are shown at below left. At below right we show an underside-view of traditional half-round copper gutters and a recently-installed round copper downspout.

Copper Gutter (C) Daniel FriedmanCopper Gutter (C) Daniel Friedman

Galvanized Roof Gutters Shape & Profile photos

Galvanized roof gutters are provided in both "K" and half-round profiles, though the half-round profile is perhaps most common. Our galvanized half-round gutter photo at below left shows that the gutter is rusted and overflowing.

Galvanized half round gutters (C) Daniel Friedman Galvanized half round gutters  (C) Daniel Friedman

At above right the half-round galvanized gutters were painted but have rusted through, sagged, and are at end of their useful life.

Plastic Roof Gutters Shape & Profile photos

Plastic roof gutters are popular with "do-it-yourself" homeowners, perhaps because the connecting gutter and downspout parts appear to snap together nicely and may include built-in gaskets in the gutter connectors. We often find that plastic roof gutter systems are under-sized, inadequately supported, and loose.

Plastic gutters (C) Daniel Friedman Plastic gutters (C) Daniel Friedman

Hung Wood Gutters Shape & Profile photos

Our hung wood gutter photo (below left) shows a common type of gutter used in North America: the gutter was actually carved out of a solid piece of wood. You can also see that while wood gutters may have lasted a very long time, sometimes up to 50 years, eventually the gutter is both rotted and filled with moss.

Wood gutters are more attractive than some metal alternatives but require considerable maintenance if they are un-lined: annual inspection, caulking at seams, and treatment with a preservative oil. The heavy moss found in this hung-wood gutter makes clear that it had not been inspected nor cleaned for a long time.

Sod roof (C) Daniel Friedman Sod roof (C) Daniel Friedman

Our second wood gutter photo (above right) was observed on a sod roof in Molde, Norway. This wood gutter approach is similar to a Yankee gutter but without brackets and using a larger timber to form the gutter side. The larger timber is used to help keep sod from sliding down or washing off of the roof surface.

Questions & Answers regarding this article

Questions & answers about roof gutters, downspouts & other roof drainage control systems

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

GUTTERS & DOWNSPOUTS - see detailed links at page left

  • Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
  • Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF - ** Particularly useful text **
  • Dampness in buildings, Diagnosis, Treatment, Instruments, T.A. Oxley & E.G. Gobert, ISBN 0-408-01463-6, Butterworths, 1983-1987 [General building science-DF]
  • Home Reference Book - Carson Dunlop The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course,
selected by ASHI the American Society of Home Inspectors and other professionals and associations.
This website author is a contributor to this course.Carson Dunlop's Home Study Course for Home Inspectors can be examined online at that company's website. More about home inspector education and other educational materials is organized at InspectAPedia.com at Home Inspector Education.
  • Certainteed Weatherboard fiber cement siding and trim products - see certainteed.com/ or see certainteed.com/resources/sidingandtrimspecsheet.pdf
  • "Flashing: the plain solution to leaky walls", Thomas E. Remmele, Manager, Technical Services, Sto Corporation, Building Standards, November/December 1999 p. 21-25.
  • "Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
  • ...

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