what is 3-course flashing

Flashing at the building foundation top or between the masonry foundation wall top and the wood sill placed atop the wall is is installed also as a damp-proofing course to stop rising damp in some climates. Flashing fantasy No. 3: half a (flashing) loaf is as good as a whole

Full Answer

What are the different types of flashing?

Roof flashing: Installed around projections or intersections to direct water from seams or joints . Wall flashing: Typically embedded in wall interruptions such as windows, either to prevent water ingress or direct water that has entered back outside. Sill flashing: Concealed under windows or door thresholds to prevent water ingress .

What is flashing and how does it work?

Flashing is a sheet of thin, impervious material used to prevent water penetration or seepage into a building and to direct the flow of moisture in walls.

What is the difference between base flashing and composition flashing?

The base flashing is designed to accommodate building movement. It laps the composition flashing at least 4". The composition flashing is extended up a cant strip then up the wall at least 10".

What is step flashing and counter flashing?

Step flashing ensures that water is directed away from the wall and ends up in the gutter. It’s installed in steps, with layers of shingles between, so that the water pours down each step and down the roof. Counter-flashing: Counter-flashing is often used to flash chimneys.

What is flashing on a roof?

Flashing is a flat and thin material used to prevent water from entering the openings and cracks of a roof. It is placed underneath the shingles of your roof and it redirects the water to another location. Roof flashing is made from metals, such as copper, aluminum, stainless steel, or galvanized steel.

How do you install flashing on an existing roof?

1:493:34How to Install Flashing on a Roof | Mastering the Roof by GAF - YouTubeYouTubeStart of suggested clipEnd of suggested clipPlace the first step flashing strip over the end of the starter course shingle and secure. The stepMorePlace the first step flashing strip over the end of the starter course shingle and secure. The step flashing to the roof with 2 nails.

What is flashing on a house?

As all builders know, flashing is a thin sheet or strip of water-resistant material that's installed at roof intersections and projections, around windows and doors, and along the tops of foundation walls to direct water flow away from the home. Flashing guides water out from the drainage plane to the exterior.

How do you flash a roof against a wall?

Place a kick-out flashing at the base of the roof and flush against the wall. Remove the flashing and apply some roofing cement to fix the flashing into place. Place the first piece of step flashing over the end of the tarter strip. Ensure that the step flashing will lead the water directly into the kick-out flashing.

What are the different types of roof flashing?

Some types of roof flashing are counter flashing, chimney flashing, step flashing, headwall flashing (also called apron flashing), valley flashing, and gutter apron flashing.

Does flashing go under or over shingles?

Flashing should overlap the roof-covering material, but on asphalt shingle roofs, for aesthetic reasons, the part of the headwall flashing that extends down over asphalt shingles is often covered with a course of shingle tabs.

Do you need flashing with gutters?

Why Flashing is So Important. Flashing creates a seal between your gutters and your roof line, which allows water to flow off your roof and into the gutter. Without it, some water would also flow behind the gutter, which would damage the building surfaces beneath the roof.

Why is it called flashing?

The origin of the term flash and flashing are uncertain, but may come from the Middle English verb flasshen, 'to sprinkle, splash', related to flask.

Is roof flashing necessary?

It's a crucial roofing material that every roof needs to have. You'll have different metal options to choose from for your roof flashing. These common types of metals are aluminum, steel, or copper.

What is the difference between flashing and step flashing?

The base flashing (or apron flashing) is the bottom piece. Counter-flashing: Placed opposite to base flashing, or above base flashing, counter-flashing completes the two-part team. Step flashing: Step flashing is a rectangular piece of flashing bent 90 degrees in the center. It is used for roof to wall flashing.

What flashing should be installed where the bottom of a roof meets a wall?

Installation of kick-out flashing is a critical component of step or continuous flashing. Kick-out flashing is a piece of flashing at the bottom of a section of roof that adjoins a wall. It is installed to direct water run-off away from the adjoining wall and usually into a gutter.

How wide should roof flashing?

The flashing shall be a minimum of 4 inches (102 mm) high and 4 inches (102 mm) wide. At the end of the vertical sidewall the step flashing shall be turned out in a manner that directs water away from the wall and onto the roof and/or gutter.”

What is continuous flashing on a roof called?

These are the key types of roof flashing you need to understand: Continuous flashing: Continuous flashing is also called “apron flashing” because it acts a lot like an apron.

What is the best material for flashing?

Steel: Steel is usually the material of choice for flashing. It’s malleable, has aesthetic value and, when galvanized, is corrosion-resistant. Building codes may demand your roofing professional use a specific material for flashing. They may also list a minimum thickness.

How many inches of flashing for Nordic shingles?

For example, 3-tab shingles usually have a 5 5/8-inch (143 mm) exposure. Typically, 10- by 8-inch (253 mm x 203 mm) flashing is chosen. Those 8 inches are more than enough to cover the exposure of typical shingles. The same size can be used to cover the longer exposure on Nordic™ shingles.

What materials are used for flashing on a roof?

However, roofing professionals in North America now prefer other materials: Aluminum: Aluminum flashing is easy for roofing professionals to form and is lightweight.

What type of flashing is used on a roof?

Types of roof flashing. Skylight flashing: While some skylight manufacturers include flashing in their products, sometimes roofing professionals have to create it or purchase it separately. Valley flashing: Open valleys have metal flashing to protect this critical area of the roof.

What is roof flashing?

Roof flashing is a thin material, usually galvanized steel, that professional roofers use to direct water away from critical areas of the roof, where ver the roof plane meets a vertical surface like a wall or a dormer . Flashing is installed to surround roof features, such as vents, chimneys and skylights.

Do you need a sealant for flashing?

Roof Flashing Sealant Types. When you install roof flashing, you will need to use a sealant. While roofing professionals occasionally use nails when flashing, they must choose whether to nail to the roof plane or the vertical wall.

Where is flashing used?

Flashing is used at the intersection of building components such as where a chimney protrudes through a roof, where roof planes meet in a valley, or around plumbing vents protruding through a roof, or at the intersection of a wall and a lower roof surface.

What is flashing in construction?

Flashing is supposed to redirect water: flashing refers to the use of a material (metal, rubber, plastic, for example) to mechanically intercept water and redirect it back out to the building exterior instead of permitting the water to enter the building structure . Water flows down hill: mostly.

What happens if you flash a building?

The consequences of a flashing error or omission on a building can cause serious building damage and even injuries or health problems as water intrusion eventually means costly mold contamination, building rot, building insect damage, and in extreme cases collapse of portions of a structure.

How far above grade should flashing be?

To prevent splash back from the roofline soaking the base of the wall, the bottom edge of the base flashing should be at least 8 inches above grade. This is a design detail that must be worked out before the foundation is poured.

How many inches should flashing be on a wall?

When more than one length is needed to span across the bottom of a wall, overlap pieces at least 8 inches. The flashing must include a drip-edge to direct any water that runs down the drainage plane away from the bottom of the wall. Weather-resistive barrier.

What is the transition between different claddings?

transitions between different claddings when more than one cladding is used at the bottoms of exterior walls where cladding systems interface with the foundation. The key to eliminating costly leaks is more than just applying a piece of flashing.

INTRODUCTION

At critical locations throughout a building, moisture that manages to penetrate a wall is collected and diverted to the outside by means of flashing. The type of flashing and its installation may vary depending upon exposure conditions, opening types, locations and wall types.

CAVITY WALLS

For cavity walls, as illustrated in Figure 1, the cavity typically ranges from a minimum of 2 in. to a maximum of 4 ½ in. (25 to 114 mm) wide, with a minimum of a 1 in. (25 mm) clear airspace if rigid insulation is placed in the cavity. Cavities wider than 4 ½ in.

SINGLE WYTHE WALLS

Flashings in single wythe walls, like cavity walls should be positioned to direct water to the exterior. This is normally accomplished using two narrower units to make up the thickness of the wall and placing flashing between them as shown in Figures 4 and 8.

FLASHINGS AT COPINGS AND CAPS

The type of flashing detail to use on low-sloped roofs will in part depend on the type of roofing membrane being used. As with any flashing detail, the materials used should result in a uniform and compatible design.

INTERIOR WALL TREATMENTS

Concrete masonry walls with an interior treatment may also utilize a through-wall flashing installation of flashings as shown in Figure 9. However, as noted in the figure, through-wall flashings generally create a bond-breaker, which reduces the structural capacity of a masonry wall.

SPLICING FLASHING

When it is necessary to splice the flashing, extra precautions are required to ensure that these discreet locations do not become sources of water penetration. Flashing should be longitudinally continuous or terminated with an end dam as shown in Figure 7.

Where should flashing extend?

Except where walls are brick, the vertical part of the sidewall flashing should extend up behind the exterior wall covering, just like with headwalls . The horizontal part of the flashing will vary, depending on the type of roof-covering material.

How big is a step flashing?

Step flashing size requirements vary according to manufacturer. Manufacturers' requirements can vary anywhere from 2 inches to 10 inches, and you probably won’t be able to see the sidewall flashing completely, anyway. The vertical side will be hidden behind the exterior wall-covering material.

What is mastering roof inspection?

The purpose of the series “Mastering Roof Inspections” is to teach home inspectors, as well as insurance and roofing professionals, how to recognize proper and improper conditions while inspecting steep-slope, residential roofs. This series covers roof framing, roofing materials, the attic, ...

Do you need flashing on a roof?

Headwall flashing should extend up behind the exterior wall covering and down over the roof-covering material, as you see here. This is true no matter what type of roof-covering material is installed. Flashing should overlap the roof-covering material, but on asphalt shingle roofs, for aesthetic reasons, the part of the headwall flashing ...

Can you overlap flashing on asphalt shingles?

Flashing should overlap the roof-covering material , but on asphalt shingle roofs, for aesthetic reasons, the part of the headwall flashing that extends down over asphalt shingles is often covered with a course of shingle tabs. Don’t mistake this condition for headwall flashing routed beneath the shingles and call it a defect.

What is flashing in a building?

Flashing is a sheet of thin, impervious material used to prevent water penetration or seepage into a building and to direct the flow of moisture in walls. Flashing is particularly important at junctions such as roof hips and valleys, joints between roofs and vertical walls, roof intersections or projections such as chimneys, dormers, vent pipes, window openings, and so on.

What is flashing made of?

There are two categories of flashing, exposed and embedded. Exposed flashings are partially exposed to the outside and usually made of a sheet metal, while embedded (or concealed) flashing can be metal or non- metal and are typically used at the base of cavity walls, above openings, at sills and shelf angles ...

What is code 3 for lead?

Code 3 (1.32 mm) is thinner, lighter and cheaper, and is commonly used for lead soakers which are the concealed waterproof sections positioned underneath slates and plain tiles . Other materials that can be used as metal flashings include aluminium which is also durable and relatively inexpensive.

What is flexible flashing?

Also known as flexible flashing materials, these include rubberised asphalt, butyl rubber, PVC and acrylic. They have different chemical compatibilities, resistance to ultraviolet light exposure, application temperature ranges and so on.

What is wall flashing?

Wall flashing: Typically embedded in wall interruptions such as windows, either to prevent water ingress or direct water that has entered back outside. Sill flashing: Concealed under windows or door thresholds to prevent water ingress . Channel flashing: U-shaped channel used where the edge of a tile roof meets a wall .

What are the materials used for flashing?

The most common flashing materials are metal, plastic, or rubber .

Is step flashing better than continuous flashing?

Step flashing offers far better protection from leaks than continuous flashing, because even if a single piece of step flashing fails, the water hits the next lower piece, which directs the water onto the shingle and drains down the roof .

What is copper flashing?

Description: Copper flashing is used wherever a wall intersects a roof. Such a system usually consists of copper counterflashing and base flashing in conjunction with roof composition flashing or coping. The counterflashing diverts water to the base flashing, which, in turn, diverts it to the composition flashing. The base flashing is designed to accommodate building movement. It laps the composition flashing at least 4". The composition flashing is extended up a cant strip then up the wall at least 10".

What is batten seam flashing?

The top of the roof pan is formed into a "bread pan" whose upper edge is just above the finished batten. Copper flashing is locked into this edge, and extends at least 8" up the wall. A copper receiver holds the counterflashing at its top edge.