Flashing is a crucial component in roof construction, used to prevent water infiltration and damage. Materials used for flashing include copper, galvanized steel, lead, aluminum, stainless steel, bituminous sheet material, and plastics. Some combinations of these materials are used, such as galvanized steel covered with bitumen to prevent corrosion when in contact with mortar. Membrane-type flashing is another option, used alone or as a layer to separate pressure-treated wood from metal flashing or steel framing connectors.
Concealed or external flashing is typically made from sheet metals, bituminous-coated fabrics, plastic, or other waterproof membrane materials. Exposed flashing is commonly made from aluminum, copper, PVC, steel, or lead, but may also take the form of a flexible rubberized sheet. Aluminum is easy to form, durable, and relatively inexpensive. Most manufacturers recommend that concrete and masonry be primed, and some require the priming of OSB and gypsum sheathing.
Flashing vulnerable areas of the roof helps prevent water infiltration. Builders may prefer aluminum flashings for visible flashing or areas that need to hold a shape or serve as a drip edge. Light-gauge aluminum flashing provides a continuous barrier of thin sheet metal that stops water from flowing through a joint or angle and into the building envelope. Most residential wall flashing today is made from light-gauge aluminum “coil” stock because it is low-cost, easy to bend, and holds paint well.
Roof flashing is a thin material, usually galvanized steel, used by professional roofers to direct water away from critical areas of the roof. It is typically installed at the base of masonry walls, above windows, and above decorative pre-cast lintels. Aluminum, copper, and galvanized steel are common metals formed into counter flashing, each with value but must be evaluated by their properties.
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What is standard flashing material?
Steel is a popular material for roof flashing due to its malleability, aesthetic value, and corrosion-resistant properties when galvanized. Professional roofers use this thin material to direct water away from critical areas of the roof, such as vents, chimneys, and skylights, where the roof plane meets a vertical surface like a wall or dormer. The flashing should run down the side of the flashing and direct water to the shingles instead of into the roof deck.
Without flashing against these walls, water could drip into the crevice between the wall and the roof, potentially causing damage to the home. There are various techniques to install roof flashing, including step flashing with a wall corner, counter-flashing on a chimney, and roof plumbing vent flashing boots.
What material is normally used for flashing?
Steel flashing is the most common type of roof flashing due to its affordability, durability, and corrosion-proof properties. Aluminum flashing is lightweight and easy to shape, making it suitable for complex roof flashing situations. Copper flashing is popular for its aesthetic appeal and durability, but it may discolor over time.
There are various types of roof flashing, each designed for specific roofing tasks. Continuous flashing is a single piece of metal that channels water downwards to shingles below. Base flashing is suitable for structures like chimneys, where multiple pieces secure the structure to the roof. Counter flashing is placed directly above the base flashing, ensuring water is always directed towards the shingles. Step flashing is a long rectangular piece bent at an angle, installed in layers between shingles to direct water away.
Valley flashing is placed in dips where water can gather on the roof, directing water away from damaging the roof. Drip edges are strips of flashing placed along the roof edges to direct water away from the walls. Kickout flashing connects the roof to the gutters, directing water directly into the gutters.
Can galvanized flashing touch concrete?
Masonry construction requires different materials for flashings. Aluminum and lead are susceptible to corrosion when in contact with wet mortar, while galvanized metals with zinc coatings are not recommended. Copper is an excellent flashing material due to its moderate price, moisture barrier, and resistance to alkalies in fresh mortar. Stainless steel is also impervious to moisture and resistant to chemicals. Polyvinyl chlorides (PVC) are widely used plastics due to their flexibility and crack-free properties.
Common flashing combinations include sheet metals coated with a flexible compound, a combination of glass fiber or cotton fabric with a bituminous compound, textured, waterproofed, creped kraft paper bonded to copper or lead sheet metals with asphalt, and a metal foil coated with a polyester film reinforced with glass fiber mesh.
What is the minimum thickness of metal flashing?
Flashing is required at wall and roof intersections, changes in roof slope or direction, and around roof openings. Corrosion-resistant metal flashing must have a thickness of 0. 019 inch (No. 26 galvanized sheet). Valleys must be lined according to shingle manufacturers’ instructions and may be made of galvanized steel, two plies of roll roofing, or one ply of smooth roll roofing complying with ASTM D 6380 Class S Type III, Class M Type II, or ASTM D 3909. Valleys covered with shingles may also be lined with one ply of smooth roll roofing.
Is all flashing aluminum?
Sheet metal materials like copper, aluminum, pre-finished steel, stainless steel, and galvanized steel are commonly used for roof-related flashings. Stainless steel and aluminum are the most commonly used materials. Aluminum and steel are durable and easy to fabricate, making them suitable for roof-connected flashings. Understanding the pros and cons of each metal is crucial before selecting a material for roof-related flashings, such as roofing, copings, penetration pockets, counter flashings, and through-wall flashings.
Will galvanized steel flashing rust?
Flashing damage can be identified by small holes, rust or corrosion, missing pieces, bends, cracks, or dents, internal leaks, mold or staining on fascia boards, and corroded spots. These issues can lead to major problems when left unsealed. Rusted roof flashings cannot effectively repel water and require cleaning, sealing, or replacement. High winds during storms can cause flashing to loosen and rip off the roof, making it a priority repair. Bends, cracks, or dents can break the galvanized coating on the flashing, compromising its integrity. Internal leaks near windows, skylights, attics, or fireplaces can also indicate damage.
Repairing roof flashing can be done by a qualified contractor using roofing cement to plug pinholes or patch holes up to 3/4 inch in diameter. However, severe corroded flashings require replacement. Working on any type of roof is dangerous and should be left to professionals. Straight Line Construction offers expert roofers to safely navigate your roof, identify issues, and make accurate repairs. Contact them for a roof inspection or if you suspect roof flashing damage.
How thick is aluminium flashing sheet?
Aluminum flashings are available in a range of thicknesses, from 0. 9mm to 3mm, and can be mill finished, pre-coated, or powder coated after bending. Furthermore, they can be bent to any size or shape, including bullnose flashings. Our website employs the use of cookies with the intention of providing a relevant experience for the user. By clicking on the option to “Accept All,” the user is thereby consenting to the use of all cookies. Furthermore, users are able to exercise control over cookie settings.
Does stainless steel flashing rust?
Ultra-thin 304 stainless-steel flashing is a new product that is as thin as a piece of paper and comes with a butyl adhesive already applied. This durable material is resistant to tearing and puncturing, making it ideal for flashings. It is the only metal flashing used along the ocean where saltwater spray and mist cause rapid corrosion of other metals. The butyl adhesive holds the flashing to any clean and dry surface, and the paper backing can be left on the flashing to avoid installation frustration. However, it is important to understand how flashings work and how they need to be fabricated and layered to create a waterproof detail.
Is galvanized or aluminum flashing better?
Galvanized steel is a popular choice for flashing due to its heavy weight and resistance to damage from heavy impacts. It can last up to 40 years and is difficult to contour, making installation time-consuming. However, if the zinc layer is damaged, the steel underneath can rust. Copper is a durable, corrosion-resistant, and attractive option, with a lifespan of over 100 years with proper maintenance. However, it is lightweight and malleable, making it easy to develop dents. Copper is also relatively expensive.
What metal is used for flashing?
Flashing is a type of impervious material used to prevent water from entering a structure or as part of a weather-resistant barrier system. It is used in modern buildings to reduce water penetration at various objects, such as chimneys, vent pipes, walls, windows, and door openings, making buildings more durable and reducing indoor mold issues. Metal flashing materials include lead, aluminum, copper, stainless steel, zinc alloy, and others. The term “flash” and “flashing” may have its origins in the Middle English verb “flasshen”, meaning “to sprinkle, splash”.
Counter-flashing, or cover flashing, is when two parallel pieces of flashing are used together, such as on a chimney. The term “apron” is still used for the piece of flashing below a chimney. Up-hill side of a chimney may have a cricket with cricket flashing, or back flashing or back pan flashing on narrow chimneys without a cricket.
Is copper flashing better than aluminum?
Copper flashing is a superior choice for homeowners looking for a durable and aesthetic option in their roofing and construction projects. Unlike aluminum flashing, copper flashing is resistant to corrosion, ensuring a longer lifespan and lower maintenance requirements. This makes it an ideal choice for roof valleys, chimneys, and over the eaves, where water infiltration and potential damage can occur.
The advantages of copper flashing include its exceptional durability, which is a key factor in its popularity. Unlike other materials, copper flashing doesn’t rust, ensuring a longer lifespan and lower maintenance requirements. Additionally, copper flashing is a unique choice due to its remarkable properties, including corrosion resistance and longevity.
In conclusion, copper flashing is a superior choice for homeowners looking for a durable and aesthetic option in their roofing and construction projects. Its exceptional durability and resistance to corrosion make it an ideal choice for protecting your roof from the elements.
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Thanks Matt for taking the initiative to film this article for us without your camera crew vs not at all. articles like this shows how much thought process you put into providing us good content. You could have very easily skipped this article till you had someone record you but you didn’t. I’m sure many of us appreciate you and your efforts! Can’t thank you enough!
Hey Matt, great article! What was the resson for the walls switching from flush with the concrete to 5-6″ inside of it? We like to have our framing flush with the outside of the slab then run the sheathing over the joint by 3″. Just before we nail it we will run a bead if expanding foam to stick the insulation of zip r to the slab. Any squeeze out gets cut away, then we go around the whole house with prosoco airdam spread over the joint. Finish out with Siga Fentrim 9″. Bomber!
Interesting product. A couple questions at the system level. Do you prefer to seal the seam between the sheathing and the slab on these thick Zip-R systems or provide some sort of condensation outward ventilation/drying? This system seemed to be an updated brick ledge flashing with a drainage screen(assuming that drainage screen wouldn’t be pinched closed by the weight of the masonry or sealed by wicking up mortar,) this system would be open to breath along the veneer/cladding drainage plane but appears to be sealed by a fluid applied sealant on the aforementioned condensation plane. Also is there an structural loss or modifications required for the masonry install where it meets the slab or otherwise to account for the loss of mortar bond to the foundation?
What else can you do at the bottom of the OSB — I see some use SIGMA Tape or some MESSY GOOPY PINK or BLACK stuff — My concern is that the SIGA Fentrim 430 product info states that it needs a “Minimum surface contact for masonry substrate of 2 inches”. Then it states “Max UV exposure 4 months” — So what happens to the 2″ stuck to the concrete after 4 months — does it deteriorate like we see Duct Tape do? What other ways can be used to seal the bottom of the LP Weather Logic OSB (or ZIP) sheathing “that is permanent” and not look like someone made a mess using some black goo? I want a clean look at the beginning of my siding! Any good ideas on what to use to keep the OSB dry at the bottoms?
Thanks for making another great article. I think the Zip flashing tape up top is a great idea, but I have to question whether it makes sense to continuously caulk the bottom part of your flashing. If water ever gets in there, its trapped. I know you did a lot to prevent that from happening, but water finds a way of getting in, especially on jobs where the boss isn’t standing directly over the installation work.
Matt, would you ideally have put that flashing down before you put the Zip-R siding on, to have a true shingling for water runoff? Looks like you are depending totally on the adherance of the Zip tape and butyl smear to prevent water from getting behind there. And since you did not push the back of the flashing material all the way back under the edge of the Zip-R, have you created a critter crawl-way behind it? Not criticizing, just asking.
It’s fun perusal these articles; goodness knows I’ve probably watched 100 hours. There’s a lot to learn with regard to technique which is good because very often I call my suppliers in the GTA (Greater Toronto Area) and learn that half of the products you show aren’t available in my area. There are different products available, to be sure, but then I need to do more research because I didn’t see it on TBS.
If I were building a custom home and had an unlimited budget, my overhangs would be so large the widows and siding would never see a drop of water. You are going to be maintaining and or replacing the roof anyway – might as well have it completely protect the siding/widows. I’ve seen so many custom homes with water rot issues. It seems no matter how they try they always miss something.
Great article as always, no need for a film crew!😆 Would love to see more article’s on block construction. Not too common in the States but I’m going to build a house in Mexico where all houses are build with block construction and all houses are extremely leaky! They leak air and they leak water, thats just the norm here but would love tips on how to build them better 😃
I’m a small time builder in a rural Texas area (outside of Wichita Falls), and the owner would fall over dead if I suggested using this stuff over a roll of felt paper 😂 not to mention having to use all of that adhesive lol. I wish I could do it the right way. But without inspections and with a super tight wallet owner, that house won’t be sealed up nearly as well as this one.
I suppose that it would make sense to also flash/tape over all of the vertical seams where those panels come together. Since there is no overlap. But other than that one shot in the second half where it was mostly your back haha, great job on the self film. It was better than previous times where there was no tripod and it was just shaky all the time.
this might have been a better install if your buddy got some practice with it first. i hate teaching new methods and products to people on such an important part of the building. i think i would have to tape the top of that total flash as well as the sealant. dont really like it much… and you didnt air seal behind there! Bring your camera man next time!
Should you wipe down the Zip tape with rubbing alcohol or acetone until the writing is wiped off before applying anything over itself unless it’s the peel Zip tape, just for better adhesion? Same with the flashing tape, mild detergent and rinse/dry concrete? I’m sure it will be fine 🙂 I’m OCD, which is why I love your website haha. Finally I finished my house because of you, thank you sir! Lol at that tube of zip flashing used for the 3 pipes, surprised they didn’t press the material up to it and cut it out
Mr. Risinger, Sir, IMO and you are the expert, but on the black corner piece I would’ve put a bead on the inner lines 12:56 also as there maybe a droop in the product. The reason is you always preach belt and suspenders and/or a bomber approach to building. While that piece Is off that’s the only time you would have to put them on. I was just thinking for the small price of maybe 1 more tube of caulking, is it worth it to skimp as your houses are built with such a high standards. Great article on an interesting concept I haven’t seen before but makers total sense.
I watched a article where the producer found a secret that most battery operated drill/drivers have that will prevent the bits from falling out. The trick is that after you tighten the chuck enough to cause it to start clicking you back it off until it clicks once and then the bit will be locked into the chuck so it will not fall out. I do not know the mechanics of how that works but he said it does.
Matt’s is obviously dealing with the same labor issues (lack of quality or any employees) that we all are. And as such, he has assumed the “general laborer” title late in his career. I would say he could have done a slightly better job brushing off the sill and I do hope the job site super addresses that with him! I still think he shows potential and they should give him a chance to prove himself…🤔 It is good to know that if this “building” things doesn’t work out… Matt can always fall back onto his quality behind the camera work! 😎 (Please read with SARCASM!!!🫤)