Peel and stick flashing tape or membrane:
This article describes the selection and installation of peel-and-stick flashing membranes used on building exteriors to seal housewrap joints and to seal against air or water leaks around windows, doors, or other openings.
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This article series discusses best practices construction details for building exteriors, including water and air barriers, building flashing products & installation, wood siding material choices & installation, vinyl siding, stucco exteriors, building trim, exterior caulks and sealants, exterior building adhesives, and choices and application of exterior finishes on buildings: paints, stains.
Details for Installing Peel and Stick Flashing Tape
We like to install flashing tape in the same sequence or overlap pattern as if it were metal flashing - that is, the upper horizontal flashing tape overlaps the vertical tape installed (first) at the sides of the window. To assure that we respect that water runs downhill, we install housewrap, window and then peel and stick flashing tape around a window in this order:
Photos courtesy of Eric Galow, Galow Homes. Eric recommends additional staples through the flashing tape to be sure it remains in place during initial curing of the bonding adhesive.
This flashing tape is very sticky on one side (peel off the waxed paper as we show). The other side of this product is covered with aluminum foil to improve its performance. This sticky flashing membrane tape will also seal nails that may penetrate its surface after installation.
Also see FLASHING WALL DETAILS
If you are building a deck see Deck Flashing at Building.
Adapted/paraphrased with permission from Best Practices Guide to Residential Construction. Steven Bliss.
Peel-and-stick eaves membranes have been used for nearly 20 years to prevent roof leaks from ice dams and other roofing trouble spots. These are typically available in 36-inch widths and are used to protect eaves, shallow-pitch roofs, and other problem roof areas. Over the past few years, a new family of related products has been introduced to help seal walls against water intrusion.
Peel-and-Stick Flashing Tapes, Types, Uses, Applications
Typically ranging in width from 4 to 12 inches, these peel and- stick membranes greatly simplify the task of creating a continuous barrier to water entry around doors, windows, decks, and other problem areas. Flashing tapes are faced with reinforced polyethylene or foil on the outer surface and a peel-away paper on the adhesive surface.
The foil faced products may be left exposed to the weather permanently, whereas the plastic-faced tapes should not be exposed to sunlight and weather for more than 30 days (longer for some brands) since UV radiation will degrade the facing.
Comparing Modified Bitumen vs Butyl Peel and Stick Flashing Tapes
Most flashing membranes are made from modified bitumen, the same rubberized asphalt used in eaves flashing. Some use a more expensive butyl rubber core, which stays more flexible in cold weather and is more stable at high temperatures. Butyl products also bond better to difficult substrates than modified bitumen and can be peeled off and adjusted during installation.
Moldable Flashing - Butyl-based
A unique butyl-based flashing tape from DuPont, called Tyvek FlexWrap®, has a wrinkled facing that allows it to be molded easily to irregular shapes such as the head flashing of round-top windows. It can also be bent to create a pan flashing at window sills without any cutting and folding at the corners. Despite the higher material costs, labor savings make this product appealing for tricky applications.
Applications for Flashing Tapes
These products offer several distinct advantages over metal flashings: They are easily bent or molded for an accurate fit, can accommodate settlement and shrinkage movement, are self-sealing around nail holes, and bond well to a variety of materials, including metal, wood, plywood, and vinyl window flanges.
Flashing tapes provide long-lasting waterproof protection if installed correctly. Oriented-strand board (OSB), concrete, and other masonry materials, however, can be problematic for some of the rubberized-asphalt flashings and may require priming for a good bond. Consult with the product’s specifications for compatible surfaces and priming requirements.
To obtain the best results with these products and be protected by the manufacturer’s warranty, it is advisable to follow the manufacturer’s recommendations. These vary from product to product, but generally they address the same issues: application temperature, priming, installation techniques, and compatibility with surrounding materials.
Temperature Effects on Peel-and-Stick Flashing Membranes
In general, the rubberized asphalt (modified- bitumen) products start to lose stickiness at around 50°F and will not bond much below 40°F. Unless you are working with a rubberized-asphalt product specifically formulated for low-temperature applications, a butyl-based product is a better choice in cold weather.
Very high temperatures can also be problematic for rubberized-asphalt membranes. When subjected to high temperatures and pressure, for example, when squeezed under a dark-colored metal flashing exposed to direct sun, the material will soften and begin to flow. Unless formulated for high temperatures and labeled “hi-temp,” most modified bitumen will begin to soften between 185°F and 210°F. High-temperature formulations can tolerate up to around 240°F, but are generally not as sticky.
Substrates: Bonding Flashing Membranes & Tapes to Solid Wood, Plywood, Vinyl, Metal, OSB
Each manufacturer specifies which products are safe to bond to and which require priming. Solid wood, plywood, vinyl window flanges, and metal are usually fine as long as they are free of oil and dust. Some manufacturers of rubberized-asphalt tapes recommend that all materials be primed for best performance, particularly in cold weather.
Most require that concrete and masonry be primed, and some require the priming of OSB and gypsum sheathing as well.
Many published details show asphalt-rubber flashing tapes bonded to asphalt felt and plastic housewraps. While these are rarely listed as suitable substrates in product literature, manufacturers of flashing tapes claim that their products will bond satisfactorily to both these materials as long as they are clean.
Do not expect a good bond to dirty housewrap that has been exposed to the weather for a month or to any dirty job-site material. For that reason, it is always best to detail flashings and to layer materials so that they shed water even if the adhesive bond fails.
Compatibility Flashing Membranes & Tapes With Vinyl
Rubberized-asphalt flashings should not be in direct contact with flexible vinyl flashings. The asphalt compound will draw the plasticizers out of the vinyl, causing the asphalt to soften and flow and the vinyl to become brittle.
The rigid polyvinyl chloride (PVC) used in window flanges, however, is generally not a problem. Rubberized-asphalt flashings should also not come into contact with any caulks or sealants unless specifically formulated for that use. Like soft vinyl, sealants may react with the asphalt, causing it to flow and stain the adjacent materials, such as window flanges.
Butyl-based flashings are compatible with most construction caulks and sealants, but they should never be installed in contact with any asphalt-based products such as roofing cement or bituminous flashing membranes.
These may degrade the butyl and undermine its ability to seal. In these applications, rubberized-asphalt is a much better choice.
Applying Pressure is Important in Stick-On Flashing Membranes
Flashing tapes must be pressed firmly into place to ensure full contact and a good bond. Some manufacturers recommend using a hard rubber roller for best results.
Splashback Protection and Other Uses for Peel-and-Stick Flashing Tapes & Membranes
While most flashing tapes are used around doors and windows, they can be put to good use wherever water penetration is an issue. Other applications include band joists, deck ledgers, inside and outside corners, and any areas subject to frequent wetting.
On wall areas adjacent to a deck or abutting a roof, for example, where splashback or snow buildup is likely to wet the siding, sections of membrane up to 36 inches wide can protect wall assemblies. Make sure to lap all layers of flashing, sheathing wrap, and adhesive membrane so that water is directed to the outside of the building, even if the adhesive bond fails.
Caution re Cold-Side Vapor Barrier: Don't Cover Entire Walls with Peel-and-Stick Flashing Membranes
Watch out: In cold climates, covering an entire wall section with waterproof membrane will create a cold-side vapor barrier, potentially leading to serious moisture problems and wood decay within the wall cavity. A section of membrane up to 3 feet wide, however, is unlikely to cause problems.
-- Adapted with permission from Best Practices Guide to Residential Construction.
List of Sources for Flashing Tapes and Membranes - where to buy
1-800-773-4777 for sales and technical assistance.
Continue reading at FLASHING for METAL ROOFS or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
Question: "blue skin" for trailer roofs
(May 11, 2014) alex said:
can you put blue skin on a travel trailer roof and paint over with rubber paint
Alex I'm not sure what the blue skin product is (name and product name would allow some research. But certainly there are a number of roof-over materials for leaky trailer roofs, including rubber coatings. Without a membrane these may not be a lasting repair.
What I would not try is simply rolling out a self-adhering flashing membrane on your trailer's roof - don't use a product that was not designed to be left exposed to the weather. It won't endure.
Question: flashing membranes adherence to old masonry chimneys
(July 28, 2014) Jean said:
Can peel and stick flashing membranes be used on masonry (old chimney) or only on wood decking?
Some of the flashing membrane product lines listed above such as FortiFlash® include products designed to adhere to cleand dry masonry.
Unfortuntately, too-often I have not seen good adhesion of a peel-and-stick flashing membrane along a masonry surface such as an older, rough-surfaced masonry brick or block chimney. And these membranes are not intended to be left exposed to the weather. Further, even if it adhered, you'd need counterflashing over the upper edge of the membrane to assure a durable installation.
Question: peel-and-stick membranes in roof valleys
(Aug 12, 2014) Donald said:
Can peal and stick membranes be used on steel roof valleys?
Donald, the flashing tapes we describe here are expected to be covered by a finish material. These membranes do add valuable leak-insurance used beneath a finsish-material placed in a roof valley.
Question: will flashing tapes seal around a screw
(Aug 31, 2014) Gary said:
Will Flashing Tapes and membranes self seal around a screw, particularly the screw that holds the exterior finish (i.e. Siding) on to the substrate?
Great question. My answer is yes ... and sometimes no.
Peel-and-stick membranes are intended to seal around small-diameter penetrants such as staples and roofing nails. Where I've seen leaks through a P&S membrane on a roof they were traced to a mis-hammered roofing nail that folded over and whose head made a significant cut in the membrane.
I've also come across a few tears in flashing membranes that were subjected to twisting forces from a screw as it penetrated the material, in particular if the flashing material was not itself thoroughly bonded to the substrate surface.
Where I've seen leaks over doors and windows that were traced to flashing tape troubles the issue was either failure of the tape to bond to an older weathered surface or to someone having driven a 16d nail through the material.
And of course no flashing tape on a building wall, say over a window, is going to be able to prevent leaks that run down behind the housewrap from some leak point higher on the building.
Question: Blueskin SA compatable for a tie-in with a 2-ply hot asphalt vapour retarder
(Sept 3, 2014) Leo said:
Is Blueskin SA compatable for a tie-in with a 2-ply hot asphalt vapour retarder on a flat roof transition?
Blueskin SA is an SBS-modified self-adhering membrane made of SBS rubberized asphalt compound that has been laminated onto a blue polyethylene reinforcing film.
Blueskin is produced by the Henry Company, 999 North Sepulveda Blvd., Suite 800 El Segundo, CA 90245 310-955-9200. Contact the company at E-mail: email@example.com Phone: 800-486-1278
The material is designed to bond or "stick to" prepared concrete, concrete block, primed steeol, mill-finished aluminum (remove any oils), anodized aluminum, galvanized metal, gypsum board and plywood.
The material (as well as others of this type) is not designed to bond to a hot asphalt-sealed surface.
(Oct 7, 2014) Anonymous said:
We will be pouring a large 70' patio with stamped concrete. What type of flashing should be used when connecting new concrete landings to the house wood frame support? The landings are both 12" wide where they connect to the house and will allow entry into two 8 foot wide doorwalls.
Please take a look at DECK FLASHING
Question: how to remove flashing membranes from concrete
11/06/2014 Steve said:
I bet this isn't asked often. Once you apply Fortiflash to concrete, how do you get the stuff off. We removed an old shed that was sealed to the concrete driveway with this stuff, and outside of grinding it off, we haven't had any luck.
Removing a well-adhered flashing membrane such as FortiFlash can be difficult on any surface. At least on concrete you could heat it gently to try peeling it off but I'd bet that the result will leave black residue on the concrete surface.
For other readers, FortiFlash(R) is a waterproof flashing membrane produced by Fortifiber Building Systems Group (R), a Fernley NV USA company. The product is a self-adhesive membrane reinforced by high-density polyethylene film that the manufacturer also refers to as “rubberized asphalt” and is described more technically as “a self-sealing SBS modified asphalt core laminated to a cross-laminated high-density polyethylene film reinforcement with a siliconized paper release sheet.”
It’s possible that the installer used Fortiflash 40(r) for floors - a vapor retarder system that can be adhered to concrete. It looks as if the composition of that product is similar.
As such if you can physically peel off the reinforced sheet you might use an organic solvent on the remaining modified asphalt adhesive. The company’s literature points out that the product is not compatible with EPDM (Rubber roofing), flexible PVC products and some sealants - but I don’t find much help from those products when considering how to remove FortiFlash membranes.
My best advice would is to contact the company directly for advice on the safest and most effective solvent to use.
Contact Fortifiber Building Systems at
1-800-773-4777 for sales and technical assistance. Website: www.fortifiber.com
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