Flashing reistant to corrosion
Flashing reistant to corrosion
(OP)
Is there any flashing that is particularly resistant to corrosion from de-icing salts? The situation is a public library where the existing deteriorated flashing extends from ahout the 4th brick course above the sidewalk down to the sidewalk. We are removing the sidewalk, sounding the garage roof slab below to detect delaminations and repairing, re-waterproofing the garage roof slab, placing a high stength drainage board, then re-pouring the sidewalk and putting in new flashing to replace the existing deteriorated flashing. I am not sure that galvanized steel flashing would be as resistant to corrosion in the salt environment as would be wanted.
QUESTIONS
Is there a PVC flashing, or any other non-metallic flashing, that could be used?
If so, are there any disadvantages to it?
Does it come in brown colour?
Is it UV resistant?
How should it be specified (thickness, etc.)?
If a metal flashing is deemed to be corrosion resistant in a chloride environment, how should it be specified...how thick, etc?
QUESTIONS
Is there a PVC flashing, or any other non-metallic flashing, that could be used?
If so, are there any disadvantages to it?
Does it come in brown colour?
Is it UV resistant?
How should it be specified (thickness, etc.)?
If a metal flashing is deemed to be corrosion resistant in a chloride environment, how should it be specified...how thick, etc?






RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
Can I be sure that itwiukd not be excessively expensive?
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
Mike Halloran
Pembroke Pines, FL, USA
RE: Flashing reistant to corrosion
.1 Prefinished sheet metal flashing: Galvanized steel, 0.71 mm [24 ga.] core nominal thickness, Z275 zinc coating to ASTM A525M. Finish to Stelco's 8,000 series or an approved equivalent, applied both sides. Colour to match existing and be approved by Owner from the 12 standard colours listed in CSSBI's General Colour Card.
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
Stainless, particularly 316 with a specified maintenance routine of semiannual washing, may be a much better performer in this situation.
See if you can find a comparative report for materials in your exposure conditions; A good report I've got in my reference materials is "Deicing Salts - Recognising the corrossion threat".
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
http://www.polyguardproducts.com/products/architec...
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
why not aluminum or galvanized?
http://www.deckmagazine.com/wood/beyond-aluminum-f...
comparison of types of flashing
http://www.maconline.org/tech/materials/Flashing_f...
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
cvg - I am not sure what material the existing flashing is. I will try to look at it again on the weekend. Thanks for the information in the links. Very interesting indeed.
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
We all know aluminum performs well in saltwater, which is why boats use it in their propellers, and they make docks, decks, and handrails near or on saltwater out of aluminum. But I guess the same cannot be said about the exposure to deicing salts, probably because the NaCl concentration is so much higher in deicing salts?
This article says stainless steel is the way to go. But it seems to be an industry website, so take that with a grain of deicing salt.
http://www.imoa.info/molybdenum_uses/moly_grade_st...
For example, there is a common misconception among architects that aluminum’s corrosion resistance is similar to that of stainless steel. This is incorrect. In locations that are exposed to chlorides (coastal or deicing salt), the corrosion rate of aluminum is typically 10 to 100 times that of stainless steel.
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
something like this
http://www.advancedbuildingproducts.com/commercial...
RE: Flashing reistant to corrosion
No, we don't all know that.
Landlocked boatbuilders use aluminum for handrails because it's cheap, looks good in the showroom, survives the warranty period in freshwater, and so far they haven't been forced to make their handrails OSHA-compliant.
Saltwater boats are different.
Mike Halloran
Pembroke Pines, FL, USA
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
So Kynar 500 finish for the flashing and the detail would be a step flashing with each piece having a term. bar at the top and the top of the flashing angled to accept a sealant cove. Or you could cut the mortar joints and do a recessed top with lead wedges securing the flashing. The bottom of the detail is going to be the worst. Unless I am missing something it looks like you have to stop the flashing at the stair sealant/wall joint. If this is the case, seems the best you could do is get the hem as low as possible and angle it out (which it normally is). Good luck. Hope that helps some.
RE: Flashing reistant to corrosion
RE: Flashing reistant to corrosion
Belwo is what an aquaintance with archotecturla background gave me for the floshing. I think this is about right and close to what groganic recommended.
Sheet Metal Flashings
.1 Prefinished sheet metal flashing: Galvanized steel, 0.71 mm (24 ga) core nominal thickness, Z275 zinc coating to ASTM A525M-80. Finish to be Stelco's 8,000 series or an approved equivalent. Finish to be applied on both sides. Colour to be approved by the Owner from the 12 standard colours listed in CSSBI's General Colour Card.
.2 Fabricate and install counter flashings in general accordance with applicable CRCA 'FL' series specifications and / or as indicated on Drawings. Fabricate counter flashings in 2400 mm maximum lengths. Provide an "S-Lock" joint at all end joints and at all horizontal joints between the vertical flashing and base counter flashing. Make allowance for movement at joints. Hem all exposed edges at least 12 mm for appearance and stiffness. Form sections square, true, and accurate to size, free from distortion, oil canning and other defects detrimental to appearance or performance.
.3 Apply isolation coating to metal surfaces to be embedded in concrete or mortar joints. Turn top edge of flashings into recessed reglets or mortar joints a minimum of 25 mm. Fasten sheet metal flashing into reglet joint at a maximum spacing of 450 mm or more often if required.
RE: Flashing reistant to corrosion
I'm sure the finishes are similar. In my mind you just want something with some ASTM weathering requirements met. The kynar is good stuff and thus all I have ever used. But I am sure there are others out there that do just as well.
I would also check into touch up paint since you are going to have direct salt contact. I am pretty sure it comes in a spray can even. Just have to make sure the contractor doesn't make graffiti art out of the flashing. If you were really worried you could look into prefinished aluminum. I've used it for a standing seam metal roof before at the coast.
RE: Flashing reistant to corrosion