Fastener type for flashing

[dan orourke]

.........

[Tim Moreira]

If it is, it should be the kind with the little rubber grommet/washer attached to prevent leaks.

[Jerry Peck]

Dan,

Are those just holding the two flashing pieces together, or are they fastening the flashings in place to the roof and wall?

If just holding them together, not as bad - IF riveted with solid rivets or screwed with washers as Tim said ... 'not as bad', mind you.

IF securing the flashing to the roof and the house, no, they should not be there. I would not even want the sealing type washers there. To great of a chance for things to move and come loose, then leak.

[Chad Fabry]

To great of a chance for things to move and come loose, then leak.:) The metal roofing industry might take offense at that statement. Screws with captive neoprene washers are the preferred method of attachment for all face secured metal.

It's unlikely that the screws are holding the flashing to the house. The siding fasteners do a good job of that. I'm not sure why the installer felt it necessary to screw the overlapping pieces together. It's a decidedly unconventional thing to do.

The failure in the future will likely occur due to galvanic corrosion. The beauty is though that it'll probably take about the same period of time for the roof to wear out.

[Mike Schulz]

If it is at the top of the roof against the Wall and is horizontal flashing it is called "apron metal". The two pieces probably did not mesh tight together so they screwed it. It appears that they used sealant between the two pieces. I don't see a problem with it. In fact the screws would probably be better to hold them together then roofing nails.

[Jerry Peck]

:) The metal roofing industry might take offense at that statement. Screws with captive neoprene washers are the preferred method of attachment for all face secured metal.

When used with metal roofing attached to the roof sheathing or purlins, I agree.

When used at pictured in the photo, there will be movement and the fasteners will loosen against the metal, creating a leak at the fastener.

The difference is that metal roofing 'is not' "water tight", there is a slip sheet and underlayment beneath it which is like the dry-in under singles, whereas flashing *IS* the watertight 'flashing' between two surfaces meeting at an angle, two dissimilar surfaces, etc..

Flashing is designed 'to make it' watertight. At least, as water tight as possible.

[Bob Harper]

Neoprene washers used on steel roofs go through a hole in the metal to a support structure allowing a slight movement of the panel for thermal expansion. It holds the panel snug--not dead tight. If it did, the roof would buckle up. Most of those neoprene washers are rated for 20-25 yrs. and must be replaced. We went through this on one of our rental properties not too long ago. Most of the washers were obliterated.

Flashing should provide for movement. That's why you have step flashing attached to the roof deck with counter flashing lapped over but not secured to the roof. This is a flexible joint. Anyone in hurricane country can testify to this phenomenon. Even in the lateral plane, the counter flashing should lap over. If it peels out, have them use stiffer metal but it should provide for elongation and flexion.

I have never seen where a nail or screw helped with exposed flashing but I've seen a ton that did damage or made things worst. Usually such mechanical fasteners are a harbinger or bad things to come. I'd go back to the drawing board.

My 7 cents worth...

[Mike Schulz]

That was a nickel to much :D

Point being is that particular joint was screwed because the lap would not pull tight where the one apron overlapped the next. Sealant was applied between the two aprons which the screws penetrated.

Seen it, done it, and would do it again. Never had a leak that I know of. At least when it was installed by me. :p

[Jerry Peck]

Never had a leak that I know of.

Words to die by. :)

[Richard Rushing]

The question was..."Screw fasteners can be allowed, used on the L-flashing at the headwall here, correct?"

I don't know of any reason the flashing should NOT be secured the way it is. That joint does need to be re-sealed.

Richard

[Mike Schulz]

The joint is sealed. What you are seeing is what was squeezed out when the two pieces where pressed together.

To make you sleep better at night you could apply along the seam and put a dab on the screws.