The original deck on my house was attached by having boards extending out from the basement joists through the brick casement (e.g. partially sistered with basement ceiling joists).

At some point over the years, that deck was replaced. They put a board up against the house and used lag bolts instead, cutting off the existing joists. Unfortunately they did not repair the brick wall behind it, leaving the edges of the untreated wood exposed. Predictably they've rotted and need to be replaced.

The deck has to be removed in order to make proper repairs to the wall. Unfortunately, I cannot remove and then reattach the deck - attaching decks this way is now apparently against code here in south western Pennsylvania.

I am hoping to get a few more years use out of this deck so I am thinking about install counter flashing above the board against the brick casement. I feel comfortable with grinding out the mortar in the right place, but I do not have the tools necessary to bend long sheets of metal.

TL;DR Is there a material that I could use for counter flashing which doesn't require the ability to bend large pieces of metal in to a Z pattern?

  • 2
    Can rent metal benders, but the flashing is usually so thin(bendable by hand only), for a small job can probably make something out of wood/metal and some clamps.
    – crip659
    May 23, 2023 at 12:41
  • What do you mean by "large pieces"? If you use say 3 foot pieces with 6 inch overlap ... or whatever size pieces are manageable ... would that do? Or, what about lead? You could hammer in the bends in place. Not best practice but might be adequate?
    – jay613
    May 23, 2023 at 12:54
  • @jay613 I guess it's ignorance on my end - I've really only seen the folks using very long rolls of flashing material, with a large metal bending tool.
    – negacao
    May 23, 2023 at 13:15
  • 1
    Large pieces = less overlap, less waste, less opportunity for errors and leaks. So a professional installing miles of it has lots of incentive to use large pieces. Also onsite fabrication reduces transport costs. You don't have the experience or equipment to do it and really no incentive. It's a small DIY project and somewhat temporary so do what works for you. The accepted answer is excellent.
    – jay613
    May 23, 2023 at 13:28

1 Answer 1


There are many nonmetallic materials available, from PVC sheet like you'd see in a shower stall to bituminous roof and window flashing membranes to good ol' fashioned asphalt felt (tar paper). You'll have to consider the nuances of your situation and make a choice based on the specific needs it presents. Consider:

  • The way you'll need to fold and shape it

  • The clearance you have behind or between the framing and brickwork, for example

  • Solar exposure

  • Overall size

  • Whether you need adhesive properties

  • How you'll fasten it and whether it must tolerate penetrations

  • Visual appearance

Based on the variation those factors present I would be reluctant to suggest anything in particular, but window flashing membrane is known to be both highly flexible (when warm) and tolerant of penetrations. It's also self-adhesive. That might be worth trying.

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