I have a place that has a corrugated metal roof under a wood deck. It's a pretty large area, maybe 40' x 40'. When it rains, water leaks through some of the nails.

The deck boards are not nailed directly to the metal roof. The decking is attached to a frame built over the top of the roof. I'm guessing I need to remove all of the deck boards and patch the metal roof under the frame.

What would be the simplest way to stop the leaking?

4 Answers 4


Carefully pull the suspect nails (or all the nails) with a small pry bar or "cat's paw" and replace with new corrugated roofing nails like these:

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Or, if appearance is not important, smear a big glob of roof patch over the existing nails' heads.

  • Appearance is not important as there is a wood deck covering the roof. Having said that, the deck will make it very difficult to get to the existing nails.
    – Homer
    Jul 10, 2015 at 18:38
  • Oh... I can't think of any way to effect a repair from the inside. Jul 10, 2015 at 19:06

Wait, you have a DECK over metal roof that is NAILED down?

You pretty much won't be able to stop leaks :/ but you can try...

1) take out all nails and use Rubber Washer screws.

2) seal each skrew and all overlaps with SOLAR SEAL 900 - you can find it online.

Best thing is to use a real waterproofing material for flat roof decks - http://www.coolflatroof.com/roof-deck.php

  • Yeah, it's a boat house, so there is a sun deck built over the roof.
    – Homer
    Jul 22, 2015 at 20:53

Take the deck up, patch holes with pop rivets & paint on a Seal-o-flex type of roof coating...the best long term solution short of a new roof.

But, All from the underside:

Any caulk or drill out visible holes to accept larger rubber plugs. Or, use Bondo (Auto body filler) or JB Weld (muffler & exhaust pipe repair) from the Auto Parts store.

None of these are permanent, but all can be repeated until there's no more roof.

Lastly, if this is a few inch clearance situation & the leaks are all over the place. You might get 20-years out of waterproof & UV resistant tarps sewn together. You'd feed an electricians fish-tape over the roof, tie on a bunch of ropes & pull those back with the fish-tape to then tie on your tarps for a pull over. The tarps could just be pulled tight & fastened or you could feed in 2x4's to pinch them to the roof with the deck.


There is no way to waterproof your roof without removing the deck. And if you remove the deck to waterproof the roof, re-attaching the deck in the same manner would create new holes where you drive the new fasteners, or puncture the waterproofing if you drive them through the same holes.

This building assembly is fundamentally, fatally flawed and cannot be salvaged. If you want a waterproof roof, your only option is to remove the deck and rebuild the assembly properly, likely with commercial-style flat roof membrane and an approved deck system rated to be installed over roofing. If the roof has a steep pitch, you could conceivably use metal roofing again and screw deck brackets through it using gasketed screws, lap small pieces of the roofing panels over the brackets, and then scrupulously waterproof the whole area with metal-roof-rated roofing tar or UV-stabilized caulk. But this would still be a fundamentally weak assembly as it would rely on caulking to keep out water rather than gravity.

  • 1
    The deck boards are not nailed directly to the metal roof. The decking is attached to a frame build over the top of the roof that the deck. I'm guessing I need to remove all of the deck boards and patch the metal roof under the frame.
    – Homer
    Aug 25, 2015 at 17:18

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