My metal roofer removed all 14 old vents and installed two new "Maximum ventilators" in its place. The remaining 12 holes are still there and not sealed and i can see the underside of the metal roof from the attic. The roofer claims that the holes serve as additional ventilation and that air will make its way out the old vent holes to the underside of the metal roof and out thru the ridge. But the manufacturer of the maximum vent says to seal off all old vents to prevent a short circuit in air flow as air should be pulled from tge soffits.

Whats the right wayenter image description here

  • Was any of this addressed in the contract? What's the gap between the wood and metal?
    – JACK
    Commented Jul 13, 2021 at 17:29
  • 1
    Would go with the manufacturer of the vents, they should know how the vents work best, not a roofer.
    – crip659
    Commented Jul 13, 2021 at 17:31
  • 1
    Wow that would fail inspection in my jurisdiction, I would check with your building codes devision.
    – Ed Beal
    Commented Jul 13, 2021 at 17:42
  • 3
    What happens down the road when someone is walking on the roof and steps where the hole is? Best case, there is now a big dent there. Worst case there is now a hole in your roof. No, this is not acceptable!
    – jwh20
    Commented Jul 13, 2021 at 17:50
  • Are you sure you're seeing metal and not the underlayment?
    – JACK
    Commented Jul 13, 2021 at 18:02

2 Answers 2


I remember reading something that even under asphalt shingles there is an allowable hole size which does not affect the performance of the shingle. I do not recall if this was content in this DIY site or some other forum.

However, I'm sure you're not interested in the aforementioned technicality.

Did the roofer do a sloppy job? Yes.

Does it increase injury risk for future roofers? Yes.

Are they blowing you off by saying it helps with ventilation? Yes.

If there is a gap between your new roof and the sheathing then bugs can more easily get in. At minimum I would screw on a piece of plywood from the bottom to keep bugs out. Just make sure not to penetrate your new metal roof!

I highly doubt you will be able to convince the roofer to rip up the new roof just to patch underlayment.

  • Anyway, you could patch the plywood from the underside. Make a patch the same size (minus 1/8") out of the same material, and then make a picture frame out of 1x2's to use as battens. Choose screw lengths carefully. Commented Jul 13, 2021 at 23:32
  • @Harper-ReinstateMonica I'm not sure how rich OP is so my solution aims to avoid cashing in a 401K =D
    – MonkeyZeus
    Commented Jul 14, 2021 at 12:39
  • Your best friend could be your local building inspector!
    – Gil
    Commented Apr 10, 2022 at 0:47

There are two primary mechanisms by which attics vent... convection, or hot air lift, and scavenging, the mild vacuum created by airflow over the roof. Between the two I doubt your attic will be significantly hotter due to those openings.

Whether they should be closed for other reasons is up for debate. Many steel roofs are installed over purlins, meaning that almost the entire roof is essentially unsupported, and you'd have to walk carefully. Obviously the gaps between purlins are in a more predictable location than these openings, but no one will punch through with a foot. At worst it'll dent.

I'd want them fixed, but it's not a disastrous situation by any stretch. If you want to do it yourself, cut some patches, press them into place, and run a 2x4 across to the adjacent trusses, tight to the deck. Use caulk or spray foam to seal the joint. If you use fasteners into the deck, be sure they don't protrude even a little. They'll cause dimples and damage to the steel.

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