I live in Canada and I just had my roof done on my house.

I recently went in my attic and found out that some part of the roof is missing plywood :( enter image description here enter image description here

In the following picture, there is no nails visible. Which means the shingles behind are not nailed in??? enter image description here

When the contractor did the estimate, he did notice places where the plywood was rotten and told me he would need to replace them. Well clearly he didn't. He just cut away the rotten plywood :(

Is that normal practice. Should I be worried or is this ok?


So I did get in contact with the contractor. Apparently, this is where the old air vents were.

He tells me that there is a metal sheet between the shingles and the membrane. He told me that the membrane that we can see in the pictures is to protect against humidity.

Is that a good practice when removing old air vents?


Thanks for all the information, really appreciate the help.

Just to clarify, because I might have not been clear, the old vents were removed and new vents installed. I was made aware of that in the contract and the new vents are more powerfully, so for every 2 old vents removed, 1 new vent was installed. I believe this is ok.

I went back in the attic and took more photos enter image description here

As for the proper amount of nailing, its really hard to tell. I'm no expert and I cant seem to see any kind of patterns with the nails. Here is a photo were I could sort of see a pattern. enter image description here


So first, I contacted the manufacturer of the shingles and explained the situation. They told me that the shingles installed over the metal sheet are NOT properly installed and that the shingles would NOT be covered under the High Wind Resistance Limited Warranty. They did suggest that I contact an inspector. The contractor that did the job was also certified with that manufacturer. So they will be looking into that.

I wrote to the RBQ, which is my province Code regulator, but did not get a reply yet.

I'm also trying to get in contact with my municipal urban department which, I have been told, can probably help me and tell me if this respects the code or not.

I was able to talk to another contractor in my region and he told me this is ok and that I shouldn't worry about it. We did have very strong wind recently and my roof did resist.

Still not sure what to make all of this. Thanks for all the comments, really helps.

  • 9
    Even the nailing is not acceptable. No shingle nailing pattern is recommended in that pattern. I’ve rejected a lot of roofing projects in the past and this is one of the worst. Is a Building Permit required where you live? I’d call the local Building Department and ask AND see if the roofer is licensed. (BTW, be careful where you walk up there.)
    – Lee Sam
    Commented Nov 2, 2019 at 20:34
  • Hi Lee,the contractor is licence. What do you mean by "nailing pattern". What should it look like? Commented Nov 2, 2019 at 22:17
  • 4
    Shingles are laid in rows. Nailing is either 4 nails per 3’ long shingle or 5 nails if you are located in a high wind area or the roof is more than a 5 in 12 pitch. Therefore, the nails should be about 8” apart (accounting for starting about 2” in from each end of each shingle) and rows of nails should be about 6-7” apart, depending on the type of shingle specified. There should also be “a pair” of nails about 4” apart where each shingle starts and stops.
    – Lee Sam
    Commented Nov 2, 2019 at 22:51
  • 1
    BTW, I’ll bet they didn’t place the nail the correct distance down from the top of each shingle either. If any of these conditions apply, (i.e.: number of nails per shingle, spacing, correct location from the top edge of each shingle, correct end distance from end of each shingle, etc.) you have no warranty.
    – Lee Sam
    Commented Nov 2, 2019 at 22:56
  • 7
    Yes, get this fixed now - before the snow comes or you're likely to end up with a snowman in your attic.
    – J...
    Commented Nov 3, 2019 at 21:10

8 Answers 8


As a R.R.C. and roofer for over 25 years, this doesn't surprise me. Anyone with a pickup truck and a ladder calls himself a roofer. This is wrong, if they eliminated vents they should have replaced the sheathing. An opening up to 4"x4" can be covered with metal, but anything bigger requires re-sheathing to eliminate a fall hazard. Also the nail pattern should be evident. Thinking you need to call an attorney. If he did this he isn't reputable so it stands to reason he won't back up his work. Always check references and reviews of your contractor. Check with the BBB to see if there are complaints. Look at their work!! Drive by a couple of their jobs, talk to homeowners if possible. Not only end result is important but being done without damaging your property and in a timely manner is just as important.

  • 1
    "An opening up to 4"x4" can be covered with metal" [citation needed], +1
    – Mazura
    Commented Nov 3, 2019 at 19:04
  • 1
    Hi Mike, thanks for that information. If you could find the citation about the 4" x 4" that would be great. Commented Nov 3, 2019 at 21:42

It is not acceptable that the roofing materials were replaced over the plywood cutouts (which actually look more like breakouts).

One can surmise that the stripping crew came one day and removed all the old roofing material and did the breakouts. Before calling it a day they rolled out the underlayment (a.k.a tar paper) and covered over the breakouts in the process.

The next day the shingle layers show up and start laying shingles not knowing about the breakouts. The wonder in this case is how they managed to avoid stepping through one of those holes!!

At this point there may be a fix by cutting a piece of like thickness plywood that can just fit into each hole. Then cut a larger piece that would span over the bottom of the hole. Use construction adhesive to glue the patch pieces in place. Short very carefully selected screws can hold the patches in place while the glue hardens (dries). In lieu of screws it may be possible to use strut pieces of wood between the patch and ceiling joists below to hold things in place till the glue sets.

This patch scheme will provide support to shingles above the hole locations. It may be difficult to resolve shingles that are not fully nailed over these holes but at least support can be restored.

  • That underlayment looks like the self adhesive stuff. They never intended on putting in the plywood.
    – JACK
    Commented Nov 2, 2019 at 20:01
  • Hi Michael, the whole thing was done in a single day. I've just updated the post since the contractor did call me. The missing plywood is where the old air vents were. Metal sheet was put over and that's what supports the shingles apparently. Still, I'm thinking of maybe using your advice and fixing just like you mentioned. Thanks Commented Nov 2, 2019 at 22:19
  • 2
    Putting sheet metal over holes like that is total crap. And how were they planning on holding down the shingles over a sheet metal.....sheet metal screws with washers?
    – Michael Karas
    Commented Nov 3, 2019 at 7:16
  • 2
    @Michael As per the photos, it seems like nails were used to hold the shingles over the sheet of metal :( I was able to talk to another contractor in my region and he told me that is was common practice :( Anyway, I will be calling the manufacturer this week to see if they consider this like proper installation. Commented Nov 3, 2019 at 21:37

WHAT, he eliminated your air vents? Wow, your update is so revealing: 1) sheetmetal is not an acceptable cover over large openings, 2) if sheetmetal was used, it was not nailed to the existing plywood, 3) he eliminated air vents,

  1. Sheetmetal is allowed to cover openings in plywood roof sheathing up to 4” x 4” only. Any opening larger needs solid sheathing. (Btw, openings need to be cut back to the next joist. It can’t just be nailed on one side to a joist.)

  2. Sheetmetal cannot be just laid on the roof or glued to the roof. It must be nailed to the roof. (I think most roofing manufacturers recommend nailing 4” on center.)

  3. The Code specifies how much venting is required. It’s not a random number. (The U.S. Code says 1 square foot for every 300 square feet of attic. I’m sure Canada is similar.) Do you have soffit vents or gable end vents? Regardless, the roofing manufacturer will void the warranty if you do not have the correct amount of venting.

I’d go to your local lumberyard and look at a wrapper on your type of shingle. (I’d photocopy it too.) You’ll see most of the requirements printed on each wrapper. Then I’d get on the internet and print out the installation instructions for your shingles. Then I’d call the Building Code office and see if a permit is required. If so, I’d show the building inspector the installation instructions and ask them to review your roofing project.

  • 1
    Hi Lee, I just added a 2nd update. The venting was removed and replaced with a better venting that required less venting units. From what I was told, it does respect Canada Code. As for the openings, I took a picture were you can see that the opening is 11" x 11" From what everybody is telling me, I might get a building inspector to come and review the work. Commented Nov 3, 2019 at 0:36

To properly answer this question requires proper interpretation of:

  • Published Building Codes (depending on what part of Canada the residence is in. Canadian Building Codes applicable to the specific region where the Re Roofing is taking place. Some are based on NBC (National Building Code of Canada) some regions are based on ICC (International Code Council Codes) for Residential that would be the ICC-IRC (International Residential Code) Chapter 9 “Roofing Assemblies” the most accepted residential standard published.
  • The Canadian NRC (National Research Council)
  • Published Manufacturer’s Installation Protocol as approved by the International Code Council
  • Published ICC – ESR (International Code Council, Evaluation Services Reports) for the shingle / roofing assembly being installed.
  • Published CSI (Construction Specifications Institute) Roofing Assembly Specifications

Below are links to all above Cited References. Determining the applicable Building Code is the first step. The second step is to connect Manufacturers ICC – ESR Report for the Roofing Assembly being installed, or the Canadian Construction Materials Center (CCMC) product approvals for the Manufacturer of the Roofing Assembly being installed, as building code relies on these product approvals to demonstrate building code compliance.

NOTE: Many parts of Canada have adopted there own Building Codes Standards, that are very similar to ICC Codes in language and divisions. CRCA Canadian Roofing Contractors Association the voice of the Canadian roofing industry since 1960, CRCA promotes collaboration within the industry from coast to coast. We also represent and defend our members’ interests, and support them to excel in business both professionally and technically.

The Canadian Construction Materials Centre (CCMC) has been an integral part of the Canadian construction product approval process for more than 30 years. We have an intimate knowledge of the process, the compliance pathways, and how Canadian construction regulators typically want to see code compliance demonstrated.


NOTE: Several links had to be removed as not more than eight links are allowed for a new user. I will gladly provide additional links / references when allowed to.


  1. Metal can be used if supported by wood blocking (pictured is CDX Plywood which is not a dimensional lumber that is also known as Wood Blacking). The width of the metal is not more than 400mm on center, it must be at least .33mm Galvanized metal or Aluminum at least .61mm in thickness.

    1. Based the provided pictures Aluminum was not used as magnets do not attract to aluminum.
    2. Sheet metal does not have the static resistance that wood does and the design wind load when metal is used in lieu of wood decking is significantly lower and has a much higher probability of failure due to wind uplift. It is recommended that if metal is used for decking repairs that metal screws of a nominal Number 8 size be used in lieu of roofing nails.
  2. Nails shall have sufficient length to penetrate a nominal 12mm (a ½”) into the sheathing / decking. If the roof deck is 15/32 CDX Plywood then at least the tips of the nails should be visible from the underside of the roof deck.
  • Referenced from: inspectapedia.com/Design/Ontario-Building-Code-2014.pdf Commented Nov 3, 2019 at 15:02
  • Ontario Building Code References: 9.23.15. Roof Sheathing Required Roof Sheathing Material Standards Table or Table CAN/ULC-S706, is permitted to be used as a roof sheathing over supports spaced not more than 400 mm o.c. provided the roofing consists of, (a) a continuous sheet of galvanized steel not less than 0.33 mm in thickness, or (b) a continuous sheet of aluminum not less than 0.61 mm in thickness. Required Sheathing Commented Nov 3, 2019 at 15:09
  • Hi Bill, thanks alot. I will be going through the links you provided for sure. To give more information, I live in the province of Quebec. Not sure if the same Code apply. Commented Nov 3, 2019 at 21:44
  • @BillHubbell, should the sheet metal be installed over or under the underlayment? I would think it should go under the underlayment. I imagine if the metal is on top then water could seep underneath it, puddle in dimples created by the nails, and come through the underlayment. Commented Dec 30, 2019 at 16:11

This is not normal practice. This isn't even shoddy workmanship. This is downright deceitful. What type of roof is on top of this? those nails punching through could be leaking now or in the future. You should definitely be giving the contractor call about this. This isn't something he can say is out of warranty. Good luck.

OK, I just asked a licensed roofing contractor who is replacing a roof damaged during Hurricane Irma down the block about this. He said he would use the the metal sheet for a small repair and removing a small vent. If doing a re-roof, he would definitely replace the wood rafter to rafter.

Not sure if this helps, it's probably up to the local inspectors.

  • Hi Jack, the type of roof is shingles. I did give a call to the contractor. See update in my post. I've also contacted the shingles manufacturer to see if they consider this to be proper installation. As for the warranty, the installation is guaranteed for life and the materials is 10 years. Commented Nov 2, 2019 at 22:23
  • @JosephPassineau Do you remember authorizing him to remove the vents? Is it in the contract??
    – JACK
    Commented Nov 2, 2019 at 22:33
  • Yes, the old vents were replace with a single better vent. That was in the contract. The new vent is actually right in between where the 2 old vents were. Commented Nov 2, 2019 at 22:38

This is completely unacceptable and the contractor is defrauding you.

If the contractor said he would replace the defective plywood and did not do so, then he didn't fulfill his contract with you. If he declines to finish the job properly then he has defrauded you.

Such large missing areas of roof cladding are not acceptable. This is not normal practice, no homeowner should be satisfied with this, no inhabitant of the house should feel safe with this, and I'm confident that any home inspector will fly into a rage when he sees this.

The unsupported roofing material will fall into the house when the winter snow piles up on it. Not to mention that anybody walking on the roof will fall through. Also, shingles that are nailed only to the tar-paper will soon work loose and fly off.

Call the contractor and tell him to come back and do the job properly, and at no additional cost. Don't let him tell you that replacing the plywood was not part of the original estimate. Nobody would believe that the original estimate was for a roof that will collapse at the first heavy snowfall.

If the contractor won't finish the job properly, call your local home inspection regulatory authority and give them the contractor's name. Show the inspector the estimate and any accompanying receipts or other documents.

Be prepared to sue the contractor. The more prepared you are for the courtroom, the more likely you are to avoid the courtroom.

Do not accept this treatment by that contractor.

  • Hi, so I was able to contact the contractor and he told me he did replace the defective plywood. Apparently, the cut outs in the pictures are where the old air vents use to be. Still not sure if that's acceptable. Commented Nov 2, 2019 at 22:25
  • 1
    But you already posted a photo of a hole which, were I to step on, would drop me through to mid-thigh and bring an ambulance to your house.
    – WGroleau
    Commented Nov 3, 2019 at 15:43
  • The hole are of a dimension of 11" x 11". There is a metal sheet over the cut outs. Not sure it would support someone stepping on it. Will definitely look into having this fix. Commented Nov 3, 2019 at 21:49

As a licensed home improvement contractor this is not acceptable at all. The roofer is a liar and don't expect much from him.

Here locally in Virginia we have a few engineering firms that specialize in building envelopes. I have had them pick 50 random shingle and inspect the nail pattern. How many nails, location over or under driven. Any nail that makes an indention into a GAF shingle is over driven and voids warranty. Nail head must be in full contact with shingle , GAF shingles must have open valleys etc....etc.

Find your local equivalent and set up a meeting and get a written report. That report then goes to your lawyer and the local contracting board that issued his license. If your in Canada this will not handle the repeated snow loads. The shingle warranty is now void.

They make pre manufactured plywood patches that have a metal flange that can be nailed to the sheathing so as not to have to go rafter to rafter.


To make it more clear without all the literature never ever should there be any voids of plywood it’s either you have your metal with your vents or there’s plywood long story short you got scammed

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