Dipping Roof Deck?


#1

Hi everyone, I am looking for some experienced opinions on my roofing issue. Here are the facts:

  1. House was built in 1962

  2. Ranch house, with hipped roof (approx 40 sq.)

  3. House was reroofed in 8/04, with 115 sheets of new 1/2 inch 4 ply sheathing. ($ 15K) Not all the sheets were replaced. It has soffit, ridge vents, and rafter mates.

  4. I bought the house in 6/05. Always thought the roof was wavy

  5. Went through first year with no apparent issue.

  6. A garage was added in the 80’s sometime, and in doing so they simply extended the roof line leaving the remnants of the old roof hip intact. I removed this old hip portion of the roof in the fall 2006. So the attic space above the house is open to the attic above the uninsulated garage.

  7. This spring, the roof is having serious issues with the plywood decking buckling/warping between the rafters . The rafters are 24" on center, no H clips were used. It is uncertain if the 1/8" gapping between sheets was provided.

  8. The nails in the worst section were noted to have some rust, which suggest moisture. However some plywood has started to buckle over top the garage which isn’t heated, but the furnace is in garage which could supply some heat. The nails in garage do not have rust.

  9. I had an energy audit done (blower door thing), and it indicated that my house is extremely tight.

Before I drop some serious money on a new roof, I would like to get some level of comfort as to why the roof is doing what it is doing or at least what your experience has been? installed incorrectly? moisture in the heating season? I understand its tough to say without seeing it.

I apologize for the long post.
Thanks for your time!
Nate


#2

What type of ventilation do you have first off? What is the length and the width of the home? What climate do you live in? How many soffit and exhaust vents do you have? How much insulation do you have, in inches if you do not know the value? Is there a bath vent venting into the attic not sealed to the roofs vent? Can you post some pics?


#3

pics


#4

They used 1/2" wood on 24OC beams is your problem. You need 3/4" minimum and yeah adequate ventilation.


#5
  1. I do not have any vents emptying into the attic. I one bath vent going through the roof, which I just put in. One venting through the soffit, which i plan to change, and one that is not in use (no vent pipe, just the unit in the ceiling covered with insulation), ultimately it will be vented through the roof.

  2. Insulation - The original fiberglass, that I am guessing is R19, covered by a recent addition of R19, unfortunately run parallel to original insulation and not perpendicular. The original R19 is compressed, so I would guess the best R value would be the R19 due to subsequent addition of insulation.

  3. I live in Syracuse, NY

  4. Code dictates a 5/8" decking, but based on all the roofers i had stop out,and the roof inspector, 1/2" 4 ply is acceptable in a gray area of the code and the norm.

  5. The sq. ft. of the living space is 2200 sq ft. I don’t know length and width exactly…guessing approximately 30’ x 65’, plus a 15 x 15 sunroom on the back side.

  6. I have a continuous ridge vent on the main roof and over the sun room. 3" round soffit vent inserts approx. every 24". I realize these aren’t the best, but its whats there. I also have two mushroom vents on each of the hips. A mechanical fan, but it is not used.

When the new roof was put on in 2004, the existing plywood from 1962 was still intact with what I would assume to have had a much lesser of a venting system, however that decking still lasted for 40 some years. Eventhough the last # of years it wasn’t in good shape. I was told the roof was in pretty bad shape before it was redone, mold and starting to leak. This current roof isn’t even holding up after 3 yrs. I even installed a radon system in the crawl space, and thereby sealing the floor with a 10 mil poly.

Try this for pics…

community.webshots.com/user/full … =community


#6

Also… the roof only started warping like this this spring. I never thought the roof looked flat, but it was never like this… I stayed on top of snow removal,so there was never a substantial amount of snow on the roof. I never noticed condensation on the roof deck, however i don’t go up there every day, but i was up there a few times this winter. I also never noted any portions of the roof where snow melted first, or had any significant ice cycles form. I was told that the previous owner had some ice dam problems, which could be the reason behind the newer insulation.

Thanks again for your input.

Nate


#7

“4. Code dictates a 5/8” decking, but based on all the roofers i had stop out,and the roof inspector, 1/2" 4 ply is acceptable in a gray area of the code and the norm."

I know you’re just posting stuff you’ve been told but I’m letting you know it’s in error. You want 3/4" minimum IMO. While there may or may not be other things causing the warping I can assure you that 1/2" and even 5/8" is not enough for 24"OC.


#8

Thanks I appreciate the response and agree with you. I am an engineer, and resultingly I tend to over engineer things, so I would have never used the 1/2 4 ply when the roof was redone.

Nathyn


#9

Are there collar ties ?


#10

I don’t know what collar ties are, but if i was to guess, I would go with no.

Nate


#11

by new york state building code 7/16 OSB is adequate with 24o/c trusses as long as they use plywood clips (which they didnt). obviously 3/4 would always be the best thing but come on…how many homeowners (outside of westchester) can afford that.


#12

Since you’re in the house faily recently & the roof is also somewhat ‘new’, I’d 1st get your realtor involved & see what they might suggest for the best way to approach the prior owner.

& Then the prior owner should run (not walk) to contact the installer & try to get them to stand up behind their work.

While I don’t do any work in cold weather climates, from what I’ve learned from the likes of Tar Monkey & Marshall, you’d see obvious water damage to decking & insulation if it was an ice damming issue.

Given the $ 15K cost for decking, it’s going to probably cost right around the same amount to get this fixed.

Don’t let anyone try to suggest doing an added brace internally to try & push these buckles back up because there is no way it will not push too high…

PS to the poster: “Mechanical engineers build weapons, structural engineers build targets.”


#13

Thanks for the replies. I have contacted the original contractor (he isn’t a registered roofer or anything… a jack of all trades type of guy) when the problem first starting this spring, and he offered free labor if I supply the materials. However now the problem affects a larger area, and I haven’t contacted him yet. I am trying to get a better understanding of the cause first.

I suspect it wasn’t one inadequacy as much as it was a lot of little things like poor nailing frequency, blow through on the nails, perhaps some moisture, no H-clips or 1/8" spacing, etc… I was just curious what everyone’s experience was when they encountered a problem like this.

Thanks,
Nathyn


#14

ill just say this.
that i think its a crazy idea to put shingles on a house that sees alot of snow.
shingles will let melting snow go rite through them.

in my opion its just the wrong roof system to put on.

gweedo


#15

[quote=“gweedo”]ill just say this.
that i think its a crazy idea to put shingles on a house that sees alot of snow.
shingles will let melting snow go rite through them.

in my opion its just the wrong roof system to put on.

gweedo[/quote]

Meet Gweedo, our resident metal head.

Gweedo, I guess all 400 million + shingle roofs across snow zone America are currently leaking?


#16

[quote=“gweedo”]ill just say this.
that i think its a crazy idea to put shingles on a house that sees alot of snow.
shingles will let melting snow go rite through them.

in my opion its just the wrong roof system to put on.

gweedo[/quote]

dont take offense gweedo…but you have no idea what snow will do to a roof. i see roofs that are 45 year old asphault that still hold up in the snow. i dont tell people how to roof in florida (because i dont know) so i dont think you should tell people how to roof in the snow…again, dont take that as me being harsh or mean.


#17

Well now i think i can say that i have heard everything now. I agree with marshall.