Thread: New roof shows deflections/sagging

I recently just had a new roof installed on a home I just purchased in florida. Before I had it replaced it looked like the roof was leaking for many years so much so that mold was growing on the drywall roof visible inside the home. A total of 16 sheets were used to replace rotten wood when I had the new roof installed. It is a 2,018 sq. ft. home with a two car garage and porch under roof additionally to that.

Now that the roof is finished I have two areas (where it was previously leaking) that the roof is actually dipping down.

The roofer says this is called roof deflection. It is common, will not leak, is structurally sound and it doesn't need to be corrected. The roof was inspected by the local county who let it pass.

Is this true or is it an oversight of the inspector and a laziness/cost excuse from the roof contractor?

It certainly doesn't look aesthetically pleasing so obviously I am not too happy.

Thanks for anyone that can help.

Pictures? Before and after? Inside attic of affected area, as well as similar area not repaired?

Without an up close inspection, it's reasonable to say that it is a just cosmetic condition. I've seen pretty ugly roof lines dried in and functioning.

Im new here. How do i post pics? I think they may be hard to see in a photo but i will try

Michael,
I the roof is only sagging where you had plywood replaced there may have been some water damage to rafters or trusses. If it is a truss roof look at the gang nailers where truss members are attached. If these are loose, or are sunk into damaged wood you have a problem. Also if you are near the coast look for corrosion on the nailers. If you see either of these you should call a good PE for further evaluation and to design a proper repair.

To insert pictures just click on the little icon third from the right in the middle bar above and follow the onscreen directions.

The likely reasons for the new replacement plywood/OSB to show/be sagging, in order of most likely cause to least likely cause (in my opinion from afar):
- improperly installed
- - not installed over two spans and three supports
- - not installed with strength axis perpendicular to supports
- - both of the above
- - either of the above and no blocking installed (and not just no edge support, intermediate blocking would be needed)
- - not installed with edge/end gaps (lack of spacing)
- not thick enough
- - material to thin, possibly in combination with one of the items above

I am assuming that the deflection is between rafters or trusses, not along their span. If so, then the cause is likely to be one of the things that Jerry mentioned. I find that when roofers are left to decide which sheets of roof sheathing to replace, they often do not replace all the bad ones. If it is soft it is a problem. If not, less likely to be a problem, but still possible. Ask the roofer why the roof is deflecting (I'd love to hear that answer).

Originally Posted by Michael Fraioli

Im new here. How do i post pics? I think they may be hard to see in a photo but i will try

example
i clicked reply with quote button
a window will open to type reply
scrolling down that page should be an upload photos button
select the image(s) you want to upload
post away or to the limit per post

it was easy enough for this guy to do it...hth

Originally Posted by Mark Reinmiller

I am assuming that the deflection is between rafters or trusses, not along their span.

Mark,

That is what I also am presuming.

The reason I use presume/presuming/presumed is that the word itself cannot be changed into a negative ... I guess one could change presume into pres-u-me, but that does not indicate or imply anything.

I've been using presume for many years now.

Sounds like the prolonged moisture on the rafter allowed it to sag. It's probably not going to give you any problems other than aesthetic. It may be possible to jack up the rafter slowly and sister another piece of dimensional lumber to it to remove most if not all of the deflection. I would call back the roofer and explain your discontentment with the aesthetic appearance and offer to hire him to remove the belly. You would have to pay to have it rectified in any case.

Originally Posted by Phil brody

Sounds like the prolonged moisture on the rafter allowed it to sag. It's probably not going to give you any problems other than aesthetic. It may be possible to jack up the rafter slowly and sister another piece of dimensional lumber to it to remove most if not all of the deflection. I would call back the roofer and explain your discontentment with the aesthetic appearance and offer to hire him to remove the belly. You would have to pay to have it rectified in any case.

Another the OP was not clear on this, I think the deflection was probably in the sheathing, but maybe it is a rafter. But hire a roofer to do carpentry? around here I don't want to even hire a roofer to do roofing. Also, if this is something that should have been noticed and addressed, and all the OP got was an excuse, that is another good reason not to hire the roofer. Just my 2 cents.

Michael,
If the sagging is between rafters only then Jerry is probably right. If it is a whole section of roof that has sagged then you have a bigger problem. Again, pictures would really help

- - - Updated - - -

Originally Posted by Jerry Peck

Mark,

That is what I also am presuming.

The reason I use presume/presuming/presumed is that the word itself cannot be changed into a negative ... I guess one could change presume into pres-u-me, but that does not indicate or imply anything.

I've been using presume for many years now.

I like it. Beats the heck out of ass-u-me!.

Originally Posted by Mark Reinmiller

Another the OP was not clear on this, I think the deflection was probably in the sheathing, but maybe it is a rafter. But hire a roofer to do carpentry? around here I don't want to even hire a roofer to do roofing. Also, if this is something that should have been noticed and addressed, and all the OP got was an excuse, that is another good reason not to hire the roofer. Just my 2 cents.

True this should have been brought to the homeowners attention but we don't know the severity.
By having the roofer do the work the warranty will remain intact.

I have to agree with Jim.
"the roof is actually dipping down" is not enough to go on and on about. Lots of 'speculation' so far.

Originally Posted by Jim Abram

"To presume is to make an informed guess based on reasonable evidence, while to assume is to make a guess based on little or no evidence."

Using presume in this instance is a stretch as there is no evidence. I this instance it could be called presumptuous.

The following definitions are from Merriam-Webster.com - not sure where yours were from.

I agree that you are presumptuous in your assumptions:

pre·sump·tu·ous adjective \pri-ˈzəm(p)-chə-wəs, -chəs, -shəs\

: too confident especially in a way that is rude : done or made without permission, right, or good reason

pre·sume verb \pri-ˈzüm\

: to think that (something) is true without knowing that it is true

: to accept legally or officially that something is true until it is proved not true

: to do (something) that you do not have the right or permission to do

Synonyms

assume, conjecture, daresay, imagine, guess, speculate, suppose, surmise, suspect, suspicion [chiefly dialect]

as·sume transitive verb \ə-ˈsüm\

: to think that something is true or probably true without knowing that it is true

: to begin (a role, duty, etc.) as a job or responsibility

: to take or begin to have (power, control, etc.) in a job or situation

Let's see the comparison between the two:
- pre·sume verb \pri-ˈzüm\
- - : to think that (something) is true without knowing that it is true
- as·sume transitive verb \ə-ˈsüm\
- - : to think that something is true or probably true without knowing that it is true

... and the difference is: assume has this in it "or probably true" while presume does not

Jim, you really need to do better than that to not look silly trying to find something wrong with everything that I post. (sigh)

Jim,

Your posted information reduces down to one common assumption on assume and presume:
- Assume vs. presume - Grammarist
- - Assume vs. presume
- - - Assume and presume both mean to take something for granted as true (among their many other definitions). The difference is in the degree of certainty. A presumption is usually more authoritative than an assumption. To presume is to make an informed guess based on reasonable evidence, while to assume is to make a guess based on little or no evidence.

I.e., everything we do is "To presume is to make an informed guess based on reasonable evidence".

Therefore "presume" is the better choice as I doubt many here, if any, actually "assume" anything as we all base what we are saying on what we see (in the photos) and read (in the posts) instead of just making a wild arse statement without considering anything related to it.

The information taken in while reading the posts and looking at the photos (here) and in seeing, hearing, smelling, touch, etc., (while at inspections) leads to one making "an informed guess on reasonable evidence" versus "make a guess based on little or no evidence".

Originally Posted by Jim Abram

The issue here is that there is no reasonable evidence therefore, there can be no presumption .

Grasshopper,

You understand so little of what you see.

You were given evidence, yet if it had been a donkey patty you would have stepped in it because you lacked the vision to recognize it as what it was.

Instead of examining the spaces between the letters you should be assembling the letters in recognizable objects ... that may help you better understand what is going on around your physical and mental space.