Thread: Wavy roof with truss lines visible

I am getting a new home built by Lennar in Florida. The roof is extremely wavy with visible truss lines. It is particularly bad on the side and front of the home. The roof has been complete for over two months, but the waviness and visible truss lines have not gone away. The roof does not look normal.

Does anyone know what could cause the roof to be so wavy with visible truss lines? The roof decking is OSB. I have included photos. Thank you

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See those short, spaced out, vertical lines?

Those are the ends where the 4'x8' roof sheathing structural panels meet. The roof sheathing should have been installed with a gap between the ends to allow for expansion of the 4'x8' panels.

The likely cause of what is shown in the photos is that the roof sheathing panels were installed tight to each other (each sheathing panel will have a grade stamp on it, and every panel will likely state "Sized for spacing" (the panels are cut under-size to allow for a 1/8" gap between the panels). Once the panels are installed, their moisture content will increase (due to humidity in the air and weather) and will expand. Heat from the sun also expands the panels. No gap between the panels and either (or both) the panels ends will push against each other and cause a pucker, and/or, the panels will flex downward or upward causing the ends to show the same thing.

I don't see that downward or upward effect as there will be another truss between those offset ends, and those trusses are holding the panels flat at the those trusses, resulting in the raised ends 8' feet apart (trusses will be 24" on center, those raised ends will be 48" on center to the offset raised ends).

Tina,

Florida is a b-i-g state (lengthwise), adding your location to "FL" would be a great help to all here in Florida (and those elsewhere who have been in Florida and understand the differences between North Florida, Central Florida, and South Florida with regard to weather and building conditions.

What did your home inspector say when they inspected it for you - you have had it inspected, right?

Appears Mom's the word on you inquiry, Jerry.

Originally Posted by Tina C

I am getting a new home built by Lennar in Florida. The roof is extremely wavy with visible truss lines. It is particularly bad on the side and front of the home. The roof has been complete for over two months, but the waviness and visible truss lines have not gone away. The roof does not look normal.

Does anyone know what could cause the roof to be so wavy with visible truss lines? The roof decking is OSB. I have included photos. Thank you

Oct-26-2019-001.jpg
11-10-2019-02.jpg
11-10-2019-03 (2).jpg
11-10-2019.jpg

Looks like the edges of the osb panels swelled a bit on the ends. It might have rained on the stack of wood before the home was built or it might have just soaked up humidity from the air. It's difficult for framers to leave a gap for expansion on the ends because after two or three sheets the plywood won't break on a rafter anymore. Not much you can do about it now and it won't really affect the function of the roof. Nobody is going to disassemble the home to fix it and if they did it still might end up looking like that.

Originally Posted by Ray Thornburg

Looks like the edges of the osb panels swelled a bit on the ends. It might have rained on the stack of wood before the home was built or it might have just soaked up humidity from the air. It's difficult for framers to leave a gap for expansion on the ends because after two or three sheets the plywood won't break on a rafter anymore. Not much you can do about it now and it won't really affect the function of the roof. Nobody is going to disassemble the home to fix it and if they did it still might end up looking like that.

I inspected a home (one year warranty inspection)in the DFW area with the same condition. The house had been inspected by the builders "third party inspector", the buyers inspector and of course the city gave a green tag. I called out the issue because the shingles wouldn't lay flat. So it does affect the condition of the roof.

The builder came out and replaced a few sheets of decking. The buyer called me to re-inspect.
The replaced decking didn't help and in fact made it worse in some spots. The builder threatened to sue me for giving the buyer bad advice about the roof. I said sure go ahead.

A few weeks later a builders rep called and apologized and said I was correct. They not only removed all decking but replaced many rafters as well. It was a Lennar home.

I inspect new construction for an energy program in Central Oregon. I almost always see Simpson "H" clips used between panels to maintain a 1/8" minimum spacing between panels to prevent just this thing. Evidently your builder didn't use these.

Originally Posted by Tina C

I am getting a new home built by Lennar in Florida. The roof is extremely wavy with visible truss lines. It is particularly bad on the side and front of the home. The roof has been complete for over two months, but the waviness and visible truss lines have not gone away. The roof does not look normal.

Does anyone know what could cause the roof to be so wavy with visible truss lines? The roof decking is OSB. I have included photos. Thank you

Oct-26-2019-001.jpg
11-10-2019-02.jpg
11-10-2019-03 (2).jpg
11-10-2019.jpg

Originally Posted by Ray Thornburg

It's difficult for framers to leave a gap for expansion on the ends because after two or three sheets the plywood won't break on a rafter anymore. Not much you can do about it now and it won't really affect the function of the roof.

If ... IF ... if the trusses (or rafters for conventional framing) are spaced at the proper spacing (typically 24" on center), and if the roof sheathing (structural panels) are properly installed ... then the panel ends WILL fall 'just short of the center' on the trusses ... just like they are supposed to (leaving a 1/8" gap between the ends).

And, least we forget, there is also supposed to be a 1/8" gap between the edges of the roof sheathing.

If ... IF ... if the roof sheathing panels start not landing on the trusses: someone isn't reading their tape measure correctly; their tape measure was made wrong; they are being careless; or maybe they are 'eyeballing' it instead of using a tape measure.

Nobody is going to disassemble the home to fix it and if they did it still might end up looking like that.

Gosh, you need to tell that to all those who have had it fixed (new constuction, of course, I agree that it will be extremely rare to get it fixed on a 10-20+ year old house).

Originally Posted by Jerry Peck

If ... IF ... if the trusses (or rafters for conventional framing) are spaced at the proper spacing (typically 24" on center), and if the roof sheathing (structural panels) are properly installed ... then the panel ends WILL fall 'just short of the center' on the trusses ... just like they are supposed to (leaving a 1/8" gap between the ends).

And, least we forget, there is also supposed to be a 1/8" gap between the edges of the roof sheathing.

If ... IF ... if the roof sheathing panels start not landing on the trusses: someone isn't reading their tape measure correctly; their tape measure was made wrong; they are being careless; or maybe they are 'eyeballing' it instead of using a tape measure.



Gosh, you need to tell that to all those who have had it fixed (new constuction, of course, I agree that it will be extremely rare to get it fixed on a 10-20+ year old house).

Thanks for your comment but...there's no reason to jump down my throat....understanding why things happen doesn't necessarily mean you condone it....btw....plywood measures 48x96 inches....just saying....easy to space them on edges because of h clips, ends often end up spaced anyway because it's sometimes hard to butt them tight for many reasons..... I think what happened here is that the plywood sat in the rain and soaked up moisture on the end grain.... or it rained before the house was felted.....framers didn't have a choice but to install the wood they had and likely didn't notice or care. Anyway....as far as I know there is no law that says a roof plane has to be as flat as glass...

Originally Posted by Ray Thornburg

...there's no reason to jump down my throat...

I'm not jumping down your throat.

However, I AM pointing out that stating "Nobody is going to disassemble the home to fix it" is a very incorrect statement to make.

I surmised the cause before I looked at the photos. Jerry is spot on. I first saw this in the early 1990s here in Colorado when builders started transitioning away from plywood to OSB for roof decking. The dark color of the roof covering only exacerbates the condition. In the case here in Colorado, the builder wound up tearing off all of the shingles, correcting the lack of expansion gaps between the sheets of OSB, and re-roofing the home. It was an expensive lesson, but this particular builder never repeated the mistake.

Originally Posted by Jerry Peck

I'm not jumping down your throat.

However, I AM pointing out that stating "Nobody is going to disassemble the home to fix it" is a very incorrect statement to make.

I stand corrected...I should have said no true Scottsman.....I've seen whole subdivisions built where you could count every piece of plywood on the roof on every house......
You know it's interesting to me how expectations have changed over the years...sometimes it seems that the people who are the most blessed (and so should be happy) are the most fearful and discontented. We have it so much better now than even a hundred years ago.....Homes are twice as big, safer, more energy efficient, built better, and with every modern convenience......Maybe I should get out more but I feel we are truly blessed here in this country. I'm thankful for the things God has provided for us. A little bump in the roof is nothing.....I guess unless you're the one having to tear it all off for free.....

Originally Posted by Ray Thornburg

I'm thankful for the things God has provided for us. A little bump in the roof is nothing.....I guess unless you're the one having to tear it all off for free.....

I wish you had not gone there ... but you did ... "God" has not provided anything to anyone.

That is, unless you think that "God" destroys some people so other people can be better off, in which case is that really a "God" you want to associate with?

Allowing, even encouraging, brothers and sisters to kill brothers and sisters?

Really?

Let me know when you want to change the subject as this forum is not the place for it.

Originally Posted by Jerry Peck

Tina,

Florida is a b-i-g state (lengthwise), adding your location to "FL" would be a great help to all here in Florida (and those elsewhere who have been in Florida and understand the differences between North Florida, Central Florida, and South Florida with regard to weather and building conditions.

What did your home inspector say when they inspected it for you - you have had it inspected, right?

Thank you Jerry. To answer your questions, I'm located in New Smyrna though the homesite is in Central Florida. The home might be a few weeks away from completion. No final inspection has been done yet. There was a framing inspection a few months ago when the roof was just newly installed with shingles. There was no mention of the decking quality/expansion gaps from the inspector. The roof was only slightly wavy at that time. But as days passed, the roof looked more wavy and concerning. When the drywall came up three weeks ago, the roof looked really bad with visible trusses. It is still the same. I also notice some nails are popping out of the roof shingles. The builder has allowed me to get a roof inspector to ease my concerns but says no one is allowed on the roof at the moment..

Originally Posted by Jerry Peck

What did your home inspector say when they inspected it for you - you have had it inspected, right?

Originally Posted by Tina C

No final inspection has been done yet. There was a framing inspection a few months ago when the roof was just newly installed with shingles. There was no mention of the decking quality/expansion gaps from the inspector.

The inspector you are referring to, is that the city/county inspector or the home inspector you had inspect it for you?

There are a couple of inspectors on this site who are in Central Florida, hopefully they will respond and you can make contact with one of them. If they don't respond, I may be able to find a couple of home inspectors if you give the city/county in Central Florida where the house is.

I don't have as many home inspector contacts as I used to have being as I retired from home inspections in 2006, but I still know a few inspectors, I'm just not sure where they inspect.

Originally Posted by Jerry Peck

The inspector you are referring to, is that the city/county inspector or the home inspector you had inspect it for you?

There are a couple of inspectors on this site who are in Central Florida, hopefully they will respond and you can make contact with one of them. If they don't respond, I may be able to find a couple of home inspectors if you give the city/county in Central Florida where the house is.

I don't have as many home inspector contacts as I used to have being as I retired from home inspections in 2006, but I still know a few inspectors, I'm just not sure where they inspect.

It was a home inspector. The home is in Saint Cloud. Any recommendations for inspectors are greatly appreciated. Thank you

Originally Posted by Tina C

It was a home inspector. The home is in Saint Cloud. Any recommendations for inspectors are greatly appreciated. Thank you

What did the home inspector say when you had them come back for a follow-up inspection?

Most home inspectors who do new construction have several inspections they recommend, including the final walkthrough after the house is finished.

Tina,
This is a bit late, but i will give advice anyway. If it were me, I would NOT sign off on that home until the roof is properly inspected and whatever corrections needed are completed to your and to your inspectors, satisfaction. That condition will certainly affect the life and usefulness of the roof. It will get worse. start keeping a record of all your communications with the parties involved, time, dates, what as said by who to who and to whoever. That is my advice.

I know that I personally, would not want my roof looking like that, like ever,

Funny that the contractor doesn't want any one on the roof right now, perhaps he is worried someone might give it a good inspection.

Originally Posted by Elizabeth Chambers

Funny that the contractor doesn't want any one on the roof right now, perhaps he is worried someone might give it a good inspection.

The OP stated it's a new build, and most builders around here now prohibit anyone on the roof (only while they own it, of course).

Originally Posted by Dom D'Agostino

The OP stated it's a new build, and most builders around here now prohibit anyone on the roof (only while they own it, of course).

While that is typically the case, one does not need to get on the roof for the issue seen in the photos.

Dom, I recall that you are somewhere around Orlando, while you may not be on the side of Orlando close to St Cloud, do you know a good HI in or around St Cloud?

do you know a good HI in or around St Cloud?

Not every inspector I know does new construction, so unfortunately right now I don't have a referral for that project.

Originally Posted by Dom D'Agostino

Not every inspector I know does new construction, so unfortunately right now I don't have a referral for that project.

I would like to see a picture looking straight up one of the high truss lines. I agree it could be osb swelling at the butt ends but I am think the problem is the trusses are not set in perfect alignment.

If the peak of a truss is even an inch from alignment it will create a high or low plane. If it is high on one side the other side will be low. The trusses could be made poorly, but I bet installation is the issue. Checking the fascia for straightness may be another clue.

Getting in the attic with a string line at the peaks or even a string line on the bottom of the top cords will give a good indication.

Scot,

The "ridges" are staggered going up the roof, every other roof sheathing panel.

An offset truss creates a 'ridge' going all the way up, not just at every other panel end.

An offset truss also creates one line up the roof, not multiple staggered lines.

One other thing that comes to mind is that the carpenters installing the sheathing stood on the open spaces between trusses when nailing the OSB instead of on top of trusses. The dips formed by their weight are made permanent.

Originally Posted by Stuart Brooks

One other thing that comes to mind is that the carpenters installing the sheathing stood on the open spaces between trusses when nailing the OSB instead of on top of trusses. The dips formed by their weight are made permanent.

I agree and this seems to have appeared in the late 80s where you could go in any subdivison especially the ones built by the initials DR and you could see every truss line, same indoors when they did the drywall and in the right light you never missed a joist or stud. I have cut into some roofs that have only 3/8 plywood on them and have fewer truss lines than OSB roofs. Sure makes it easy to install purlins when putting a metal roof over top of them.