Special offer

"Sheathing Panels Not In Plane"

By
Home Inspector with Jay Markanich Real Estate Inspections, LLC 3380-000723

When from the outside of a house, with what's touted to be a "completely new roof," you can see dips between the defined lines of the trusses every 2', the report can only say, "sheathing panels not in plane."

Roof sheathing is not as strong as it used to be.  It used to be plywood, and thicker than it is now.

What we most often see now is Oriented Strand Board (OSB), used where Fire Retardant Treated Plywood is not.

What almost always I see used for roofs is OSB, and 17/32" thick.  That is just a hair over 1/2" thick.

OSB is not as strong as plywood.  It acts differently than plywood too, in that it will expand and contract more, especially swelling with heat and humidity.

As such, it needs support between the trusses.  And the panels need to be separated somewhat so they don't rub one to another.

How is that done?  With clips.

These clips do two things.

They provide a surprising amount of support to the panels between the trusses.

And, importantly, they separate the panels one to another by 1/8".

This allows for swelling and prevents the panels from rubbing against each other.

It is important that these clips be added when roof sheathing is replaced.  When they are not present sagging can be the result. 

So, when I saw sagging on the outside of this house, I predicted what we would see from inside the attic.

And we did.

All over the roof there were sheathing panels not in plane.

And they used plywood, which is typically stronger than OSB!

You can see the edge of one sheathing member highlighted by my flashlight.

And they used nails that are properly long.

So why not use the clips?

Unknown.

The code does require a minimum thickness for sheathing.  But the code does not REQUIRE the use of clips.

Why?  Because clips are not load rated.  They do demonstrably increase stiffness between trusses however.  And this study suggests that between 24" on center trusses, it increases the psi rating by 190 pounds.

I EXPECT THEY ARE NOT USED HERE SIMPLY BECAUSE THEY ARE NOT REQUIRED BY CODE.

But again, why not use the clips?  It might not be required to use them, BUT IT CERTAINLY IS BEST PRACTICE.

I might answer my own question as to why they are not used.  Because the job becomes quicker and cheaper?

MAYBE, BUT MINIMALLY SO!

My recommendation:  a roof is intended to last a long time.  So why not utilize every best practice when putting one up?  Look to make sure your roof is set up for the long haul.  The next hefty snow fall might prove the difference!

 

 

Posted by

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


Comments (36)

Debbie Gartner
The Flooring Girl - White Plains, NY
The Flooring Girl & Blog Stylist -Dynamo Marketers

I recently went to a newly constructed home...builder had fled the country and there were all sorts of issues.  I was brought in to give an estimate on hardwood flooring. Unfortunately, OSB was installed rather than plywood.  Very cheap and incompetent builder.

Sep 03, 2012 07:26 PM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I agree with that William, and that is why I started the Best Practices group.

There are two thicknesses James, with act differently with different woods and apparently they can't arrive at a single standard.

Debbie - I can't remember the last time I saw plywood sub flooring here!  Under anything.

Sep 03, 2012 08:38 PM
Kenneth Cole
Weichert Realtors Appleseed Group, 2043 Richmond Ave. S.I.N.Y. 10314. office phone 718-698-9797, Appleseedhomes.com... - Staten Island, NY
NYS Licensed Real Estate Salesperson

Another great lesson professor, thank you.

Sep 03, 2012 10:13 PM
Scott Seaton Jr. SLS Home Insp
SLS Home Inspections-Kankakee Will Iroquois Grundy Counties - Bourbonnais, IL
The Home Inspector With a Heart!

I recently bounced around on a roof I was inspecting that had 3/8 plywood on top of trusses. The roof was a train wreck and they are paying for it now. New sheathing, new shingles and vents. Turns out the whole subdivision is built this way. How some builders can sleep at night is beyond me.  

Sep 03, 2012 10:16 PM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Thanks Ken.  More to come!

Scott - they do that because they think they can get away with it.  Once in a new subdivision with wood shakes the stamp on the attic side said, "This Side Up."  The supervisor told my buyer that those stamps didn't matter...  The buyer, not a dope, didn't believe that!

Sep 03, 2012 10:24 PM
Michael Setunsky
Woodbridge, VA
Your Commercial Real Estate Link to Northern VA

Jay, we don't get big snows here very often, but the 190 pounds psi could have saved some roofs a couple of years ago. It makes sense to use the clips if they prevent sagging and provided added strength.

Sep 03, 2012 10:34 PM
Randy Ostrander
Lake and Lodge Realty LLC - Big Rapids, MI
Real Estate Broker, Serving Big Rapids and West Central MI

Good morning Jay. Another great lesson from the expert. I have seen the sags and now know what to look for.

Sep 03, 2012 10:38 PM
Tom Arstingstall, General Contractor, Dry Rot, Water Damage Sacramento, El Dorado County - (916) 765-5366
Dry Rot and Water Damage www.tromlerconstruction.com Mobile - 916-765-5366 - Placerville, CA
General Contractor, Dry Rot and Water Damage

I think I can count the number of times that I've seen the Simpson clips used on one hand Jay, certainly not a common practice.

Sep 04, 2012 12:43 AM
Wayne Johnson
Coldwell Banker D'Ann Harper REALTORS® - San Antonio, TX
San Antonio REALTOR, San Antonio Homes For Sale

Jay-I love the way you break things down so I can understand. I don't need to know as much as a roofer, or carpenter, but you do a great job of explaining the what and why along with illustrations. Thanks.

Sep 04, 2012 01:41 AM
Joshua Frederick
Home Inspector for ASPEC Residential Services, LLC - Defiance, OH
Home Inspector in Defiance & all of Northwest Ohio

Do you put the lack of H-clips in your report?

Sep 04, 2012 02:16 AM
Anthony Daniels
Coldwell Banker - San Francisco, CA
SF Bay Area REO Specialist

A smart roofer would offer it as a recommended upgrade.

Considering the obvious benefits, it's a no brainer, IF the client is made aware of the option.

Good post, thanks for sharing it.

Sep 04, 2012 02:46 AM
Nan Jester
Exit Real Estate Gallery Jacksonville Beach, FL - Jacksonville Beach, FL
Realtor, Exit Real Estate Gallery

Construction tips and repair tips are always welcome to me. Thanks.

Sep 04, 2012 03:38 AM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Mike - that bad winter a couple ago did a lot of damage to a lot of roofs!  It's not like we don't get the weight.

Randy - there are other reasons for sags, but this is a big one.

Wow, Tom, I see them on probably 98% of roofs here!

You're welcome Wayne.  Learning is why I come to AR, and it is fun to instruct as well.

Sep 04, 2012 05:28 AM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Joshua - yes I do.  I consider them best practice and on the few homes that don't have them I feel I need to inform.

Anthony - like I said above, I see clips on probably 95%+ of all homes.

Great Nan.  I'm glad you enjoyed it!  My grandmother's name was Nan.

Sep 04, 2012 05:30 AM
Steven Cook
No Longer Processing Mortgages. - Tacoma, WA

Jay -- thank you for this helpful information.  I will have to remember it when we have our roof replaced in couple years.

Sep 04, 2012 06:19 AM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I'm glad it could be of use to you personally Steven!  Keep your eyes peeled!

Sep 04, 2012 06:49 AM
Robert Sole
REM Inspections LLC - Winter Springs, FL

Sounds like you are actually in better shape in your area.  Here in Central Florida, the norm is 15/32 OSB.  I seldom see 17/32. 

You are absolutely correct about the clips but I have seen one other problem.  the clips are designed to help space the panels but too often the framer will pound the panels together and eliminate the 1/8" space.  When you look at the roof in the early morning, you can see a hump at the edge of each panel.

 

But look at the bright side.  If they did things right, we inspectors would not have a job.

Sep 04, 2012 07:19 AM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Wow, Robert, I don't remember seeing 15/32!  Maybe, but I don't remember.  One reason for that problem you mention is the guns.  They have them set way too high in spots.  And they drive nails in at angles.

Sep 04, 2012 07:29 AM
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

I see this all the time. Usually you can tell the clips are missing on a truss roof from the street. 

Sep 04, 2012 10:33 PM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

As I did on this house Jim.  This was a newer roof, so I suspected clips to be the problem.

Sep 04, 2012 10:36 PM