Thread: OSB Roof Sheeting Issue /Question -

Have a roof that has small raised ridge at the junction of the 4 ft edge of the OSB sheeting that appears across the roof. You can see the ridge run the 4 ft junction and then jump to the left and right to the next junction points (staggered across the roof) see picture (look carefully and you can see the small ridge lines ). The raised area appears to be caused because the OSB was not installed properly. Installer did not leaving a 1/8 inch gap at the 4ft edge between the OSB sheets. The sheet appear to have expanded due to humidity (Georgia). As a result, at the junction of sheets, they have been pushed together and one or both sheets have expanded or lifted off the roof trust a little.
My question is - has anyone seen this before? What are the long term issues and does this need to be repaired.
Have talked to the American wood Council about this issue - but would like more inspector input
Thanks
Gus

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Originally Posted by Gus Franke

Have a roof that has small raised ridge at the junction of the 4 ft edge of the OSB sheeting that appears across the roof. You can see the ridge run the 4 ft junction and then jump to the left and right to the next junction points (staggered across the roof) see picture (look carefully and you can see the small ridge lines ). The raised area appears to be caused because the OSB was not installed properly. Installer did not leaving a 1/8 inch gap at the 4ft edge between the OSB sheets. The sheet appear to have expanded due to humidity (Georgia). As a result, at the junction of sheets, they have been pushed together and one or both sheets have expanded or lifted off the roof trust a little.
My question is - has anyone seen this before? What are the long term issues and does this need to be repaired.
Have talked to the American wood Council about this issue - but would like more inspector input
Thanks
Gus

Did they use "H" clips on the roof decking?

Roofs are not going to be level. Truss roof systems are notorious for the appearance of waves in their decking.

Who told you that the sheets of OSB have expanded or is this an assumption?

They used "H" clips on the 8 ft sides, but not on the 4 ft sides were the ridge has developed. We pulled the shingles and t paper up over on ridge area. You could see that the sheeting was pushed together and a raised area was formed at the ends of each OSB sheet. This is not a question of the trust system having a variation. You can clearly see the the small ridge line is only at the 4 ft joint of the OSB sheet and moves across the roof at every 4 ft joint. If you started at a bottom sheet joint you would have the raised ridge for 4 ft , then it is flat were the center of the OSB sheet is, the ridges are now on the left and the right at the junction of the 4 ft edge on the next sheet. If you go up to the third sheet ( 4ft junction point) the ridge appears again directly above the junction on the first row -
OSB expands by nature when it absorbs mosture / humidty, the sheet junction that we looked at was so tight that it was forcing one sheet to climb over the other.

the problem is probably due to the lack of spacing. i asked an apa rep if they would warranty the osb that was installed without a proper gap and he said no problem? it may look like $hit and destroy the roof covering but the osb is o.k. the raw edge you exposed requires edge flasing btw.

Brian - Since the APA Rep said that this is not a OSB problem as the OSB is still good. The roofing material above the ridge line is going to be the issue for the home owner as it will more than likely fail early due to the ridge or be more vulnerable to wind damage. Since the issue is caused by improper installation is there a course of action the home owner can take? Against the builder/ contractor or sub contractor that installed the OSB

Originally Posted by Gus Franke

Brian - Since the APA Rep said that this is not a OSB problem as the OSB is still good. The roofing material above the ridge line is going to be the issue for the home owner as it will more than likely fail early due to the ridge or be more vulnerable to wind damage. Since the issue is caused by improper installation is there a course of action the home owner can take? Against the builder/ contractor or sub contractor that installed the OSB

Hi Gus,

My advice is to contact a good inspector in your area who does litigation support inspections. Let them look at the roof and provide you with a professional opinion as to its condition and what your next step should be. You might find that it could be several items that are causing what you are seeing. Also, keep in mind that APA is an association of manufacturers and does not produce any of the material or warranty any of the material.

If this is a new home, then most likely your gripe will be with the builder. The builders sub-contractors are responsible only to that builder. Are builders licensed in GA? If so they have specific requirements that they must perform under, those requirements are also time sensitive.

Gus, the first thing I would do is go in the attic and pull a string along the rafters to see how well they plane from on end to the other. If you look closely at the rafter tail in the first picture, the fascia is running down hill. In 1 1/2 of rafter tail, it is out about an 1/8 inch, and the plywood seems to be running at an angle to the rafter. I don't see enough compression between sheets of plywood to create a ridge in the roof line. I think it has more to do with your roof than the plywood. let us know what you find.

Scott

Scott - I understand what you are saying and Yes, there is some variation in the roof rafters - BUT, if the variation was significant then the rafter would stand out for the full length of the rafter in a vertical line on the roof. The issue that is clearly seen on the actual roof is a ridge line which runs 4 ft then jumps 4 ft to the left and right ( at every OSB sheet joint) then comes back to the smae line for the next 4 ft (OSB joint). The ridge line, if you stay on one rafter and start at the bottom near the gutter runs up 4 ft, then goes flat ( this is now the middle of the OSB sheet above the joint) then reappears 4 ft above the flat area at the next OSB sheet joint. When you look at the roof in total you can clearly see every joint because it is at these points were the small ridge line appears runs the4 ft length of the joint and then stops, is flat across the middle of the next sheet then begins again at the next sheet joint and this continues up the roof. The low resolution of the attached image makes this hard to see. I can send you a larger image if interested. Thanks for the feed back