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-   -   sheathing blocks instead of h-clips, help needed (http://www.diychatroom.com/f9/sheathing-blocks-instead-h-clips-help-needed-139593/)

roof52 04-08-2012 12:00 AM

sheathing blocks instead of h-clips, help needed
 
Hi everyone, I need some help here. I just had my roof replaced (tear off) by one of the best roofing contractors in my area. They are A+ rated by the BBB and have GAF certification. I have a gable roof with roof trusses 24" o/c and 3/8 plywood sheathing with h-clips. The roofer replaced all the sheathing along the ridge, but didn't install h-clips on the new sheathing. After researching this, I've found that blocking can be installed at the sheathing seams in place of the h-clips. I have some concerns about this, such as: How exactly is this blocking accomplished (a picture would be very helpful), is adding blocking a good substitute for h-clips, even if the blocking adds support to the sheathing, it doesn't do a thing for the expansion and contraction issue. The replaced sheathing on the ridge of my house was less than a full sheet of plywood and is only about 10" wide. I've read:huh: the narrow sections of sheathing required more support than full sheets, thus multiple h-clips are recommended on all sides. What would be the best course of action to take for area?

I want to resolve this with the roofer but I DO NOT want my roof to be compromised because of an error made by the roofer. Should I demand that he tear it all off and do it over correctly using h-clips? Thank you

gregzoll 04-08-2012 12:09 AM

Just because the BBB states that they have a A+ rating, there is information out there to show that the rating can be bought. Also any roofing contractor out there can be GAF certified. If they did not install the clips, and they are required as stated by your AHJ, I would be having the contractor come back and correct it. But first having your city inspector look at the workmanship and state if it passes or fails their inspection, so that you have something to go on, plus the city can play hell on the contractor if they really want to. But on the offside, it can cause headaches for you if they give you a Red tag. First I would go and talk to the AHJ before having an inspector come on site. Also are permits required by your AHJ before tear off, regardless who does it?

joecaption 04-08-2012 12:21 AM

I would never ever use 3/8 sheathing on a roof, to thin and not rated to span 24". A bare minimum would be 1/2. Only time I've seen it used that thin is on mobil homes and cheap sheds.
I also would never install a piece along that edge less then 24" wide.
With 24" spans you must use H clips. It would take way to long to do the blocking and your right it would not preset the spacing needed.

roof52 04-08-2012 12:28 AM

Hi gregzoll,

I'm not familar with the initials AHJ, and there is no permits required for any type of roofing in my area. And even when the city requires a permit, they will NOT act on your behalf to force a contractor to correct their work. They will just simple not approve the work and it's entirely the responsibility of the homeowner to get the work corrected so that it received the approval from the city.

roof52 04-08-2012 12:34 AM

Joe caption, thank for your reply. 3/8 sheathing 24"o/c center meets all codes here in upstate NY. What's the issue with a narrow width of sheathing at the ridge? Can you explain exactly what this blocking consists of? and possible include a photo? So, are you saying I should demand that he tear it all out and redo it using h-clips?

gregzoll 04-08-2012 12:38 AM

AHJ = Authoritive Having Jurisdiction (ie City hall permit/inspection office/regulatory dept.).

gregzoll 04-08-2012 12:43 AM

Quote:

Originally Posted by roof52 (Post 894170)
Joe caption, thank for your reply. 3/8 sheathing 24"o/c center meets all codes here in upstate NY. What's the issue with a narrow width of sheathing at the ridge? Can you explain exactly what this blocking consists of? and possible include a photo? So, are you saying I should demand that he tear it all out and redo it using h-clips?

I would and do it at their costs if it is required. That is why I am glad that my roof decking is 1x6 boards, and there is only one area that is 3/4" Exterior rated plywood on my roof, but it is on a dormer that is the entrance to my home.

BTW, did they use any Grace Ice & Water shield for the first 3 feet above the gutters, then 30# felt, or just use the bare min? Can you post pictures of the decking from inside the attic, and from outside showing the workmanship? Especially around any penetrations such as chimney, flue, vent piping? Also, did they do proper venting on the roof, such as ridge venting if you have soffits?

joecaption 04-08-2012 12:58 AM

http://osbguide.tecotested.com/pdfs/en/el807.pdf

3/8 Is the bare minimum to meet code.
Personaly I'd never use it on a roof with 24" spans.

Anytime I see a roof done with 3/8 sheathing it's all wavy from all the sagging between the rafters or trusses.
Trying to just get the nails into a narrow piece would not be much fun because of all the bouncing when trying to attach the shingles.

gregzoll 04-08-2012 01:26 AM

Joe, even 1/2" is just as bad as 3/8ths. Min. should be nothing more than 5/8ths period, with OSB not being allowed. Even with Ply you have problems with it deteriorating as quickly as OSB if not covered properly.

Gary in WA 04-08-2012 01:34 AM

Check to see if you are under the "I" Codes, they accept 3/8" sheathing (rated 24/0) or roof = 24" on center support rafter/truss, floor = not applicable. BUT, 24" o.c. require clips or edge support; first chart, second column =3/8"----footnote "d"; http://publicecodes.citation.com/ico...003_par004.htm

Without the support, you can span maximum 20" o.c. He needs to add 2x4 blocking, flat, directly under the joints of sheets, perpendicular to the rafters, tight to the sheathing.

Gary

Ravenworks 04-08-2012 07:33 AM

Quote:

Originally Posted by gregzoll (Post 894199)
Joe, even 1/2" is just as bad as 3/8ths. Min. should be nothing more than 5/8ths period, with OSB not being allowed. Even with Ply you have problems with it deteriorating as quickly as OSB if not covered properly.

Everything on my roof is 3/4" wouldn't have it any other way.

sixeightten 04-08-2012 11:07 AM

In 30 years, I have only installed 3/4 on a roof once. 5/8 is a nice premium upgrade, most are done with 1/2" and perform just fine. 3/4" is overkill for no good reason in my opinion.

Ravenworks 04-08-2012 12:36 PM

Quote:

Originally Posted by sixeightten (Post 894349)
In 30 years, I have only installed 3/4 on a roof once. 5/8 is a nice premium upgrade, most are done with 1/2" and perform just fine. 3/4" is overkill for no good reason in my opinion.

Ummm it was free is good enough reason to use it, I don't know the name of the product but it was red and designed as sheeting.

roof52 04-08-2012 06:28 PM

GBR in WA, Hi Gary, You stated "He needs to add 2x4 blocking, flat, directly under the joints of sheets, perpendicular to the rafters, tight to the sheathing"

Can you show me a picture or two of what this exactly looks like? This is what I invision. A 2 x 4 fitted between the 24" span of the truss, pressed tight against the sheathing edges and toenailed in place with 2 screws on each end of the 2 x 4 for a total of 4 screws per 2 x 4. Also, would it be advisable to use an adhesive sealer or glue in between the 2 x 4 and the sheathing? Does it matter if some of the sheathing has h-clips and some has blocking? What about expansion and contraction were the blocking is used? And as I said a picture of what this would look like would be very helpful.

thanks roofer52

packer_rich 04-08-2012 09:41 PM

I have done more than a few roofs with clips and there were times we used blocking. With a small rip, the size you mentioned, I don't think expansion and contraction will be a big problem. You should make sure the blocking is installed just as you said above.


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