# T1-11 with no sheathing - remove or go over?



## ngny (Aug 1, 2018)

Hi Everyone, 



Have a house built in 1965 with T1-11 siding. There are a few rotted spots where it is installed to the ground along with the seam in the middle of the house. What surprised me is that the siding is nailed right to the studs over felt paper. 



Should I remove, add sheathing and new siding or just repair the rotted sections and go on top of the t1-11 with new siding?


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## roofermann (Nov 18, 2013)

T-111 acts like sheathing. I'd patch the bad spots and side right over it. Good time to install housewrap too.


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## rjniles (Feb 5, 2007)

I built a cottage in 1975 with 5/8" T111 directly on studs. Installed vinyl 1992. Covered with Tyvek and the vinyl. As long as T111 is solid it is a good nail base. Not sure I would do it with 3/8" T111.

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## w0j0 (Dec 29, 2017)

roofermann said:


> T-111 acts like sheathing. I'd patch the bad spots and side right over it. Good time to install housewrap too.


I've been pondering this for some time, too, as I would like to side over my existing t1-11... You say to use house wrap over t1-11 despite there being felt paper already installed between the framing and existing siding/sheathing? I've been struggling with the thinking of using 2 vapor barriers. Or is that acceptable? I'm not questioning you or your advice in any way but rather seeking a better understanding of a topic of which the waters are quite muddied.
My house has bitumen/creosote/homasote(whatever you call it) board as sheathing under the t1-11, what is recommended to be used as the WRB/underlayment for vinyl siding in this case?


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## Nealtw (Jun 22, 2017)

w0j0 said:


> I've been pondering this for some time, too, as I would like to side over my existing t1-11... You say to use house wrap over t1-11 despite there being felt paper already installed between the framing and existing siding/sheathing? I've been struggling with the thinking of using 2 vapor barriers. Or is that acceptable? I'm not questioning you or your advice in any way but rather seeking a better understanding of a topic of which the waters are quite muddied.
> My house has bitumen/creosote/homasote(whatever you call it) board as sheathing under the t1-11, what is recommended to be used as the WRB/underlayment for vinyl siding in this case?


House wrap and felt are not vapour barriers, they both shed water but allow breathing. If I was repairing bad sheeting I would not worry about any missing felt. but I would not worry about it being there.


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## kwikfishron (Mar 11, 2010)

I just want to add that when you cut out a section of the t-111 you need to add 2x blocking in between the studs so you have full premineter nailing of the seam that you just created.


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## Nealtw (Jun 22, 2017)

kwikfishron said:


> I want to add that when you cut out a section of the t-111 you need to add 2x blocking in between the studs so you have full premineter nailing of the seam that you just created.


 We have a vapour inside so we leave gaps in sheeting for breathing unless the wall was a specified stress wall .
Different rules for different places.:surprise:


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## kwikfishron (Mar 11, 2010)

Nealtw said:


> We have a vapour inside so we leave gaps in sheeting for breathing unless the wall was a specified stress wall .
> Different rules for different places.:surprise:


Nothing to od with breathing.

The t-111 is acting as the shear for the wall and needs full perimeter nailing.

If you don't block between the stud(s) to be able to get that extra nail in there (8" perimeter vs 16") two things happen, 

1) you lose shear strength. 

Not a big deal if the patch is small and and we're talking about a couple of studs but if you're replacing a foot or whatever of rot around the entire wall then it affect shear greatly.

The blocking is just serving the same purpose as the top/bottom plate or stud for premimiter nailing.

2) If you don't that seam can/will buckle at that location and telegraph (show) through the new siding.


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## Nealtw (Jun 22, 2017)

kwikfishron said:


> Nothing to od with breathing.
> 
> The t-111 is acting as the shear for the wall and needs full perimeter nailing.
> 
> ...


 Like I said different places different practice.
Here horizontal sheets have 1/2" gap between them and holes drilled in any closed cavities like below or above windows or a stress walls that do have solid blocking.


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## kwikfishron (Mar 11, 2010)

Nealtw said:


> Like I said different places different practice.
> Here horizontal sheets have 1/2" gap between them and holes drilled in any closed cavities like below or above windows or a stress walls that do have solid blocking.


So installing sheathing that doesn't break on a plate or stud is ok in BC?


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## Nealtw (Jun 22, 2017)

kwikfishron said:


> So installing sheathing that doesn't break on a plate or stud is ok in BC?


I was only talking about the horizontal join, yes.


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## kwikfishron (Mar 11, 2010)

Nealtw said:


> I was only talking about the horizontal join, yes.


A half inch open gap on horizontal seams would make a great fire chase. :surprise:


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## Nealtw (Jun 22, 2017)

kwikfishron said:


> A half inch open gap on horizontal seams would make a great fire chase. :surprise:


Repaired a few houses never seen one spread sideways on that line. Never thought about it.
Then again everything changes when they build houses 8 ft apart. We follow all the same rules to get framing passed and then they cover the outside with exterior drywall and seal it up tight. solid soffits that have to bring air from front and back.:glasses:


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## ngny (Aug 1, 2018)

Thanks for the feedback everyone. 

Its 5/8, so I will patch any rotted T 1-11 then wrap with Tyvek and choose a siding.


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