# R3 Rigid Foam for sheathing??



## brockmiera (Oct 9, 2012)

Can you post some pictures?


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## joecaption (Nov 30, 2011)

May be Celotex, one of the horrible ideas, right up there with partical board.
http://inspectapedia.com/structure/Fiberboard_Sheathing.htm#H1

Have not seen that used in modern constrution in many years.
They were suppost to use plywood in all the outside corners.
Foam and Celotex has about 0 shear strength so you can expect some nail pops and funky noises when the wind blows due to the house moving.


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## iteach4jeeps (Oct 16, 2012)

It looks like some of the celotex in the link. Is this something that would need to be replaced with plywood in the future? 

I can't post pics since I'd have to pull some more vinyl siding.

The house definitely creaks in high winds, bangs a lot, vinyl I'm assuming. 

Is the foam sheathing normal? I am 100% certain it's sheathed in foam.


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## iteach4jeeps (Oct 16, 2012)

In the attic for sure, there is not plywood in any corners at all, it is 100% celotex or whatever that crap is. Not only is it up, it has random holes throughout like someone had a leak hunt and took a hammer or their fist to random places to find a leak. The vent cover is covering the most foul looking hammer busted up hole, I am not sure why they felt this was necessary and couldn't cut it out like normal people.


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## joecaption (Nov 30, 2011)

Normal? I've seen it done years ago. I know I would never have used it.


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## iteach4jeeps (Oct 16, 2012)

Yeah using foam as sheathing just looks and feels completely cheap. With home prices rising, I cannot believe I paid for a foam covered house. It seems ridiculous, its not even taped. 

I wonder if anyone locally can chime in because I read somewhere that it was used in certain geographical areas due to climate. We get milder winters and pretty hot summers but it has gotten pretty cold. 

I also wonder about the ability to keep out insects and other unwanted biological thingamajiggers with just foam laying over the bottom 2x4 plate. 

Our home builder is still building homes in this area and I am thinking of giving them a call to find out what the heck they were thinking.


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## joecaption (Nov 30, 2011)

We had one poster that said his new house in Hawaii was done with James Hardee siding with just foam under it.
Last one I saw we had to cut out a window anyway do make it into a door way and I showed the house owner to get in the house all I had to do was kick the wall.


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## woodworkbykirk (Sep 25, 2011)

ive built several large high end homes that were sheathed in foam with no plywood on most walls. only the tall walls and shear walls were sheathed.. its common place now for most new homes and renos to get foam over top of the wood sheathing for added r-value and to act as a thermal break

you said there is 1/4 gaps in the foam. do they atleast have house wrap over the foam. if not your looking at a major risk of air leakage and water getting in which will increase both the heating bill and the chance of rot and mold


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## cleveman (Dec 17, 2011)

I've built 3 homes with 1" t&g xps as sheathing, but there was metal diagonal bracing in place. They also got a brick veneer with a lot of ties into the studs. I don't know if any studies have been done showing that the wall ties in the framing/brickwork improve the structure, but I don't think it can harm anything.

I've always been hesitant to build anything like this and then just side it with vinyl because of only nailing 16" oc. But I recently sided a large garage which had the black asphalt impregnated sheathing (celotex) and I was just nailing into the studs every 16" and it seemed to work out ok.

So if I have the opportunity in the future, I wouldn't hesitate to brace a garage well, then sheath it with xps and side it with vinyl.


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## iteach4jeeps (Oct 16, 2012)

There is no house wrap and no tape on the seams. It is frigid in the winter but we try to keep the heat on 72 at the max. It seems very drafty in this house. When you pull outlet covers, you can actually feel wind blowing through.


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## woodworkbykirk (Sep 25, 2011)

the gaps in the foam is the issue then its not stopping cold air from blowing into the wall cavity and taking any warmth from the insulation. if the outside walls are bare do yourself a favor and install house wrap

as for the metal t braces that get installed.. ive done this their only good if the brace is more than 7 `long and run on a 45 degree angle from the bottom plate to end stud.. in a wall thats full of glass the framing is really chopped up so bracing is useless it really needs sheathing before the foam


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## iteach4jeeps (Oct 16, 2012)

Am I going to have issues with moisture with a house wrap? I have no exposed walls but it could be a project for me this summer. I can take down a wall of vinyl siding and wrap it, then put the siding back up.


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## iteach4jeeps (Oct 16, 2012)

Is there any other way to fill in the gaps in the foam? Expanding foam, tape or any other product I do not know about. Trying to research every avenue so I might not have to wrap.


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## Gary in WA (Mar 11, 2009)

Contact your local AHJ, ask them about shear wall requirements in a high-wind area; charts 1/2 way down (looks like you live in a 90): http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_3_sec001_par004.htm

This would apply for your shear wall panel requirements per location: eg.- http://www.awc.org/pdf/WFCM_90-B-Guide.pdf

Bracing with metal struts- minimal resistance: http://bct.eco.umass.edu/publications/by-title/insulating-on-the-outside/

If you add structural panels: http://www.apawood.org/pablog/index...Sheathing-be-Installed-Horizontal-or-Vertical

Size of fastener, fastener spacing, stud spacing, per MPH wind Zone, Chart 603.3(3); http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_6_par013.htm?bu2=undefined

Read the first 3 on (code required) water resistance and WR barriers, also the last one on vinyl siding/foamboard; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_7_sec003.htm

Foamboard shrinks, breaking any air-sealing joint tape connection; http://www.buildingscience.com/documents/published-articles/pa-foam-shrinks

Gary


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## iteach4jeeps (Oct 16, 2012)

This link you sent me is quite interesting. 

It says the use of a water resistive barrier is required. I just have foam board. Does that qualify, I would think not since there is 1/4 gap between each board. That is nowhere near water resistant.

It also says that nailing the siding directly to the studs is not allowed, according to a chart that outlines the wall covering. Nailing to the studs is the only way you would get the siding up since there is no plywood sheathing. This tells me the use of plywood sheathing is required, with a water resistive barrier on top.

I really wish I would have had the sense to pull back the vinyl siding before buying the house. Not sure if it would have prevented me from buying it though. 

I really am not concerned with wall strength, bracing and all that since the house has been standing for close to 20 years and has withstood hurricane force winds. 

I am just concerned about getting it waterproof or close to it, holding in heat better and getting the walls wrapped up properly to keep in warmth and water and cold out. 

I guess my options are to remove all vinyl, put up plywood then housewrap and tape all seams or leave out the plywood and just housewrap the foam that is already up. 

Then I am left with the task of trying to identify where all the nails can penetrate the house wrap into the studs since there is no freaking plywood behind it!

I also had such fun trying to nail up vinyl to the celotex in the attic, freaking nails just push through like thumbtacks with your hand, wind resistant, I think not!


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## iteach4jeeps (Oct 16, 2012)

I've been thinking about it and I have more issues. I cannot simply house wrap my house the way it is with the foam sheathing. That does not provide enough structure for nails/staples. I doubt the tape will hold the house wrap up on the foam for a long period of time. I would have to take down all the foam, replace with plywood and then wrap it. 

What other option do I have? I'd like to leave the foam sheathing up as to save money vs buying plywood and putting that up. But how do I attach house wrap so it'll last? Nail it to the studs, that wouldn't work because the foam has a 1/4 gap between, the wrap would push into the gap.


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## iteach4jeeps (Oct 16, 2012)

I did more inspections today. Apparently all the corners are sheathed in plywood with the rest in foam board. When I pulled the front corners nearest the front brick veener I found gaps between the stud nearest the front and the next one on the opposing corner wall. I will insulate that with some insulation for now. 

On another wall, there was a bunch of cardboard nailed up, not sure why, but it was in small pieces and I did not find anything weird behind it. 

I also was able to find out for sure that some areas are sheathed in celotex, it actually had the branding on it. The attic area and the vinyl covered chimneys and the one uninsulated garage wall. 

All of the vinyl siding is nailed to the studs.


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## Gary in WA (Mar 11, 2009)

The foam board acts as required backer for vinyl siding, you cannot fasten vinyl to ONLY bare studs. The corner sheathing/every 25' passed minimum code for your area. I started framing, installing Celotex in '73, very "now" then. It was structural with amount/length/spacing of proper fasteners. The foam shrinks (have a few other links in my library), that is a fact= hence the 1/4" gaps. 

Remove/replace siding is pretty quick (number them on inside face), only problem is don't break any as replacement won't match the weathered look. Use some from the back/side of house for the new pieces, using old for more noticeable areas. Add the housewrap. 

Remove siding and foam board, add housewrap with stapler to bare studs, add foam and siding. *Wall #2, pp.13*: http://www.buildingscience.com/documents/guides-and-manuals/gm-guide-insulating-sheathing

Gary


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## iteach4jeeps (Oct 16, 2012)

Thanks for the input. I appreciate all the help you guys have given me. 

I think eventually I will strip the siding and then housewrap on top of the existing sheathing/rigid foam and then install the vinyl siding. I will have to attach the housewrap carefully using nails to the studs and tape, possibly staples to the foam with tape over top.

I would love to add a second layer of rigid foam all the way around but that proves costly and time consuming with windows and trying to meet the siding to the front brick veener. An extra layer would make the vinyl channel not meet with the brick veener. Maybe I will do it on the sides of the house with no windows.


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## tylernt (Jul 5, 2012)

iteach4jeeps said:


> I will have to attach the housewrap carefully using nails to the studs and tape, possibly staples to the foam with tape over top.


Why not just use dabs of construction adhesive here and there?


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## Windows on Wash (Aug 30, 2011)

tylernt said:


> Why not just use dabs of construction adhesive here and there?



Solvents in a bunch of the construction adhesives with melt both the foam and the Tyvek.

You can use sealants and caulking, they just have to be compatible and most folks will find it easier to staple up or cap nail it.


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