just ripped open a 50 year or so house for an addition, and to my surprise found drywall under the beveled siding!
….yup, that’s what I said drywall – or a least some form of it. it appears to have a red paper on both sides of it, and it seems to have a slightly heavier consistency than the stuff we see now days. ( almost like plaster – but not quite)
it all appears to be in great shape , at least the little that has been exposed so far. there is no building paper of any kind only the paper that the rock is faced with, which also means there is no overlapping. but the siding appears to have held up extremely well therefor allowing no water/moisture penetration.
QUESTION is, now what do with this stuff? was this ever a practice ? the wall that got ripped open will become an inside wall now, which means I won’t have to worry about it for the time being. but the next project the owner will being replacing the beveled siding with vinyl… do I tell him he’s got to rip it all off and put up some plywood? I’m thinking of course I do…. But I would be like to get some thoughts. anyone ever seen this before?
Replies
possibly rock lath...
what size are the sheets?
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!
I'll have to look again but I think ... I think..they are of a 4 x8 nature. I know early drywall/sheetrock came in 16" strips, but I know it wasn't 16".
what is rock lath and how would it affect my situation
rock lath was the new high tec replacement for wood lath used as the base of plastered walls
generally it came in 16x48" pieces and a varity of colors... sometimes it was 24x48"...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
ever hear of it being used on the outside? they have it on inside and outside.
yup..
there is rock made for exterior applications... name escapes me at the moment... you'll find it mostly in commercial applications...
could have been a cost cutting thing at the time.. this is what we have on hand...or a fire code issue...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
took a look and they are 24" wide. not sure how long 'cuz I was looking from inside and couldn't see where the joints are.
anyway...what should I do with this stuff? tell him to rip it off and replace with regular sheathing before vinyl goes up?
find out if it was to meet a fire code...
no... cover over it with osb or ply... or tear it off .. sheath and side..
yes... do not disturb....can the vynal plan and go with hardie plank...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
It's called Densglas (Georgia-Pacific) - as you said it is pretty well the industry standard for exterior sheathing in commercial applications, even behind brick cavity walls.http://www.gp.com/build/product.aspx?pname=DensGlass+Gold%c2%ae+Exterior+Sheathing&pid=3515&hierarchy=pc
dat's da stuff....Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
What you found was gyprock,used even today when a wall exterior sheathing must be fire rated.Easiest way to side over it is to install 1/2" cdx over it. Be careful of the code though,might have been a specific reason for the gyprock.Is there another building in close proxsimity to the home your working on? You could just nail into the studs.This stuff was even used for soffits years ago,held up very well as long as the roof above did not leak.
mike
Exterior gyp sheathing is still used today although it is losing favor to densglass lately.
If you have to replace some, it comes in 4x8 or 2x8 t&g usually a grey/black paper
Why change something that looks great after 50 years?
Mike
Trust in God, but row away from the rocks.
Edited 5/5/2006 9:24 pm by ruffmike
The structure I'm framing right now is being built within the 'set-backs' .... and therefore is requiring that I use 5/8" fire-core drywall on the OUTside of the cdx and under the final siding as a fire stop. Also requires same on inside of wall as double fire-block. Standard requirement where structure is closer to another structure than inspectors are comfortable with.
When I began I called downtown and asked them 'how necessary' it was. The reply was "you recall the Great Seattle Fire where half the city burned down? ... Well our requiring you and everyone else to use drywall on the outside of the wall means that'll never happen again"
Terry
OK...this is all very intriguing....
I 've never seen or heard of this before. Never thought that drywall had a better structural rating than plywood of any kind. what type/size of ply (or OSB) is structurally rated?
The house I've encountered fire hazard could not have been the reason as nearest house is 150' away and never has there been one close. In Vancouver down town and east side here in BC. you will find house after house within arms reach of each other all with ship lap. ( similar to old Seattle I presume.) The house I grew up in was that way in North Vancouver B.C.
The stuff on this house is in 2' widths so I don't know if that has the same structural strengths of a x 8 sheet wether drywall or ply.
So what do I do on this house? The addition is already flush with the exterior drywall. so placing ply overtop would skew things. it was mentioned by IMERC I think to leave and use Hardi Board. because of the irregularities in the original framing I would hesitate to use Hardie Board which would tend to show all the flaws....not only that but HB would not be in the owners budget.
if the rock is left as the exterior sheathing I'm guessing papering it would be prudent. with the existing siding with out paper it is easy to catch all the studs with a 10" board since one can easily tell where all the studs are. but If I cover with paper that would change, so I would have to chalk lines so as catch the studs.
OK...this is all very intriguing....
I 've never seen or heard of this before. Never thought that drywall had a better structural rating than plywood of any kind. what type/size of ply (or OSB) is structurally rated?
---------
No no ... wasn't meaning to imply in any way that the drywall had any sort of structural integrity/rating. The drywall I am required to use on the 'house' that I'm building in my backyard is totally related to fire-spread stoppage. If my place is consumed in a raging fire within ... 'they' (downtown) don't want it to break out to my neighbors place. Hence, I am required by code to put up fire-code rated 5/8 gypsum as the first covering over framing on the inside walls which face neighboring propeties. And on the outside of framing the same material is required so that in the event of a fire at the neighbor's place it doesn't 'jump' to mine and begin the second Great Seattle Fire. Therefore, on the outside of my framing I have the normally required 1/2" cdx sheathing .. and on top of that, 5/8" fire-core rock. THEN .. on top of those, I'll have my siding, which, in my case on the 'neighbor-facing' walls at least, will be metal panel siding ... big and cheap and good looking and long lasting.
I am, btw, building WITHIN the normally honored set-backs ... building right up to the property lines ... and this is why it is required in my case where it otherwise is not .. in 'normal' residential construction.
T.
Not only is drywall weak, it's also heavy. Heavy is bad in earthquake country. The earth is going to move however far and fast it's going to move, no matter what we build on it. The amount of energy that motion imposes on the building is determined by the weight of the building. So, by making you put two sheets of 5/8 gyp on your walls, the city is helping with one problem but making another worse. Here in LA, SOP for sheathing is Struct #1 rather than CDX, for earthquake reasons.
What kind of metal siding are you using? Does it weigh less than stucco or Hardie?
-- J.S.
As well as in a fire code situation, gyproc was used simply as a replacement for board/ply sheathing starting in the 60's. Still used today if you wish or need the structural rigidity it gives. For housing, the codes in most of Canada (I don't know BC quake resistant code) only require one layer of drywall (of sufficient thickness) for anti-racking qualities.
That's why we can use insulation sheathing only (has no structural value) on the exteriors. With temporary wall bracing during construction, upon installation of the interior drywall the needed structural strength is achieved. Using this system, when there are walls with large expanses of windows in relation to the amount of drywall, you may want to install some inlet bracing or a bit of wood panel sheathing for insurance.
Edited 5/6/2006 6:32 am ET by experienced
Yet another good reason to not disturb the rock is the chance it may contain asbestos. Fibers not discernible by merely looking at the board. Asbestos is more commonly found in the taping compound, but it was also used to strengthen board products.
I had a frame addition put on my house couple years ago here is Chicago. 5/8" gypsum board for exterior sheathing was a code requirement. My builder put plywood at the corners for stiffness. They are fine with that, but definetly don't want the whole thing covered in ply. The gyp board is intended as a fire stop. It was then covered in house wrap before being sided.
I live in Levittown on Long Island, NY. All Levitt ranches had this type of sheathing under whatever siding the latest people had. It was real easy when I was installing wall air conditioner units. I used to use a diamond blade on my circular saw if they had vinyl siding and I used to be able to cut entirely thru the wall in one pass. I'd finish the corners with a sawzall and pull out the section. I was putting them in in 30 minutes flat
I've already had a look at the insulation and it appears to be "rockwool" which I found out from an earlier post is derived from a metal.
would you leave up the board then and paper over it. If I get a guy to put vinyl on I guess I'll have to snap stud lines for him.
I don't KNOW that your board has asbestos in it, but it was used to strengthen board products in days gone by, though it was more commonly found in the taping compound even to a much later date. (I assumed this exterior board was not taped.) In any case, why disturb it if it is in good shape, might kill you if you do, and gives you fire protection for when the BBQ sitting too close to the wall catches that vinyl siding on fire?Point of interest...mid-60s seems to be the high point for asbestos use creating most mesotheliomas (lung cancer). You said this board was 50 years old is why i mentioned it. Getting it tested is the only clear answer on whether it contains asbestos, however, and only you can decide if you want to open up that can of worms. Just a few fibers of asbestos can cause cancer, and a standard demo face mask won't keep it out of your lungs.
Asbestos was my first thought too. I'd stop the project until you get the stuff tested. Bag the opening with 6mil palstic and duct tape until you get it tested. Did your client give you a asbestose report or a "clean report"before you started the job? If not and you continue to work around this stuff and it's hot not only are you putting yourself at risk but if the owner ever found out there was stose suspended in the air during the course of your work and putting the family living there at risk you'd be opening yourself up for a world of hurt.
in the 1980s all multi family housing in New Haven Ct. had to be sheathed in exterior firecode sheetrock, did 80 condo units like this had to let in continuous diagonal bracing in 48 ft, 16ft, and 4ft setback walls, couldn't use metal T-strap had to let in minium of 1x4, at that time 2x4s were less so got pretty good at whalin 2x4 chunks with a single blow "damn knots". All this was because some meathead put his hot grill away under exterior stairs and burned the vinyl & chip board off 3 floors before the fire dept. got there
Drywall used as exterior sheeting
My house has some paper board on the outside (1/2" thick), it then has two layers of 1/2" drywall under that.
I thought it was 4'x8' sheets, but I just took an inside wall out. The stuff is 16"x8' strips. It is -10*C out, an enormous amount of water is now seeping all over the floor from the edge of the wall. The studds at the bottom are all black and the drywall is soaked on the inside. Most of the insulation has black on it is variious locations.
It will be pretty hard to replace the stud walls and the floor (how do I hold the roof up), so I'm a little stuck on what to do...
My home was built in 1978. The exterior paper board seems water proof as long as there is 1/4" of paint on on it but to a point. They put a metal angle at the bottom where the floor joinsts are and this parts is rotten alll the way around the house. This lip allows water an snow to sit which cause the water to seep through the paper board even with 1/4" of paint on it. What a mess!
Your situation isn't the fault of the sheathing used.