It’s time to discuss roof sheathing. I have a question or two I think you gentlemen can answer.
Last night, after work, I went to Home Depot and Lowe’s looking for 3/4″ exterior rated tongue and groove roof sheathing. They had none. The guys knew less than me about roofing, and I know next to nothing.
Was I looking for the proper material? It’s usually a bad sign when they don’t have what you want.
They had 3/4″ exterior BC plywood that looked really nice but it didn’t have the tongue or groove feature. It looked so nice I almost bought it anyway but they also did not have panel clips, so I diodn’t buy it.
They had tons of 3/4″ Sturdi-I-Floor (SIF) tongue and groove but this was rated as exposure category 1, not exterior. Would this stuff be okay? The SIF also had two grooves cut into the short end of each panel. What is that for? All their OSB sheathing was for flooring.
Tomorrow, I am going to the local lumber yard. They know their stuff.
Replies
3/4" T&G is not normally used as roof sheathing--it's subfloor. Usual is 1/2" or 5/8" CDX, or OSB. You can get 5/8" T&G Advantech in some places, and apparently it's the bomb.
I looked at the Advantech web site. The material appears to be advertised mostly as a subflooring. Most of the application notes and file downloads are about subflooring applications. They show it used as wall sheathing but I don't recall any roofing applicatoins.
According to the Advantech web site, there are no local sources of supply in my area.
3/4" is usually for flooring...
5/8" T&G is what you want for roofing...
if you 16" OC look for 1/2"....
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!!!
The problem remains the same. All they carry is SIF exposure category 1, not exterior roof sheathing. They had no OSB roof sheathing, either, it was all rated as subfloor sheathing.
Neither had Advantech.
I checked the APA web site to make sure I wasn't barking up the wrong tree. They clearly show 3/4" exterior T&G sheathing and the labeling for it. They have all the specs for installation and allowable live and dead loadings,... etc.
I wanted 3/4" so the roof would be a little stiffer and stronger. Other than the added cost and weight of the sheathing, is there a problem with using 3/4"?
Edited 11/24/2009 1:16 am ET by Mike_Mills
I once helped a cousin put 3/4" T&G on his roof. After we got done he said he felt stupid - It was ridiculous overkill.I feel the same way. Using 1/2" is fine. Going to 5/8" may be overkill. Going all the way to 3/4" AND using T&G is over the top.
gains on 3/4 over 5/8 is neglagible if any...
negatives are as you already said...
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!!!
"Some days it's just not worth chewing through the restraints"
I just checked for local suppliers of Advantech. According to the Advantech web site, there are none within a 30 mile radius of me (the max distance their search function allows).
Is sheathing, sheathing? Is there a distinction between roof sheathing and wall sheathing?
Edited 11/24/2009 1:35 am ET by Mike_Mills
try decking and sheathing instead...
it's all interwoven biut not the same...
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!!!
"Some days it's just not worth chewing through the restraints"
Decking and subflooring I understand. I found a lot of both. I am not seeing anything specifically called roof sheathing, as opposed to exterior (shear wall) sheathing. Is there a difference between the products used for walls and roofs?
ply count and orientation of installation...
other wise ... no...
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!!!
"Some days it's just not worth chewing through the restraints"
lowes has 5/8 T&G ply for roofs...
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!!!
"Some days it's just not worth chewing through the restraints"
It was all labeled as SIF (Flooring), exposure category 1. I was just there two hours ago.
use this to narrow yur field...
Panel Grades
Veneer Grades
Panel Thickness
Glue Bond
Load Spans
Span Rating
Finish
Formaldehyde
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Guide to APA Trademarked Panels
Examples of Sanded, Sheathing, Floor and Siding trademarked panels
Click on any number 1-12 on the trademark images below to find out more details
Understanding trademarks gives you a summary
SANDED
SHEATHING
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FLOOR
SIDING
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1 Panel Grade- Back to top
Identifies panel in terms of veneer grade used for panel face and back (e.g., A-C, B-B, etc.), or by a name suggesting the panel's intended use (e.g., single-layer floors, siding [cladding], etc.). Veneer grades define veneer appearance in terms of natural growth characteristics and allowable repairs made during manufacture (See Veneer Grades)
2 Bond Durability Classification - Back to top
EXTERIOR - fully waterproof bond, designed for applications exposed permanently to the weather or moisture. EXPOSURE1 - highly moisture resistant bond, designed for applications where ability to resist moisture and weather during long construction delays is required, or where high moisture conditions may be encountered in service. Not intended for permanent exposure to weather. Exterior and Exposure1 panels have WBP durability equivalence.
3 Span Rating - Back to top
Denotes the maximum recommended centre-to-centre spacing of supports in inches over which the panel should be placed with the long dimension across three or more supports. The Span Rating for Rating Sheathing consists of a left-hand number referring to installation over roof supports, and right-hand number referring to installation over floor joists. (See Load Spans)
4 Species Group Number - Back to top
Relates to the species of wood used for panel face and back veneers. Species are classified on the basis of bending strength and stiffness into five Groups identified by number. Group1 species are the strongest, then Group2 and so on. Douglas-fir and southern pine, the predominant species, are in Group1 and are interchangeable.
5 Thickness - Back to top
Most trademarks show the panel's thickness in terms of inches. (See Panel Thickness for millimeter equivalence.) When ordering panels from U.S. suppliers, specify thickness in terms of inches.
6 Sized For Spacing - Back to top
Indicates the panel is manufactured to dimensions that help accommodate recommended panel end and edge spacings when installed. Panels measure 1220 mm (48 in.) by 2440mm (96 in.) with a plus 0, minus 3 mm (1/8 in.) tolerance. Spacing between ends and edges helps prevent buckling caused by moisture absorption. Recommended spacing between panels is 3mm (1/8 in.) at both end and edge joints; unless otherwise recommended by the manufacturer.
7 Tongue-And-Groove (T&G) - Back to top
Indicates panel has tongue-and-groove pattern at the edges, which eliminate need for blocking beneath panel. Material removed to create the tongue may reduce panel face width by approximately 12.5 mm (1/2 in.) Other T&G patterns may be used, but are not identified in the trademark.
8 Product Standard Conformance - Back to top
Indicates panel is manufactured to meet provisions of U.S. Product Standards PS 1-95 for Construction and Industrial Plywood.
9 Performance Standard Conformance - Back to top
Indicates panel is manufactured to meet provisions of APA PRP-108 Performance Standards and Policies for Structural-Use Panels.
10 Government Recognition - Back to top
Indicates special recognition by the U.S Federal Housing Administration for structural uses.
11 Face Grade Designation - Back to top
Refers to number and type of repairs allowed on siding face ply. "S" means synthetic material, "W" means wood material.
12 Mill Number - Back to top
Code number of producing mill of the representative quality assurance agency.
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!!!
"Some days it's just not worth chewing through the restraints"
Yes, thanks for doing that. I understand the information and have double checked all that just this evening after returning from my unsuccessful shopping expedition.
They had nothing but Sturdi-I-Floor in T&G in 5/8" and 3/4". They had no sheathing at all, neither plywood nor OSB. By "they" I mean my local Home Depot and Lowe's.
They did have some nice 3/4" exterior AC plywood but it had no T&G feature. :-(
If I could find some of them, I could use panel clips and strategically placed blocking beneath the seams.
If the lumber yard doesn't have any sheathing, I will get what they recommend.
use the clips and 5/8"...
what you can't find there we can find here...
more than likely the other way around too...
gotta be a regional thing...
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!!!
"Some days it's just not worth chewing through the restraints"
"I understand the information"Are you sure of that?Earlier, you said ( I think) that they have exposure one but no exterior rated. Well guess what exposure one is?
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There is a difference between exterior and exposure 1. Exterior is superior to Exposure 1. Exposure 1 is only good for 30 days, then has to be protected (painted, covered, etc. The ratings show exterior to be superior.
The roof I'm doing is a flat roof and will not be shingled. Another reason I want the thicker wood is so it creates a flatter surface. I'm just explaining my thinking on this. I hear a fairly loud and clear message that 5/8 is all that's needed. Got it.
Given that I am the roofer,...
"The roof I'm doing is a flat roof "NOW the 3/4" TG makes sense!
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"The roof I'm doing is a flat roof..."
That info would have helped out a heck of a lot earlier in the thread...
Love is like a roller coaster: when it's good you don't want to get off, and when it isn't... you can't wait to throw up.
That info would have helped out a heck of a lot earlier in the thread...
That thougt crossed my mind too. You'd think we'd all have learned to interrogate the newbies better, after so many "Oh did I mention that the roof is on Sampan in the harbor at Hong Kong?"
Pifin,
Are you are saying not to worry if all I can get is Exposure 1 and can't get Exterior grade?
FYI, there are metal clips sold which perform the same function as T&G on roof sheathing. They are placed in the middle of each 24" span.
As others have said, it's overkill to use anything more than 5/8" OSB on a roof. Spend that extra money on something else.
Edited 11/24/2009 2:05 am by Hudson Valley Carpenter
While considering the useof the flat edged 3/4" plywood, I went searching for panels clips. Neither Lowe's nor Home Depot had any. Well, Home Depot had some but they were for 1/2" material and I was after 5/8" or 3/4" thick material. I searched each store for about an hour (a frustrating, two hour trip).
Home Depot doesn't have these?http://www.strongtie.com/products/connectors/PSCL-PSCA.asphttp://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&productId=100375273&langId=-1&catalogId=10053&ci_sku=100375273&ci_src=14110944&cm_mmc=shopping-_-googlebase-_-D22X-_-100375273
Edited 11/24/2009 2:35 am ET by RalphWicklund
7/16" just like the OP said...
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!!!
"Some days it's just not worth chewing through the restraints"
Mike, are you trying to kill your carpenters?
T&G on other than a flat deck will make your carpenters hate you. T&G is tough enough when it is on the floor to get it togrther.
As far as specific ply for roof sheathing, no such thing that I know of.
3/4 ply on the roof is overkill also. 5/8 is plenty. If you use 5/8 you don't need plywood clips that HVC is talking about.
I am the carpenter. :-)
P.S. - It is a nearly flat roof. I want it to be truly flat and to stay flat.
Edited 11/24/2009 12:42 pm ET by Mike_Mills
By flat are you saying low slope? If you are, carry on!
WOODA MADE ALL THE DIFFERENCE IF i COULD HAVE READ HIS MIND
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And he found the proper material at a real lumber yard instead of HD, etc.John
>G<
metal clips do not give you the same rating as t&g...
here ...in 110 mph zone we have to either block all edges ... or use t&g roof sheathing.... they sell tons of advantech 5/8 t&g here
we switched back in 2004Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
If I had to block, I'd use T&G too! Its much faster than clips isn't it? On a roof, it just taps in easily. Or, I should say, slides/slams in easily. http://thewoodshedtavern.com. = no peer mods!
Edited 11/28/2009 8:01 pm by jimAKAblue
the first time my bi explained the wind uplift requirements to me ... i looked at his blocking requirements and started looking for t&g... the advantech is the cats meow... very flat... does't absorb water .. goes together very easy
almost every roof around here is using it... what we spend extra for the advantech comes back in labor
i did see a Can-ply 1/2" product that used a V-groove to acheive the T&G effect.... but i've never found a local source
if i had a reliable 1/2" t&g i'd go back to 16" oc roof framingMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Very flat but heavy. Using 5/8" advantch might make it bearable up there on the 12/12s. Of course, I'm a registered sissy now LOL. I don't think I can lift a 3/4 Advantech anymore.http://thewoodshedtavern.com. = no peer mods!
Exposure 1 material is rated for weather exposure during the framing process. Not for use as siding or other constant exposure aplications, of course, but it's what you should be using to frame your house.
3/4 on the roof because it's stronger? How about two layers of 3/4? That would be even stronger....point is that the process has been engineered and proven in countless projects. Want to be right up to snuff, use 5/8 for 24" o.c. applications, 1/2" for 16" o.c. applications, definitely h-clips for either one. It has worked, it will work, and it's less work.
Hey, I almost forgot, what fasteners do you use for sheathing, nails or screws? Do you use adhesive between the rafters and the sheathing?
My plan so far is to use deck screws and Liquid Nails to attach the sheathing.
I do plan to screw to the blocking. I do not plan on H-clips because the sheathing is tongue and groove on the long edges and the short edges get screwed to the rafter tops.
Dont glue it.
don't waste money on liquid nails.The reason for construction adhesive on a deck sheathing is to prevent squeaks in the floor as you walk over it.I don't see that being a problem on roof decking.'course someone will make a case for the extra integrity it offers in a hurricane or tornado, but if that is your concern, you want a waterproof structural adhesive, like PL Premium, not a trim glue like LN.
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No need for gluing and screwing. Waste of time and money. Use ringshank nails if you want.Joe Carola
What do you guys think is acceptable deviation or error in the slope? Remember, this is a low slope, single pitch roof (3/4" per foot) that will be covered by something other than asphalt shingles. Asphalt shingles, especially the highly textured ones, can hide a lot of imperfections.
I measured the tops of the rafters to see if they were at the correct height. I am reusing the 2X8 rafters from my patio cover. I knew some were not, as you can see it with your eyeballs and can feel it when you walk on the loose sheathing.
1. One rafter is bowed such that it is about 1/2" too high. I was thinking of power-planing this down a bit before sheathing over it.
2. There are others that are 1/4" to 3/8" too low. I was thinking of shimming between these and the sheathing.
What do you guys think about bringing the rafter tops into line? Are there other ways to deal with this? Is it okay as is and I should just go ahead and sheath it, or what? Talk to me.
Thanks in advance.
Edited 11/27/2009 2:29 am ET by Mike_Mills
One rafter is bowed such that it is about 1/2" too high. I was thinking of power-planing this down a bit before sheathing over it.
2. There are others that are 1/4" to 3/8" too low>>>>>>>>>>>>>>>>
As long as the high one is not next to the low one, don't worry about it.
I do think you will have trouble getting T&G together on a roof, though.
With just ¾ inch per foot slope, you will have a wavy roof with the size changes and bowing that you describe. You will then have puddles.You need a flatter roof.Could you add more slope?
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
>> 1. One rafter is bowed such that it is about 1/2" too high. I was thinking of power-planing this down a bit before sheathing over it. <<Tat means it's has a 1/2" crown to it. You should cut it with a saw or plane it down. 1/2" is o much. >> 2. There are others that are 1/4" to 3/8" too low. I was thinking of shimming between these and the sheathing. <<Why are these to low? Did you install them upside down? Meaning, is the crown down instead of facing up?>> What do you guys think about bringing the rafter tops into line? Are there other ways to deal with this? Is it okay as is and I should just go ahead and sheath it, or what? Talk to me. <<Are the top of the rafters sitting on a top plate or a ledger?Joe Carola
Hey Joe..whats shakin brother?
I was thinking...what if he uses the ZipSystem just for the roof? I'm really starting to like that stuff.
Any thoughts on that?View Image
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I'm hanging in there. How about you? I've never used the Zip System yet. I'm always willing to try something new.Joe Carola
It's basically Advantech with a special covering/film on one side.
Cool thing about using it for the roof is you won't need tarps to keep the weather out if you're not ready to roof it yet. That alone saves a ton of time. The cost is about the same as any good sheathing but the tape for the seams is what runs into the additional money.View Image
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"what if he uses the ZipSystem just for the roof?"Bad move if he uses EPDM which is incompatible with bituminous products
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whoops...didn't read that part...started in the middle of the thread. Sorry!View Image
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No apology needed - that was an IF
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Your roofing material most definitely cannot be shingles of any type, you're way too flat for a shingled roof. Around here [Minnesota]it would be rubber, either adhered or ballasted with river rock. There are other traditional materials such as Pitch&Gravel or Hot Mop but those are outside the scope a homeowner, and I like the rubber better anyway.
Like others, I wonder how you have achieved the height variations in your rafters, but I have done 1/4" per ft slopes that shed water fine, and believe that a 3/4" per ft slope roof should not have puddles even with the variations. Framing adhesive is capable of bridging gaps to a certain limited extent. Course your rafters have to be properly sized and spaced, but it sounds as if that cake is baked.
I am roofing and enclosing the patio cover on my house, so the rafters are old. I will not likely ever again reuse materials. I had planned to install them all crown up but either I goofed (most likely) or the old rafters are just warped. Oddly, the worst offenders are the ones I managed to get "crown up". These two or three seem to have a very high crown on them.
I did spend the day leveling out the rafter tops. No biggie, it's done. It's not anything you'd want to do if you were trying to make money on the job but I can afford to do it as I am the owner.
I do have two or three low spots. I will most likely glue some wooden shims to level them out. I am also toying with the idea of using a "liquid shim". A "liquid shim" is really just epoxy that fills the gap and cures in place. After it cures you screw it down from above, as you would normally do.
"One rafter is bowed such that it is about 1/2" too high"This s ccalled a crown and is the norm, don't worry about it. It resists loads better his way."There are others that are 1/4" to 3/8" too low. "This is where the framer forgot to crown the joist and set it upside down. Shimming would not be a bad idea, but is probably not necesary, depending....
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Mike - I worked my way to the end of your thread which was when I realized, along with others who were advising you, that the roof you are contemplating is flat, or almost so. Grumble grumble, you should have stated that in the first place, but oh well.
This roof should be treated like a floor, meaning 3/4 t&g OSB or plywood. Yep, t&g means no h-clips. Glue it with a PL200/Liquid Nails product, then screw it. Six screws at the butt joints, five into the rafters in the field. I'm assuming you are roofing with rubber, my roofer requires a screwed assembly to eliminate high or cocked fasteners that could produce holes in the rubber, so set those screws a good 1/8 below the surface of the decking. I would use torx #9 screws.
I agree about it being a floor/deck. I came to that conclusion after getting the sheathing up there. I am VERY glad I bought 3/4" plywood. Yes, it is tongue and groove.
I have a case of Liquid Nails sitting here, too. I am not a fan of Liquid Nails. Should I exchange it for PL200?
I did not see anything other than Phillips-type screws at Lowe's when I was there.
<rant mode on>
They had some square drive in stainless steel but I have used those before and I won't use them ever again. This comment applies only to the brand sold at Lowe's and Home Depot. The steel is too soft and the bit strips, typically when it is almost all the way in, making removal both necessary and extrememly difficult. They use soft steel to make the screw fabrication easier/cheaper but it is a false economy because the product functionality/quality is very low.
<rant mode off>
I took all my cues on the roof sheathing from Holy Hammer in this thread. Look at his pictures. He seems to know what he's doing. I will likely use the Sonoguard roof coating product he used, as well. I just can't find a local supplier, so I may have to order it and wait.
http://forums.taunton.com/tp-breaktime/messages?msg=126433.1
Edited 11/27/2009 11:41 pm ET by Mike_Mills
at least PL400 or PL Premium...
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!!!
"Some days it's just not worth chewing through the restraints"
I just went searching for info on the two materials you mentioned, PL 400 and PL Premium. I've used polyurethane adhesive before (Bull Glue and Gorilla Glue). They were a mess but they worked well. I did not like the 24 hour cure times (too slow). I guess in this application, cure time is irrelevant, as it occurs after screwing the sheathing down.
Honestly, I am not sure exactly how to fill in the low spots. I may just glue a wooden shim and power-plane it level to the adjacent rafter tops. Once the shim is bonded, planing it level is easy to do. Once the sheathing is installed and screwed in place, the shim is100% permanent (glued and screwed).
Edited 11/28/2009 12:31 am ET by Mike_Mills
PL is construction adhesive...
hands down.. the best out there...
not anything like what you been exposed to... you won't regret using it..
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!!!
"Some days it's just not worth chewing through the restraints"
SS is a softer, more brittle steel by nature
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
"I'm assuming you are roofing with rubber"He has not made up his mind what product to use, which is a mistake for at least two reasons.One is that the pitch of a roof is determined by the requirements of the roof product to a great degree.And the other is that he is ready to install the decking material, but has not yet ordered the roofing, so there is high chances that the decking can be damaged by weather before roofing ever gets delivered, let alone installed."my roofer requires a screwed assembly to eliminate high or cocked fasteners that could produce holes in the rubber,"Your roofer is talking shortccuts by putting his responsibility off onto you.. He should be installing an underlayment suitable for rubber instead of gluing it directly tot he plywood
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Don't agree on the underlayment, especially for an adhered membrane. Glue it to the deck, not another product applied to the deck. A ballasted system is another thing, rigid fibreglass or something along that line for an underlayment is the way to go.
1/2" 5ply fir maybe
I would go with 5/ and clips..
stand alone EPDM or 94# and tin...
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!!!
"Some days it's just not worth chewing through the restraints"
You will be fine using the 3/4 on your roof. I've laid 3/4 t and g on a roof when I had ten sheets extra and was happy to use it up and get it out of my barn.
I don't know that I'd use the square edged bc product though, especially from HD. If you got caught in a rain, there might be a huge chance of instant delamination because of the species used in it's construction. It looks great because its normally used on interiors and wont stand up to even a little water.
The subflooring is different. It is manufactured with the knowledge that it will take a few poundings of water. It has to stand up to a good soaking, or two, and still perform.
Once you get the shingles on, you will be good to go.
JimAKAblue, the 3/4" B/C T&G plywood was rated as EXTERIOR which is superior to Exposure 1, correct?.
I understand you want to upgrade, but let me tell you what is standard, then you can go from there. I'd guess that a vast majority of homes being built today get 7/16 osb for roof sheathing. 7/16ths is often used interchangeably with 1/2". The H-clips are used on square edge sheathing that is installed on 24" OC trusses or rafters. Roof sheathing and wall sheathing is often interchangeable. A few times I have seen wall sheathing that could not be used on the roof.
What they should have is 5/8th if the rafters (trusses) are 24" OC. If the rafters are 16" OC then 1/2" is fine and if you really want to upgrade use the clips. The T&G is an upgrade and is available only in 5/8s and up, but really anything thicker is un-necessary.
If you want to go with the 5/8 T&G it may be available at the lumber yard, or you may have to special order it.
Advantech is considered an upgrade too. It is roughly 80% more expensive than the least expensive sheathing.
Exposure 1 means exterior glue, meaning that it can take some exposure to weather but should be covered before too long. When at the store and you saw "exterior plywood" I really think that was exposure 1. You have to read the lumber stamps.
Before talking sheathing, lets talk roof. What kind of roof, style, and roofing material and what snow load you have that makes you think you need 3/4" T&G anyway?
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No snow load, ever. This is southern California, at the coast.
Flat roof - 3/4"/foot pitch, single slope (shed roof)
Roofing material is STILL TBD. That's whole other topic on this discussion board. Right now, it is looking to be a membrane roofing material. I know I am not going to like the look of that, so I am exploring options to cover it with standing seam metal.
The BIGGEST hang up I am having is finding the materials. All they sell at my local Home Depot and Lowe's is shingles. None of the more sophisticated roofing options are available through them. Several of the candidate materials are not available in the State of California due to our various environmental and health restrictions which cause suppliers to opt out of doing business with Californians.
Edited 11/24/2009 12:51 pm ET by Mike_Mills
what's the rafter's spacing...
16 or 24"???
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!!!
"Some days it's just not worth chewing through the restraints"
16" rafter spacing.
5/8" it is...
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!!!
"Some days it's just not worth chewing through the restraints"
I just got off the phone with the local yard. They have exactly what I want and will deliver it tomorrow.
Score one for the real building pros. They deserve the businesss.
Thanks for all the help, gentlemen.
Now, about that roofing material ...
Edited 11/24/2009 1:00 pm ET by Mike_Mills
This is southern California, at the coast.
There's an ABC roofing in Anaheim or thereabouts if I'm remembering right.
You might fill out your profile so's some of the advice you get isn't too regional to do you any good. What works at Piffin's place doesn't necessarily apply in Newport Beach.
You need a supply house, not a big box.
I'd stay with the 3/4" on a roof that flat, a little sag and you have a lake.
Lot of tilt ups in Southern Cal with flat roofs and lakes.
Joe H
Somewhat related comment - my understanding of standing seam steel roofing is that under about a 4:12 they want you to use Ice/Water sheild in leiu of asphalt impregnated roofing felt.
If you want standing seam on that flat roof you might want to look at some system whereby the SS roofing is purely decorative and does not compromise the rubber membrane.
This advice is just an observation on my point. I am not a pro, just a DIY'er
http://jhausch.blogspot.comAdventures in Home BuildingAn online journal covering the preparation and construction of our new home.
Great minds think alike. I am pursuing exactly that option. Right now, the plan is to use a "rubber roof" and cover it with standing seam metal just for appearances.
Remember, the advantage of rubber [EPDM] is that you are covering the roof with a continous sheet of waterproofing - no penetrations. Fastening a standing seam system thru the rubber penetrates that sheet and results in waterproofing the space below with a system - the standing seam - that has too low a pitch. Your pitch is fine for EPDM but not for standing seam. And from what vantage point will you be seeing that roof anyway? A 3/4"per ft pitch is virtually invisible from the ground.
My friend, the Breaktime format might not be giving you everything you need. I think you could use some advice on this project, either from someone with boots on the ground, or by means of consultation with plenty of photos and documented existing conditions. Plenty of carpenters/contractors would be willing to consult with you for a reasonable fee, probably $500 or less for an advice-only visit to your property. Don't mean to be insulting to you at all, but a number of your questions show an experience level that could benefit from advice. I do this kind of consulting myself but I'm located in Northern Minnesota.
It appears that this is a porch roof and not living space, and that he is thinking of using a paint on liquid roof product, calling it a rubber. I f he is going to roof over it anyways, he would be better off with just ice and water shield that will self seal around those fasteners.
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Agreed, ice shield would be the thing below a metal roof, but I don't think he has the pitch for a metal roof, which goes back to EPDM, Pitch&Gravel, or Hotmop - flat roof systems in other words. A paint-on system...dunno dunno...but I doubt a satisfactory result.
I have little confidence in painted on systems too, but since this is not enclosed living area and it is dry SoCal, he can probably tolerate minor leaking.
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That would be a terrible waste of a good rubber roof - to put holes in it for the metal roof.Keep in mind that you absolutely have to select a type of metal roof that is designed for such a low slope application. Most of those I am aware of arr commercial, more expensive, and ugly as sin.
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I really prefer to see 3/4" on the roof and consider it essential under slate and heavy shingling (Grand Manor Shangle, etc.).
You can always tell the roofs (tract houses) around here with 3/8" or 1/2" because they look ... corrugated.
Jeff
The sheathing was delivered yesterday afternoon. I schlepped about half of it up onto the roof. I think it will be fine but, honestly, I wish I had purchased the 1" material.
In my study of this "roof", I am coming to the conclusion I am really designing a "deck". No one other than the roofers will ever walk up there but in terms of design, it is a deck, not a "roof" in the sense that most (including I) conceive of them. It has a very shallow pitch and needs to be dealt with as if it were a waterproof deck.
P.S. - With the help you guys have given me in the last few months, this is turning out to be a really nice project. It would not be as nice as it is, if it were not for you guys. Thanks very much for all the help.
Edited 11/25/2009 8:40 pm ET by Mike_Mills
If you are still concerned then block between your rafters at the seams and perimeter nail the sheathing. Your analogy or description of a deck really isn't viable IMO.
If the only ones ever walking on it are the roofers then it will never have a live load applied to it in your climate, that unless you have a lot of standing water due to clogged or improperly installed roof drains.
Edited 11/25/2009 10:04 pm by dovetail97128
I just did a roof on my carport. I had 16" OC and used 1/2" OSB. I kept rain off it before the felt went on to avoid trapped moisture. Probably not necessary but made me feel better! Solid roof.
hey there i have done roofs that customers have requested 3/4 sheeting wich was way over the top and added more cost. Well i never recomend 1/2" spend a few more dollars and put on the 5/8". I would strongly say that 90% of the time 5/8" in plenty sufficent. And T&G is just not worth the hassel.
HA! I still haven't installed a single piece of sheathing. Soon, though, very soon.
I worked all weekend getting the rafter tops corrected. I glued wooden shims and planed them to fit. Eventually, the rafter screws will hold them in place, too. They are DONE!
When I'd finally finished with that, I began to install edge blocking but had to stop due to darkness. I did get a few pieces in, enough to know they add a lot to the rigidity of the platform that will be the base for my roof. I have not yet installed any regular (pressure?) blocking and the roof (the deck) is already MUCH better. Those few boards have proven this thing will come together very well. It will be done as soon as I get the work done.
I am also going to install 2X6 blocking between the rafters. In addition to stiffening and strengthening the deck, I will be using them to support a drywall ceiling. The drywall infill between the exposed rafters will cover the electrical wiring and the (thermal) insulation. I will most likely be using rigid foam insulation.
I'm very happy it hasn't rained in a while. If it holds off for a few more weeks, I will have a roof when it comes. I have a giant plastic tarp in case it comes sooner.
Once again, I want to thank everyone here for all the suggestions and help to get this thing done. I know, I know, I ask a lot of questions. But hey!, that's what this board is here for, right? Thanks again.
Edited 11/30/2009 3:57 am ET by Mike_Mills
Since you are insulating, I would suggest using polyisocyanate boards on the decking for the least expensive and highest Rvalues. This stuff is designed for flat roofs.
I was looking at those the other night at Lowe's. I'm not putting anything on top of the roof until after I talk to the roofers. Depending upon which material I select for the roof, this might be the way to go.
So, working on this roof today, I finished the edge blocking. It went really well. Right now, I am very pleased with how everything has turned out, especially the roof rafters and the blocking. Leveling the rafters and installing all the blocking was a lot of work but it truly was worth it.
I had about 75% of the sheathing laid out and it's looking really good. It is rock solid when you walk on it and the sheathing isn't even screwed down yet. I want/need to install some additional blocking before I glue and screw the sheathing.
I just realized from your name who you are and what this project is, I think. Didn't dawn on me before. But I thought this was a porch/patio roof - are you enclosing this area? The insulation comment makes me ask to sort out my confusion.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Plywood that is designated for flooring, such as "sturdi floor", is required to plug the top two laminations. This prevents something like a spiked high heel of your missus from plunging through the linoleum or carpeting.
The non floor rated plywoods can have voids in the second layer.
I've never used either PL400 or PL Premium. Tell me, how do they differ in consistency (thickness/viscosity) from Liquid Nails.
The instructions on PL Premium imply it is a relatively low viscosity liquid. Is it as thin and runny as Bull Glue and Gorilla Glue, or is it hick enough to stay where you put it, like Liquid Nails? The MSDS calls it a "mastic" which, to me, implies a very viscous material.
The instructions on PL Premium also say it has a 30 minute working time. I like that part, as I am working alone and, well, things just take more time when you work alone.
I have the same questions about PL400.
I've never used either PL400 or PL Premium. Tell me, how do they differ in consistency (thickness/viscosity) from Liquid Nails.
thicker... never seem to harden or get brittle like LN.. preforms well under questionable applications.. EXTREMELY strong bond... way stronger than LN by far... 400 is more of a mastic and not runny at all... a really hot day will lower the viscosity quite a bit..
http://www.stickwithpl.com/Products/detail.asp?PLProductID=12
as where Premium is a poly urathane and is thicker than 400...
http://www.stickwithpl.com/ProductsList.aspx?ID=POLYURETHANE-SEALANTS
The instructions on PL Premium imply it is a relatively low viscosity liquid.
I wouldn't say so..
Is it as thin and runny as Bull Glue and Gorilla Glue,
NO! urathane caulk viscosity or close to it..
or is it hick enough to stay where you put it,
yup..
like Liquid Nails?
way better.. since when did LN become coopertive???
The MSDS calls it a "mastic" which, to me, implies a very viscous material.
The instructions on PL Premium also say it has a 30 minute working time. I like that part, as I am working alone and, well, things just take more time when you work alone.
don't get too far ahead of yurself... you can speed it up by adding a little bit of water from a spray bottle or flashing it..
I have the same questions about PL400.
same applies.. less adding the dampness..
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!!!
"Some days it's just not worth chewing through the restraints"
yur up...
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!!!
"Some days it's just not worth chewing through the restraints"
Both PLPremium and Gorilla glue are polyurethenes chemically, but that is where the similarity stops. PLPrem const adhesive has solids and squeazes out like caulk or Liq Nai. it stays where you put it, including on your hands or in your hair.but the bond is much stronger.It goes further than PL 400 adhesive because it will expand slightly as it cures ( nothing like Gorillia glue tho) so minor depressions or gaps fill meaning you get more surface contact per foot ~ more adhesion = stronger jointPLP is also water proof once curred
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
It sounded good so I went and bought a case during my lunch break. I'll take the Liquid Nails back for a refund. I hate LN, anyway, it's junk.
I understand about the hair, hands and clothing.
We're getting rain this weekend, so no sheathing for at least another ten days or so.
Work during the week. Rain on the weekend. Of course, who knows what's coming the weekend after that, weather-wise. Then, Christmas is coming, too.
argh!
So, it seems reasonable that I might pay a roofer to come in and get this sheathing finished up and get the roofing down during the week while I'm at work. That is, if the weather cooperates during the weekdays. I'll have to make some calls.
Well, yesterday I finally got around to putting the sheathing down. I got delayed first by rain, then by some last minute changes to the rafters (added more steel for better earthquake protection), then by adding the insulation and some firring strips,... the list is long.
I measured and cut the sheets. Then, I laid down a bead of PL Premium adhesive and screwed the boards down. The sheathing is 3/4" T&G plywood.
I am very happy I bought that new screw gun with its multiple, rechargeable batteries. I went through three or four batteries in this one job, and through several boxes of deck screws. In fact, I ran out of screws and had to switch over to some stainless steel screws I had left over to finish the job.
When I finished, as a precautionary measure, I laid down some thick plastic sheeting and weighted it down with scrap plywood and boards. I used a lot of weight thinking it would be needed if it got windy. Overnight a weather front moved through bringing with it 40 mph winds. Somehow, the "weather men" on the news didn't know enough to warn us about the wind but cautioned us about rain that never materialized. I was lucky, very lucky, I had planned ahead.
When all is said and done, it's all ready to be roofed. Now, if only I knew what roofing to use and could get a break in the weather to do it.