Plywood decking Log Out | Topics | Search
Moderators | Register | Edit Profile

Slate Roof Central Message Board » Slate Roofs » Plywood decking « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Joe (Joe)
Moderator
Username: Joe

Post Number: 814
Registered: 07-2006


Posted on Saturday, January 25, 2014 - 01:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Run horizontal nailers such as furring strips over top of the poly, screwed through the poly into the rafters. Nail your slates to this. You will have to run a row of nailers for every course of slates. Alternatively, run them vertically directly over the rafters, then resheet the roof with 3/4" boards screwed to these nailers, felt, and slate normally.
Top of pagePrevious messageNext messageBottom of page Link to this message

Ecologic (Ecologic)
New member
Username: Ecologic

Post Number: 1
Registered: 01-2014
Posted on Wednesday, January 22, 2014 - 07:10 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I am building a small cottage that I initially planned to roof with standing seam, then I read the Slate roofers bible and I am now contemplating going with slate. The building has a 50degree slope, 2x10 rafters on 2' centers, 3/4" cdx plywood decking and a 2" layer of rigid polyiso insulation on top of that. I realize that if I decide to use slate my first mistake was the plywood, too late now, but what about the 2" polyiso? I am concerned about the weight of the slate on the nails and potential sagging. Should I just stick with my original plan to use the metal roofing? Has anyone tried this before? Any advice is truly appreciated. Thanks
Top of pagePrevious messageNext messageBottom of page Link to this message

Joe (Joe)
Moderator
Username: Joe

Post Number: 759
Registered: 07-2006
Posted on Thursday, January 17, 2013 - 06:57 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Via email (Sorry, man. I normally have no trouble with this sort of thing. Can you throw this one up in the "Plywood Decking" thread of Slate Roofs? Thanks. Andy)

"How about slate over OSB? Spare me the judgments--I know it's crap, but
bear with me here, people. I'm building a house for myself with Structural
Insulated Panels (SIPs), which is styrofoam sandwiched between OSB. The
roof structure will be SIP, allowing for the attic to be fully
conditioned.


I want to put the best possible roof on. Slate, right? Seems logical to
use timber battens nailed to the SIPs, even though conventional wisdom in
the SIP community is that you can install any roof directly on the SIP as
if it were conventional OSB sheathing over rafters.


I'd appreciate feedback from anyone with experience with slate over SIPs.
If that's not forthcoming, I'd appreciate feedback from anyone with a
reasoned opinion about the concept.


At least OSB won't delaminate...although what it does when wet may be even
worse.


Besides the relative weakness and impermanence of OSB, the concept is
troubling because with a SIP roof structure, it's impossible to monitor
the underside of the roof for leaks. Besides the required 30lb felt, I've
wondered about installing other barriers between the OSB and the timber
battens."
Top of pagePrevious messageNext messageBottom of page Link to this message

Joe (Joe)
Moderator
Username: Joe

Post Number: 755
Registered: 07-2006
Posted on Sunday, January 06, 2013 - 12:57 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Robbins Super-Elite Plus
BS1088 Marine Plywood Guaranteed for 25 Years

This is our top-of-the-range board! Cost: Medium to High

Stick with solid lumber. Guaranteed a century or two and cost is very reasonable.
Top of pagePrevious messageNext messageBottom of page Link to this message

Old_school (Old_school)
Senior Member
Username: Old_school

Post Number: 934
Registered: 01-2009
Posted on Friday, January 04, 2013 - 09:08 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

welcome Lou, I see it is your first post. good to have new posters.
Top of pagePrevious messageNext messageBottom of page Link to this message

Lou_hale (Lou_hale)
New member
Username: Lou_hale

Post Number: 1
Registered: 01-2013
Posted on Friday, January 04, 2013 - 08:56 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

One reason I have always sighted not to use plywood is plywood expands and contracts across both axis where as wood will only move across the grain (width). Slates are free to move up and down with seasonal movements in solid lumber where as movement across the length of a sheet of plywood can lead to broken slates.

I don't know if it's true or not because I only install slate over boards but that's what the old timer I learned from told me and it seems logical
Top of pagePrevious messageNext messageBottom of page Link to this message

Scottishslater (Scottishslater)
Senior Member
Username: Scottishslater

Post Number: 145
Registered: 01-2012
Posted on Thursday, September 20, 2012 - 01:11 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

http://www.robbins.co.uk/marine/sheet_materials.asp
Top of pagePrevious messageNext messageBottom of page Link to this message

Scottishslater (Scottishslater)
Senior Member
Username: Scottishslater

Post Number: 144
Registered: 01-2012
Posted on Thursday, September 20, 2012 - 01:04 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Marine plywood is manufactured from durable face and core veneers, with few defects so it performs longer in humid and wet conditions and resists delaminating and fungal attack. Its construction is such that it can be used in environments where it is exposed to moisture for long periods. Each wood veneer will be from durable tropical hardwoods, have negligible core gap, limiting the chance of trapping water in the plywood and hence providing a solid and stable glue bond. It uses an exterior Water and Boil Proof (WBP) glue similar to most exterior plywoods.
Marine plywood can be graded as being compliant with BS 1088, which is a British Standard for marine plywood. There are few international standards for grading marine plywood and most of the standards are voluntary. Some marine plywood has a Lloyd's of London stamp that certifies it to be BS 1088 compliant. Some plywood is also labeled based on the wood used to manufacture it. Examples of this are Okoume or Meranti
Top of pagePrevious messageNext messageBottom of page Link to this message

Scottishslater (Scottishslater)
Senior Member
Username: Scottishslater

Post Number: 143
Registered: 01-2012
Posted on Thursday, September 20, 2012 - 12:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

here better grade ply is called marine ply
Top of pagePrevious messageNext messageBottom of page Link to this message

Lazeyjack (Lazeyjack)
Senior Member
Username: Lazeyjack

Post Number: 72
Registered: 04-2012
Posted on Thursday, September 20, 2012 - 04:39 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Futhermore, (marine ply) no such thing, all construction ply rely on same glue
There are ply timbers such as oregon pine, spruce, that'll stand up betterbut at the end of the day, if I and other build a boat out of ply we protect the ply
So please if you are going to comment abt this be very sure of facts
signed--a boatbuilder:)
best rgds
Stuart
Top of pagePrevious messageNext messageBottom of page Link to this message

Lazeyjack (Lazeyjack)
Senior Member
Username: Lazeyjack

Post Number: 71
Registered: 04-2012
Posted on Wednesday, September 19, 2012 - 03:19 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

as I have said many times here
Ply will last a very long time BUT only it is either painted with 300microns of high qual epoxy two pac or, it is coated in resin two pac
if not, then the first layer will soon absorb moisture and rot
Simple because the ply will be thin layers of to put it mildly, fast grown crap
However if you had say ply of spruce or oregon pine then your chances are better
Taking it to extreme , if you had teak pl;y, made up of 7 plys, then also you would be ok
The short answer is PLY NEEDS PAINT
best rgds
Stuart
Top of pagePrevious messageNext messageBottom of page Link to this message

Old_school (Old_school)
Senior Member
Username: Old_school

Post Number: 878
Registered: 01-2009
Posted on Saturday, August 25, 2012 - 10:28 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

The laminated woods will last, but not forever. The "sarking" boards will last a long time.(yours was 140 years old)and while they will rot, they can't "delaminate" because they are solid. what you have will last as long as it doesn't leak. It is good, but not as good as it could be. that is why we recommend solid decking.
Top of pagePrevious messageNext messageBottom of page Link to this message

Scottishslater (Scottishslater)
Senior Member
Username: Scottishslater

Post Number: 141
Registered: 01-2012
Posted on Friday, August 24, 2012 - 12:37 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

some will use marine ply it aint unheard of it just dosent last as long as sarking board
Top of pagePrevious messageNext messageBottom of page Link to this message

Rdsherman (Rdsherman)
New member
Username: Rdsherman

Post Number: 5
Registered: 11-2011
Posted on Friday, August 24, 2012 - 10:59 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I had some slate work done on a 140 year old house by a very, very reputable company. While doing the work, they found structural damage. I was very grateful they were able to fix it at that time. However, when I got the change order I found out they used 3/4 plywood instead of hardwood decking. Isn't this a big no-no? I pointed this out and the on-site supervisor pointed out they the work comes with a 10 year warranty. How do I handle this?

Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action:

Topics | Last Day | Last Week | Tree View | Search | User List | Help/Instructions | Program Credits Administration