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mx2
millennium club
Joined: 18 Jan 2006
Posts: 1968
Location: Miami, Florida
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 Posted: Wed Jun 06, 2007 2:04 pm Post subject: ROOFING: Wood Shakes/Shingles |
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Okay, I have a question, especially for you Northerners... 
...I'm detailing a cedar shake roof and have to call for solid sheathing (hurricanes and all) and the typical underlayment, but I found that this system rots the shakes very quickly (moisture build up), and since this is a very hot and humid area, wanted to detail this better. So I found something called a "continuous ventilation underlayment" and that's as far as I could go...
do any of you have a manufacturer or better terminology for what the heck this thing is? I picture wood strips to create air space but that's not an underlayment...any ideas, anyone? Thanks in advance.
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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kmapro
Joined: 03 Mar 2006
Posts: 129
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kmapro
Joined: 03 Mar 2006
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phansford
Joined: 18 Apr 2004
Posts: 556
Location: SW Ohio
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| Posted: Thu Jun 07, 2007 7:30 am Post subject: |
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mx2
I have specified three shake roofs. The best advice I can give is require the installation to be in strict accordance to the CSSB's requirements and guidelines, which was already provided as a link. Require the installer to submit proof of experience also..... very important. If any of the manufacturers require the installation to be inspected by their representative, make sure that requirement is specificed.
Another thing to specify and stress to the owner is proper maintenance. From my experience, the shake is NOT to be scrubbed clean as it ages. The "mossy" look adds to the protection of the shake..... if memory serves me correctly.
Basically, make sure the roofer supplies copies of installation requirement per the CSSB to the Owner and then trains the owner on proper care.
Depending on location, you might need to spec a fire-treated shake/shingle. Check the code and CSSB. I can't remember if straight shakes/shingles are considered Class A.
A shake roof costs a lot, but they do look great. |
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mx2
millennium club
Joined: 18 Jan 2006
Posts: 1968
Location: Miami, Florida
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| Posted: Thu Jun 07, 2007 10:42 am Post subject: |
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Ha! Thanks Kmapro...I had just figured it all out and came across the same product. The Cedar Breather is mint! And it's not spec'd in the CSSB's details at all...they mostly assume spaced sheathing. That won't fly around here (actually it would...hurricanes and all). And the humidity is insane here so...this works great!!
I'm with you phansford. All that you say is right on...had a spec written already with the same language you allude to. Not convicned about the moss though...found a recommendation for zinc strips to be laid at top course. I had a question about copper flashing as well...found two opinions saying copper is bad and copper is good with cedar. I spec'd the Cert-Last cedar (longer lasting pre-treament) and confirmed with the treatment manufacturer that copper has no more bad effect than any other material. Now my problem is venting....
Venting: don't have a soffit but detailed a "vertical soffit" (2" net free) just where the underside of the roof deck meets the wall but I have this odd pointy ridge...like a triangle with a 90 degree vert face on the backside. They don't make ridge vents in that shape....having trouble detailing a vent...any ideas on that?
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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kmapro
Joined: 03 Mar 2006
Posts: 129
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| Posted: Thu Jun 07, 2007 11:01 am Post subject: |
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Glad I could help..or atleast provide some insight
You've got me on the venting issue though. I guess I would handle it in the same manner as you seem to have already done...custom designing a vent that could be built as both, efficient for the application and aesthetically pleasing.
If I read your posting right, I am assuming that you applied a drip edge on the outset of the roof face and then stopped the fascia short of reaching the roof decking.
The drip edge could be deep enough to hide the visibility of the actual vent.
I probably read you wrong and trying to picture your situation is rather difficult without actually seeing it. |
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mx2
millennium club
Joined: 18 Jan 2006
Posts: 1968
Location: Miami, Florida
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| Posted: Thu Jun 07, 2007 4:50 pm Post subject: |
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Funny business trying to explain details with words...not our usual manner of communication. I'll try again, by explaining what I propose to do;
For proper attic venting, I need a soffit vent (intake) and a ridge vent (exhaust). Since I don;t really have a soffit (I have exposed rafters and T&G deck) I had to detail a wall vent. The roof eave itself is 3'-0" from the face of the wall, but the wall goes right up to the underside of the roof deck...
...anyway, at the ridge, I have wood framing for the sloped deck (with wood shingles...and Cedar Breather, etc  ) which reaches a peak that returns vertically straight down to a flat roof (like the back of a mansard).
so as I pitch up 3-1/2:12 at my ridge it returnsstraight down. It's a very acute angle and I need a vent there. I tried all sorts of configurations but settled on (so far) attaching added spaced blocking at the back of each truss (roof framing that is) near the peak to give me my 2" space. Then I cut back the sheathing and voila!
It's still a bit odd but so far it's the best I can think of...unfortunately my "posting" quota has maxed out so I can't show any sketches...maybe you could sketch what you think I said and I can see if you get it. Not easy describing these things...ha! Anyway, I appreciate the feedback already...it has been helpful, but at a minimum confirming something I was unfamiliar with. Thanks!
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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phansford
Joined: 18 Apr 2004
Posts: 556
Location: SW Ohio
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| Posted: Fri Jun 08, 2007 5:16 am Post subject: |
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| mx2 wrote: | | I'm with you phansford. All that you say is right on...had a spec written already with the same language you allude to. Not convicned about the moss though...found a recommendation for zinc strips to be laid at top course. I had a question about copper flashing as well...found two opinions saying copper is bad and copper is good with cedar. I spec'd the Cert-Last cedar (longer lasting pre-treament) and confirmed with the treatment manufacturer that copper has no more bad effect than any other material. |
I might be using the word "moss" incorrectly..... my point is that some people will get up on their cedar roof and scrub it with bleach, which I have heard is not good. My point is to make sure the installer provides maintenance instruction to the Owner. And from what I can tell about my limited experience with cedar roofs is that there are opinions on both sides of every topic 
| mx2 wrote: | Now my problem is venting....
Venting: don't have a soffit but detailed a "vertical soffit" (2" net free) just where the underside of the roof deck meets the wall but I have this odd pointy ridge...like a triangle with a 90 degree vert face on the backside. They don't make ridge vents in that shape....having trouble detailing a vent...any ideas on that? |
I think I get what you are doing here.... the "cedar roof" is a false front or a mansard that is used on the Public facade of a large building.
For open soffits, I have drilled three 1" diameter holes in the closure board (the one between each rafter). I install insect screen on the back side (attic side) of the closure board. When I have a sloped ceiling and I am building with 2x's, I also drill a hole in the joists at the top of the roof, to allow the air to flow from joist space to joist space.
Now I won't claim to have developed these ideas, but whenever I have gotten an old set of documents from a building owner/architect, I study the detailing. Of course, I am talking about quality architects. Some sheets I have copied and kept. The best stuff of course is really old drawings...... lost art type of stuff. My structural engineer is third-generation and about 75 years old. His grandfather, father, and brother were well-known architects here in town. This guy is a wealth of information about detailing and doing really cool detailing. It's a freaking shame that this wealth of knowledge will not continue to the next generation. 
I have also seen a detail by Hugh Newell Jacobsen or Grahamn Gund. They take the closure trim and leave a continous slot. Stainless steel flashing is installed at the slot. (Insect screening again is somewhere in that detail). Check out Jacobsen's first monograph (AIA Press). It has some of his detailing in the back, including the slot detail.
If I understand the "mansard" detail, just install a wall vent high on the back side of the mansard. That will create your positive air draw. |
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mx2
millennium club
Joined: 18 Jan 2006
Posts: 1968
Location: Miami, Florida
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| Posted: Fri Jun 08, 2007 12:07 pm Post subject: |
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My first thought was a wall vent however it's difficult to keep wind-driven rain out of the attic this way. Soffit vents have the added benefit of being horizontal and facing down...my lower vent is luckily covered by a 3'-0" overhang. But up near the ridge/peak, the vertical face would leave a continuous vent slot open to the elements and if I flash over it, then it defeats the purpose of venting. Instead, I'm trying to vent up through the deck over the ridge, under the flashing and roofing, down and around spaced blocking that is covered by flashing resulting in a continuous open 2" wide slot facing the roof deck.
Man I wish I could draw it for you guys....oh well. BTW, this is for a high-end residential project that we're adding onto a historic building and have to meet existing eave and ridge heights. The historic house has an added clerestory tower that the main roof dies into...and we're extending that roof line beyond...resulting in a flat roof between the two parallel exterior walls. It's a lot of detailing in order to retain the integrity of the historic character of the building. A challenge for sure...
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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phansford
Joined: 18 Apr 2004
Posts: 556
Location: SW Ohio
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| Posted: Sat Jun 09, 2007 5:19 am Post subject: |
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What if you extended the rafters past the vertical plane at the "ridge" and install another "soffit" vent? Something like this
There is a single-sided "ridge" vent out there for shed roofs that terminate into a vertical plane or a different sloped roof.... I just can't find a link.......
As far as this particular project..... PHOTOS!!!!!! Give us link to your firm's website. Love to see what others are doing. |
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mx2
millennium club
Joined: 18 Jan 2006
Posts: 1968
Location: Miami, Florida
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| Posted: Sun Jun 10, 2007 3:49 pm Post subject: |
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Hey that's exactly what I was trying to detail!!!! I didn't even think about the shed roof....of course! That link is awesome....you da man phansford (assuming you are a dude that is). 
That vent will work perfectly.
As far as photos and webpages...I'm not sure I am allowed to. I was never comfortable giving out info on the company I work for if I'm giving out personal opinions and getting itno a few heated discussions form time to time...and what happens if I gove (gulp) bad advice every once in a while...
sh*t. I just thought of all that....hmmm....
Is ther any legal recourse through this medium? Anyone?
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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phansford
Joined: 18 Apr 2004
Posts: 556
Location: SW Ohio
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| Posted: Sun Jun 10, 2007 4:38 pm Post subject: |
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1. Yes I am a guy .... check the website. (Its linked)
2. Don't sweet giving a link to your firm. If there is a website, we can probably find it....... I just like to see what others are doing. There are lots of architects doing good work and who could care less about getting published. So the website is a great place to see some nice work.
3. I don't think there is any legal obligations from posting on a public forum. But you need follow how you feel about these things. |
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mx2
millennium club
Joined: 18 Jan 2006
Posts: 1968
Location: Miami, Florida
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| Posted: Mon Jun 11, 2007 4:33 pm Post subject: |
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cool webpage...I like Sam's project there...(I assume the apple doesn't fall far from the tree huh?...cyou're not trying to talk him out of it?)
I'm still on the fence, about publicly announcing the firm I work for. Instead, I'd rather send you the info in private...
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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phansford
Joined: 18 Apr 2004
Posts: 556
Location: SW Ohio
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| Posted: Mon Jun 11, 2007 5:28 pm Post subject: |
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| mx2 wrote: | | cool webpage...I like Sam's project there...(I assume the apple doesn't fall far from the tree huh?...cyou're not trying to talk him out of it?) |
I put Sam's project on my website so people could go there to see the project before making a donation. He placed an annoucement in the Parish Bulletin for several months asking for donations. Once we posted the project on the website, the donations came pouring in. Sam raised nearly $1,800 in both cash and in-kind donations of materials.
The good news is that Sam completed the project over the Memorial Day weekend. He is now working on the paperwork. He has completed all of the leadership, service and merit badges for Eagle. Its an exciting time watching him complete his Eagle rank. But this is one focused kid.
Sam did the design on his own using Powercadd which is the program I use. |
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