With this approach, I will need to use thicker trim. Any suggestions from those who have done this, on thickness of trim needed?
Thx,
Dan
With this approach, I will need to use thicker trim. Any suggestions from those who have done this, on thickness of trim needed?
Thx,
Dan
Traditional lime wash still has tons of useful applications.
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Replies
My Hardie plank works with 3/4" corner boards and trim. I had thought I'd be wanting 5/4, but I was wrong.
So, with that said, depending on the furring thickness( which I did NOT do) add that to 3/4" for trim thickness. I'd still not wantto go fatter than 5/4 tho' myself.
Oh, see the thread on Hardie trim, the votes are in, majority of users here prefer other trim options.
Thx, I had already decided to go with Azek trim. Nice to see the validation though.
Dan
Can't say anything about the furring strips, but I have CVG cedar over the product that preceded rainslicker. (Mine is black instead of yellow, but I bet it's the same). I screwed the cedar to Polysteel ICF over the rainscreen. You'd think it might be wavy, but it's not. Seems to be doing the job. The siding is 5 years old now without any problems.
I don't think a rain screen for FC siding. I would use rainslicker with cedar but not FC. Check out some of the house wraps with drainage channels and small air movement like weather trek http://www.valeron.com/weathertreknew/. There are a few others.
I personally do not like hardie with 3/4" trim. It works fine with cedar but the FC is a little thicker and doesn't allow the trim to stand proud of the siding.
Edited 8/1/2007 8:27 pm ET by DDay
systembuilder,
I have the same question you have. I have attended many building science classes and posted on this forum. I always ask the instructor "do I need furring strips behind fiber cement siding in my climate(Dallas) or will a drainage-type housewrap suffice?" the answers have been "yes,no,yes,no" and "probably not but I would use the furring strips on my house" Some people say "why not just use furring strips?" "what's the big deal?"
I think the furring strips add complication around door and window openings and at corners....you also need to consider an insect screen at the bottom and top of the cavity and wonder if you are violating the building code by creating a draft space.
I hope that a drain screen housewrap will do the job...I just wish I could get a consistent or at least better than 50/50 answer. I want my walls to last 100 years at least.
"the furring strips add complication around door and window openings and at corners....you also need to consider an insect screen at the bottom and top of the cavity"
The have made rainscreen construction mandatory here. At first it was a bit chaotic, but standard details and materials for corners, the top and bottom, windows etc. are all in place now. Exterior penetrations for outlets, heat pumps, light fixtures etc. are really taxing the ingenuity of electricians, but soon enough they will be thought through too.
I don't think the complexity should put anyone off. It's just whether it is appropriate or necessary in any given climate. Here in the PNW it seems to make good sense for multi family projects, and houses with exposed walls with inadequate overhangs.
F&T,
Do you use separate "strips' under the window casing or do you use wider strips so that the siding and the casing "ride" on the same piece? Or do you double up your window trim? Rain screen practice is rare in our zone and I have only witnessed poor technique. What is the preferred method at the bottom of the cavity..between the strips? Do you use mesh or corrugated spacer at the bottom?
I understand why homes with less roof overhang would benefit but why multifamily?
Usually they use wider strips at the windows. The main strategy there seems to be the careful layering of peel and stick. Above and below the window the vertical strips are staggered to allow airflow. The top of the wall is either unvented, or left open into the soffits. Careful with that though. In some areas the void is considered a concealed space for fire spread reasons if it exceeds a certain thickness. For the bottom of the wall they sell a perforated galv. j trim, which deals with both insect and rodent protection.
Multi family residential buildings were where we experienced some 2 billion in damages in our "Condo Crisis" here in BC. They tend to feature more what I think of as high risk design choices for this climate such as flat roofs, decks over living spaces, and materials like acrylic stucco that do not have any redundancy in them should their application not be perfect.
Hey fingersandtoes,Are the details available online? On the CMHC website somewhere?Thanks, Todd
No, unfortunately I think they are only available as a disc or book as part of their "Best Practices" series. God knows why they don't make all of them AND the Building Code available free online. Crown Printers wants $300 for the BC Building Code. No wonder few builders or trades have a copy.
F&T - thanks for the info. Is the book you are thinking of "Best Practice Guide: Building Technology Wood-Frame Envelopes in the Coastal Climate of British Columbia"? It sure would be nice if these guys could catch up with the times.
I found a pdf file of details published by the warranty provider which is pretty good.
nationalhomewarranty.com/NEWPDF/ACCEPTED_RAINSCREEN DETAILS-4_july-2007.pdf
Edit: Sorry I can't seem to make the address link directly.
Edited 8/4/2007 12:32 am ET by fingersandtoes
Edited 8/4/2007 6:38 pm ET by fingersandtoes
Edited 8/4/2007 6:41 pm ET by fingersandtoes
Thanks F&T, that fits the bill perfectly. I've also been hunting around for details on using exterior foam board with a rainscreen. The simplest way seems to be to use a house wrap outside the foam, under the furring, though the guys at Building Science frown on that. They prefer the wrap under the foam, where it's less likely to be damaged, but I can't wrap (haha) my mind around how to detail windows and doors that way.
Qwkbrnfox, I am also looking for details(photos preferred)that integrate rigid insulation,furring strips and widows/doors. If you put the housewrap under the rigid (per some of the Building Science details) and keep the housewrap and window flange "together"then the rigid insulation and or furring strips push the window casing out too far to line up with standard window profiles.
"the rigid insulation and or furring strips push the window casing out too far to line up with standard window profiles."
It's a common enough problem that Starline Windows has come out with a Rainscreen Window with a deeper profile. I imagine other manufacturers may follow suit.
Have you guys in the PNW tried this product?
http://www.battensplus.com/
I heard that it is popular in California
Nope, I haven't, though I've seen it mentioned here (BT, that is) before. Looks like a good idea, and I have thought about ripping down heavy corrugated plastic for shingle rain screen, where the strapping would be horizontal.
Here's a link to a photo album from a guy who used the corrugated plastic: http://imageevent.com/okoboji_images/deloreshouse?n=121&z=2&w=0&x=0&c=4&m=24&p=120
Rain screen details start a picture # 134. Lots of other interesting ideas too.
-Rich
Rich, I think the link you sent is excellent..lots of good ideas. I also like the guys photos of the 1800 house and the building science
John told me that there was some talk about my delores house picture site, so I thought I'd check in and see whats being said.
the 1800s house is simply amazing, the detail that was put into it, knowing full well, there was no electricity when it was being built.
Rollie
Rollie, your stuff is very interesting...and I am determined to figure out this rainscreen stuff...did you look at the 30# felt suggestion further up in this thread?
I would like your opinion
John
John,
I looked at the post, and find it interesting. maybe not quite interesting enough to use it, but without a doubt, it will work, as designed. I don't think you can get much cheaper than the corrugated plastic, plus, you can manipulate the direction of the channels,vertically and horizontally, which is a good thing.
I think Paul Eldrenkamp really addressed this question well in a recent letter to the editor of Coastal Contractor Magazine. (see link below, also I pasted in the letter for y'all to see. We are using 1/2" OSB strips instead of the rain slicker/ cedar breather product on board siding with no vent channels for bugs to get in through. Cedar Shingles we still just apply direct tot he house wrap and don't seal them with any paint or sealer. But we also use a 35" roof overhang so they don't get much water. http://www.coastalcontractor.net/cgi-bin/article.pl?id=156 Drainage vs. Drying
I liked Mike Guertin's article on sidewall shingles ("Best-Practice Wall Shingles," May/June 2007). I have to dissent, though: He says that if you're using furring strips to create the air space behind sidewall shingles, "back kerfs are essential for allowing drainage and airflow between the horizontal strips." The expense of these kerfs has dissuaded him from using furring strips. In my experience, his concerns are unfounded. We've been using horizontal 1x3 strapping to batten out wood cladding — not only shingles, but vertical tongue-and-groove and shiplap siding as well — for nearly 20 years now. We've never bothered to back-kerf and, having monitored a range of such projects (including my own home) during those two decades, I can say with great confidence that lack of back-kerfing has never caused a problem. The building science behind the idea of the air space behind wood siding still seems rather fuzzy even to the top researchers. I've been hearing about the air space for 20 years now at a range of conferences and symposia, and the rationale for it keeps shifting. At first it was all about air pressure equalization; from time to time about moisture and temperature consistency on both faces of the siding; now, apparently, it's all about drainage. The fact is, if you have so much water getting behind your cladding that you really need significant "drainage," then you've probably got some serious issues that even the best-designed building envelope could have problems handling. A good exterior wall assembly, for the most part, needs to deal with only moderate amounts of water getting where it doesn't belong, and in my experience it deals with that water by giving it a chance to evaporate before the water does any real damage. It turns out water can take a pretty long time to evaporate before it does any damage, if I'm properly interpreting moisture meter readings I've taken over time on a range of projects we've done. What seems more important than quick drying is even drying. A piece of wood that does not experience wide moisture variations within itself seems to hold a coat of paint much longer than if there's significant variation from one point to another. My experience indicates that the mere fact of a sizable air space behind your wood siding seems to be enough to ensure even drying — whether or not there's significant drainage allowed for (there's always going to be some drainage, planned or not) and whether or not it's vented. This is important because placing an unwarranted emphasis on drainage or on venting will add costs incommensurate with the benefit. I would be keenly interested (and, I have to admit, surprised) if anyone knows of a situation where wood siding failed because it was installed on an air space that was unvented and "undrained." Another big factor in how long exterior wood siding lasts, not specifically mentioned by Mike, is whether the siding is sealed on all sides prior to installation. We have found that wood siding primed on all sides and installed over an air space can hold a coat of paint for at least 15 years — and still counting, with no sign of losing adhesion. This has been true not only of shingles but of clapboards and tongue-and-groove boards. This is important in the context of the article because siding that holds a coat of paint longer will also keep water out of your walls longer. Thanks very much for a great magazine. Paul Eldrenkamp
Byggmeister, Inc.
Newton, Mass.------------------
"You cannot work hard enough to make up for a sloppy estimate."
Shelternerd,
Are you saying that you are closing the gap between the vertical furring strips with osb? I am not clear on what is going on at the bottom of your wall. About your shingles directly on housewrap...are you using drainage-housewrap?
We close the bottom of the wall up completely with galv. flashing and OSB. We are not ventilating the 1/2" space behind the siding at all, just using 1/2" x 2" strips of OSB to hold the siding away from the house wrap so it won't hold water by capillary action. Unlike Eldrenkamp we put the siding up unpainted and spray the face only. I agree that all six sides is best practice but I'm not ready to spend that much cash on my projects at this time. (we have done that on some projects in the past and would do it if requested by a homeowner but it hasn't made it into our standard specification largely due to the size of our overhang. We haven't used the cedar breather yet but probably will in the near future esp. on two story houses, most of our stuff is handicap accessible one story with a 35" roof overhang so very little water gets to the siding anyway.------------------
"You cannot work hard enough to make up for a sloppy estimate."
Shelternerd,
Concerning painting siding on all 6 sides are you talking about wood siding or fiber cement? I have seen a Lstiburek paper that says to NOT paint the back side of fiber cement siding. I heard from another source that fiber cement siding continues to give-off moisture from the manuf. process. The siding in question was not Hardi-plank but a cousin of Hardiplank
You are correct, I'm talking about wood. For what it's worth I'm no fan of fiber cement, It feels like your siding your house with a sponge given it's ability to absorb and transmit moisture.M------------------
"You cannot work hard enough to make up for a sloppy estimate."
Yup. Certainteed preprimed is not (fully) primed on the back, and they say not to prime or paint it on the back.
ShelterNerd,
There must be a climate/site condition where a drain/rainscreen is not needed at all and other climates where an extreme rainscreen is critical. In between will be conditions where a drainage-type-housewrap will do the Job. How can we calculate what is appropriate for our micro-climates and interior ventilation strategies?
What do you think of the 30# felt solution? Would it "do the job" in North Carolina?
What about with OP SystemBuilder's climate and siding choice?
John
John"There must be a climate/site condition where a drain/rainscreen is not needed at all and other climates where an extreme rainscreen is critical. In between will be conditions where a drainage-type-housewrap will do the Job. How can we calculate what is appropriate for our micro-climates and interior ventilation strategies?What do you think of the 30# felt solution? Would it "do the job" in North Carolina?What about with OP SystemBuilder's climate and siding choice?John"OP is from southern Penn and is "about to use Hardiplank for the first time. I am planning on building rain screen wall. Plywood sheathing, Tyvek housewrap. Then either vertical furring strips of exterior grade ply (either 1/4 or 3/8, maybe 2 inches wide) or the Benjamin Obdyke product (Rainslicker?). Any comments from those who have done it this way? Thickness of ply furring strips, or experience using the yellow mesh BO product?"As previously stated I'm no fan of Hardi plank and you have a very good point about some climates not really needing a rain screen (ie hot and dry) I still think the OP's location warrants a rain screen but I can't say where the cut-off point is. It seems to me that the drainage plane wraps are a lot of money when you can rip up all your OSB scrap and achieve a better break. Maybe it's just too darned hot and I'm babbling here. I do agree with putting strips of thirty pound felt behind the joints of hardiboard. I'm not ready to stop taping my house wrap and go to lapped tar paper yet. Here are a couple of photo's of a rain screen we're doing on a pole barn dance studio this week which will have vertical poplar board and batten siding. Sorry to be so inarticulate today...
------------------
"You cannot work hard enough to make up for a sloppy estimate."
I used FC plank over 1x2 furring strips, which i put over 3/4" beadboard over 30# felt. The foam did two things...gave me a thermal break and was soft enough that when i stringed (?) my walls (the house had been moved 35 miles) i was able to get the fur strips in place by just scewing the furring strip into the foam the right distance, or spacing them off the foam with shims of the felt. It was a lot of fussing, but once that was done, the Hardie went up in no time. I also used felt behind each butt joint. I've got some really nice, straight walls now.
For the corners, i mitered a couple pieces of composite decking and fastened them together with poly glue and (i forget which now), scews or nails. One that i haven't installed yet has weathered a couple winters without problems leaning up against the house with the joint exposed.
Use Strips of #30 felt.
View Image
Troy Sprout
"A free people ought not only to be armed and disciplined, but they should also have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government."
-- George Washington
Edited 8/2/2007 6:31 am by Hackinatit
Hackinatit,
Nice concept. I have considered using "sill-seal gasket" the foam gasket that is commonly used between bottom plate and slab. I have also looked into 3 inch wide strips of rigid foam. I would like to see others photos of their "rain/drain-screen" details? What I like about your solution is that it is simple and not "building out" so far.
The felt won't block moist air like sill seal. It doesn't compress. It's easy to manage hundreds of feet at one time.
It's cheap.
It's cheeeeaaap!
Troy Sprout
"A free people ought not only to be armed and disciplined, but they should also have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." -- George Washington
Good answer
A local builder here in Iowa sold me on this idea - as thermal break mostly. He carefully vented his 1/4" gap under the hardiboard into a 2" sealed cold roof cavity so that air can move under the hardi into the cold roof cavity. On the west facing walls he says it gives a great benefit to reduce the afternoon heating of the wall. He used 1/4" furring and folded flyscreen on the bottom for insect barrier. Increased the trim to 1". It seemed pretty simple to me so I plan to do that.
Edited 8/2/2007 9:51 am ET by BrianH
The bugglies don't seem to come in where felt strips are used. The void behind the siding still serves as a narrow thermal break.Troy Sprout
"A free people ought not only to be armed and disciplined, but they should also have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." -- George Washington
Hackinatit,
I should have said "Good answer,Good Answer!"
I think the felt will also "dry" better than other options
Dries well.
Use standard trim (Miratec in my case)Troy Sprout
"A free people ought not only to be armed and disciplined, but they should also have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." -- George Washington
3/4" trim? Does that leave enough gap for air to move?
Brian,
I prefer thicker trim(5/4 actual 1 inch) myself same reason as stated earlier
I think it makes a nice shadow on the siding...it is one of those subtle things about the older homes that just looks good
Thanks - agree with you on that.
The felt firring at trim locations needs to be wide enough to fir the trim AND the siding,Troy Sprout
"A free people ought not only to be armed and disciplined, but they should also have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." -- George Washington
I just removed an 8' x 3' section of brick under a window on a 50 yo house. (french door retrofit) The #30 felt (heavier than today's #30) was absolutely perfect.
50+ year durability translates into extremely low cost/ft/yr.Troy Sprout
"A free people ought not only to be armed and disciplined, but they should also have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." -- George Washington