*
Whoa! This got me thinking too….Here’s a direct reply from Dupont:
Thank you for your inquiry. Simply placing housewraps in contact with wood
siding does not affect the properties of the housewrap. It is possible that
if sufficiently wetted, unprimed wood siding could bleed and have an impact
on water resistance of both building papers and housewraps. Tyvek® HomeWrap®
performed equal to or better than building paper in testing against
extractives. Extractive bleeding , as it is called, can be eliminated by
back-and-end priming of wood prior to painting and installation according to
the American Forest Products Lab and the Western Red Cedar Lumber
Association: http://www.wrcla.org/ The Forest Products Laboratory has the
following guidelines for preventing moisture accumulation within exterior
siding: use dry materials during construction, provide adequate clearance to
grade and drainage at grade, design with adequate roof overhangs, and
install appropriate flashings. For further information regarding
installation of Tyvek® HomeWrap®, please visit our web site:
http://www.tyvekconstruction.com/products/index.html or contact us at
800-448-9835.
Replies
*
Folks,
I am correctly doing a kitchen remodel that has involved new cedar siding. I put Tyvek on the sheathing, and back (and front)primed the cedar claps with water based Kill. I then painted them with latex paint(yellow). After the first rain, I had very slight brown, what look like water stains on the exterior surface. These "stains" wipe off very easily with a damp rag. There is no space between the claps where water or moisture could have flowed.
Did I do something wrong?
Thanks, Rick
AS: The remodel is still ongoing so there is nothing on the interior studs.
*
Rick,
We put on an addition to our home about 7 years ago and used redwood clapboard siding. On the first side that we painted we also used a water-based primer (not Kills) and had the same problem: a light brown stain which appeared after the finish coat was applied. I think that the problem is the water-based primer. It just doesn't prevent the bleeding of the acids in redwood and cedar. For the other two sides we switched to two coats of oil-based primer (alkyd) followed by a finish caot. Those sides still look fine. On the fist side, I went back over a portion of it about 5 years ago with only mixed results: the stain seems to have gone but I've had some peeling. I'm going to have to do it again next year. Any advice short of sanding down the whole side?
*so when is the last time any of you guys back primed 20 squares of western red cedar shingles - before installing (not that you would consider it after installing) - just curious.
*I'd never considered staining cedar shingles...I think they look best when left nekked to weather naturally.
*Hi Chip,I worked in Newfoundland for some 10 years and hung heaps of spruce clapboard as you describe. Cedar would cost the earth there ifyou could find it. Pine is easier to find but not as good as spruce because of dead knots and crazy grain. Both pine and spruce are installed dripping wet and the 6" stock can shrink 1/2" after installation. This doesn't sound like Fine Homebuilding, does it? I used to prefer oil-based stains to paint. I still have a special saw I made for cutting clapboard in place - we did a lot of repair work. Spruce and even fir are the original Newfoundland boards and they were usually painted with homemade fish oil and ocher paint- or is that stain?
*buz.. if that's what it takes .. that's what we'd do..but i would just spec the job with factory stained shinglesif they were RC.. they'd be R&R, Factory stained..the extra cost for materials would come back in reduced cost for the painting...if they were WC.. they'd be maibecs..or i'd talk the homeowner into setting up a tank and dipping them on site..""gimme a call when you got those 30 squares dipped ...""
*Buz, 1983, if white cedar shingles count. I seem to remember something just over 20 sq. The kids still hate me...Another thing I would like to toss into this backpriming seminar is what effect do you think backprimed siding has on house wrap when the primer is not completely dry? It seems most pre-primed siding is a little less than fully cured.
*I don't know you guys - I've been installing red cedar siding (shingles/beveled/channel/board & bat) for many years here on the north oregon coast and looking at some of my earliest work, it looks like you would expect after 20+ years. I back primed one project back in 1986 8" TK beveled cedar (from bear creek) and it looks no better or worse than any of the other projects. I've never (except for a short while in the late eighties) been a fan of "tyvek", maybe that is why my installations are holding up - they are all over 15# felt (currently use 4 Sq 15# felt)
*Hi Ron The pine clapboard I saw being installed in Newfoundland appeared to be kiln dried. I'm pretty sure it came from "off-island" (probably Quebec or New Brunswick). Once painted, it looked fine. However, I had never seen the rough side left exposed to the weather but folks may do that elsewhere. You may be right about spruce and fir as the original Newfoundland clapboard. I'm not sure. Anyway, I didn't see much cedar undoubtedly, as you say, because of the cost. I did notice that local lumber was used a lot for studs and sheathing and much of that was, indeed, very wet. In any case, the houses continue to stand and many are quite lovely: all and all, a beautiful place to vacation.
*Reading through this thread, and others on similar topics, it seems the common problem is moisture (either the tannons or moisture driven through the back from the wall) being trapped in the siding, and blistering the paint.I'm no painter, but it seems to me you could avoid this problem by eliminating the paint altogether and use a pentrating oil, either natural, or pigmented. I don't think these oils form a skin over the pores of the wood and moisture can come and go as ambient moisture levels change. Am I all wet here?
*hey Chip! What are you doing over here on the wild side? Nice meeting you; how was Newfoundland?
*There's a ton of good information in this thread. I thought you'd all like to know that we have an article upcoming about a rainscreen wall that was retrofitted to a house that had a stunning housewrap failure (Unprimed cedar over Tyvek). Joe Lstiburek, in fact, uses photos from that job in his presentations. Look for it in the February/March 2001 issue.Andy
*Jim; I'm not an expert on exterior finishes, but here's my take...the finish is supposed to deal with moisture exiting/ and entering the house, and help preserve the wood. Penetrating oils have practically no resistance to water or water vapour, so the water vapour isn't going to be trapped inside the wall, but they won't keep water out of the wood, and they require a lot of upkeep (things like Watco resist water to some degree, but that is because of the varnish that is added to lots of those finishes). In my climate anyway, on wood siding, the only things I trust are a film forming finish like paint, or cedar shingles. I've never had occasion to use the new 'stains', but I think they have to be film forming finishes to work well.
*Okay, but oil and water don't mix, right? So if your boards are saturated with oil, they can't absorb any of the water that hits them, yet, moisture vapor can move through there...maybe? In fact, isn't this the same principle behind creosoted poles or pilings?
*Ok, so here's what I'm digesting,(assuming were painting)1. If installing cedar claps with the smooth side out, lightly scuff to remove the mill glaze.2. Use SS Nails. What length?3. Use a scarf joint at breaks, no butt joints.4. The most common exposure is 4" using 1/2 x 65. Always backprime claps. Use a oil-based primer with a latex top coat.6. Caulk all joints around window trim, corner boards, facia, etc...(with a paintable caulk.)7. No one likes to use Tyvek unless a free sheet of corian is included with each roll purchased.8. The preferred wrap is 15lb felt paper. Which still requires backpriming.9. If using Tyvek, a rain screen is highly recommended. Backpriming is manditory.10. May the force be with you!A couple of things I did not see in here, details on nailing pattern, such as size of nail, is setting and puttying required? Spacing? Distance of nail up from butt edge?Details on rainscreen, I assume your refering to using 1/4" lath. What is the width of the lath or other strips? And what about spacing? 12" on center, 16" on center? Of course all trim gets bumped up to 5/4"Did I miss anything?
*jeff.. you got it..the nail depends on what it's going intoyou want minimum 3/4 inch penetration so the minimum length would be inch & half.. we usually use a two inch ring shank SS siding nail with a small waffle head... we've also used silicon-bronze ringshank boat nails .the nail only goes in ONE PLACE (see post #1).. and the nail only goes thru one clapboard.. just OVER the top of the one below.. if claps have two nails in them ... they splitb but hey, whadda i no ?
*
When you butt two pieces take a small (5 x 5) piece of tar paper and put it under the butt joint. When the crack opens up in the future the rain will hit the tarpaper and exit, otherwise it could go behind the lower clapboard.
*
It seems I use the same nails as Mike. I nail over the studs, and all clap joint break over studs as well. I pre-drill before nailing board ends.
I do butt joints, cut a tad long and snapped into place. Joints stay tight.
If rainscreen, lathe falls over studs as well.
In a rush...best of luck!
*
I think that most of us agree that some of the basics of siding with cedar include: ss nails, backpriming, housewrap instead of felt, etc... but how about two lesser discussed topics:
1. What is the most common exposure 4, 4 1/2, or 5"
2. Cost? Here in upstate N.Y. 1/2" x 6" VGC Cedar can be had for .73 cents a lin. ft. What type of prices are you guys getting in your part of town?
My supplier also stocks mahogany clapboards, also strange as it seems Home Depot stocks no clapboards at all.
Thanks Jeff
*jeff, i've used the mahogany.. didn't like the results... the grain was too unpredictable... and some of them moved and bent like pretzels after they were up and stained..a 1/2 x 6 is 5.5 and the exposure is 4 inches with 1.5 inch lap..some of the colonial details would start at the bottom course with say a 2 inch exposure and gradually increase to the full 4 inch..by the time they got to the bottom of teh window sills..on the theory that the bottom ones got more abuse (?)make sure it's CVG.. and the nail only goes thru one clapboard.. just OVER the top of the one below..we like to break our joints with a scarf joint over the framing, rather than a butt joint..your price sounds about right.. but i've paid about that for CVG factory primed with Cabots Problem Solver.....
*Don't go nailing that Cedar directly on the housewrap... use furring strips or a breathable membrane between.Nailing to felt is ok... but not housewrap. Cedar will damage the housewrap.
*good on ya george... this is just like tag-team wrestlin....i dint wanna hit him with the tyvek news......Happy labor Day to All !
*Mike, Could you elaborate on your nailing method. I am in process of constructing an addition where the rest of the house is nailed such that the face nails in each course penetrate the course below. I assume that that your method allows for cross grain movement. The house I am working on shows no signs of splitting etc., due to the nailing pattern.ThanksTom
*Mike,I hate to say it but in my area we have pretty much only one supplier of cedar (red or white). Anyone else is basically piece-meal if that and way over priced. Needless to say I have to drive to Boston to get anything primed. Is Cabots Problem Solver a latex or oil based primer? Does it have pigment? I can assume that if you purchase unprimed cedar that you also use Cabots to preprime?One last thing, am I missing something about installing cedar over Tyvek? Didn't Fine Homebuilding publish a story by Rick Arnold and Mike Guertin on installing clapboards and in the pictures, with exception to felt flashing around windows, the cedar was being installed over Tyvek. I get the impression that you guys don't like this.
*George, Can you elaborate a little more on your Tyvek and felt comparisions? I thought that Tyvek was a breathable membrane.Furring strips seems like a lot of extra work including upgrading sizes on trim plus the warpage factor from not being able to lie flat against the wall sheathing. Although I totally understand the need for an air space for other reasons.Also how much are you paying for cedar clapboards in your area?
*When we added an addition to our house 7-8 years ago we sided with redwood clapboard. Redwood clapboard is no longer available in my area (Michigan) and I wonder if cedar may also become a thing of the past or, at least so expensive as to make alternatives more acceptable. On a recent vacation to Newfoundland I noticed that builders were using pine clapboard. The clapboard is 5/8" or 3/4" at the but end and the rough side was left exposed to the weather. The idea is that the rough side holds paint better. Knots were sealed with shelac and then the clapbard was back primed. As I understand, pine clapboard was the original clapboard in Newfoundland and New England and much of it still survives. Finally, here in Michigan, most builders use a story pole to determine exposure. While exposure tends to be around 4" that figure varies a bit so that narrow clapboards are avoided around windows.
*Jeff, Cabot's Problem Solver Primer is an oil based primer and does have pigment. Of all the primers I've used, it is my favorite ....it seems to work well on weathered wood. It may be available in latex, also ......not sure don't have literature handy. Some clapboard makers offer factory primed clapboards. As far as exposure, many of the older homes I've worked on had less exposure on the north side, some as little as 3 1/2". Be aware if you decrease exposure, you may want to increase the thickness of the cornerboards and trim so the clapboards don't stand proud of the trim .......5/4 stock works fine and even with larger exposures I think it looks better.
*Jeff, You don't want to have nekked cedar touching Tyvek, so you can either backprime, use a rain screen, or use tar paper). If you're in a coastal, high wind, horizontally driven rain environment I highly recommend the rain screen. Furring is simple, but the trim does have to be brought out as well. Depends on how (well) you want to do it.For the graduated exposure Mike mentioned, in many locales this detail was originally just used on the non-gable ends of the house. Prices vary, but I'm looking at .85 to 1.05 per foot (CT).Always stainless.No double-nailing.
*So, somebody answer the question, what's wrong with puttin western red cedar siding directly on tyvek?I have never seen furring strips used on it anywhere, and, particularly here in central NC. I like to do things right when I can, so, hip me.That narrower exposure at the bottom of buildings in the Northern climes, has to do with snow drifts, at least that's the way it was explained to me when we were working on some Shaker buildings in upper NY. I guess that's a kind of Mother Naturely abuse.Sided plenty on Tyvek, do I need a lawyer? BB
*the tannic acid in untreated cedar apparently decomposes the Tyvek, so it becomes brittle and subject to failure..the lawyer might not be a bad idea.. you wanted for anything else ?(besides the tyvek high crimes & misdemeaners)
*Jeeze, I need more than apparently. Anybody really see this happen? Is there an info center for this? And, I'm not wanted for anything else, nothing...well, I did put the Tyvek on upside down once.. hmmmPay no attention to the man behind the curtain, BB
*Hey BillyI'm with ya on this one all the way. Tyvek sure seems like some pretty durable stuff and I also like to hear some solid evidence to this. Too bad someone from Tyvek couldn't come on so we could hear their point of view. Hey Andy ??????????One more thing, is everyone saying that if you back prime cedar its ok to place directly against Tyvek?
*Whoa! This got me thinking too....Here's a direct reply from Dupont:Thank you for your inquiry. Simply placing housewraps in contact with woodsiding does not affect the properties of the housewrap. It is possible thatif sufficiently wetted, unprimed wood siding could bleed and have an impacton water resistance of both building papers and housewraps. Tyvek® HomeWrap®performed equal to or better than building paper in testing againstextractives. Extractive bleeding , as it is called, can be eliminated byback-and-end priming of wood prior to painting and installation according tothe American Forest Products Lab and the Western Red Cedar LumberAssociation: http://www.wrcla.org/ The Forest Products Laboratory has thefollowing guidelines for preventing moisture accumulation within exteriorsiding: use dry materials during construction, provide adequate clearance tograde and drainage at grade, design with adequate roof overhangs, andinstall appropriate flashings. For further information regardinginstallation of Tyvek® HomeWrap®, please visit our web site:http://www.tyvekconstruction.com/products/index.html or contact us at800-448-9835.
*Extrative bleeding? What the bloody hell is that?What am I gonna have to fix now? BB
*Sap
*"Sap"..Kind of...Cedar and redwood have mostly water soluble extractives. Oils, tannins, phenolics, etc. It's mostly softwood species like fir or pine that have pitches and resins which are not water soluble. If the siding is kiln dried that usually is sufficient to harden the sap so it will not bleed. Green siding, or air-dried siding is much more susceptible to pitch or sap running after the siding is installed. Sap or pitch is most often found in the knots.For cedar and redwood...the big problem is that most building envelopes push moisure through the exterior walls, from the interior living spaces outward, to the exterior. This moisture will pass through a spun-poly housewrap. It may then condense on the back side (not the show side) of the cedar siding. If the back face of the siding is untreated, unsealed, unprimed, the cedar will absorb the moisture. As it is absorbed into the wood (and even if it just stays on the wood surface) it will dissolve the water soluble extractives in the cedar.These extractants, some of which can act as surfactants, can adversely affect the housewrap. The surfactants and polyphenolics can create a bit of a problem with the micropores in the poly housewrap. It eventually loses it's ability to do one of the jobs that it was designed for, passing water vapor, and the housewrap ends up acting as a condensing surface and may hold the condensed water against the house sheathing. Not good.Some moisture that enters the back side of the siding passes all the way through the siding, carrying the extractives with it. When the water hits the show side of the siding, it will evaporate. The extractives are left behind on the surface of the siding. This can result in anything from subtle blotchiness to outright, very obvious brown or reddish-brown stains.Ever see a cedar clap house which turned blotchy within a year or two of being stained? More noticeable with transparent or semi-transparent stains...but thats a good sign that the siding was never backprimed. It also depends on how the house envelope handles moisture.So...if you're installing nekked cedar, either don't use a spun-poly housewrap, or install a rain screen. Simpler to go with tar paper.If you're going to coat the show face of the siding, backprime it before you install...no matter what housewrap you use. Moisture can pass through the backside of claps that have not been backprimed, and as it passes through to the front it can lift the paint on the front and cause pretty amazing water blisters.
*Mongo,That summary would get me an "A" in English composition. If the cedar is backprimed, where does the moisture go to when it passes through the Tyvek and hits the primed back of the cedar? Does it just sit there and accumulate?If the show side is to be painted with latex, what should the front and back be primed with latex or oil-based primer?
*Thanks, Jeff.If you install a rainscreen the vapor will simply dissipate via the air space.With claps against the sheathing excessive vapor will typically pass through the overlap in the claps to get to free atmosphere. One of the "fixes" on the market for too much moisture in the walls is placing tiny wedges between the claps to make it easier for vapor to escape from between the claps and the sheathing. I've never used them, but have heard others give favorable reports when they're used on sick houses.If for some reason you had an excessive amount of moisture vapor condense within the "siding sandwich," or had wind-driven rain blown behind the claps, or even had faulty flashing that allowed water to somehow get behind the siding, the housewrap should do it's job and simply shed the water downward.Oil-based primer.
*yay, mongo... best explanation yet i've seen..not bad fer a jet jocky....
*Do any of you buy claps at Bear Creek Lumber? While you may have to plan ahead I've been happy with them but. Cedar and redwood. http://bearcreeklumber.com/On double nailing, there was an interesting letter to the editors exchange - like 6 months of so - in FHB 10 or so years ago. About split between the fanatic traditionalists that would never double nail and the pragmatists who believe contemporary claps are too flat sawn and too new growth to lay flat. Very interesting discussion and quite civil.
*
OK, I have been reading this thread and I have a couple questions. I will be using 4 inch bevel on an old (1904)house with 7/8" inch shiplap (I think) sheathing. I have icynene in the walls. The home is in N. Illinois. It will be painted.
1. Is a "rainscreen" basically an air pocket between the sheathing and the siding? Why is this necessary? Would the thickness of paint stirs be enough?
2. The current siding has 21/2-31/2 exposure. With the 4 inch siding, is 1/2" overlap enough?
3. As to choice of woods, redwood, cedar, VG pine? It seems the old siding is Southern Pine. What about grades/grains?
4. As far as attaching, what about stainless screws? If they are countersunk and covered with Abatron? It seems it would save wood, and wouldn't the screws hold in the 7/8" sheathing? Drawbacks? (Besides time)
Thanks,
Dirk