*
do you recommend backpriming cedar siding with a sealer if it will be stained with an opaque stain?
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Skim-coating with joint compound covers texture, renews old drywall and plaster, and leaves smooth surfaces ready to paint.
Featured Video
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
*
I always recommend back priming cedar siding. I usually just back it with what ever goes on the face side. I've seen first hand what this does on my own house. It cuts down on expansion and contraction, cupping and checking and caulk seems to adhere better.
*I second kcoyner's advice. Definately backprime. - jb
*Calvin, Ditto the others.Backpriming does several things:*It will prevent the cedar from coming into direct contact with your housewrap, thus eliminating the cedar/surfactant issue.*It stops cedar stain bleed-through. Obviously more important to prime the face of the board in this case to prevent the stains from bleeding through your finish top coat.*By coating the back of your claps, it helps minimize water absorption through the back of the clap which could then cause blistering/failure of the top coat on the front/face of your clap.*By coating all faces of the board equally, it does make the board more stable as kcoyner outlined in his post.IMO, factory priming may be insufficient. Depends on the manufacturer. Some prime better than others, but most look like a transparent whitewash. I always orser the claps nekked and prime on site.
*...oil based primer?
*yessir
*...was that you who mentioned rainscreens a few months ago?
*yessir
*...do tell...please...
*jb, are you asking for a description of a rainscreen? If so, try this blast from the past. Scroll through the thread, the info is buried there somewhere.
*Well, I just thought the conversation about rainscreens goes hand in hand with questions about backpriming Cedar and installing it against housewraps. When you guys brought it up back then, I had never heard of it and I think it's a great technique. In fact, I tend to believe it eliminates the need for backpriming so any tannons or moisture in the Cedar can work their way out of the siding through the back, reducing the blistering-paint adhesion problems we have all seen. Thanks for the link. - jb
*Whenever I put a coating on the front face of a board, I like to have a similar coating on the back. The only time I don't backprime is when applying cedar and the owner wants it unfinished and unsealed, just raw wood. In that case the rain screen takes on a bit more importance, not just for shedding those runaway wind-driven raindrops, but also for keeping the cedar off the housewrap.I'd still be a bit concerned over having a solid stain on the face of a board and having nothing on the back. In regards to both board stability and possible moisture working through the board and blistering the stain. I believe (read: I may be wrong!) that the only way the tannins will come to the surface of a board is if they are brought out by moisture. Thus, if you keep the board "dry" (seal all sides), you should not get any leaching.My concerns may very well be unwarranted, but it's one of those things...t'was the way I was taught, y'know?
*Yup, I know exactly what you mean about reusing old techniques until it is clear that they should be changed.And I have long been a proponent of "ballancing" surface treatments on each side of a piece of material - whether it is a table top or a piece of siding - so I'm with you there. Do you think this idea has merit? - The weather side of siding takes much more abuse, UV rays and water, than the back does. This makes me think that within a couple years you don't have a ballanced piece anymore anyway and any moisture will try to leave the board through the face, since it constantly has air of different moisture contents and temperatures moving across it. By using a rainscreen and leaving the back raw, you allow air to move across the unpainted surface where it can absorb any moisture. This is only an idea I have, but what do you think? - jb
*I bought my first house back in 1985. Back then I had very few building skills, even less money, but lots of energy. A previous owner had used a disc sander to remove old paint - leaving the cedar siding pitted and gouged everywhere. Obviously, the paint had had a severe peeling problem. I wanted to paint it but knew it would never look very good. Someone gave me an old window so I decided to install it on the house. When I removed the siding, I was surprised to see that the back of the wood was beautiful, clear old-growth cedar. This house was built in 1940 in Seattle - no roof overhang at all. I got this bright idea to carefully remove all of the siding on the house, power plane off the painted edge, and reinstall back side out. So thats what I did. Of course some of the siding was too damaged to re-use so one small area was replaced with new. I remember I painted the house with 7-year Fred Meyer paint and it looked great when I sold it. Well I drove by my old house last weekend, 13 years later. My paint job still looks good, except for the part of the house that I replaced with new siding.The moral of the story? The old siding is effectively "back primed" with the old paint and is still holding up well.jim
*We've been backpriming and edge priming since '76. The only time we didn't was on Marvin windows that came thru factory finish in '85. All the trim on those windows has been replaced with 5/4 cedar, back and edge primed. The Marvin casing wicked and rotted from the bottom up.Two of the Capes we built in '76 are a block up the street. I see them every day. 5/4" pine trim with red cedar 1/2" x 6 clapboards 4" to weather. Everything on those two houses was oil primed, front, back and edges and all cuts were primed at installation. Two coats of SWP A-100 latex.Both houses still have original paint , no peeling. A little fade on the blue one. But the yellow one looks great. 23 years on a paint job. I'll backprime til I drop.
*Mike - that's impressive.
*Use Zinsser primer sealer staincoater. It will seal in the tannin that will bleed right throught the alkyd primers.
*I think any moisture absorbed by the clap, regardless of which side it entered, would tend to be drawn back out through the face of the claps. Combine sunshine, breezes, a delta-T with the face of the clap warmer than the back, and I'd think moisture would mitigate to and leave the board via the face.Not all houses have decent envelopes, and thus pass moist air through the walls, from interior to exterior. Having a bare back would, to me, only be an invitation for more water to enter the board. Does it leave via the way it entered, out the back of the clap? Does pressure force it deeper into the clap, causing the face paint to fail? I dunno.I do know, with no rainscreens:*I've seen paint jobs on houses without backpriming fail. Big time. Big paint blisters filled with water. Being able to peel off a chunk of paint 8 feet long with my fingers due to no adhesion, etc.*I've seen stain jobs with no backpriming turn blotchy every two years as moisture is carried through the board to the face, bringing the cedar's stains through with it.*I've seen paint and stain fail prematurely on siding that hasn't been backprimed. Less spectacular failures, but failures nonetheless.*I've seen early morning condensation on siding highlight the wall studs as a result of thermal telegraphing.Now, on houses with backprimed siding, I've never seen any of the above problems except the last one, the condensation telegraphing the stud locations. Longer lasting paint/stain jobs as well.On houses with siding backprimed and with a rainscreen, I've seen no problems at all. Zero. Paint/stain also lasts years longer than in the other instances.Many of these moisture problems are caused by who ever built the place not constructing a decent envelope, one that reduces moisture in the house.jb, once again, I may be wrong...I just think I'd be courting a problem by not backpriming, rainscreen or no rainscreen.The cost in labor and materials to backprime is insignificant. I will ALWAYS recommend doing it. The cost to add a rainscreen is more problematic, only due to occasional trim considerations. However, the cost of both is nothing compared to the aggravation, cost, or embarrassment of a failed house that I'm responsible for. Some folks truly don't want rainscreens. They do provide a benefit, however it is intangible to some. In coastal (high winds, wind-blown moisture) areas near where I live, the benefits are understood. Everyone, however, wants backpriming once the downside is explained.Sorry to yak for so long. You bring up good points, I really had to do some head scratching there...I think a bare-backed clap on a rainscreen might perform decently, I also think it could fail miserably...I just don't want to be the one doing the experiment!
*Thanks. No arguing with that logic. - jb
*thank you all very much. the homeowner with the checked,cupped,and pealed siding that needs replaced (on the sun and weather side) also thanks you.this internet stuff is a beautiful thing! the knowledge and experience that is offered here, continually amazes me.woodstock nation, on the hoof.
*From what I've read and seen in our middle-aged neighborhood, I agree with Mongo completely. It makes so much sense -- some moisture is expected to get into the wood, and it has to be able to leave gracefully or you'll get rot/leaching/paint failure etc. (hence a rain-screen rather than sopping housewrap); and you want the moisture to distribute evenly through the wood, so you treat both sides the same to avoid cupping, etc.Oil primer, including Zinssner, block tannins and moisture ... I like the Zinssner because it dries a million times faster than the anti-VOC-formulated oils so you can get on with your life. With a sprayer you can do it all very fast. Latex/water base Zinssner doesn't seal the same, but I assume it's still OK if you provide back ventilation and backprime? Bare cedar would be the most exposed treatment, and of course it needs to breathe too.On the rainscreen, I was looking at CedarBreather the other day. It's basically a loose plastic mesh like one of those kitchen sink scrubbers. I'm wondering whether it might be a good middle ground -- faster than a rain screen to install with fewer problems like trim or wavy siding, and 'open' so that liquid water won't get caught behind the siding. Anyone tried it? I'm actually thinking of putting it behind fiber-cement siding, to protect the paint and to keep the siding from touching any aluminum flashing that remains.
*Excuse the digression, but what's this about Hardi type siding and aluminum flashing? Is that a bad combination? Thanks - jb
*Used cedar breather under cedar shingles. great stuff, but I don't see any need for rainscreen or cedar breather behind Hardie type cement siding. And yes, we use aluminum flashings with cement siding, colored coil stock, bent on site in our break. Also stainless nails for facenailing.
*I've been back priming siding and trim for 25 years, now that we work with Hardi products, they say that back priming is unnecessary. Kind of hard to get used to.... Any thoughts about this??
*Well, I know you can't use it within 6" of the ground or vegetation because it will absorb water and disintegrate, similar to wood, so...it seems at least resonable to ask if it can absorb moisture from the air like wood does. Good question.
*I remember reading -- I assume on the hardie site, I wish I could find where -- that the alkaline nature of this cementious product could corrode aluminum. Makes sense, doesn't it? Maybe it's nothing major to be worried about.The material will absorb a certain amount of moisture, so I wonder whether paint retention will depend at all on whether the backs of the planks can breathe. Probably overkill, but I am curious. I like the idea of giving the housewrap (which will be tarpaper in my case, incidentally) room to dry.
*What's the problem with cement products and aluminum? Is this something else well known that I'm ignorant about?
*jim, supposedly the lime maybe corrodes the aluminun. have not seen this happen but cannot say it ain't so.
*Yep, that's the theory. Can't figure out now whether it's important. They do caution loudly to use alakali-resistant primers. Perhaps paint is protection enough. I'm not -that- worried, just mentioning I'm sure I read this -somewhere-....Well, I found an -example-, from an old JLC (5/98) 'letters to the editor'. This isn't where I read it, but maybe I saw it on an mfr Web site? Pretty sure it wasn't Hardie's.:Fiber-Cement Details To the Editor: I was delighted to see the article “On Site With Fiber-Cement Siding” (1/98), ... I have also thought of using aluminum siding type corner pieces. Some help would be very much appreciated. Guy Groulx Center Town Home Repair Fort Worth, Texas David Frane responds: ... Be careful about using aluminum trim pieces to get that wraparound look. Raw aluminum will corrode when placed in contact with alkaline materials like cement. Check with the manufacturer before you use nonstandard details, because they might void your warranty.
*I always thought all those stock flashings at the lumber yard were aluminum (except the few galvinized). Do they make a line of standard flashings for Hardi products then?
*I'm going to be real surprised if the Cement siding guys say not to use aluminum flashings. I've read Hardie and Abtco (now Ashland Davis) literature and talked to both before we did our first job. None of the lierature says anything about materials for flashings, they do talk about the nails, and venting and vapor barriers and keeping the siding 6" above grade level. Their detail drawings show typical window cap flashing details, but never talks about aluminum.If this were true, how could anyone use it without going to lead-coat or copper. I think we're into urban mythology here, but I'd like someone to quote chapter and verse from Hardie or Abtco (Ashland Davis) to settle the issue. I mean roofs terminating at vertical walls, rakes landing on roofs, window cap, decks, sheathed chimneys, you name it. what would you use if you're not site bending flashings on your protable breaks ?
*I'm going to be real surprised if the Cement siding guys say not to use aluminum flashings. I've read Hardie and Abtco (now Ashland Davis) literature and talked to both before we did our first job. None of the lierature says anything about materials for flashings, they do talk about the nails, and venting and vapor barriers and keeping the siding 6" above grade level. Their detail drawings show typical window cap flashing details, but never talks about aluminum.If this were true, how could anyone use it without going to lead-coat or copper. I think we're into urban mythology here, but I'd like someone to quote chapter and verse from Hardie or Abtcb to setle the issue. I mean roofs terminating at vertical walls, rakes landing on roofs, window cap, decks, sheathed chimneys, you name it. what would you use if you're not site bending flashings on your protable breaks ?