I’m taking off the vinyl siding on my house (built 1985) and am replacing with cedar shakes (pre-primed). Under the vinyl is 30# tar paper. Some of the paper is torn which I’ll replace but want to add some additional insulation board. Do I add the board on top of the tar paper then install the cedar or do I need the insulation board beneath the tar paper? I’m also replacing the aluminum soffit material with painted cedar w/vent. Any helpful advice greatly appreciated.
Thanks!
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Replies
Why do you want the additional insulation? It'll just complicate things around doors and windows, and anything thinner than 2" is unlikely to make much difference for a 1985 house.
Better to do a good job of housewrap and weather sealing.
Thanks DanH. This is just the discussion I was looking for. The house is well insulated already (2x6 walls & double batts in attic) but I figured while I had the opportunity to add...why not. I didn't know the <2" rule. Reading an old issue of FHB, installing a rain screen wall, I think, the author provided his opinion about tar paper vs. tyvek or other housewrap. Do I simply fix the paper or is there value in removing the paper and installing a housewrap?
Also my first time installing cedar shakes. I'm ordering them pre-primed and I'll paint once installed. I'm thinking that the reveal is 7" is this standard? The sales guy said that most people are using a stapler to attach, any other suggestions.
Thanks for your opinions/expertise.
I'm going to disagree with Dan and the sales guy in one fell swoop!ANY added insulation has a benefit. The biggest benefit would come from the tight seal that you CAN get if you install the foam panels neat and snug, and tape the joints. I am not a big fan of putting it on the exterior side of the wall assembly generally, but it depends somewhat whether you have a tight VB on the inside and on what your climate is.FG batts allow a trremendous amt of convection loss within the stud cavities which even a 1/2" foam panel would buffer. stapling shingles is the worst waste of time you can make in this project. staples commonly cause spllitting in the shingles and reduce the lifespan from a lifetime job to only fifteen years if you are lucky. Google the install intructions from the cedar beurea to see how the nail head should not be driven deeply enough to penetrate the wood. salesmen know sales, not quality craftsmanship. Let him stick to selling prioducts and listen to the manufacturer and to craftsment for installation advice.Exposure? Mike Smith would have more to say and local practice influences styles. Around here, 5" is the norm for cedar shingles, but if yours are really thickbutt shakes, 24" long, then anywhere from 7" to 10" can be fine. Too many folks cionfuse the diff between shakes and shingles.
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Between the studs and drywall is a plastic vb on the exterior walls. I don't want to screw up our vb by adding insul board on the exterior. I had the 1/4" fanboard in mind but could go with the 1/2" sheet material but again don't want to screw up the vb which is working well currently. I'm in Michigan so we get all 4 seasons... You were right I was confused... what I ordered were cedar shingles. I visited the cedar bureau and now I'm wondering if I can use a power nailer or if I need to hand nail... :-( Please say it aint so!...I was going to have to buy the stapler so your insight for the proper tool is needed.
What ever you do you don't want two vapor barriers. This can trap water in the wall. If you have a vapor barrier on inside do not add insulation that has a plastic vapor barrier on it. Personally I would not insulate. I would fix the old tar paper and be done. There have been great debates here on tar paper vs house rap. No one good answer.
Side note on Cedar shingles. Check with manufacturer and see if you need to shim out shingles to let air circulate behind them.You get out of life what you put into it......minus taxes.
Marv
Thanks. I did some reading in the archives and got a bit more educated. I now understand what nailer to get but the question I still have is if I need to add furring strips. Please advise.
I am an old hand nailer, but Mike Smith has good luck with a siding nailer with an adjustable depth tip. I vaguely remember it to be a bostich N60 ? Mike???For breathing behind the shingles - I don't worry much about that with natural shingles or prestained that have finish on both sides. Breathing is extremely important for roofing shingles which get soaked through. But since the rain runs off the siding faster, it is a tiny percentage of the water that penetrates the materials. A drainage plane will certainly help the material last longer.The added depth of the plane is a consideration, but easily dealt with in most cases. A backband can be added to casings to increase depth there, if needed.The product called Rainslicker is a woven mesh that provides for drainage plane. I have also used riopped 3/8" material stapled on horizontally in four foot strips, leaving a gap at butts for drainage.
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As you said, the biggest benefit is a tight seal. With 6" FG walls there is adequate (though maybe not great) insulation for most parts of the US, and one will gain much more for your time/money/effort spent achieving a wind-tight seal on the outer envelope than one will gain from more insulation.You can install 1/2" foam, but it will provide very little in additional insulation, percentage-wise (and understanding that there's a diminishing return from additional insulation), and it will be difficult to seal it tightly, especially around windows/doors.
Let me argue that from an academic standpoint - just for discussion only, since with a tight VB inside, I would not recommend adding foam outside on this one - but if you have a 6" wall with batts rated R-19 (ignore for the moment that at zero degreees with a thirty MPH wind blowing, that R-value is negligable) and add 1/2" of foil faced iso rated at R-3.5, you have increased the R-value on a still day by 18.5%.That is hardly providing very little in added insulation.Then when the wind is blowing on a cold day, the buffer against convection currents in the stud spaces actually increases the real effectiveness of the batts in the wall, so the addition of the foam can increase the resistance to heat loss about 20% overall.of course, that will not lead to a 20% savings in fuel because the windows and doors til make the greater opportunity for heat loss, along with infiltration at sills with exfilltration at the top.
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But you're talking theory, about a "perfect" wall. Tain't no such thing, especially in your average tract home with vinyl siding. With any sort of wind the effective R is cut about in half, and placing foam on top of that won't make a bit of difference if you don't cut out the infiltration into the FG.The big leverage is in cutting infiltration.
I guess I'm not making my point well enough. let's try for the third timeTHE FOAM WILL DEFINITELY CUT THE INFILTRATIONAND BUFFER THE TEMP DIFFERENTIAL!done now;)
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Well, we've been through this before, and neither of us is likely to change the other's mind, so let's leave it at that.
If I were doing it, I'd probably rip off all the J-channel, etc, then install a housewrap of some sort, taping seams carefully, and taping to window/door frames. Then install new brick mold (or your trim of choice) around the windows (trapping the housewrap edges), strap the housewrap with 1/2" or so furring strips, and nail the shingles/shakes to that. Caulk carefully where shingles meet trim, or use a trim detail that laps over the shingles. This is for an "average" northern climate, with relatively rare hurricane-force winds.For a site with significant wind-driven rain potential a full rain screen constuction would be more appropriate.
Great thanks again. I'll follow the advice. Since these shingles are primed & painted does it matter if they are red or white cedar. Reading some of the previous forums showed white reacting like a "potato chip" to weathering. Will this occur with a primed & painted shingle (which is installed on a furring strip)?
I also attached some shots of what I have gotten done so far...added pool and remodeled deck to meet it. Keeping in mind that next spring I'll remove the rest of the old deck and begin adding a 4 season screened porch centered on the doorwall. The other pic is the barn I built 3 years ago and am proud to show off in front of a group of craftsmen that I can do it ...but probably couldn't get paid for it :-o
When installing the shingles do you use a gauge of some sort to make sure your spacing along all of the axis is good/consistent (between courses & previous row shingle)?
The "potato chip" effect occurs mainly when the shingle/shake is wetter on one side vs the other. (This isn't just surface moisture from a rain, but moisture in the wood.) Having pre-primed shingles helps a lot by slowing down the rate at which moisture moves in/out and evening the moisture content out across the thickness of the wood. Having a ventillation plane behind the shingles also helps.
Is there a preference to what type of finish paint/stain that I use? Sales guy recommended latex but I'm not trusting his advice currently! I've used Pratt & Lambert on my other interior jobs and expect they have a good exterior product but would like your experienced opinions.
You can buy maibec shingles predipped in Cabot's.most of the prepainted or prestained siding of all kinds that we use is Cabot's in factory.
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I'm going to use a house wrap minus the insulation and good advice on taping/sealing.
When you are hanging the individual shingles do you build a gauge or have something to provide consistent 1/8"-1/4" spacing and then consistent reveal?
Thanks
It depends on the shingle and the look you're after. If they're really wet sometimes it's best to butt them together, but usually they're spaced. The supplier should have a recommendation for min/max spacing. If you want nice even courses scab a board below and rest the shingle tails on that.IIRC, the standard shingle hatchet can be used for spacing -- the blade for spacing between rows, and the handle length for spacing between courses.
I don't think anyone else told you this, but cedar shingles have a bad effect on Tyvek (from what I've read on this forum), so tarpaper would be better from that standpoint.
There's some debate re Tyvek, it's not reportedly a problem for Typar, et al,and using furring strips would eliminate any potential problem with Tyvek. Building felt has two problems: 1) it's hard to get a good seal at the seams (and there are many more of them), and 2) it doesn't let trapped moisture escape very well.