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I have a wood shingled porch roof which is leaking due to ice damming. The slope is a little under the minimum 3 in 1, but the rest of the house is shingled in wood and I wanted consistancy. I’m perfectly willing to pull off the problem area and put down a membrane before reshingling but then I have the problem of no air space under the shingles. Can someone tell me of a nail self sealing shingle underlay membrane to use and how much I’ll shave off the normal wood shingle lifespan if I use this approach?
Thanks in advance, Jim
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jim
I would think anything like Ice and Water shield would do as it's "self sealing", but you should be looking for the root cause of the ice damming which is heat rising from underneath. Eliminate this source with adequate insulation and the ice damming will disappear.
-pm
*"adequate insulation" and ventilation.But why would adding a membrane affect the airspace under the shingles? Put the menbrane on the sheathing and build-up the roof as before.And why don't you just shovel off your roof? I can't imagine snow sitting on wood shingles is a good thing.
*Adding the membrane under the shingles to prevent the backup of water from entering the roof. There isn't any sheathing, only furring strip. Shoveling the shingles is easy to say, not so easy to do. I was up there twice, this storm, it's a big dangerous job. One contributing factor is that there is an upper roof from which there is added run off. I will put a gutter up there this summer. That only aggravates the leaking, doesn't prevent it. The ceilings are well insulated, but there is a 16" overhang that starts the dam.Thanks, Jim
*I wasn't aware you didn't have sheathing, Jim. I doubt that a membrane will be very effective if not applied over sheathing, but if you want to go that route you can sheath the last 4 ft of the rafters, apply membrane, and install a ventilating underlayment. The ventilating underlayment is about 1/4", and should give you a level surface to shingle over that will do what you want. If the ventilating underlayment comes a little thicker, or you want to use a thicker plywood, you could recess the ply below the tops of the rafters. As for the shoveling thing, I hear you. If my plow doesn't move snow it doesn't get moved, but maybe you could get one of those long roof shovels and just pull the snow off the edge as high as you can reach easily.Oh well, good luck with this...
*Thanks, Qtrmeg, the sheathing between rafters, then membrane and ventilated underlayment sounds good. I have to solve this without resorting to physical snow removal.Jim
*Plus, you really want to be careful walking on the shingles. Have seen more than one roof's life shortened by a few uneducated steps.
*QtrmegJust found my way back here.I don't agree with your "ventilation" add-on and I ain't alone.Read up on Hot roofs vs. Cold Roofs. Read up on Joe Lstibruek http://www.buildingscience.com/ .try here to start:http://www.buildingscience.com/FAQs.html#anchor810986Educate yourself!!!-pm
*Patrick, seeing that you are the educated one, could you tell me if not venting roofs applies to any house, in any location?I see, by what little education I endured with your link, that not venting in a cold climate prevents snow from entering the attic space. Did I miss something?
*QtrYeah you missed a lot. There's a pile of info there. You can lead a horse etc.,Here's some morehttp://hem.dis.anl.gov/eehem/99/991111.html#99111101Also the Breaktime archives are full of discussions under "hot roof", "ice dams", "attic venting" etc. Here's a recent one Steve Zerby "Installing attic vent from inside" 1/3/01 5:54pm-pm
*ya got two problems here.. one is the ice dam.. the other is premature failure of the wood shingles because they aren't ventilated from behind .. as with a skip-sheathed roof....you can do the cold roof.. if you want..or the ventilated roofeither way you can start with a solid sheathing...then ice & water membrane...then i would use Cedar Breather.. then the wood shingles....you can vent below the sheathing or not.. as you see fit.. but the Cedar Breather is neccessary if you use solid sheathing...if you keep the skip sheathing.. you can't do the cold roof (non-vented) because you can't pack the roof cavity without defeating the skip sheathing....b but hey, whadda i no ?
*Patrick, I didn't miss that you have to pay anal-like attention to insulation and air filtration, insure a perfect vapor barrier, stop using asphalt shingles, and then hope that everything has been done to perfection. In addition, now that you have people living in a bubble, assure safe indoor air quality & control moisture. Etc, etc, etc. The non-vent theory is an option, and I don't believe either of us could know if it is feasible and/or cost effective for this situation without actually being there. I have to work in the real world and deal with what is handed to me, and sometimes proper ventilation is the most sensible solution, sometimes it is not. I get the impression that you can only see things as black or white, but I have spent over 30 years dealing with many shades of gray.
*none of your info is appropriate to the use of wood shingles
*All the roofs of this house are cold roofs over ventilated crawl spaces. The insulation in the addition is 6" of extruded polystyrene (I bet you've never seen that before) over the living space. The snow stays forever. The real problem is the relatively low roof pitch, 1 in 4, on the porch, admittedly too low for wood shingles (or any other shingles for that matter), compounded by an upper roof draining down without gutters. I will add gutters this summer, but I want to continue using the wood shingle look to match the rest of the house. I think I need to go with some underlayment and/or sheathing and sacrifice some shingle life. I'm not sure wether I'll have a shingle curling/warping problem also.Jim
*so jim...you got the insul..now u gotta take care of the low pitch..strip it, apply ply. roof sheathing, ice & water (attention to detail).. flashings..Cedar Breather... wood shingles..
*Qtri "I get the impression that you can only see things as black or white, but I have spent over 30 years dealing with many shades of gray. "Now that's pretty funny seeing as how, if I wanted to be beligerent, I woulda said the same thing about you, except you might have 5 years experience on me (if your "30 years experience" was in hands-on building). .. course it didn't take me 25yrs to figger out how dumb it is to send heat out through the roof and fix the negative results by venting. That's like leaving your thermostat set permanently at 80F and opening a window whenever it gets over 70F inside.Ya see it really is only common sense to pay what you derisively call "anal like attention" to insulation and air barriers. These of course are actually fairly easily retrofitted, and of course one doesn't, as you incorrectly state, have to give up on asphalt shingles.i "In addition, now that you have people living in a bubble, assure safe indoor air quality & control moisture... "That's really sad man, I guess I should feel sorry for you, caught as you are in a 1960's mindset.Venting is a band-aid. It's actually easier to seal the ceiling below the roof and add insul than it is to repair the damage from ice dams, or retro-fit venting which usually doesn't even perform it's intended task(there are studies that show how inefective it usually is).Black, white, grey. .. how about cost effectiveness and common sense? How about energy conservation?This ain't rocket science. Get a brace for your knee jerk!-pm
*jimWhat's not appropriate, just because skip sheathing was used?-pm
*Wow Patrick, I thought I was having *my* period.i "Now that's pretty funny seeing as how, if I wanted to be beligerent,"You started it with crap like "educate yourself, etci "Ya see it really is only common sense to pay what you derisively call "anal like attention" to insulation and air barriers. These of course are actually fairly easily retrofitted, and of course one doesn't, as you incorrectly state, have to give up on asphalt shingles."Yes Patrick, I agree, common sense, but paying anal-like attention must be part of the process. The asphalt shingle point was from one of your links, not me, as well as something about attics filling up with snow because of ventilation. i ""In addition, now that you have people living in a bubble, assure safe indoor air quality & control moisture... " That's really sad man, I guess I should feel sorry for you, caught as you are in a 1960's mindset."I'm sorry, don't you think this is very important, and also must be part of the process? And the 60's weren't all the great, except for the cars. i "Venting is a band-aid. It's actually easier to seal the ceiling below the roof and add insul than it is to repair the damage from ice dams, or retro-fit venting which usually doesn't even perform it's intended task(there are studies that show how inefective it usually is)."Not always Patrick. That is why I asked you if not venting applied to every building, everywhere. That is why I also got the impression that you could only see this issue as black or white, and I think this is the only real place we may disagree. i "This ain't rocket science. Get a brace for your knee jerk!"Is this me being beligerent again? Lol, I'll be nice if you will. As for the experience thing, ya it has been hands on for over 30 yrs, and you can add a couple of degrees and some special training. Do I know everything? Hell no, but I do the best I can. To be honest, I think this point we are beating to death is very complicated and difficult to soundbite. I have worked on homes built as early as the 1600's to new hunks of crap and every job is different. I may have to deal with preserving original features, previous framing & remodeling nightmares, code restrictions, material supply, budgets, and homeowners that constantly change the end game. You also have to understand that I don't always have free rein to do as I please, and frequently work as a sub/slave. I think we are polluting this poor guys thread with this pissing contest, and it may be better to take it a new thread where it can get the attention it deserves. Matt
*Wow , you guys really go at it here, well if I could throw in my little bit of 15 yrs. exp. of roofing the first question I would ask is, are you using a hand split shake? If you are, the cedar breather is not needed because as the manufacture states the bumps and dips on the face of each shake provides enough air flow for the shakes to dry.If you are not using hand splits then you will need either the cedar breather or open sheathing as you first mentioned. What you could do is run the Ice and water shield 3' or 6' from the bottom up and then install your cedar breather and shakes.Use 1/2" cdx as sheathing with the cedar breather and you should be close enough.PS. use some cross bracing to support the 1/2 " sheathing. good luck, Ron
*QtrThis is really quite tiresome. You pulled a quote from my first post and appended your "ventilation" comment like you were the "expert". You didn't say "how about?", or"what about?" You weren't polite. You set the tone.You continue to misqoute regarding asphalt shingles. What is clearly written is that by not venting you "might" lose a couple of years off the advertised life expectancy but that it is a worthwhile trade-off! You also can't seem to grasp that b energy conservation is the primary reason for not venting. The "no snow in the attic" detail is a pleasant side benefit.Perhaps you consider what I think of as normal workmanlike attention to detail to be anal, I don't. There's still plenty of room after that to be anal .. I guess we work to very different standards.Of course indoor air & moisture quality is important, it's extremely important, but it is not a concern unique to the non-venting of roof cavities. You give the impression that you prefer leaky energy guzzling houses rather than attend to these details. . . too anal. Too bad for your customers. Whether "non-venting" works for i "every building everywhere" is not my concern because I work strictly in a "heating" zone, and so, obviously, is the building in question. Lstiburek, however, has a paper on one of those links that addresses "cooling zones" and he recommends non-venting there as well!! His group changed the building code in Las Vegas and built 300 unvented roof assemblies there as of Dec. 1999. I would be very surprised to run into a building in a "heating zone" that I couldn't improve by sealing and adding more insul and unventing the roof. Given current energy prices the payback would be quick regardless of the effort required.What you do in your day-to-day has little to do with the difference in our philosphy.There's no need to take this to a new thread. I've been here for over three years and it's been discussed many many times...check the archives.-pm
*on all of the wood shingle roofs that we frame. and we have framed quite a few... the fist course of sheathing is 3/4 cdx plywood for the water and ice shield to ad hear to... after that we use spruce skip lath appropriately spaced for the rest of the roof... valleys also have 3/4 ply for the W+I shield... at the ridge the lath is stacked tight for 3 courses so the roofers have something to nail to and we leave space for a ridge vent...btw we also use 2 inch continuous soffit vents
*jason.. that sounds like a neat roofing plan...now , RON: about this...[[[[.((hand-split shakes))if you are, the cedar breather is not needed because as the manufacture states the bumps and dips on the face of each shake provides enough air flow for the shakes to dry]]]]fair enough, but.....if you're using hand-splits, you are also using an 18 inch strip of felt at each course, again improving the ((breathing )) and the wicking of moisture to the exterior..this is NOT true for sawn-back splits, which get used a lot....in this case you do need Cedar -breather or skipped sheathing....b but hey, whadda i no ?
*Mr Smith, do you water and ice just the eaves or do you do the whole roof?..I have seen some roofers just W+I the eaves and then using heavy tar paper (30lb felt?) for the rest of the roof with the cedar breather on top of that
*eaves, rakes, valleys, any penetrations..all get ice & water... and all the rakes,eaves & ridge are vented with a copper "F" style flashing..the rest is 30 # felt or Roofers Select .. we like the way it lies down after it gets wet, we like it's strength, don't like the way it itches on a hot day... ( fiberglasss reinforced )....
*Hey Mike good to hear from you , your on the money with your roof systems. Most , if not all of my shake roofs are installed with open slats. While cedar breather is a good product, it just is not as effective. Every now and then when Im forced to use plywood, Cedar breather is a must. My advice to the first letter was just a remedy for his case. Another way to get great venting for shakes and still have the plywood, is to install slats vertical over the plywood on every rafter and then install your slats as usual and shakes, you could also install a product at the bottom called vented soffit edge and allow great air flow under the shakes now that will dry them up. Oh by the way, to whoever it was that does not believe in venting . I have seen many without it , many with mold problems in the attic ,many with rotted sheathing caused by lack of venting,many a nightmares. Do your customers a great service and install venting as a rule.
*RonI'm the one promoting non-venting, but you've missed the most important detail of the entire concept. Air Sealing the ceiling below the roof is the heart of the approach, without that moisture damage would be inevitable. If you seal it properly, and pile in the insulation you simply don't need the vents.A hybrid system that I have used several times on steel roofs I've built would also work with skip sheathed cedar. I use a roofing steel that goes on over skip sheathing, and have had condensation concerns because the locale was lakeside so I devised my own system to provide direct ventilation under the steel while keeping the rest of the attic area, or cathedral assembly unvented. I fitted sheets of Glasclad (a compressed f/g board (R4/") with Tyvek type paper on one face)between each rafter, up to the skip sheathing but stood off with 1x2 on edge, from soffit to ridge and caulked the seams. Each rafter then has an enclosed,1-1/2" insulated bay from continuous soffit vent to continuous ridge vent. Since I did my last steel roof Glasclad has gone off the market, but I will find a substitute for any future jobs. Styrofoam would work but is less forgiving of the irregularities in rafter bays, although cut slightly narrow and foamed in would also work.-pm
*ron... yur not going to take that lying down are you ?this is february.. i think paddy wants to start the third annual venting / non-venting war...personally i think he's a horses ass... but then you're the one who who wants to defend venting and he's the only one willing to challenge you... so you could hone your skills on him until the real heavy artillery arrives..too bad he's such a light weight.. hardly seems fair... do it ?ah well, nothing good on tv anyways...
*Hello roofers and fellow shingle bangers. Hey Patrick nice to meet ya,I noticed you included ridge vent and soffit venting in your system. "Right on" thats all you needed, superior system you have there, nice idea. I was under the impression you did not use any. The way I see it, the average home costs about 150,000.00 dollars give or take a couple grand. Average ventilation costs, somewhere around 200.00 dollars, give or take a few pennies. Roughly about .15% of the homes cost, "small price to pay for a good insurance policy." By the way what do you guys use for treating your shakes, cost per gallon, and warranty?
*MikeAfter a post like that you're callingi mea horse's ass???????LOLOnly in America.-pm
*The monster is dead. Defeated........................... See that Mike, his last post, spoken like a true 12 year old in the middle of the school yard, who's just soiled his pants and now every ones laughing at him,..... Im sorry Patricia.
*Patrick, I am sorry to have wasted your time. Now I know that unventing is the way to go everywhere, thank you for giving me your imput. Also, thank you for understanding everything I said correctly, gosh, I am in awe.Now that you are done here, could you find some time to tell this person how to un-vent his home? >>> person in need of wisdomBefore you enlightened me I would have thought the best he could have achieved was an imperfect insulation envelope, where positive ventage would have been of some benefit. I also noticed a few other threads where you have refused to impart your wisdom, is that because you like me so well and just couldn't focus on anything but me? Ahhh, smiles and hugs baby.Oh, and despite the fact that nothing you said had anything to do with resolving Jim's problem, why don't you see if you can find out how he misinterpreted the solution. It is right there in "black & white". The sad thing is that I would have addressed it if you weren't such an asswipe.
*QtrPoor fellow.If I've misunderstood one of your thoughts(?) perhaps you should learn to express them better. You might start with your last paragraph above which is at best convoluted.I posted links to acredited "expert" opinion for the benefit of those who might like to learn something. Clearly they were wasted upon you.I don't need to become involved in the thread you linked, Steve Zerby will give him excellent advice.Unlike yourself, perhaps, I don't have unlimited time to cruise this board handing out advice, nor the requisite ego. I donated my time in the advice department for several years before you arrived here when it was mostly builders talking to builders. How utterly childish of you to criticize me for not answering some other thread. You're callingi mean asswipe????? LOLLike many people with terminal knee jerk you conveniently forget the sequence of events. Pertinent details for the original question were dolled out in several different posts over about 8 days, by that time you and I were "debating" the relative merits of venting, that's how discussions often go on this board. And it was you who first brought up venting, I was prepared to leave it alone as my first post proves. Now you're mad cuz someone else beat you to the answer????? You're a sad case, get some help.-pm
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I have a wood shingled porch roof which is leaking due to ice damming. The slope is a little under the minimum 3 in 1, but the rest of the house is shingled in wood and I wanted consistancy. I'm perfectly willing to pull off the problem area and put down a membrane before reshingling but then I have the problem of no air space under the shingles. Can someone tell me of a nail self sealing shingle underlay membrane to use and how much I'll shave off the normal wood shingle lifespan if I use this approach?
Thanks in advance, Jim