Caulking in the cold weather

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Old 02-19-15, 08:36 PM
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Caulking in the cold weather

I have caulking to do around a couple of newly installed vinyl windows.
Also, as I've been replacing the exterior sheathing of my house with plywood, I've been caulking all of the seems.
It's cold here now and recently I tried to use OSI and, even though I had left the caulk indoors until I was about to use it, it was very difficult to squeeze out of the tube with the caulking gun.

So, first, is the caulking between plywood sheets a good idea or is it overkill?

Regardless of whether I continue to caulk between plywood sheets, there are other areas (like around the windows) where I need to caulk. Is there a good, mold/mildew resistant, caulk that can be applied in cold weather?

Thanks in advance.
 
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Old 02-19-15, 09:09 PM
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You probably need a better caulking gun because you should have no problem with OSI Quad in low temps, especially if the tube is being kept warm.

You can caulk plywood seams if you want, but no- that's not a standard practice. Vulkem is also a good choice but if you have trouble squeezing a gun with Quad, I dunno what to say... try silicone maybe.

Make yourself a box with 2 holes. One for the caulking gun to stick into... one for an electric hair dryer (set on high heat) to set in.
 
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Old 02-20-15, 04:32 AM
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Are these new tubes of caulking? Like X, I detest using a cheap caulking gun - the more expensive ones do work a lot better!
 
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Old 02-20-15, 04:52 AM
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A few years back I had a case of that same brand I had to return. When new and warm (really warm as X suggested) it should pour out. For general caulking of everything that can move I use the large tubes of construction adhesive, PL3x I think.

As for caulking the seams on the plywood, in a really tight home they do that, but it there are normal leaks all around, it wouldn't make a difference. But it doesn't hurt and when the caulk is flowing smooth it only takes a few minutes. I would focus on any seams not secured to a stud.

Bud
 
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Old 02-20-15, 10:37 AM
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Thanks XSleeper, marksr, and Bud9051
Each of you have made good points.

I have used OSI Quad in the past and never had such resistance. I know I've used it into November before (which is often in the mid 30's to mid 40's around here).

My caulking gun is a fairly cheap model and has definitely seen better days. It's funny, I see new caulking guns with widely varying price tags and good reviews for all of them. It makes me wonder how much to spend for a good one.

I have wondered about the age of the caulk. I bought it recently (within the past 2 months), but I wonder how long it was on the shelf at HD. I brought out a magnifying glass to inspect the tube to see if there was a date stamped on it. I didn't find one. There is a number that doesn't look much like a date.

All of my plywood seams are either on a stud or on blocking that I have added.
 
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Old 02-20-15, 11:16 AM
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From a building science standpoint, you do not want to caulk the seams of exterior sheathing. Most exterior plywood products are actually undersized by an 1/8" to allow for an air space between the sheets.

The theory behind this is that any moisture in the cavity needs to escape through the outside of the wall. Otherwise, there is potental for warm moist air trapped in the wall cavity to consendaste on the sheathing, and cause a potental for rot and mould. Your building wrap on the outside of the wall is what will prevernt air movement from the outside of the building to the inside. This building wrap is designed to stop air from entering your house but allow water vapour to flow out of your house. Since the glue in plywood makes it a vapour barrier, by caulking the seems you are trapping any moist air that may enter the cavity and not giving it anywhere to go. Remember that a properly installed vapur barrier on the inside of the house is just as important as the building wrap on the outside.

As for a good cualk for doors and windows, I use Geocel Proflex. In my experiance it works good for temps down to -10c. Also remember that a good quality caulking gun ($50 or so) goes a long way to making the caulk easier to apply, especially in cold temps.
 
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Old 02-20-15, 12:54 PM
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Keith, a gap between sheets is there for expansion, it's not there to allow air flow for drying. Plywood is sufficiently vapor permeable (a class II vapor retarders) that does not act as a moisture barrier.
Vapor Barriers or Vapor Diffusion Retarders | Department of Energy
Bud
 
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Old 02-20-15, 01:06 PM
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I paid $17 each for the last caulking guns I bought but that was 15-20 yrs ago. If you were to provide us with a link of the caulking gun [s] you are thinking of buying we could offer our opinion. The main thing is to stay away from the extra cheap ones!
 
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Old 02-20-15, 01:21 PM
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Bud, that is not what we are taught here in Canada, but I wont argue with you on the point. But I still would not caulk the joints of plywood as you will not get any benifit from it at all. Your Building paper should stop your airflow, not your sheathing.

This it about the grade of gun I use as a professional.

http://www.homedepot.com/p/PC-Produc...0550/202017659

This is what you want to stay far away from.

http://www.homedepot.com/p/HDX-90-20...-129/202036531
 
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Old 02-20-15, 01:50 PM
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That $30 gun looks a lot like my $17 ones - biggest difference seems to be the color They work well and last a long time!
 
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Old 02-20-15, 02:31 PM
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The only real difference is the quality of the construction and how much leverage you get from the design. I cant count how many cheap guns I have either snapped the handle off or bent trying to apply caulk in cold weather. They just are not designed to last.

The one I use everyday was $50 from Home Hardware here in Canada. It is 10 years old and still going strong. A good gun will pay for it self in no time, and your hands will thank you for it since it makes applying cualking alot more effortless.
 
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Old 02-20-15, 10:00 PM
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Thanks for the comments.
Building Science is an interesting field. There is logic to what Keith said about gaps allowing moisture to escape but I've mostly heard what Bud said about the gap's purpose for expansion and plywood is moisture permeable. I think it's largely Building Art still. We really won't know for another 50 years or so how effective the current "state of the art" building techniques stand up over time.

That $30 Home Depot caulking gun looked good to me too. I've looked at it in the store. If it looks like the one @marksr uses, it's good enough for me

Now I just need to decide who's science I'll follow with respect to caulking the seams between the plywood sheathing.
 
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Old 02-20-15, 10:18 PM
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The premium insulation crews around here will caulk the seams between any double studs (king-trimmer, for example) three stud corners and sill plate-floor. The idea is to stop air infiltration.

IMUO (uneducated opinion ) in a cold climate, it is more important to prevent cold air from hitting warm air in the wintertime because that's when most condensation (sweat) occurs. Caulking the INSIDE helps with that. During winter months, your warmest moist air is inside the house, ad you don't want to let it find an easy way out. (it's going to anyway) If you caulk the outside and not the inside, you are basically letting that warm interior air escape out through the cracks in the framing to the cold surface where it can then condense.... inside the wall.

The WRB, which can also be installed as an air barrier is always vapor permeable, so any moisture in the wall cavity can always dry to the outside.

I'm sure someone has studied this sort of thing.
 
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Old 02-21-15, 03:43 AM
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I don't think Canada's energy practices are that much different from state side, a gap between sheets of sheathing is NOT an intentional approach to ventilate those walls, it is for expansion. But I do understand the abundance of confusion with old practices mixing with a constant flow of new thinking that has to be interpreted by the folks that actually do this work in the field. All too often builders have to invent their own approach to keep the work flowing, and I'm not faulting that, I'm faulting the science guys that seem to make changes on the fly, do it this way today, that way tomorrow.

Advice on air sealing varies from "you need to seal somewhere" to the ridiculous "you have to seal everywhere." I'm in agreement that 50 years down the road we will find out which was right, but someone will have to dig me up to tell me about it.

Here's the most complete discussion I could find on this topic.
Airtight Wall and Roof Sheathing | GreenBuildingAdvisor.com

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Old 02-21-15, 06:11 AM
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When I said that is not what they teach us in Canada, I was referring to plywood acting as a vapour barrier, especially if you are using OSB. I do know there are some areas where inspectors will look for a gap in sheathing, and if it is not there, they will make you cut one. Some even want as much as an inch gap.

I agree no one will know for a long time if these new practices pan out, but I think with the amount of testing done today, there is a very good chance we are on the right track. The biggest problem with building science and application is getting people to actually do the job up to the standards that are required. That means sealing your interior vapour barrier as good as possible, running your air barrier under your sill plate and out so you can seal to it, and making sure the insulation job is done properly. With new products like ICF's and spray foam, it is getting much easier to do these things.

As for caulking the plywood joints, the only time I would do that is if you are trying to create a vapour barrier, such as on a floor over a crawl space. Let the air barrier on the outside wall do the job its supposed to.
 
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Old 02-21-15, 07:10 AM
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I hate to drift, but the op asked for help on deciding whose science to follow in regards to caulking those seams.

Keith, I'm sorry but, quoting what some inspectors might require is not always a source of best practices. Cutting a 1" gap in the plywood sheathing to ventilate moisture to the outside would be ridiculous in Vancouver where the summertime humidity is very high. In a purely heating climate it would be less disastrous, but still a poor practice when building an energy efficient home.

Yes, the house wrap acts somewhat as a wind barrier, but without extreme sealing, seams, staples, doors and windows, top and bottom, air is going to get past the wrap. Inviting that airflow in and through the insulation defeats too much of the desired r-value.

I provided a good article on air sealing the envelope of a house. You have provided your opinion. Can you provide any code requirements or trusted papers supporting your statements?

Bud
 
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Old 02-21-15, 08:11 AM
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Here are a couple interesting articles

WHAT DOES IT MEAN TO SAY A WALL MUST BREATH?


http://www.ecohome.net/guide/interio...vapour-barrier

I don't understand what you intended to gain by caulking the seams of plywood. You are restricting the expansion and contraction, sealing off areas to allow the outside wall to breathe, and potentially holding in moisture which will condensate on the inside of the sheathing. What benefits could possibly be gained by doing this? A properly installed air barrier and cladding with keep the air and water out of your wall cavity.
 
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Old 02-21-15, 11:09 AM
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1. The op is in the Rochester, NY area with about 6,500 HDD and probably will use both heat and ac.
2. The author to the first article is clearly in Canada and talking about much colder conditions, and does not provide any references. A quote from that article:
"Warm, humid air leaking into the walls of a house is like a faucet flooding the tub."
The air and vapor barrier is at the drywall plane and there should be no warm air or moisture movement past that point.
3. The second article is about using OSB as a vapor barrier (vapor diffusion retarder is a better term) on the "inside" of a wall assembly and yes, I would expect in that application to see all seams and penetrations sealed. But that application is not where we are at.

Last try, article from a known expert on energy matters Dr Bailes.
5 Reasons House Wrap Is Not an Air Barrier
 
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Old 02-21-15, 03:07 PM
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We will have to agree to disagree on this one. The auther in the first article is a very well known building science expert in Canada. I posted the second to show that OSB is in fact a vapour barrier.

Personally, I would never caulk the seams of exterior sheathing. That is my expert opinion and nothing more at this point so I guess take it for what it is worth.
 
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Old 02-21-15, 03:39 PM
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Canada must have a different definition of vapor barrier. Maybe because they get more frost inside walls than we do down here in warm sunny USA where the winters aren't as harsh.
 
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Old 02-21-15, 04:09 PM
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Same definition, but IMHO plywood is still enough of a vapour barrier in this case to be a problem. If it does not let the moisture through immediately, it WILL condensate on the back side of the plywood before it can permeate through it. Unless you take extreme precautions with your interior vapour barrier, you are still going to get some moisture entering the wall cavity from the inside of the house. That moisture needs to escape both summer and winter. This is even more important with new construction since framing lumber is almost always wet when it is closed up. Even at below 19% moisture content there is still a lot of water in that wood that needs to come out and go somewhere, and the last thing you want to do is trap it in the wall cavity.

Let the air barriers do the job of the air barriers, and the sheathing do the job of the sheathing. It is not hard to install a very effective air barrier on the outside of the building. Lap and tape your seams and seal it properly around openings.

If we are talking far enough south that you are primarily using AC instead of Heat, then we are talking about something different. In that case, yes, you want your vapour barrier on the outside. But IMHO New York is not far enough south for that. Where I live the temperature swings from 40c in the summer to -40c in the winter.
 
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Old 02-21-15, 04:32 PM
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This is what I am talking about. The picture below is the roof sheathing in an attic, but the exact same pricple happens in the wall cavity. If the warm moist air cannot escape fast enough, it will condensate on the inside of the sheathing and eventually lead to rot and mould.

Name:  attic_frost_600.jpg
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Old 02-21-15, 08:54 PM
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I'm enjoying the debate folks. Honestly.

So, with respect to caulking the seams of the sheathing, no matter what I do, I'll be doing the right thing in some peoples' minds and the wrong thing in other peoples' minds.

I'm with you Bud. I won't be around in 50 years to know how things turn out in the long run (except they won't need to dig me up--just lift the lid of the urn ). It is possible, however, that my son could be in this house. He seems to like it.

I will say this, the sheathing that I'm replacing was Homasote. It always seemed to me that the Homasote held too much moisture, which, I think, contributed to the fact that the cedar shingle siding could not hold paint. So, how do I interpret that; too much moisture from the outside in or too much from inside out? There were plenty of gaps between the Homasote sheets in some areas.

I'm certainly not going to leave a 1" gap between sheets, but maybe the caulking just isn't needed on the 1/8" seams. But, if I did use caulk, I doubt that would significantly inhibit wood expansion.

Oh. One other reason to caulk is to keep the ants out.
 
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Old 02-21-15, 10:12 PM
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I could share some stories on ants, ug!
I've owned a home with cedar siding, but never installed it. From what I have read it likes an air gap behind it for ventilation and just looking at how it is installed I would want the house wrap (drain plane) back there as wind blown rain or snow has to get past. I suspect the moisture in the Homasote was coming from precipitation, not moisture passing through the walls.

What does the rest of your wall assembly consist of, insulation, vapor barrier, and drywall??

Oh and for the ant issue, I have had to deal with carpenter ants and one of their itty bitty cousins. Very small, but I have 2 mating pieces of 2" rigid foam board I will be framing as a display to show people just how much damage even the smallest of ants can cause. At least be sure to seal down low.

Bud
 
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Old 02-22-15, 08:23 AM
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Thanks @Bud9051

Re: ants, since there are lots of trees in our neighborhood, we tend to get a lot of carpenter ants. One neighbor opened up a wall and said the ants just came pouring out. Ugh! is right.

To clarify, I'm not putting cedar back up. I've had it with cedar. I have replaced large sections of it; in fact, the entire north end of the house. The method they used around here includes the use of backer board--another absorbant material even worse than the Homasote sheathing. Ants love it when wet.

Between the woodpeckers' love of the cedar and the ants' love of the backer board, I've been working toward less palatable materials; Roxul insulation, plywood sheathing, weather resistive barrier (HardieWrap), and HaridiePlank cladding.
 

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Old 02-22-15, 08:37 AM
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Paint peeling from your siding is an indication that moisture is entering the siding and pushing the paint off. This could be from excessive moisture in the home working its way through the wall, or from water getting behind the siding somehow. If the old sheathing was as wet as you say, I would lean more towards the water coming from outside getting behind the siding.

Proper building practices today to prevent that type of peeling would consist of an air space between your air barrier and the siding, and also ensuring all sides of the siding are primed before installing it.
 
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Old 02-22-15, 08:51 AM
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Thanks @Keith Weagle

I was concerned about the need for, as you said, "air space between your air barrier and the siding". I asked a Hardie rep if I should create a rain screen. He was fully aware of what a rain screen is, but said it was unnecessary. I'm using the pre-painted Hardie (ColorPlus), but I did ask "is it beneficial to prime the back of the HardiePlanks?" The answer was "No".

Now, I'm not inclined to cut corners, but I am working alone, so I do want to cutout unnecessary steps.

I will say, however, the idea of the air space makes sense to me, that's why I asked the Hardie rep about it to begin with. I've seen some information about the Benjamin Obdyke Hydrogap WRB that is pretty convincing (it has lots of bumps to allow draining). It very well could be a big improvement over other WRB's.
 
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Old 02-22-15, 09:05 AM
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Hardie board is "supposed" to be sealed on all sides from the factory, so you really would not need the rain screen or primer to prevent paint lifting. The rain screen is still not a bad idea in any application only becasue you can be 100% sure you wont have any moisture trapped behind the siding that could possibly penitrate the wall. Even if there was a huge gap between two peices that rain could enter, it would simply run right out the rain screen instead of being trapped behind the siding until it either evaporates or finds somewhere to run out.
 
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Old 02-23-15, 11:07 AM
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I like the idea of creating a rain screen, but it would create a lot of work (for example, needing to build out window trim etc...).

Back to one of my original questions, I now think that I ended up with some very old OSI Quad. I used the same old caulking gun outdoors yesterday with Liquid Nails. It squeezed out just fine. If I can find the receipt, I'll return that partially used tube of OSI along with the unused tube I bought at the same time.

Regarding caulking between the seams, I'm going to leave the seams open on the south side of the house, I'll take a picture and send it to Keith.
I'll caulk the seams on the north side, I'll take a picture, and send it to Bud.
 
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Old 02-23-15, 11:24 AM
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Na, na, I'm more to the south and Keith is up north .
I' always amazed at how "things" can be viewed as hard and fast rules and then all of a sudden the experts reverse themselves. Besides all of the changing within the energy fields, I have long enjoyed my bacon and eggs fro breakfast and had to endure all of the finger wagging telling me my cholesterol is going to explode. Now the new dietary guidelines that just came out are saying go ahead and enjoy that high cholesterol diet as there has been no indication that doing so has anything to do with cholesterol levels. 40 years of abuse and suddenly they change their minds.

Sorry for drifting, but vapor barriers today, and none tomorrow, the experts just don't stop changing.

Just be sure to post back in 20 years to let us know if the building is still standing.

Bud
 
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Old 02-23-15, 11:35 AM
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I think both Bud an I can agree that you should NOT have a vapour barrier on the inside and outside of a building. Assuming you do have one on the inside like you should in a heating climate, you don't want to make another. Where we differ in opinion is whether or not plywood is a vapour barrier. I say it is, Bud says it isn't. The only way for you to decide is by doing the research yourself and coming to your own conclusions.

No offence to you Bud, but it sounds like you are more old school and not a believer in vapour barriers. Back when houses were not built tight and the wind could blow right through them, moisture in the wall cavity was not an issue. Today where we are trying to build energy efficient tight homes, it is something that needs to be addressed.
 
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Old 02-23-15, 01:47 PM
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Keith <No offence to you Bud, but it sounds like you are more old school and not a believer in vapour barriers.>
LOL
Vapor barriers are for the most extreme climates if at all. Air leakage is well recognized as the major contributor to the movement of moisture. Here's some reading for you Keith:
Do I Need a Vapor Retarder? | GreenBuildingAdvisor.com

Here is the bottom section of that article:
* Most buildings don’t need polyethylene anywhere, except directly under a concrete slab or on a crawl space floor.
* The main reason to install an interior vapor retarder is to keep a building inspector happy.
* If a building inspector wants you to install a layer of interior polyethylene on a wall or ceiling, see if you can convince the inspector to accept a layer of vapor-retarder paint or a “smart” retarder (for example, MemBrain or Intello Plus) instead.
* Although most walls and ceilings don’t need an interior vapor barrier, it’s always a good idea to include an interior air barrier. Air leakage is far more likely to lead to problems than vapor diffusion.

Bud

Haven't read all the way through this, but it will make a Canadian connection.
http://www.buildingscience.com/docum...apor-barriers/
 

Last edited by Bud9051; 02-23-15 at 02:04 PM. Reason: addition
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Old 02-23-15, 02:50 PM
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Wow, I can see why we are in such disagreement now. You can not build a house in Canada without a vapour barrier, it is required by code and is essential as part of an energy efficient home. The climate here is virtually identical to where you live, and I am certain if you check the codes in the US, you also must have a vapour barrier. Where it is located within the wall depends on your climate.

Your wall assembly should be as follows from inside to out.

-Drywall (or other interior finish)

-6mil Ultra+ Poly (taped at all seams and sealed at floors and protrusions to prevent both vapour AND air movement)

-Fiberglass batt insulation (with careful attention not to leave air pockets, especially on the warm side)

-Plywood sheathing (that is not sealed air tight at seams)

-Tyvek or Typar (taped at all seams and sealed around sills and openings to the vapour barrier)

-Foam core or better (to prevent thermal bridging)

-Outside cladding (with a rainscreen as well depending on the cladding type)

If you are in a cooling climate, you would switch the locations of the air and vapour barriers.

This is minimum building code requirements in Canada, and I would suspect the same for the US.

If all these things are done properly you will have a super airtight and efficient home (which means no air or vapour leakage that carries heat with it). Leave one thing out and the whole assembly will not function correctly.

I would love to hear someone else's opinion on this because everything I know as a Red Seal Certified Carpenter with 20 years experience tells me I am right.
 
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Old 02-23-15, 06:55 PM
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Bud & Keith, I really do enjoy the debate.

If either of you would like others to weigh in on the "correct" way to use vapor barriers/retarders, insulation, and ventilation, perhaps the topic would be better served if it were re-posted with a different subject. Maybe the "Heating, AC, and Ventilation" forum contributors would have input on the topic. I know how this thread wove its way into discussion about vapor barriers, etc…, but, for someone who hasn't been following the thread, he/she may not have guessed that "Caulking in the cold weather" would have taken us down this road.

@Keith Weagle. I am surprised that any code would specifically call out for fiberglass batting--especially when there are so many alternatives like cellulose, denim, and, like I'm using, Roxul.

Also, I think that the rules for "old work", such as what I'm doing, have to be modified significantly from what is possible with new construction. Even if I was convinced of the need for 6 Mil Poly behind the drywall, I wouldn't be able do that since I'm working from the outside in.
 
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Old 02-23-15, 07:04 PM
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As I said, the code I posted is "minimum" requirements. Of course, there are better materials available, and depending on what you use, some things may change in that design.

You are right that there are exceptions for repair work, but that does not change the fact you do not want a vapour barrier on the outside wall (unless you are in Florida).

Fun fact, two coats of oil paint on your drywall is considered a vapour barrier. A good solution if you want a vapour barrier without removing the interior finish. ( you would still need to seal up any protrusions in the wall.

You are right we have gone a bit off topic, and since I can not add much more to the discussion than what I have said, I will end it here. Until next time...
 
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Old 02-24-15, 07:48 AM
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@Keith Weagle, I didn't mean to say we were off topic. Rather, I think we were drilling down deeply into issues related to part of my original question about the merits of caulking seams between sheathing. The subject and location of the thread may be keeping away other contributors who may have expertise in the area of proper construction of the building envelope as it pertains to comfort and moisture control.
 
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