3 ms·

That is what I originally thought it might mean, but the article uses the term "rain control barrier", and has a separate item for vapor control. With regard t

That is what I originally thought it might mean, but the article uses the term "rain control barrier", and has a separate item for vapor control. With regard to their relative placement, see, for example, the caption to figure 2: "Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.] The author also writes, in the caption to fig. 1: "The claddings function is principally to act as an ultra-violet screen", thus seeming to differentiate it from any of the control layers he listed at the start of the article. In addition, the author also lists a separate item for air control, but later writes "What about this air control thing? Well air can carry a lot of water and water is bad for the structure" - further muddying the issue, as now he seems to be discussing water vapor. I guess this could all be attributed to being sloppy about definitions, to the point of being unambiguously wrong when it comes to roofs.

throw0101a 5y ago
> The author also writes, in the caption to fig. 1: "The claddings function is principally to act as an ultra-violet screen", thus seeming to differentiate it from any of the control layers he listed at the start of the article. The cladding can not stop any water and, if the control layers beneath the insulation are properly installed, it won't make any difference. The fact that the cladding does help in blocking rain is just a nice bonus to its primary function. In some locations it may be difficult for the cladding to do this: think of any place very foggy. There's no way to make the cladding air tight, so high humidity (100%) air will get behind it (stopped by the c. layers). Or if you have shingles on your roof that leak (or get blown off in a storm), they can still block UV, but there will be dripping. And that's why you want the control layer(s) further in. Water can destroy a structure very quickly if you don't allow for easy/quick drying. Defense in depth. > In addition, the author also lists a separate item for air control, but later writes "What about this air control thing? Well air can carry a lot of water and water is bad for the structure" - further muddying the issue, as now he seems to be discussing water vapor. At the top of the article he lists the control layers in order of importance. Controlling for air is more important than control for vapour, as this video explains: * https://www.youtube.com/watch?v=FXXgjvOJcYI https://www.youtube.com/watch?v=FXXgjvOJcYI It's just if you control for air you also just happen to do a lot of controlling for vapour. There's can be a lot of moisture in air, i.e., humidity. Further there can be some subtleties with moisture/vapour: in many case you want to stop any flow either in or out of the building; in other cases you want to control air but let moisture out: * https://www.youtube.com/watch?v=zhkGcklWB_Q https://www.youtube.com/watch?v=zhkGcklWB_Q * https://www.buildingscience.com/documents/building-science-insights-newsletters/bsi-016-ping-pong-water-and-chemical-engineer https://www.buildingscience.com/documents/building-science-i... * https://www.buildingscience.com/documents/insights/bsi-077-cool-hand-luke-meets-attics https://www.buildingscience.com/documents/insights/bsi-077-c...
- mannykannot 5y ago
  > The cladding can not stop any water... The fact that the cladding does help in blocking rain... Clearly you are using some words differently than I do, but it is not clear to me which ones. >...blocking rain is just a nice bonus to its primary function. In our house and our neighbor's houses, blocking rainwater is its primary function - we do not live in a desert. > Or if you have shingles on your roof that leak (or get blown off in a storm), they can still block UV, but there will be dripping. And that's why you want the control layer(s) further in. And that is when you need to fix your roof, regardless of what is underneath. In your replies here, you seem to be trying to turn this into a discussion about water vapor, but I have made it very clear that a) my questions are about what the author has to say about rain and water, and b) the author himself makes a distinction between water and vapor control. Tellingly, you have nothing to say about this quote from the article: "Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.]
  - throw0101a 5y ago
    > In our house and our neighbor's houses, blocking rainwater is its primary function - we do not live in a desert. Wherever you live the sun shines, and UV damage can be extensive against materials that are not designed against it. Cladding is about physical protection to the layers underneath. > And that is when you need to fix your roof, regardless of what is underneath. Yes, when you notice it. The shingles may be leaking into the roof structure without you seeing it for a while. Then once the roof has disintegrated, the leakage may go into the attic, which most people don't visit/inspect very often. So by the time it gets to the ceiling in the livable space, where it is actually noticeable, there could be a lot of damage done. > "Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.] You can call the things Foo, Bar, Baz, or whatever you want. The important points are the principals in the design and the order in which the different layers are (ideally) put together. If you want to argue Joe Lstiburek, be my guest: * https://en.wikipedia.org/wiki/Joseph_Lstiburek https://en.wikipedia.org/wiki/Joseph_Lstiburek

throw0101a 5y ago

> The author also writes, in the caption to fig. 1: "The claddings function is principally to act as an ultra-violet screen", thus seeming to differentiate it from any of the control layers he listed at the start of the article. The cladding can not stop any water and, if the control layers beneath the insulation are properly installed, it won't make any difference. The fact that the cladding does help in blocking rain is just a nice bonus to its primary function. In some locations it may be difficult for the cladding to do this: think of any place very foggy. There's no way to make the cladding air tight, so high humidity (100%) air will get behind it (stopped by the c. layers). Or if you have shingles on your roof that leak (or get blown off in a storm), they can still block UV, but there will be dripping. And that's why you want the control layer(s) further in. Water can destroy a structure very quickly if you don't allow for easy/quick drying. Defense in depth. > In addition, the author also lists a separate item for air control, but later writes "What about this air control thing? Well air can carry a lot of water and water is bad for the structure" - further muddying the issue, as now he seems to be discussing water vapor. At the top of the article he lists the control layers in order of importance. Controlling for air is more important than control for vapour, as this video explains: * https://www.youtube.com/watch?v=FXXgjvOJcYI https://www.youtube.com/watch?v=FXXgjvOJcYI It's just if you control for air you also just happen to do a lot of controlling for vapour. There's can be a lot of moisture in air, i.e., humidity. Further there can be some subtleties with moisture/vapour: in many case you want to stop any flow either in or out of the building; in other cases you want to control air but let moisture out: * https://www.youtube.com/watch?v=zhkGcklWB_Q https://www.youtube.com/watch?v=zhkGcklWB_Q * https://www.buildingscience.com/documents/building-science-insights-newsletters/bsi-016-ping-pong-water-and-chemical-engineer https://www.buildingscience.com/documents/building-science-i... * https://www.buildingscience.com/documents/insights/bsi-077-cool-hand-luke-meets-attics https://www.buildingscience.com/documents/insights/bsi-077-c...

mannykannot 5y ago
> The cladding can not stop any water... The fact that the cladding does help in blocking rain... Clearly you are using some words differently than I do, but it is not clear to me which ones. >...blocking rain is just a nice bonus to its primary function. In our house and our neighbor's houses, blocking rainwater is its primary function - we do not live in a desert. > Or if you have shingles on your roof that leak (or get blown off in a storm), they can still block UV, but there will be dripping. And that's why you want the control layer(s) further in. And that is when you need to fix your roof, regardless of what is underneath. In your replies here, you seem to be trying to turn this into a discussion about water vapor, but I have made it very clear that a) my questions are about what the author has to say about rain and water, and b) the author himself makes a distinction between water and vapor control. Tellingly, you have nothing to say about this quote from the article: "Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.]
- throw0101a 5y ago
  > In our house and our neighbor's houses, blocking rainwater is its primary function - we do not live in a desert. Wherever you live the sun shines, and UV damage can be extensive against materials that are not designed against it. Cladding is about physical protection to the layers underneath. > And that is when you need to fix your roof, regardless of what is underneath. Yes, when you notice it. The shingles may be leaking into the roof structure without you seeing it for a while. Then once the roof has disintegrated, the leakage may go into the attic, which most people don't visit/inspect very often. So by the time it gets to the ceiling in the livable space, where it is actually noticeable, there could be a lot of damage done. > "Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.] You can call the things Foo, Bar, Baz, or whatever you want. The important points are the principals in the design and the order in which the different layers are (ideally) put together. If you want to argue Joe Lstiburek, be my guest: * https://en.wikipedia.org/wiki/Joseph_Lstiburek https://en.wikipedia.org/wiki/Joseph_Lstiburek