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We Should Know Better: Top 10 Multifamily Design Mistakes with Steve Klocke, Part 1
Manage episode 237278466 series 2407405
The residential building industry has made incredible progress toward sustainability and energy efficiency goals. At the same time, Senior Sustainability Consultant and Registered Architect Steve Klocke finds many new buildings under-performing because designers continue to make simple, avoidable mistakes.
Based on lessons he’s learned from certifying over 1,200 dwelling units over the past seven years, Steve discusses the top ten multifamily design mistakes being made over and over again – and how to avoid them.
Episode Guest: Steve Klocke, RA
Steve Klocke is a Senior Sustainability Consultant at Steven Winter Associates and a registered architect with 18+ years of experience in architectural design and building science consulting in residential buildings. He provides comprehensive green building certification support for the LEED for Homes, ENERGY STAR and Indoor airPLUS programs with a focus on lowrise multi-unit new construction and gut rehabs.
Steve is an integral part of the initial strategic planning sessions and workshops with builders, architects, and homeowners, setting goals and scopes of work for projects. The certification support he provides for project teams includes energy and building systems analysis, architectural design support, and project management. As a HERS Rater and LEED for Homes Green Rater, Steve inspects projects under construction for compliance with energy performance, durability, and health and safety standards. His performance testing expertise includes whole-house infiltration and duct leakage, as well as infrared thermal imaging.
Episode Information & Resources:
Presentation slides (mostly graphics): Top 10 Multifamily Design Mistakes
Steve’s Multifamily Design Mistakes 1-5:
- Overcomplicated Geometry
- Design Irregularities
- Thermal Bridging: Roofs & Walls
- Thermal Bridging: Slabs
- Poorly Detailed Air Barrier
Check out Part 2 of this episode for mistakes 6-10!
Other Resources:
Air Sealing Guide for Multifamily Masonry Construction
Building America Solutions Center
What comes to Robb’s mind when Steve mentions illicit, high-flow shower heads…
We Want to Hear From You!
Send your feedback and questions to podcast@swinter.com
About Buildings and Beyond
Buildings and Beyond is a production of Steven Winter Associates. We provide energy, green building, and accessibility consulting services to improve the built environment. For more information, visit www.swinter.com.
Hosts
Production Team
Heather Breslin | Alex Mirabile | Dylan Martello
Music
Song: Slotcar | Artist: Podington Bear
Next up on Buildings and Beyond…
We Should Know Better: Top 10 Multifamily Design Mistakes with Steve Klocke, Part 2
Guest: Steve Klocke
CLICK HERE TO LEARN HOW TO SUBSCRIBE
Kelly: 00:06 welcome to buildings and beyond
Robb: 00:09 the podcast that explores how we can create a more sustainable built environment
Kelly: 00:13 by focusing on efficiency, accessibility, and health.
Robb: 00:18 I’m Rob Aldrich
Kelly: 00:19 and I’m Kelly Westby.
Robb: 00:22 This episode I talked with Steve Klocke who is an architect and senior sustainability consultant here at Steven Winter Associates. He works with a lot of builders and developers, largely multifamily, especially low rise multifamily, and he’s been asked to do a presentation at several events-several conferences, called “We should know better, top 10 multifamily design mistakes” and it really resonates with folks and certainly resonates with me. He gets big audiences, so we figured we’d try and talk about it on a podcast. We’ll link to the slides he uses in his presentation, which can help visualize some of the things he talks about, but it was really good to chat. This was a long chat. So this week we have the first five of his top 10 multifamily design mistakes.
Robb: 01:13 All right. Number one over complicated geometry
Steve: 01:21 yeah. Okay. So I won’t get too deep into architectural theory and what we all learned in school and what we should’ve learned in school.
Robb: 01:31 We should say that you are a registered architect.
Steve: 01:34 That’s true. I’ve been for 13 years now. And I wouldn’t ever say that I was ever a “hot pencil”- would be the term, like designing things that look great. I can make them work but, and then make them look good, but making like the really great stuff that wins awards, not my jam. Hence senior sustainability consultant. But anyway, so at some point in architecture we got the impression that to make a building interesting, you had to make it sculptural, blame frank Gary or whatever. And so architects are for some reason driven to make their buildings do funny things sometimes. And to me funny things mean: bump outs, bump ins, setbacks, jogs in the building footprint. I mean, I’ve seen building sections that look like a human spine. They jog in and out, and I guess it’s to make things look interesting, but it makes the building work a lot harder than it has to. And really it’s all subjective. And you know, again, not being a hot pencil, I can just say that, just because I was never good at it means I can trash it, but really very few buildings are going to go out and win a design award. Right. Very few buildings you’re going to look at and be like, “Yep, everyone agrees that it’s a great building.” Mostly everyone is going to have a different opinion and some people are going to hate your building no matter what you do. So its very subjective. Things that are not subjective include: gravity, heat, wind, rain, all these things that the building has to resist over its entire life. Those things are not subjective. They are all objective. And so I think sometimes we put too much of a priority on these subjective design desires, and not enough on these objective things that really maybe matter just as much if not more.
Robb: 03:34 As an engineer, I’m exercising excellent restraints, I think right now. I couldn’t agree with you more.
Steve: 03:42 It helps that you’re tied up with leather belts. Sorry.
Robb: 03:47 I mean the more surface area, the better, sometimes seeing how many gables can we cram on this, or how many dormers can we cram on this roof? And it gets silly
Steve: 03:56 yeah, I drove by one on the way home from Albany yesterday and I almost stopped to take a picture to add to the next time I give this presentation, but I didn’t, too much traffic.
Robb: 04:05 And it turns into all framing and there’s no room for installation issues.
Steve: 04:08 Yeah. You’re making the building work harder. And the basis of, of where I’m coming from is making the buildings easier to actually build. And so I think that results in a building that is going to be more efficient. It’s going to be probably less expensive. It’s going to be easier to maintain. It’s going to be easier to build in that you’re not giving your subcontractors a bunch of surprises. If you can build predictability into the design and a little bit of modularity, even, you can really get some momentum going. You make the lives easier for the guys and gals who are actually building it and you’re going to get a better product.
Robb: 04:49 Better quality control. Yeah. And that actually leads very nicely into number two. Which is design irregularities.
Steve: 04:57 Right. Which again, maybe they could be seen as the same thing, but they’re a bit different.
Robb: 05:02 You’re talking about like the exterior form versus the plans. Is that kind of what you’re getting at?
Steve: 05:07 Yup that would be one thing, you know, in a midrise, high rise building, they’re very good at lining up their apartments. Right. In nice clean stacks, in low rise, which is my jam, it’s not always the case. You have units overlapping each other. I have a project right now, I swear they were playing Jenga and designing at the same time and there was some cross pollination there. And it makes it hard to do your take offs for energy models. It makes it really hard to energy model. I’ve got so many funky little ceilings and floors and whatever. It makes it hard for the contractor. That stuff is going to eventually sag and yeah, it’s got more thermal bridging, more structure, they got to work harder to make the building do what it wants to do. So yeah, just, you know, don’t get cute, build sensible or design sensible buildings.
Robb: 05:58 Yeah, I mean there’s a lot. Making a simple building look interesting seems like quite an art and there are some people that are very, very good at it. I’ve seen some very simple plans, simple forms, very functional- I’m not licensed to express an aesthetic opinion- but it’s good. I mean, we’re not talking about shoe boxes.
Steve: 06:28 yeah. I mean, in my presentation, I’ve got a slide from park slope where I used to live, and the town homes all look exactly the same. Do you think those people paid $6 million for their brownstone because it looked the same as the neighbors or they didn’t care that it looked the same as the neighbors? Does it maybe even add to the urban, you know, the street fabric? I don’t know what the right design term is, but you know, is there value in things kind of looking more the same instead of everything having to be just a little bit different and putting all that energy into these little tweaks when you could be putting the energy into refining your details, building some standard practices in that everyone can build efficiently.
Robb: 07:11 All right. Now we’re switching gears a little bit
Steve: 07:16 More technical now. That was all very fluffy. Yes and No.
Robb: 07:21 I can’t say that you can say that. I’d be pilloried. Alright. Thermal bridging- roofs and walls. This is a nitty gritty performance issue.
Steve: 07:34 Yes. And we have our passive house friends to thank for really making this more obvious to the rest of us. So when we do all these energy models, actually, my friend Charlotte, she’s working on a project in Toronto where one of the key things that they’re looking at is the difference between modeled performance and actual performance in these buildings.
Robb: 08:01 There is a difference.
Steve: 08:03 There is a difference, and where did that difference come from? And one of the things in the envelope, that contributes to this, is thermal bridging. So roofs, you know, in New York City…
Robb: 08:14 Should we define thermal bridging?
Steve: 08:14 Go ahead
Robb: 08:17 Well, in a framed home, for example, if you have a two by six wall and it’s filled with R19 bats, the studs themselves only are about R-5 or something. So t week, that lesser odd value kind of diminishes the performance of the whole wall. And by adding rigid insulation on the outside, Bill and I talked about this in the envelopes, podcasts, you add more. If you put R5 rigid on the outside, you add more than R5 to the whole assembly because you reduced the bridging.
Steve: 08:56 Yup. And that’s the point. So in roofs, in New York City at least, with mostly low slope roofs, it’s not a problem because the typical detail is, you know, a few layers of poly ISO on top and you’re good to go. I will say though, that in the newest version of the building code, they added a table that was actually only in the residential code for years, where if you have an unvented ceiling or attic assembly, a certain percentage of the R-value, if you’re using your permeable installation, has to be above deck. So if it’s an r 38 roof, you have to have r15 continuous above, and then you can do your best down below. And it doesn’t apply if you do spray foam or whatever. But I still see drawings come across my desk that haven’t picked that up. And you know, again, thermal bridging is not only a loss of performance but it’s also potential for moisture condensation and then you’ve got durability issues and indoor air quality issues and etc.. So yeah, low slope roofs aren’t bad except for when you get around roof drains. A good architect will say, r15 minimum at the roof drain instead of going from zero to whatever. The walls are really where it’s at. And especially masonry and especially steel framed walls, that metal is so conductive, I mean, if you’re not putting rigid insulation on the outside, and I know for Code that’s an option, or you can try to load your wall full of closed cell spray foam, but who wants to pay for all that? Just do some bats on the inside and then a couple of inches of rigid on the outside.
Robb: 10:34 Do you see steel framed walls with insulation in the cavities and nothing else?
Steve: 10:44 I see it come across my desk. I don’t let it off of my desk
Robb: 10:48 You still see drawings where you have steel framing bats in the steel framing and nothing else?
Steve: 10:53 Yeah, I still see low slope wood-frame roofs with, you know R-38 bats between the joice and nothing on top. You know, and a lot of this is, the title of the presentation is, we should know better and so I have to tell people at the beginning of my presentation, look probably, hopefully, you will have heard about all these issues before or at least hopefully been aware of them and maybe just need to be reminded or whatever. But it’s not rocket science. These are things that we should have figured out a long time ago, and they just for some reason keep finding their way into these construction documents. So the sub category, or the next one for thermal bridging, is that slabs, and this is how I would say at least 50% of my project first time I see the drawings, and this is hard to do on the radio or podcast or whatever, but the installation is drawn behind the foundation and under the slab. If you have a slab on grade foundation, and so you have an inverted L, but you have continuous concrete vertically and horizontally. So A. you don’t need both the vertical and the horizontal, you only need one B. You need to get installation either on the outside of the foundation and make sure the top of it is contiguous with the above grade wall insulation, or you can leave it on the inside of the foundation and at least separate the slab from the foundation if you don’t have a structural slab. And man, that’s one that architects for some reason, just have a really hard time wrapping their heads around.
Robb: 12:26 First of all, I think passive house people wouldn’t necessarily agree with you, that you don’t need sub slab insulation.
Steve: 12:34 Right, let me clarify. So my projects are mostly low rise, multifamily, affordable. We’re not pursuing any of the advanced certifications. We’re just pursuing the base energy star, you know, LEED for homes or green communities.
Robb: 12:49 And when you’re talking about slabs, are we talking about basement floors? Were we talking about slab on grade?
Steve: 12:54 Slab on grade. There is a difference. Well yeah, and a diagram in my presentation shows we’ve got insulation starting at six inches below grade going down to 24 inches below grade. What about zero to six inches below grade? That’s the coldest part. The ground gets warmer the farther you go down, hence the frost depth for your footings. And so, the coldest part of the foundation is a part that’s getting any installation.
Robb: 13:21 Yeah 20 years ago I was dealing with that. Yeah, I’ve seen it so many times, where in a basement, insulating the outside of a foundation wall, and you get to above grade, well, I don’t know. I don’t want the foam above grade. I’ll just cut it at grade and then leave the top 18 inches.
Steve: 13:44 Yeah because they want to see that concrete. Or they don’t want to cover it. And it is a tricky detail to cover it on the outside if you have a lot of exposed foundation.
Robb: 13:49 Yeah and this is one of the trickier details I think to get right.
Steve: 13:54 I will definitely concede that
Robb: 13:56 In the show notes can we put links to some resources you think? There are good details, we can put a link to at least one of your PowerPoints.
Steve: 14:07 Sure. Absolutely. It is not rocket science though.
Robb: 14:16 No, but it can be challenging and it can be different, and anything different is hard.
Steve: 14:25 Yeah. Right. Agreed. If it was easy, we would have wrapped our heads around a long time ago and it wouldn’t be on my top 10.
Robb: 14:38 Yeah, fair enough. Number five, poorly detailed air barrier.
Steve: 14:44 The trick to air barriers is that you have to draw them.
Robb: 14:49 So this is on plans?
Steve: 14:49 Zone plans. Or sections. Yeah. And so actually that’s really how it should work, is you have that air barrier continuity, big fat dashed line running across your building section, top, sides and bottom. And then you zoom in and you’re looking at every jog in the building. If you just couldn’t help yourself. Every material transition, every assembly transition, you know, floors to ceilings to walls, etc. And you’re zooming in all the way down to the level where the general contractor should not have any questions about how you expect their leakage requirements to be met. Now he or she can say, “oh, I would rather do it this way.” That’s fine, but if you don’t have something to start from, what happens is, I get out there in the field as the building’s being framed, contractor looks at me and says, “what do we got to do?” And I say, “well, what’s in the drawings?” And they say, “this is what’s in the drawings, but we don’t know what it means” or it’s just buried in the spec somewhere because it’s buried in the code somewhere. And, you know, who looks at the specs? Let me take that back. Several general contractors look at specs, but are they sitting out there, you know, in the job trailer or are they in someone’s tool belt as they’re walking around building? No.
Robb: 16:24 It’s hard to find things from specs. Oh my God, it really is. What are some of the examples you see? I mean, give me an example of an air barrier that’s just..
Steve: 16:35 well, first of all, we should probably shouldn’t mention any trade names, but let’s say the sheet air and water barrier product, that one would typically apply to wood framed construction on the outside of a building. Building paper, house wrap, no brand names. Something like that can work well as a water barrier, if it’s installed correctly, which between you, me, and whoever’s listening, it never is. It can be, there’s less of a chance that it’s going to be an air barrier. And I can safely say it is never installed in a way that is going to achieve complete air barrier, like you and I would expect it to be.
Robb: 17:23 And they stopped claiming that. Those manufacturers have not been claiming that. They call it a water resistant barrier or drainage plane.
Steve: 17:32 Okay so they do know better by now, but do the people using it know better?
Robb: 17:36 Well that’s the issue, yeah. I have house trap, that’s my air barrier. And you’re right, it’s not. Its lapped, it’s got staples
Steve: 17:46 And who knows, its flapping in the wind for however many months while they’re waiting the weather to warm up so they can put up their clatting or whatever.
Robb: 17:52 Gotcha. Whereas, so if this was the frame construction, what do you like to see for an air barrier?
Steve: 17:58 Well, we started seeing a lot more of the, again not naming any products, but the sheeting with air and water barrier built into the outer layer. That seems to have a lot better results because it is more manageable.
Robb: 18:16 And tapes all the seams there? It’s very important to tape those seams properly.
Steve: 18:19 Exactly, and a liquid applied air and water barrier, we don’t see all that often on low rise wood frame, but you know, obviously in steel and masonry, it’s this the norm.
Robb: 18:31 cock and foam from the inside?
Steve: 18:34 Cock and foam from the inside. Yeah. You know, we’re starting to back pedal a little bit on spray foam. Spray foam is good to use in certain areas when it was really hard to do anything else. But you know, if you’re looking at the global warming potential and all that stuff, we just really started to see, you know, either fiberglass bats or cellulose. As long as you’ve got a good layer of insulation on the outside, which also has its own, you know, global warming potential. Unfortunately, it’s all a bunch of tradeoffs really. You can achieve the same tightness if you’ve got a good air barrier in that assembly and all the way around.
Robb: 19:18 Thanks for listening. That’s the first five of the top 10 multifamily design mistakes. We’ll do the other five next week. Thanks.
Heather: 19:27 Thank you for listening to buildings and beyond. For more information about the topics discussed today, visit www.swinter.com/podcast and check out the episode show notes buildings and beyond is brought to you by Steven Winter Associates. We provide energy green building and accessibility consulting services to improve the built environment. Our professionals have led the way since 1972 and the development of best practices to achieve high performance buildings. I’ve production team for today’s episode includes Dylan Martello, Alex Mirabile and myself, Heather Breslin, thank you for listening and we’ll see you next week.
69 episodes
Manage episode 237278466 series 2407405
The residential building industry has made incredible progress toward sustainability and energy efficiency goals. At the same time, Senior Sustainability Consultant and Registered Architect Steve Klocke finds many new buildings under-performing because designers continue to make simple, avoidable mistakes.
Based on lessons he’s learned from certifying over 1,200 dwelling units over the past seven years, Steve discusses the top ten multifamily design mistakes being made over and over again – and how to avoid them.
Episode Guest: Steve Klocke, RA
Steve Klocke is a Senior Sustainability Consultant at Steven Winter Associates and a registered architect with 18+ years of experience in architectural design and building science consulting in residential buildings. He provides comprehensive green building certification support for the LEED for Homes, ENERGY STAR and Indoor airPLUS programs with a focus on lowrise multi-unit new construction and gut rehabs.
Steve is an integral part of the initial strategic planning sessions and workshops with builders, architects, and homeowners, setting goals and scopes of work for projects. The certification support he provides for project teams includes energy and building systems analysis, architectural design support, and project management. As a HERS Rater and LEED for Homes Green Rater, Steve inspects projects under construction for compliance with energy performance, durability, and health and safety standards. His performance testing expertise includes whole-house infiltration and duct leakage, as well as infrared thermal imaging.
Episode Information & Resources:
Presentation slides (mostly graphics): Top 10 Multifamily Design Mistakes
Steve’s Multifamily Design Mistakes 1-5:
- Overcomplicated Geometry
- Design Irregularities
- Thermal Bridging: Roofs & Walls
- Thermal Bridging: Slabs
- Poorly Detailed Air Barrier
Check out Part 2 of this episode for mistakes 6-10!
Other Resources:
Air Sealing Guide for Multifamily Masonry Construction
Building America Solutions Center
What comes to Robb’s mind when Steve mentions illicit, high-flow shower heads…
We Want to Hear From You!
Send your feedback and questions to podcast@swinter.com
About Buildings and Beyond
Buildings and Beyond is a production of Steven Winter Associates. We provide energy, green building, and accessibility consulting services to improve the built environment. For more information, visit www.swinter.com.
Hosts
Production Team
Heather Breslin | Alex Mirabile | Dylan Martello
Music
Song: Slotcar | Artist: Podington Bear
Next up on Buildings and Beyond…
We Should Know Better: Top 10 Multifamily Design Mistakes with Steve Klocke, Part 2
Guest: Steve Klocke
CLICK HERE TO LEARN HOW TO SUBSCRIBE
Kelly: 00:06 welcome to buildings and beyond
Robb: 00:09 the podcast that explores how we can create a more sustainable built environment
Kelly: 00:13 by focusing on efficiency, accessibility, and health.
Robb: 00:18 I’m Rob Aldrich
Kelly: 00:19 and I’m Kelly Westby.
Robb: 00:22 This episode I talked with Steve Klocke who is an architect and senior sustainability consultant here at Steven Winter Associates. He works with a lot of builders and developers, largely multifamily, especially low rise multifamily, and he’s been asked to do a presentation at several events-several conferences, called “We should know better, top 10 multifamily design mistakes” and it really resonates with folks and certainly resonates with me. He gets big audiences, so we figured we’d try and talk about it on a podcast. We’ll link to the slides he uses in his presentation, which can help visualize some of the things he talks about, but it was really good to chat. This was a long chat. So this week we have the first five of his top 10 multifamily design mistakes.
Robb: 01:13 All right. Number one over complicated geometry
Steve: 01:21 yeah. Okay. So I won’t get too deep into architectural theory and what we all learned in school and what we should’ve learned in school.
Robb: 01:31 We should say that you are a registered architect.
Steve: 01:34 That’s true. I’ve been for 13 years now. And I wouldn’t ever say that I was ever a “hot pencil”- would be the term, like designing things that look great. I can make them work but, and then make them look good, but making like the really great stuff that wins awards, not my jam. Hence senior sustainability consultant. But anyway, so at some point in architecture we got the impression that to make a building interesting, you had to make it sculptural, blame frank Gary or whatever. And so architects are for some reason driven to make their buildings do funny things sometimes. And to me funny things mean: bump outs, bump ins, setbacks, jogs in the building footprint. I mean, I’ve seen building sections that look like a human spine. They jog in and out, and I guess it’s to make things look interesting, but it makes the building work a lot harder than it has to. And really it’s all subjective. And you know, again, not being a hot pencil, I can just say that, just because I was never good at it means I can trash it, but really very few buildings are going to go out and win a design award. Right. Very few buildings you’re going to look at and be like, “Yep, everyone agrees that it’s a great building.” Mostly everyone is going to have a different opinion and some people are going to hate your building no matter what you do. So its very subjective. Things that are not subjective include: gravity, heat, wind, rain, all these things that the building has to resist over its entire life. Those things are not subjective. They are all objective. And so I think sometimes we put too much of a priority on these subjective design desires, and not enough on these objective things that really maybe matter just as much if not more.
Robb: 03:34 As an engineer, I’m exercising excellent restraints, I think right now. I couldn’t agree with you more.
Steve: 03:42 It helps that you’re tied up with leather belts. Sorry.
Robb: 03:47 I mean the more surface area, the better, sometimes seeing how many gables can we cram on this, or how many dormers can we cram on this roof? And it gets silly
Steve: 03:56 yeah, I drove by one on the way home from Albany yesterday and I almost stopped to take a picture to add to the next time I give this presentation, but I didn’t, too much traffic.
Robb: 04:05 And it turns into all framing and there’s no room for installation issues.
Steve: 04:08 Yeah. You’re making the building work harder. And the basis of, of where I’m coming from is making the buildings easier to actually build. And so I think that results in a building that is going to be more efficient. It’s going to be probably less expensive. It’s going to be easier to maintain. It’s going to be easier to build in that you’re not giving your subcontractors a bunch of surprises. If you can build predictability into the design and a little bit of modularity, even, you can really get some momentum going. You make the lives easier for the guys and gals who are actually building it and you’re going to get a better product.
Robb: 04:49 Better quality control. Yeah. And that actually leads very nicely into number two. Which is design irregularities.
Steve: 04:57 Right. Which again, maybe they could be seen as the same thing, but they’re a bit different.
Robb: 05:02 You’re talking about like the exterior form versus the plans. Is that kind of what you’re getting at?
Steve: 05:07 Yup that would be one thing, you know, in a midrise, high rise building, they’re very good at lining up their apartments. Right. In nice clean stacks, in low rise, which is my jam, it’s not always the case. You have units overlapping each other. I have a project right now, I swear they were playing Jenga and designing at the same time and there was some cross pollination there. And it makes it hard to do your take offs for energy models. It makes it really hard to energy model. I’ve got so many funky little ceilings and floors and whatever. It makes it hard for the contractor. That stuff is going to eventually sag and yeah, it’s got more thermal bridging, more structure, they got to work harder to make the building do what it wants to do. So yeah, just, you know, don’t get cute, build sensible or design sensible buildings.
Robb: 05:58 Yeah, I mean there’s a lot. Making a simple building look interesting seems like quite an art and there are some people that are very, very good at it. I’ve seen some very simple plans, simple forms, very functional- I’m not licensed to express an aesthetic opinion- but it’s good. I mean, we’re not talking about shoe boxes.
Steve: 06:28 yeah. I mean, in my presentation, I’ve got a slide from park slope where I used to live, and the town homes all look exactly the same. Do you think those people paid $6 million for their brownstone because it looked the same as the neighbors or they didn’t care that it looked the same as the neighbors? Does it maybe even add to the urban, you know, the street fabric? I don’t know what the right design term is, but you know, is there value in things kind of looking more the same instead of everything having to be just a little bit different and putting all that energy into these little tweaks when you could be putting the energy into refining your details, building some standard practices in that everyone can build efficiently.
Robb: 07:11 All right. Now we’re switching gears a little bit
Steve: 07:16 More technical now. That was all very fluffy. Yes and No.
Robb: 07:21 I can’t say that you can say that. I’d be pilloried. Alright. Thermal bridging- roofs and walls. This is a nitty gritty performance issue.
Steve: 07:34 Yes. And we have our passive house friends to thank for really making this more obvious to the rest of us. So when we do all these energy models, actually, my friend Charlotte, she’s working on a project in Toronto where one of the key things that they’re looking at is the difference between modeled performance and actual performance in these buildings.
Robb: 08:01 There is a difference.
Steve: 08:03 There is a difference, and where did that difference come from? And one of the things in the envelope, that contributes to this, is thermal bridging. So roofs, you know, in New York City…
Robb: 08:14 Should we define thermal bridging?
Steve: 08:14 Go ahead
Robb: 08:17 Well, in a framed home, for example, if you have a two by six wall and it’s filled with R19 bats, the studs themselves only are about R-5 or something. So t week, that lesser odd value kind of diminishes the performance of the whole wall. And by adding rigid insulation on the outside, Bill and I talked about this in the envelopes, podcasts, you add more. If you put R5 rigid on the outside, you add more than R5 to the whole assembly because you reduced the bridging.
Steve: 08:56 Yup. And that’s the point. So in roofs, in New York City at least, with mostly low slope roofs, it’s not a problem because the typical detail is, you know, a few layers of poly ISO on top and you’re good to go. I will say though, that in the newest version of the building code, they added a table that was actually only in the residential code for years, where if you have an unvented ceiling or attic assembly, a certain percentage of the R-value, if you’re using your permeable installation, has to be above deck. So if it’s an r 38 roof, you have to have r15 continuous above, and then you can do your best down below. And it doesn’t apply if you do spray foam or whatever. But I still see drawings come across my desk that haven’t picked that up. And you know, again, thermal bridging is not only a loss of performance but it’s also potential for moisture condensation and then you’ve got durability issues and indoor air quality issues and etc.. So yeah, low slope roofs aren’t bad except for when you get around roof drains. A good architect will say, r15 minimum at the roof drain instead of going from zero to whatever. The walls are really where it’s at. And especially masonry and especially steel framed walls, that metal is so conductive, I mean, if you’re not putting rigid insulation on the outside, and I know for Code that’s an option, or you can try to load your wall full of closed cell spray foam, but who wants to pay for all that? Just do some bats on the inside and then a couple of inches of rigid on the outside.
Robb: 10:34 Do you see steel framed walls with insulation in the cavities and nothing else?
Steve: 10:44 I see it come across my desk. I don’t let it off of my desk
Robb: 10:48 You still see drawings where you have steel framing bats in the steel framing and nothing else?
Steve: 10:53 Yeah, I still see low slope wood-frame roofs with, you know R-38 bats between the joice and nothing on top. You know, and a lot of this is, the title of the presentation is, we should know better and so I have to tell people at the beginning of my presentation, look probably, hopefully, you will have heard about all these issues before or at least hopefully been aware of them and maybe just need to be reminded or whatever. But it’s not rocket science. These are things that we should have figured out a long time ago, and they just for some reason keep finding their way into these construction documents. So the sub category, or the next one for thermal bridging, is that slabs, and this is how I would say at least 50% of my project first time I see the drawings, and this is hard to do on the radio or podcast or whatever, but the installation is drawn behind the foundation and under the slab. If you have a slab on grade foundation, and so you have an inverted L, but you have continuous concrete vertically and horizontally. So A. you don’t need both the vertical and the horizontal, you only need one B. You need to get installation either on the outside of the foundation and make sure the top of it is contiguous with the above grade wall insulation, or you can leave it on the inside of the foundation and at least separate the slab from the foundation if you don’t have a structural slab. And man, that’s one that architects for some reason, just have a really hard time wrapping their heads around.
Robb: 12:26 First of all, I think passive house people wouldn’t necessarily agree with you, that you don’t need sub slab insulation.
Steve: 12:34 Right, let me clarify. So my projects are mostly low rise, multifamily, affordable. We’re not pursuing any of the advanced certifications. We’re just pursuing the base energy star, you know, LEED for homes or green communities.
Robb: 12:49 And when you’re talking about slabs, are we talking about basement floors? Were we talking about slab on grade?
Steve: 12:54 Slab on grade. There is a difference. Well yeah, and a diagram in my presentation shows we’ve got insulation starting at six inches below grade going down to 24 inches below grade. What about zero to six inches below grade? That’s the coldest part. The ground gets warmer the farther you go down, hence the frost depth for your footings. And so, the coldest part of the foundation is a part that’s getting any installation.
Robb: 13:21 Yeah 20 years ago I was dealing with that. Yeah, I’ve seen it so many times, where in a basement, insulating the outside of a foundation wall, and you get to above grade, well, I don’t know. I don’t want the foam above grade. I’ll just cut it at grade and then leave the top 18 inches.
Steve: 13:44 Yeah because they want to see that concrete. Or they don’t want to cover it. And it is a tricky detail to cover it on the outside if you have a lot of exposed foundation.
Robb: 13:49 Yeah and this is one of the trickier details I think to get right.
Steve: 13:54 I will definitely concede that
Robb: 13:56 In the show notes can we put links to some resources you think? There are good details, we can put a link to at least one of your PowerPoints.
Steve: 14:07 Sure. Absolutely. It is not rocket science though.
Robb: 14:16 No, but it can be challenging and it can be different, and anything different is hard.
Steve: 14:25 Yeah. Right. Agreed. If it was easy, we would have wrapped our heads around a long time ago and it wouldn’t be on my top 10.
Robb: 14:38 Yeah, fair enough. Number five, poorly detailed air barrier.
Steve: 14:44 The trick to air barriers is that you have to draw them.
Robb: 14:49 So this is on plans?
Steve: 14:49 Zone plans. Or sections. Yeah. And so actually that’s really how it should work, is you have that air barrier continuity, big fat dashed line running across your building section, top, sides and bottom. And then you zoom in and you’re looking at every jog in the building. If you just couldn’t help yourself. Every material transition, every assembly transition, you know, floors to ceilings to walls, etc. And you’re zooming in all the way down to the level where the general contractor should not have any questions about how you expect their leakage requirements to be met. Now he or she can say, “oh, I would rather do it this way.” That’s fine, but if you don’t have something to start from, what happens is, I get out there in the field as the building’s being framed, contractor looks at me and says, “what do we got to do?” And I say, “well, what’s in the drawings?” And they say, “this is what’s in the drawings, but we don’t know what it means” or it’s just buried in the spec somewhere because it’s buried in the code somewhere. And, you know, who looks at the specs? Let me take that back. Several general contractors look at specs, but are they sitting out there, you know, in the job trailer or are they in someone’s tool belt as they’re walking around building? No.
Robb: 16:24 It’s hard to find things from specs. Oh my God, it really is. What are some of the examples you see? I mean, give me an example of an air barrier that’s just..
Steve: 16:35 well, first of all, we should probably shouldn’t mention any trade names, but let’s say the sheet air and water barrier product, that one would typically apply to wood framed construction on the outside of a building. Building paper, house wrap, no brand names. Something like that can work well as a water barrier, if it’s installed correctly, which between you, me, and whoever’s listening, it never is. It can be, there’s less of a chance that it’s going to be an air barrier. And I can safely say it is never installed in a way that is going to achieve complete air barrier, like you and I would expect it to be.
Robb: 17:23 And they stopped claiming that. Those manufacturers have not been claiming that. They call it a water resistant barrier or drainage plane.
Steve: 17:32 Okay so they do know better by now, but do the people using it know better?
Robb: 17:36 Well that’s the issue, yeah. I have house trap, that’s my air barrier. And you’re right, it’s not. Its lapped, it’s got staples
Steve: 17:46 And who knows, its flapping in the wind for however many months while they’re waiting the weather to warm up so they can put up their clatting or whatever.
Robb: 17:52 Gotcha. Whereas, so if this was the frame construction, what do you like to see for an air barrier?
Steve: 17:58 Well, we started seeing a lot more of the, again not naming any products, but the sheeting with air and water barrier built into the outer layer. That seems to have a lot better results because it is more manageable.
Robb: 18:16 And tapes all the seams there? It’s very important to tape those seams properly.
Steve: 18:19 Exactly, and a liquid applied air and water barrier, we don’t see all that often on low rise wood frame, but you know, obviously in steel and masonry, it’s this the norm.
Robb: 18:31 cock and foam from the inside?
Steve: 18:34 Cock and foam from the inside. Yeah. You know, we’re starting to back pedal a little bit on spray foam. Spray foam is good to use in certain areas when it was really hard to do anything else. But you know, if you’re looking at the global warming potential and all that stuff, we just really started to see, you know, either fiberglass bats or cellulose. As long as you’ve got a good layer of insulation on the outside, which also has its own, you know, global warming potential. Unfortunately, it’s all a bunch of tradeoffs really. You can achieve the same tightness if you’ve got a good air barrier in that assembly and all the way around.
Robb: 19:18 Thanks for listening. That’s the first five of the top 10 multifamily design mistakes. We’ll do the other five next week. Thanks.
Heather: 19:27 Thank you for listening to buildings and beyond. For more information about the topics discussed today, visit www.swinter.com/podcast and check out the episode show notes buildings and beyond is brought to you by Steven Winter Associates. We provide energy green building and accessibility consulting services to improve the built environment. Our professionals have led the way since 1972 and the development of best practices to achieve high performance buildings. I’ve production team for today’s episode includes Dylan Martello, Alex Mirabile and myself, Heather Breslin, thank you for listening and we’ll see you next week.
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