[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

GSBN:(LONG, multi-responses) Re: TLS #38, Roofs & Foundations

<x-flowed iso-8859-1>At 11:50 PM 2/13/02, you posted:
>I'm hoping I can enlist some of you for direction,
>advice and material...
>I'm looking for:...
>Ready to be stunned by your responses...

At 10:40 AM 2/20/02, you accidentally posted:
>To date it's netted exactly zero response!

Joyce said that she liked the detail of your post; here's a friendly opposing viewpoint from my experience:

Though it's always a crap shoot, something I learned when I was on the CREST list, and which was reproved when I was editor at TLS, is that the wonderfully thoughtful people of SB (like most wonderfully thoughtful people anywhere) almost never respond well to requests for the very general, nor for the very specific. On the one hand, imprecision opens the door to a universe of discourse in which almost nobody want to get mired (and those that do get tiresome quickly)... and on the other hand, the very precise leaves almost no wiggle room for people to obliquely fit in their own related experiences.

Personally, I can respond to almost nothing on the list you posted. Most of it's too specific. Finding targets for those darts will take a lot more concentrated effort than a wideband broadcast, even in such a select and august group as that gathered on the GSBN.

You wrote, "I don't think there's any way to do this job but to approach people individually, with an assignment already in mind." Some of the best articles in my time came in completely unsolicited, and others from general calls for submissions. But what you said is also true, especially in light of the list you presented. In my experience, approaching people one-on-one with a somewhat tight (but not completely firm) idea about a topic you know that they know about worked most consistently in getting articles. Which, to avoid hitting up the same people over and over (which gets annoying for them and for the readers) means keeping on top of news and gossip.

Being subscribed to and actually reading not just the CREST list, but the regional lists and Euro lists and Aussie list and other nonSB lists (cordwood, earthship, cob, etc). Reading magazines. Developing relationships with people, not just thinking of them as sources... keeping in mind that first and foremost, they're *people*, and as such they're unique and interesting and multifaceted and they're about WAY more than SB. Imagine what it's like to be one of the "important" folks who are constantly badgered by people wanting things from them. Imagine that the only time they ever hear from TLS is if TLS wants something from them. I know how I'd feel. Sometimes people like to know that their value as an individual extends beyond what they can do for whoever happens to be on the other end of the email or phone or handshake.

The situation reminds me of something. A few years ago, a couple guys in Canada sent out some excited emails - they had a big barn at their disposal and were going to do some SB experiments in it. I replied, asking if they'd keep me informed about what they were up to. Never got a reply. A couple months later, I sent an email asking how things were going. No response. A few months more pass, and I asked again. Then I gave up. Later, these guys decided to write a book, and sent another email around asking for submissions. Remembering how I'd been treated by these people, I chose not to respond. Usually, our futures are written by our own hands.

	Anyway, that's what I think, not that you want or need to hear it.

At 11:50 PM 2/13/02, you wrote:
>I'm looking for:
>-insulation options, including thoughts on bales as roof insulation

There's a place in Maryland that used shredded blue jeans for roof insulation; available commercially, I don't remember the name of the product. Pics at http://www.potkettleblack.com/misc/williams.html , contact the owners from there.

I also recall at least one party using raw wool purchased from the Navajo Nation, but don't remember any details. Rob Tom might.

Bales as roof insulation, my thoughts. They need to be sealed on all sides with wet-applied plaster. Talk to Kelly Lerner, one of her Mongolia projects had bales in the ceiling which caught fire. Cost-benefit analysis of beefing up the structure to accommodate the extra weight vs using lighter-weight conventional insulation needs to be considered.

>-leads on good people to talk to about living roofs, thatch, slate,
>and other traditional roofing systems

	Living roofs are addressed at length below.

Thatch, do a search at http://www.google.com on the phrase (using quotation marks) "master thatch."

Slate, get with Joe Jenkins if you can. http://www.jenkinspublishing.com (I think)

>-thoughts on the aesthetics of roof design

Contact Ann Edminster. Use the phrase, "fussy, anachronistic roof lines" and tell her I sent you. Get a copy of her book Efficient Wood Use In Residential Construction, available from the NRDC. Balance the isolated consideration of aesthetics with environmental and pragmatic concerns.


OK, now I'll get general. I'll just start riffing. (I don't really have the time or desire to research and write an article myself. Though I'm willing to do reviews in exchange for a copy of the thing reviewed, mostly because I enjoy writing reviews. Well, maybe I'll co-author something if somebody else takes the lead.)

Most interesting roof thing I've seen lately was Sam Droege's "out"sulation method... see pics at http://www.potkettleblack.com/misc/sam1.html ... I think he'd be quite helpful in providing good details, just drop him an email from the pics pages. Actually, thinking about it now, it's a lot like the insulated earthship roofs (which are nothing more than living roofs, really), but without the dirt. Could incorporate that angle, too. (Just don't use the first earthship book as a reference - the thing has enormous, horrible flaws in it.)

You could sic somebody on the relative ecological-vs-practical merits of various roof cladding options. I'm told that Ondura, f'rinstance, is significantly comprised of recycled content - but how's it last? Can you catch rainwater on it? There was a recycled-content fibrous-cement shingle on the market a while back that got pulled because it reacted adversely to water. Just what you want in a shingle, right? (Details in some old EBN somewhere.)

Could get with Shay Salomon, too, if you wanted, who's used metal printing plates to roof a couple vault projects.

Pat Newberry made his temporary-quarters roof out of cement-soaked carpet (while he's been building his weird SB/earthbag hybrid, previously in TLS).

	There was a tire-roofing article from Matts a while back.

Could have somebody review appropriate chapters of books like The Owner-Built Home for other homebrew options.

The Steens have tried various things in Mexico, nearly all of which I've found fascinating.

Does the book A Pattern Language have anything interesting to say about roofs? How about the Canadian Home Builder's Guide?

Catherine's given presentations about living roofs at the last two Build Here Now events. You might do a little 'net search for other people too - there's at least one company out there specializing in living roofs, and I recall that they had a decent website. I visited a SB place under construction in PA that hired them and was satisfied, but it was a short visit and I didn't have my camera. I also seem to recall reading that one of them big cities in Switzerland (was it Stockholm?) passed legislation that all new roofs, or roofs being repaired, were required to be made into living roofs. The first code-approved SB house in Minnesota had a partial living roof; someone could contact them or their architect to see how it's holding up over time. Their contact info should be in the second Moisture issue, I think, and they were previously a Regional Rumbling. (Note that the area code may have changed since then - unless you call their architect, Jono, who was in Minneapolis.) Rob Roy has always done living roofs; could cite his books, or contact him for an interview.

Oh, and there's the fascinating reciprocal roof; there's a SB place in England with one, and I think John Glassford's done one, and Robert Andrews ( http://www.balewatch.com ) could be a good contact about it. See some pics at http://www.strawhomes.com/build/here/now2000/tour/10.html

But this is probably mostly too hippie-dippie. For the pro/normal end of the spectrum, somebody could research the general topic in EBN, JLC, even FHB and like-that.

Could discuss the merits and drawbacks of various truss designs vs rafter/ridge-beam affairs. (I like scissor trusses, though dropped-heel trusses are OK... but the rafter/ridge-beam approach will always be nearest my heart.)

I think you should definitely do something in no uncertain terms on flat roofs, they're ?ü¢kïng pernicious for SB, always have been and always will be, and people STILL want them. Talk with Jeff Ruppert, and see if DE and Matts can discuss their expert-witness dark secrets yet. There are old turn-of-the-century photos from New Mexico pueblos that can be dredged up... they show flat roofs, yes - but flat roofs with OVERHANGS. (And again, adobe ain't SB.) People get so wrapped up in that evil "southwest" look. Oh, that's another thing on this topic: research the *actual* origins of "Santa Fe Style." It was self-consciously derived, based on *pieces* of reality which were sometimes taken out of context. A few months ago, the Smithsonian Museum of American History had (maybe they still do) an exhibit about New Mexico, which had a presentation about the area's architecture; a sign in that presentation read, in large type: "To give Santa Fe the look that tourists expected to see, the city planning board in 1912 asked a group of archaeologists and artists to define a Santa Fe style. The group, which included archaeologist Jesse Nusbaum and anthropologist Edgar Hewett, urged that all new buildings near the old plaza have flat roofs, protruding roof beams, and adobe like surfaces. One observer noted that 'Santa Fe was a place fast becoming what it should have been.'"

Pertinent to roof concerns, here's an email I answered recently - additional/opposing viewpoints could be solicited:

At 10:55 AM 2/12/02, Patrick Geile jonene@... wrote:
>I have a question concerning the application of
>stucco between the two base plates on the top
>where the joists fit. Is it necessary to apply
>stucco between these two base plates?  This
>is where the rafters attach and it is difficult to
>apply stucco up there.

	There's plenty of people who wouldn't and haven't. I'm not one of them.

A Couple Reasons To Do It

1) To create a complete air barrier. It's been shown that the stucco/plaster/render is a very important part of the thermal resistance of the wall system. If there's an air gap between the straw and stucco (which could potentially develop during or after application), computer modeling has shown that the R value can be decreased by up to half due to convective loops. Following that logic, if the top of the wall isn't sealed - whether or not there's an air gap between the bales and finish - it could act like a chimney, and not perform to its thermal optimum.

2) To keep out buggies and beasties. It's often said that critters don't like nesting in bales because the bales are inconveniently tight. That's basically true - but the generally unsaid part is that it's not *always* true. Particularly if there are less-dense cracks between stacked bales (since critters are usually just as happy to follow the path of least resistance as we are). I visited a SB house in Colorado that had a rats-in-the-wall problem. In that case they came up from below on the outside of the house, tunneling along the seams between bales, finally hollowing out a nest at about eye level. That house had a too-low stemwall that only brought the bales above ground level six inches or so; and this stemwall wasn't as wide as the bales, so the bales cantilevered over it three or four inches. The stucco was applied as you might suspect: leaving a three- to four-inch gap which opened directly to the bottom of the bales.

That said, the sealer doesn't have to be cement stucco. It could be an earthen plaster from the site.

Since you're foresightful enough to ask about this, I think it's probably safe for me to assume that you're going to detail to prevent condensation or leakage from dripping onto the top of the wall.

	Foundations. Uh.

You could do something about basements vs not-basements... y'know, the traditional full foundation with basement compared to something like FPSF or even pier. Sara Mock of http://www.moxvox.com is fully in favor of basements (though she seems to particularly mean walk-out basements), where other people (Ken Kern was one, as I recall) are dead against them as foolish and pointless and little-used and needlessly expensive. Does it cost more to add sf by going down or up? That's first-cost, of course... what about life-cycle costs? It can be easier to heat those extra sf if they're in a basement, but at the same time basements can be a potentially significant contributor to heat loss. But in a milder climate with wide diurnal temperature swings, earth-coupled basement-like areas can be utilized to excellent effect. Stuff like that. Which leads into discussions of theories like John Hait's book Passive Annual Heat Storage, which I know by reputation only but seems to contradict the excellent research done by the Underground Space Center of the University of Minnesota (defunct).

Could do something on self-draining foundations, an old-Europe thing. Go to the Amazon Nails website and download the terrific pdf document Guide To Straw Bale Building and check out the section on foundations for this (and other low-tech thoughts). You could ask Barbara to expound. But it can also raise some questions: What about air movement? What about ingress and egress into the bales for little nasties - or big ones, depending on the design? (Flashback to the house with the rat problem described earlier.) In drainage practice, what's the big difference between a self-draining foundation and a typical 'Murrican-bale toe-up detail that incorporates a weep system?

What's better: A typical FSPS scheme where the insulation is employed in a horizontal skirting - or where the insulation goes vertically straight down into the ground (like basement walls), isolating the earth/mass directly below the footprint? How climate-dependant is the performance of each option?

Could revisit ways to avoid the "superwide footing" that so many people *still* seem to assume is required for SB construction.

Could talk about cantilevering, which isn't really foundations but is usually low to the ground and could be introduced by way of a discussion of pier foundations. I know of a place in West Virginia (pirated without permit, and as secret at the owner's request) that's built with a pole frame, and the bale walls are outside the poles on cantilevering plates and joists. Which leads to questions about the best way to insulate the joisted floor.

Do followups on people who have done unusual foundation things as reported in previous issues of TLS. Contact 'em, see how it's going, and if they'd do it again.

There was some sort of ruling recently in the US about some stuff used to treat wood. Don't know what it was. But it opens the door to a discussion of permanent wood foundations. I think there's a booklet from CMHC on the subject. (I think CMHC has something on EVERYTHING.) Research for an article on this topic could include the book The $50 And Up Underground House, which details ways to waterproof UNtreated wood-framed *underground* structures. I've been to a place in Minnesota a couple times that was built this way well over a decade ago, and it's outstanding and gorgeous and I feel completely safe inside it. No evidence of moisture intrusion ever, anywhere. See pics at http://www.strawbalecentral.com/lilac/lilac2.html

Go to http://www.google.com and type in (with quotes) "alternative foundation".


At 12:29 AM 2/22/02, Joyce wrote to Chris:
>Could you let me know more about the non-GSBN interest
>and offers you are receiving - maybe forwarding them to me
>so I get an idea of who and what and when.

As things concern TLS, I think each staffer (and I think of everyone as a staffer - NO hierarchy) should always know what the other is up to - *especially* if one of them thinks that it's none of the other person's business. Because that usually means that there's an ego getting freaky.

IMO, *all* TLS email should go through the TLS email address. Bill C should be able to set it up like a miniature email list which resends incoming mail back to each staff member. This relies on each staff member either setting up their email program with a TLS "personality" that has the return-address field filled in with the TLS email address (so when people hit the reply-to button the response goes to the TLS email address), or setting up a personal TLS-only email account in the same way through one of the free services, like Hotmail or Yahoo.

	GSBN isn't really the best venue for it, IMO... snicker...


At 07:04 PM 2/22/02, Joyce wrote:
>They are watching us and talking to each other about us

I think this accidental series of posts has been more funny than anything. If anybody's judging you harshly as a result, I hope it remains *their* problem and not something that gets hung around the neck of TLS. What I've seen is a couple people trying VERY hard to uphold (and, if possible, improve) the legacy that is TLS. The only thing I haven't really cared to read was the idea of being manipulated toward some hidden goal... but I have to admit having done the very same thing in the past on the CREST list. (I'm still too awed by the people on GSBN - probably always will be - to try to pull anything over on them.)


At 01:44 PM 2/22/02, you wrote:
>I have seen several living roofs go on bale buildings here
>in Ontario, and I'm dubious about their value from an
>environmental point of view. Anybody have thoughts, ideas
>or suggestions for a well-balanced article on living roofs?
>Otherwise, my article will end up with a slightly negative
>tone, based on what I've seen installed.

When a building is built, what was (usually) previously a patch of CO2-munching greenery becomes a patch of composite shingles or steel roofing or some other nonliving surface. And that doesn't include trees and other vegetation cleared to make yards and swimming pools and driveways and parking lots. Bale walls are carbon sinks, but the bale walls won't last forever and eventually that carbon will be released. In the meantime, a living roof can be working to offset that eventuality, as well as the emissions included in the overall embodied energy of the structure. Potentially, if it became a common practice, it seems that green roofs could be a sizable part of the step toward housing that actually contributes something back to the physical environment... as well as the emotional environment.

Along both of those lines, gandering at a copy of Malcolm Wells' book Recovering America might prove illuminating.

I ain't got numbers, so I don't know what the EE and other non-building-performance tradeoffs actually are. (It would, of course, vary enormously one example to another.) The frame will typically need beefing up to accommodate the extra load. In desert climates, people might end up wanting to water the roof like they water their unnatural lawns, and that would be a stupid thing to do in the face of shrinking aquifers - though it would increase the performance of the roof for reducing cooling loads. And I don't know how much C02 can be converted to 02 by green roofs of varying sizes and plant types. So you're right, I'm just yappin'. (Which is a cop-out say of saying that the variables are tremendous and need to be considered on a case-by-case basis, which is why it bugs me to no end when I read articles that are climate-centric and otherwise not encompassing... locally-derived opinion - and subjective to boot - disguised as universal fact.)

As for how they perform, a typical uninsulated living roof in a severely cold climate is almost pointless in terms of any benefit of thermal resistance. A typical living roof should be as well-insulated as a nonliving roof.

The book Earth Sheltered Housing Design published by the Underground Space Center of the University of Minnesota in '78 has a wealth of data about this stuff, particularly with regard to the widely-disparate seasonal climate(s) of Minnesota. Cutting through the numbers, it notes, "...in order to compete effectively with standard insulating materials, soil depths in excess of 2.75m (9 ft) would be required on the roof." That speaks specifically to a climate like Minnesota's; less depth would be required in milder climates to achieve the same results.

Nine FEET of dirt? Yikes. An insulated compromise version with comparable thermal resistance would have 10cm (3.9 in) of polystyrene insulation covered by 46 cm (18 in) of earth. Both are equivalent to 12 cm (4.6 in) of polystyrene and no earth cover. (Here we might remember Sam Droege's "out"sulation that I mentioned earlier. He used 9"-thick foam sheets that he got from a supplier to SIPs manufacturers.)

The difference between the performance of these models (which didn't consider any greenery, just the earth cover) all have to do with mass. Just like the fabled thinly-distributed high mass of SB helps moderate temperature swings, thereby reducing space-conditioning requirements, so too does the mass of the earth on a living roof moderate things.

A comparison of performance in Minnesota-January weather was made between an 18"-earth/4"-polystyrene roof ("Roof A") and a no-earth/4.6"-polystyrene roof ("Roof B"). Each had the same level of thermal resistance, and both were supported by concrete planking. The model weather outside was -12C, followed by a cold front where the temperature went down to -18C for five days, after which it went back up to -12C.

	Quoting the book:

"Due to its low thermal mass, Roof B responds immediately to the change outside and within two days reaches a new maximum heat loss which is maintained for the remaining three days. When the temperature returns to normal, Roof B responds at once and after two days has returned to its normal January operating level. Roof A, however, requires a full day before the ceiling begins to indicate that more severe conditions now exist outside and once it does begin to respond, does so much more slowly than Roof B. After five days, when the outside temperatures return to normal, the heat loss of Roof A is still gradually rising having attained only 77% of the increase of Roof B. Roof A requires another full day before responding to the return of normal weather conditions.

"...despite the much longer total response time, Roof A require 8% less total energy than Roof B to cope with the severe period. At the same time, Roof A exhibited a peak increase in load which was only 85% of that of Roof B. Furthermore, Roof B's low thermal mass required almost twice as much additional energy (196%) during the five-day period in which outside air temperature were most severe, thereby placing the bulk of its demand during the period when the outside to inside air temperature differential was at its greatest and required the most energy input from the furnace to bring ventilation air up to room temperature."

The R-value for these assemblies is given as "R=4.35 m2K/W" which I don't remember how to translate and I don't have the references with me that I need to look it up.

The text does not directly address moisture content; but if the soil is saturated, it will be much more conductive than if it's dry. In the book's appendices, it's suggested that the calculations were based on "very dry" soil. Also in the appendices: "In studying a single case with moisture contents ranging from 18% to 37%... it was found that the winter heat loss was increased by 28%, while the summer cooling rate increased 49% for the wet soil as opposed to the dry. While such variations show little impact upon the general conclusions with respect to the advantages of earth sheltered housing to conventional housing, they do emphasize the impact the moisture content has on the thermal characteristics of the soil."

Almost glossed over in the book are the summertime benefits of a living roof. "A final consideration which comes to light in determining the thermal value of earth cover on a roof is that of the boundary condition which exists at the upper surface of the roof. Vegetation on this surface can contribute to the thermal efficiency in a number of ways, such as shading effects, improved insulation due to air trapped in the foliage, and more important the elimination of solar heat gain to the roof during the summer months."

It goes on to cite a study in which temperatures beneath asphalt surfaces were found to be over 140F while the air temperature was no more than 90F... and at the same time, temperatures under grass cover were consistently up to 7F below ambient, depending on the length of the grass.

What's any of it mean? That it's like anything else. A person's gotta research what's right for their own situation. Sometimes a properly-implemented living roof will provide reasonable thermal benefit, and sometimes it just won't be much better than other approaches. There are situations where the pragmatic trade-offs might favor *not* having a living roof. But it's about more than just thermal performance.

I mean, what's uglier than looking at your neighbor's decrepit composite-shingle roof with its curling corners?