<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>First .... to all who have worked so hard on SB code issues over the years - thank you for your dedication and passion.</div><div>There is a resounding ring of hope circling the globe as Martin's latest news spreads and congratulations roll in. So inspiring.</div><div>-------------------------------------------------------</div>Hi Jacob,<div><br></div><div>Thank you for your thoughtful comments on my question about insulation/air barrier options for the Morris.</div><div>I will share them with committee members and let you know what transpires.</div><div><br></div><div>Regarding access to the wall cavities - removal of damaged plaster and inserting holes</div><div>as needed to pack cellulose (or other insulation) have been discussed. Your mention of</div><div>drying time for straw clay are well taken - this is certainly an issue in our climate. We have had an</div><div>air source heat pump donated to the project which could, we conjecture, (this is new technology to me)</div><div> contribute to accelerated drying of whatever materials we use.</div><div><br></div><div>Am continuing to work on the wool insulation option - the local agricultural college is doing experiments in this area and</div><div>we hope to use some of their products this year. They are using success of wool batt and blown in, in UK and NZ for their marketing plans.</div><div><br></div><div>All the best,</div><div><br></div><div>kim</div><div><br></div><div>BTW I do indeed know Annie M, Nova Scotia is small! Just had a view of her starring role in S*** </div><div><br></div><div>Also you may be interested in having a look at a report I did a few years ago for CMHC looking at best practices and challenges for </div><div>building with straw bales in Atlantic Canada. While wood cladding and/or other rain screens are being used on many projects, I wouldn't say</div><div>they are the norm. Adding this extra skin is generally recommended on a case by case basis - it is especially effective where a building is exposed to </div><div>our driving horizontal rains, however for material conservation and aesthetic it is often not specified. Verandas and generous overhangs are often used as well.</div><div><br></div><div>Report can be ordered for free from Tel. 1 800 668-2642. Be sure to ask for the full report </div><div>which includes a 20 min dvd of interviews with bale builders and a data base of the of 40+ buildings profiled.</div><div>Straw Bale Construction in Atlantic Canada</div><div>HIghlights and Full Report #65828</div><div>Order desk: <a href="https://www03.cmhc-schl.gc.ca/b2c/b2c/init.do?language=en">https://www03.cmhc-schl.gc.ca/b2c/b2c/init.do?language=en</a> </div><div><br></div><div><br></div><div><br><div><div>On 2013-04-28, at 11:55 PM, Jacob Deva Racusin wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
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<div class="moz-cite-prefix">Kim,<br>
<br>
Wow, what a great project! That's a really dramatic image of the
Morris House next to the massive glass-faced skyscraper...good on
ya!<br>
<br>
I'm a bit hesitant to reply given the tremendous wealth of
knowledge on this list, but it's a great question so I'll take a
crack. My understanding of 'nogging' is brick non-structural
cavity infill, yes? And you are looking to insulate the empty
cavity sections above the brick?<br>
<br>
The concern about creating a moisture problem by introducing
insulation is a valid one - there is plenty of precedence for this
unfortunate dynamic. The introduction of insulation reduces the
drying potential of the assembly, and can create condensation
problems which did not previously exist. Insulation can be
introduced safely, however, if moisture sources are considered and
mitigation strategies are designed into the work. First and
foremost, keeping bulk liquid moisture out of the assembly is
critical (wind-driven rain and window leaks are two notorious and
insidious examples). That's the most significant source of
moisture damage, and even a small window leak that might have
previously gone undetected can become a bigger problem when heat
loss from inside the building is shut off and drying potential is
reduced. The next step involves air-sealing, which you reference
would be part of the protocol. This is critical to reduce
bulk-loading of moisture vapor into the wall through air leakage.
When I do building performance work, I see plenty of examples of
weatherization work done in the 80s, when insulation was added in
attics without air sealing, and it is not uncommon to see evidence
of moisture damage in particularly leaking locations. I'm unclear
as to how you would be accessing the interior of the cavity and
addressing air leakage, but this would be an important move prior
to/in concert with insulating (I note that none of the insulation
materials you reference are air barriers themselves, requiring a
separate air sealing approach). In your climate, air-sealing from
the interior - stopping the moisture drive at its source - is
desirable, although a primary air barrier on the exterior can work
well too if the detailing is tight and the air barrier is vapor
permeable enough to allow drying to the exterior as need be. You
mention that there is no vapor barrier in the wall assembly;
myself, I prefer such vapor-open strategies, but it is very
important that these be deployed with rock-solid water control and
air-tightness measures to be effective. Diffusion through
materials alone is very unlikely to cause a problem, but can push
conditions in a wall or ceiling into a danger zone if there are
other moisture issues also at play. <br>
<br>
I like dense-pack cellulose because it has a relatively high
R-value compared to other in-fill insulation, is fire-retardant
without the use of HFRCs, performs a notable amount of air
circulation retardation (not an air barrier, but does slow
movement down a good bit), has a high hydroscopicity that allows
concentrations of moisture to disperse throughout the material
(avoiding higher concentrations in specific areas) and dry out if
given the opportunity, is pretty ecologically-benign and not too
industrially-intensive (depending on the specific product), and
installs dry - a big plus compared to many of the wet-wall natural
building materials I otherwise favor using. I am unfamiliar with
aerogel in practice, only in theory, so I won't comment, but my
bigger concern around straw-clay and hempcrete would be the amount
of built-in moisture you are introducing into the cavity.
Provided you can ensure adequate drying within a reasonable amount
of time they could work fine if you are alright using a relatively
lower-R material, but since moisture is a chief concern of your
committee that might be a harder sell. We don't have much access
to affordable wool insulation, but that could be an attractive
option - again, providing thorough air sealing measures are taken,
as it will be unlikely to stop air flow to any appreciable
degree. I like the idea of the reused brick - the lowest
insulative value of any on your list, but I like the nod to
finishing the original design, for whatever that's worth (perhaps
not much, if your goal is to maximize comfort for the
inhabitants).<br>
<br>
I hope that helps. There are some great case studies on both
<a href="http://GreenBuildingAdvisor.com">GreenBuildingAdvisor.com</a> and <a href="http://BuildingScience.com">BuildingScience.com</a> that provide some
good examples of similar situations, I can dig up some examples
off-list if you have trouble finding them. Best of luck, keep up
the good work!<br>
<br>
Jacob<br>
<pre class="moz-signature" cols="72">Jacob Deva Racusin
New Frameworks Natural Building, LLC
P.O. Box 15, Montgomery, VT 05470
(802) 782-7783 (c)
(802) 326-2209 (h)
<a class="moz-txt-link-abbreviated" href="http://www.newframeworks.com/">www.newframeworks.com</a>
<a class="moz-txt-link-abbreviated" href="mailto:jacob@newframeworks.com">jacob@newframeworks.com</a></pre>
On 4/26/2013 12:50 AM, kim thompson wrote:<br>
</div>
<blockquote cite="mid:5187D3E6-3008-47AD-8A09-AD6B99A9BEF2@ns.sympatico.ca" type="cite">
<div>Hello all,</div>
<div><br>
</div>
<div>I have had a note in progress for GSBN'ers for weeks to ask a
question related to Jacob's.</div>
<div>A building I am currently involved with was built in 1764. We
recently moved the 2.5 storey home </div>
<div>nearly 5 km through central Halifax to a lot where it will be
rehabilitated and used for affordable housing for youth.</div>
<div><br>
</div>
<div><a moz-do-not-send="true" href="http://morrishouse.ca/">The
Morris House</a> has become an interesting demo of how we can
make heritage buildings more energy efficient (and</div>
<div>keep them out of the land fill). It has a number of unusual
(for Halifax) features including solid brick nogging which fills
the cavities in the</div>
<div>first and half way up the second floor levels of the Georgian
timber frame. There has been considerable discussion amoung
committee members</div>
<div>involved with the Project about whether or not to fill in the
currently uninsulated wall sections, and if so with what.
Heritage folks want to employ </div>
<div>minimal intervention strategies and add nothing - they are
concerned that introducing insulation will bring with it
moisture which will </div>
<div>compromise the timber frame.</div>
<div><br>
</div>
<div>I have proposed a few options and would so appreciate
thoughts from this group on the building science side of things
for</div>
<div>our northern maritime climate. Thermal comfort (cold walls
especially) will be important to the young people living there,
as will be </div>
<div>heating costs... construction materials and systems on this
project will certainly be cited as recommendations for future
heritage rehabs. </div>
<div><br>
</div>
<div>So my question is what might be the pros and cons of
insulating the currently empty wall cavities above the nogging
with one of the following:</div>
<div>(a) dense pack cellulose (b) light straw clay (c) hempcrete
(d) reuse of brick from the chimneys of the Morris. (e) blown
in or batt wool (f) aerogel.</div>
<div>Assuming any one of these would be installed with great care
to avoid air leakage. </div>
<div>Exterior cladding is painted cedar shake, interior is lime
plaster/lathe, no vapourbarriers and removal of the nogging is
not an option.</div>
<div>Are there other choices apart from providing "extra sweaters"
for the tenants that would not compromise of the structure.</div>
<div><br>
</div>
<div>Am hoping that John S. in particular might chime in on this.</div>
<div><br>
</div>
<div>Thank you all!</div>
<div><br>
</div>
<div>Kim Thompson</div>
<div><a moz-do-not-send="true" href="http://www.themorrisproject.ca/">www.themorrisproject.ca</a></div>
<div><br>
</div>
<br>
<div>
<div>On 2013-04-25, at 11:46 PM, Jacob Deva Racusin wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
<div>Hello,<br>
<br>
My apologies for the cross-post, but I'm trying to do a very
quick and broad survey.<br>
<br>
I was just contacted by a former student I am advising, who
is project managing a building currently in design phase, in
the mid-Atlantic region in the eastern US. The wall
assembly was initially to be straw-clay, with plaster finish
on both sides. Budget and logistics have directed an
insulation switch to cellulose. He is currently advocating
for wood lath with lime-stabilized earthen base coat, with
finish lime coat (our standard approach for finish exterior
plaster). The architect is balking, suggesting that the
moisture storage and release dynamics for which we rely upon
the plaster in straw-based designs will not play out the
same way with cellulose, that the cellulose will be
overwhelmed with moisture and push the dew point deep into
the wall. This is all second-hand reporting of the
conversation - I know no more than what I just reported -
but I am due to speak with the architect and client tomorrow
on my student's behalf, and I'm curious as to whether or not
any of you have direct experience with earth base plaster
over wood lath outboard of a dense-packed cellulose-insulate
wall, or any reason to believe the cellulose would not
behave adequately in concert with adjoining plaster (as
opposed to straw).<br>
<br>
The architect is spec'ing (outward from the framing)
plywood, housewrap, drainage gap, stucco lathe, plaster. My
impression is that this suggestion would certainly work, but
is hardly the natural wall system initially intended. It
seems to be playing off of the concerns of sun-powered vapor
drive pushing vapor deep into the wall cavity as a result of
a reservoir cladding adjoining the insulation. As long as
there is no interior vapor barrier or Class II vapor
retarder, I feel this dynamic is identical to that we've
created with straw-insulated walls, and if anything the
cellulose would stand up better to incidental vapor or
liquid moisture intrusion. Also note generous overhangs and
24" grade separation are spec'd in the design, as is
multiple coats of limewash (and potentially a silicate top
coat for durability), which will further reduce bulk water
absorption and minimize incidental solar-powered vapor
drive. The wall is designed to dry to both sides of the
assembly, in keeping with the variable moisture drive of
that region.<br>
<br>
Perhaps there is another concern here I'm not understanding
- I'll find out more tomorrow - but in the meantime if
anyone has any perspective on why this situation would work
for straw, and not cell, or any direct experience in a
comparable climate executing such a system, I'd be grateful
for your input.<br>
<br>
Thanks so much,<br>
Jacob<br>
<br>
-- <br>
Jacob Deva Racusin<br>
New Frameworks Natural Building, LLC<br>
P.O. Box 15, Montgomery, VT 05470<br>
(802) 782-7783 (c)<br>
(802) 326-2209 (h)<br>
<a moz-do-not-send="true" href="http://www.newframeworks.com/">www.newframeworks.com</a><br>
<a class="moz-txt-link-abbreviated" href="mailto:jacob@newframeworks.com">jacob@newframeworks.com</a><br>
<br>
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