Wednesday, February 29, 2012

The Story of the Gazebo (VI)

In today's post I want to delve a little further into the design I have come up with for a gazebo with a reciprocally-supported roof and a lantern. As noted in the previous post in this thread, I decided to place the reciprocal beams so that they cantilevered off the wall plate and could help support an outrigger beam, or dashi-geta as the Japanese call them, at the midpoint. At the upper end, where the reciprocal beams lap atop one another I wanted the crossing point to be along the centerline of the hip rafters. I also wanted the crossing point to be more or less in the half-span distance between the wall plate and the center of the building, as this would enable the reciprocal rafter set to act as a cantilever to support the outrigger beam more effectively. The closer in towards the center that the reciprocal beams crossed, the better  the cantilever effect would be, however the smaller the opening in the middle of the roof for the lantern. So, ideally, something like a crossing point just inside of the distance of the roof half-span would be perfect. another idea would be that the reciprocal beam would be aligned to the wall plate - I think when the framing gets a little busy, that keeping as many parts in alignment to one another is a desirable goal.

Can an arrangement be found which will satisfy these diverse requirements? I decided to explore different polygon shapes to see if one might offer any advantages over another. First, I started with the square plan:


The square plan was pretty much a no-go from the start. It is not actually possible to place the reciprocal beams so that they can lap one another under the centerline of the hip rafters and still cantilever out to the mid-point of the wall plate run, nevermind have them align to the wall plate lines. Scratch that.

Next I looked at a pentagonal plan:


Here the holy grail would appear to be realized: the reciprocal rafters cross one another under the hip rafters,just a bit inboard of the middle of the span, and the beams are able to cantilever out to the mid-span of the wall plates. The angle of the cantilever relative to the common rafter line is only modestly askew, and yet the line of the cantilever is parallel to the line of the wall plate. This was looking good.

How about a hexagonal plan?:

 

Here the arrangement is not too bad, however the crossing point for the reciprocal beams is now a little outboard of the mid-span zone. The reciprocal beams are radically more askew in relation to the line of the common rafters, which is less desirable. A little less ideal all around than a pentagonal plan I would say.

Next I considered a heptagonal plan, one of my favorite polygons if one can have such a thing, and the result was even less satisfactory:


As  you can see, the reciprocal rafters now cross even further outboard and the line of the reciprocal beam in relation to the common rafter line is yet more severely askew. Getting worse.

Just in case things might get better, I checked out an octagonal plan:


Worse again - decidedly. I could see that the greater the number of sides, the further outboard the crossing point would get, and the more askew the reciprocal beam centerline would be from the common rafter line.

It was obvious to me that the pentagonal plan offered the best configuration for my requirements.  Some may be wondering whether having so many requirements might unnecessarily constrain the design somehow - I guess I'd ask you to hold off that assessment until you've seen the full development of this plan.

Since the reciprocal beam would project beyond the wall plate, and would have its end cut to be in plane with the wall, if left as a rectilinear section the beam would appear to look like a parallelogram section. I therefore decided to make the reciprocal beams parallelogram in section in the opposite direction so that once in place, the appearance on the end of the beam would be of a rectilinear section. Also, making the beam into a parallelogram section, which is akin to taking the backing, makes for some more straightforward joinery - for example, the connection of the reciprocal beam atop the wall plate, and placement of stub posts on the reciprocal beam.

In all of my layout texts, in 4 different languages, had no resources to draw upon for determining the geometry of parallelogram-shaped reciprocal beams - I don't know whether it has ever been done before. So, I worked it out on my own. I've been studying the topic of descriptive geometry for carpentry sufficiently long now that I can usually solve most layout problems - not always with immediate elegance and ease, but I get there in the end. It is a field of ongoing, life-long study.

I'm not going to spend time here discussing in detail the geometrical solution, as that would involve several posts and veer seriously off topic. However an overview of the drawing I will happily share:


A little closer view shows the reciprocal beam, inside and outside faces:


Once the beam shape was sorted, I placed the pieces atop the wall plate ring:


Click on any of these drawings to see an enlarged view.

Next up were the lower exposed hip rafters - these have to tie into the lap-crossing point of the reciprocal beams, and be of a slope which relates to the slack pitch of the decorative eave rafters, or keshō-daruki. I tried a variety of solutions. In the end, I decided to place the upper end of the hip so that it tenoned into the neutral axis of the lower reciprocal beam. In order to meet cleanly without overhanging bits, the lower hip section was turned into an irregular hexagonal. A complex solution, perhaps, but the result is clean I think:


Here's a closer look at the tenoned connection joining the upper end of the hip to the lower reciprocal beam:


Next I placed the ring of the dashi-geta:


The dashi geta purlin ring sits a bit less than half-way out along the eave's total projection distance.

A view from underneath reveals how things are shaping up aesthetically:


Just getting started with this roof of course, and many of the joinery details are not in the drawing yet. In the next post in this series I'll continue a look at the build-up of this roof and share more of the design process.

Thanks for coming by the Carpentry Way. Comments always appreciated.  On to part 7

Saturday, February 25, 2012

Cap and Boots (VII)

So far in this series about at old houses and their problems, we have taken a look at foundation and roof design shortfalls, antiquated wiring systems, lead plumbing components, lead in paint and varnish, asbestos, and then mold. If these issues weren't enough to give pause to those contemplating buying or living in an old house, there is another hazard, and this hazard is by no means confined to old houses. It is a hazard you can't see, hear, or smell, and it is estimated to be responsible for 21,000 deaths annually in the US.

If you've even wondered how a person might die from lung cancer without ever having smoked, been exposed to second hand smoke, lived near a refinery, etc., or worked in a coal mine or similar hazardous environment, well: have you heard of radon?


Radon, atomic symbol Rn,  is the second largest cause of lung cancer after smoking, and, if you do smoke and are exposed to radon gas in your living/working environment, well, your risks compound. It's one of those areas where synergy is not such a good thing.

Radon is an odorless, tasteless and invisible gas produced by the decay of naturally occurring uranium in soil and water. It was discovered in 1900 by Friedrich Earnst Dorn, and was the fifth radioactive element ever found. The source of radon is the radioactive decay of uranium - radon is in fact a form of ionizing radiation. It is also the only gas that is radioactive under normal conditions. Radon in the air is all but ubiquitous on the planet. It is in soil, it is in rocks, it is in the oceans, it is even in lakes, rivers, streams and groundwater. The source of radon for our homes has to do with the type of soil and bedrock where we live. If there is a lot of uranium present in the soil or bedrock upon which our homes are built, then there will be lots of radon produced as well. If your home relies upon groundwater, and there is radon present, then your tap water will have radon in it, the gas being emitted every time you turn on a faucet or have a shower.

However some geographic zones are much worse than others. Growing up on the West Coast of Canada, radon was, apparently, all but an irrelevancy and not subject to much conversation. Here in the East Coast, the situation is a little different. Here's a radon potentials map of the US:


If you live in one of the areas colored pink in the above illustration you live in an area with high radon levels. Iowa and the southern Appalachian Mountains in Pennsylvania are the worst locales for radon in the US. The light blue areas on the map have the lowest radon levels. I live in Western Massachusetts, which is rated 'medium' for radon exposure. According to one E.P.A. study I perused, 63% of homes in North Dakota have radon levels above a 'safe' standard.

As mentioned, some parts of Pennsylvania are quite bad for Radon, and in fact heightened radon contamination in homes was discovered by chance in the mid 1980's by events surrounding a certain Stanley Watras, a construction engineer at Bechtel's Limerick nuclear power plant in Pottstown, Pennsylvania:

"One day, on his way to work, he entered the plant and set off the radiation monitor alarms which help protect workers by detecting exposure to radiation. Safety personnel checked him out, but could not find the source of the radiation. Interestingly, because the plant was under construction at the time, there was no nuclear fuel at the plant. They discovered the source of radiation exposure when Watras's home was tested and was measured to have very high radon levels (2,700 pCi/L)."

Every time Watras went to work he had to spend 3~4 hours in the decontamination facility before he could even enter the work site - at a nuclear plant! According to his later testimony (in 1985) to the US House of Representatives Subcommittee on Natural Resources, Agriculture Research and the Environment, a clipping I snatched right off the document (available online):


The E.P.A designated 'safe' limit for radon exposure is 4 pCi/L - or picocuries per liter. The levels in Watras' home were 700 times the E.P.A.'s safety line. A picocurie is 0.000000000001 (one-trillionth) of a Curie, an international measurement unit of radioactivity. The term 'safe' however must be taken a bit provisionally, as even the E.P.A. states,


"Because there is no known safe level of exposure to radon, EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L. The average radon concentration in the indoor air of America's homes is about 1.3 pCi/L. It is upon this level that EPA based its estimate of 20,000 radon-related lung cancers a year."

At 4 pCi/l there will be approximately 12,672 radioactive dis-integrations in one liter of air, during a 24-hour period. By comparison, a radon level of 15 pCi/l has about the same risk of causing lung cancer as smoking a package of cigarettes a day.

Canada seems somewhat less plagued by radon over all, except for New Brunswick and Nova Scotia:

 

I do wonder though, looking at that map and comparing it to the US example, and considering the similarity of much of the underground geology, if the map suffers a bit from insufficient data.

Canada uses a different measure for radon gas levels, denoting the concentrations in Bq, or 'becquerels'. A becquerel is named after Henri Becquerel, who shared a Nobel prize with Marie Curie in 1903. The becquerel is an international method of measuring radiation. To convert picocuries to becquerels, divide by 27.027. If you convert the E.P.A. value of 4 pCi/l you obtain 148 Bq/m3. Notice that the map above shows a threshold line of 200 Bq/m3? It seems that various countries cannot quite agree yet upon what is 'safe' and what isn't. While in the US a suggested 'action level' for radon is 4 pCi/l or 148 Bq/m3, in Canada the "suggested" action level is 400 Bq/m3. The European Union recommends action be taken when concentrations reach 400 Bq/m3 (11 pCi/L) for old houses and 200 Bq/m3 (5 pCi/L) for new ones. County Kerry, Ireland apparently has tested houses in some spots where the radon levels are 13,797Bq/m3, which is some 70 times above the EU limit, equal to an exposure of 47 chest x-rays per day!

The risk of lung cancer increases by 16% per 100 Bq/m3 increase in radon concentration, according the the World Health Organization.

Radon is less an issue in the general environment than it is in our homes, where it tends to accumulate. According to a geology blog I was reading,

"Radon is a noble gas. This means it is very un-reactive in the environment and does not interact readily with other compounds or elements that are present around it. This means that in the environment radon travels all on its own and does not attach itself to other elements as a way to get around. This does not hinder the ability of radon to transfer from air to water and back again, in fact, radon transfers very readily...Radon accumulates in confined spaces such as in our houses or other buildings, particularly in basements as radon is heavier than air. In the open air there is no threat from radon, however, Canadians and many other cultures spend a great deal of their time inside, especially during winter (it is  -20 with wind chill as I write this). This is a major concern as all of this time spent indoors can greatly increase radon exposure."

 If you live in a place known to have high levels of radon gas, you should have your home tested. If you then learn that radon levels are above an acceptable threshold for your peace of mind, then you can either move or look into radon mitigation. Typically, radon mitigation involves:
  • improving the ventilation of the house
  • avoiding the passage of radon from the basement into living rooms
  • increasing under-floor ventilation
  • installing a radon sump system in the basement
  • sealing floors and walls
  • installing a positive pressurization or ventilation system
A common solution is the radon sump - drilling a hole or two in the concrete floor slab and fitting a vent pipe or pipes. This pipe is then routed outside of the house and has a vent fan attached. The fan creates negative pressure under the slab and sucks any radon out. To test, a few small holes are drilled elsewhere in the slab, the sump fan is turned on, and a smoke test applied to the small holes to check if there is suction. If it is working well, then the small holes are sealed back up. This a relatively inexpensive remedy in most cases - perhaps $1000~1500. In some houses the pipe (usually 4" pvc as smaller pipes have higher air flow rates and can be noisy) is routed internally until emerging out the roof, while in other cases is too much of a hassle to route the piping inside the walls, so the pipe emerges just above ground level and pvc pipe is then run up the exterior wall to the roof peak. If you are house hunting and notice that houses in the area in which you are viewing have 4" white pvc pipes running conspicuously up the walls, then you can be fairly sure that radon is a problem in that area.

However, if you live in an old house without a poured concrete foundation and slab floor, it is not so easy to seal off the radon. Old houses with stacked stone of brick foundations, and cracked concrete floors or dirt floors provide innumerable places for radon gas to penetrate:

In order to provide a barrier of some sort for the radon sump to work, typically the entire basement, floors and walls, needs to be sealed up with plastic sheeting. Depending upon how accessible the basement is and how complex the situation, the cost of sealing the basement with plastic, admittedly not a great long term solution, is going to vary.

In high radon areas, old houses with leaky foundations are going to be a hassle. The agriculture department of North Dakota State University has a humorous cartoon showing the ideal radon mitigation system for such places:


Humorous, of course, to those who don't own homes in such places.

If you live in an area with high radon levels, it is vastly preferable to have a basement that is poured concrete, with an under-slab vapor barrier, as it can be more readily sealed and a radon sump fitted. And of course, fitting of a radon sump in new construction is quite easy. If you have an old house and look for a long term solution, then replacement of the foundation is one option, albeit a costly one. Since crummy old foundations are sources of many problems in a house, complete replacement yields many benefits, and may be worth a serious look if the remained of the house has those almost-mythical 'good bones'.

One more post to come in this series. Thanks for coming by the Carpentry Way.

Tuesday, February 21, 2012

Evolutionary Design is Healthier than Visionary Design

As I grow and develop as a designer and maker, a process which is not often linear but iterative, I sometimes have a pause and think about those people and works which have provided me with the most useful guidance and inspiration. One of the most particularly affecting of my thoughts about design was Stewart Brand's 1994 work How buildings Learn, and I have referenced it several times on this blog in past years.



How Buildings Learn cleanly articulated a feeling I had been experiencing, and gave coherence to a perspective that I had been forming for many years about why most modern architecture is a failure - if not simply ugly - the buildings produced are conceived of as akin to fine works of art, or 'statements' when in truth architecture is is ultimately about the occupants and their lives - keeping them warm, safe and dry really is the bare beginnings of what architecture should be. Since modernism came along, especially, architecture has become increasingly divorced from its core purpose of providing shelter and more and more about expressing philosophy or the architect's ego. Some architects are even proud of how useless their buildings are, believe it or not. Case in point would be Frank Lloyd wright and his leaky roof comment: "That's how you know it's a roof - because it leaks." Another case in point involving FLW was when the chairman of the Johnson Wax company called him to complain that the roof of his new house was leaking and water was actually dripping from the skylight onto his head at the dining table, Wright told him to move the table(!). Did Wright learn from this sort of thing and change how he designed his buildings to keep the weather out? No. He was more in love with his own idea about how a building should be than in the 'petty' concerns of his clients or any considerations of practicality.

The building phase is brief, but the occupancy phase, ideally, is long and those who occupy a building are going to modify it if they need to so, to make that building work for them. If the building can't be made to work for people it is often hated and soon torn down or abandoned. Few architects seem to recognize this issue it would appear, preferring not to revisit their earlier works to see how they are doing, and few architecture schools seem to be instructing the new disciples in anything other than the abstractions of architectural theory.

I've had Brand's book listed in my 'Worth a Read' section (now found at the bottom of the page) since I started this blog and its not going to be leaving the list anytime soon. Some readers however may not have the time for as much reading as they might like, and I was pleased to recently learn of a video documentary about Brand and his work, How Buildings Learn. Though Brand is an American, leave it to the British and the BBC to come up with a fine documentary.

As an aside, I've always wondered why the Brits can produce such excellent documentaries while most American documentaries I have come across are shallow, incoherent or otherwise invariably suck wind. Compare, for instance, the BBC's series The Planet Earth with David Attenborough, with anything put out by National Geographic. If someone could explain the reason for that phenomenon to me, I'd be most grateful!

Anyway, the BBC series is six parts long, each about half an hour in length, and here's part one:

Here's a link to:

part II

part III (I think this might be the best part!)

part IV

part V (I also think this might be the best part!)

part VI

I hope you'll take the time to watch the other parts which can be accessed by a quick search on Google Video, or will seek out the book and take a deeper look. It's well worth it.

Monday, February 20, 2012

The Story of the Gazebo (V)

Here we are at the 5th post in this series, the 1st post, if I might be optimistic, of the next 500 posts to come on this blog. It is only fitting, I suppose, with 'fives' coming up everywhere, that the subject of today's post also revolves around 5, literally and figuratively.

I spend a lot of time designing things, many of which I might never build. The process is incredibly valuable however as each time i work through a design I learn new things and re-confirm previous conclusions, often with fresh insights. I've come up with a timber framing system which makes use of Japanese joined timber framing, an adapted form of German wall framing method and natural infill. It's different than anything else out there, at least which I've come across, and I look forward to the chance of prototyping the design with a real building someday. Maybe I'll do some posts on that at a later date.

I've also been working upon designs for various pavilions, which are simpler structures in certain respects, and if you've perused the previous posts in this series, you will see that there is a fairly wide range of structural approaches out there. By and large, the Western approaches I've seen don't do much for me, either in structural ingenuity or aesthetics. The Chinese forms are a bit overly flamboyant for my tastes, though i have found considerable inspiration in some of the structures I have come across. In the end, the Japanese forms of pavilion are of the greatest interest to me and I find them the most satisfying in visual terms.

One of the forms of framing I looked at in a previous post in this thread was reciprocal framing, as is well exemplified in the Bunraku Puppet Theatre. I'm not new to reciprocal framing. Nearly 10 years ago I built a reciprocal roof model while working in California:


You can see the developed drawing dimly on the piece of plywood in the background.

I didn't come up with the drawing method on my own - I found a few pages on it in the German text, Bassiswissen Shiften. Like a lot of German timber work that I've seen, the joinery tends to be on the simpler side, from my perspective at least - for the above model, the connections between the reciprocal rafters were basic lapped notches on the underside of each stick. This makes for reasonably straightforward assembly of the parts, however the joint allows for a slight amount of creep in one direction as the parts sink onto one another - multiply this by 8 sticks and the structure will compress down below the design height. Further, if the structure is loaded from above, then the end grain face of the half lap presses against the side grain face of the timber below, and thus a bit of crushing ensues, which causes the whole thing to slide down a little further. And any sliding means that the rafters effectively push outward at their base, which is less than ideal. Of course, one can use timber screws to keep things more or less in the correct place but, obvious to me at least, the joinery solution could use improvement.

I've seen reciprocal structures in which the reciprocal rafters themselves are the roof rafters instead of supporting elements. Olga Larsen's book Reciprocal Frame Architecture has a section which details the work of Englishman Graham Brown, framed structures which are entirely of this type - here's his 'Whisky Barrel House':


Another example which I came across on an Australian site:


This arrangement, in which the external roof form lies directly atop the reciprocal rafters, has several problems, in my view. The aesthetics are a matter of taste, and to me the roof form does not look all that attractive from the exterior. More important by far though is that the roof membrane is chopped up into sections, with short triangular walls introduced at each rafter point. These transitions make a greater percentage of the roof area vulnerable to leakage.

It is a general rule of roof design, if keeping the water out is going to take center stage (and isn't that the main point?), that the roof have a minimum of such transitions, like valleys, dormers, chimney penetrations, etc. The more places in which the roof covering is replaced with flashing, the more potential there is for leaks down the line. The above picture shows a framing system in which the top of the wall has been angled, along with the window and its frame, to fit against the underside of the roof, and this adds extra work and complication for dubious gain. It most likely means fixed windows.

Finally, many of the reciprocal frames end at the wall and thus the resulting structure has no eaves, which means that the wall envelop takes a lot more punishment from the weather. And fitting gutters to such a roof shape would seem awkward, with separate gutters and downpipes needed for each roof facet.

It makes a lot more sense to me to use the reciprocal frame as a support structure for the roof rafters above, and not make the reciprocal frame the roof itself. The idea of creating a double roof so that the interior and exterior structural and aesthetic modes can be somewhat separated from one another happens to be a Japanese invention - and one which I admire. Indeed, the Bunraku Puppet Theatre is a fine example in which the external form of the roof makes good sense in terms of keeping the weather out, and has deep eaves, while the reciprocal support structure inside remains hidden from exterior view:


There are many different structural framing systems used on gazebos, and I am choosing to employ reciprocal framing because it readily provides a clear opening in the enter of the roof for a top-mounted lantern, which will allow light in to the structure - that light makes for a much more pleasant space, and shows the framing off to good effect.

Many reciprocal frame designs that I have come across place the lower ends of the reciprocal beams directly atop the corner posts. Since the reciprocal rafters are at a different orientation, plan-wise, than the posts, the connection between the post and the reciprocal beams is often a bit awkward.

I decided to place the reciprocal beams atop the wall plate beams which span from post to post. Further, I chose to lengthen the reciprocal beams so that their lower ends project out beyond the wall to help support the eave:



The reciprocal beam is colored brown in the above drawing, and does double duty as a support for both the inner and outer roof structure. It acts party as a cantilever.

Now, coming up with an interior arrangement of reciprocal beams which would cleanly tie in with a polygonal plan and the raised lantern and a double roof structure was not all that easy. In fact, as it turned out, the most ideal plan for this structure is pentagonal. In the next post, I'll explain why pentagons 'r us, and look at this framing solution in more detail. Thanks for dropping by the Carpentry Way. Comments most welcome.  ➜ on to post 6

Saturday, February 18, 2012

Realistic thinking: Peak oil and the Environmental Challenges Ahead

This is a re-post from Dimitri Orlov's site, and I think this 30 minute animated clip explains the issue of peak oil - peak everything really - in a succinct and relatively non-threatening way:



Is your foot on society's growth accelerator, or on the brake? Does the simple calculus of the situation prompt you to action, or immobilize you with fear? Will you wait until the situation becomes dire, or be proactive? Become the change that you seek in the world, or be tossed on the current passively? I think whenever faced with the sort of information in the above video, we are challenged to consider our positions about such things. Some would immediately move to push it away and deny, and that is also a choice, though perhaps not a conscious one.

Another film I saw recently which was provocative and perspective-changing was Cool It. I had heard all sorts of negative press about 'the skeptical environmentalist' and went into a viewing of this film expecting to dislike Bjorn Lomborg, and instead found to my surprise that his position is a reasonable and rational one and that he actually makes a very persuasive argument. That in turn led me to reflect on the way an idea can be seized upon by the media and various groups to support their agenda, and how my own impressions were colored by that and not the actual words or thoughts of Lomborg.  I also reflected on the time I saw Gore's Inconvenient Truth a few years back and came away at the end a little disturbed that after making his case about all the environmental horrors to come, Gore essentially suggests we buy energy efficient light bulbs and a Toyota Prius to feel better. It was as if he was mostly trying to scare people and not actually effect real change, that we could somehow consume our way out of any problem. It seemed a little weaksauce, as they say.

Lomborg is not skeptical about climate change as a man-made phenomena, he's skeptical about the solutions being proffered by the world's governments and their negotiated agreements. And he has some realistic ideas about how we could do much more real good in combating the challenges ahead and spend quite a lot less to achieve that good - at the very least, he re-frames the conversation away from doomsday scenarios. The problem with incredibly dire negative predictions about the future is that they tend to engender numbness and inaction on the part of those who hear them, especially when the message is pounded home time and again. Here's a presentation Lomborg gave, about an hour long, and which features in the longer film and will give you a sense of his position:



What kind of society do we want to leave behind? What kind of legacy as a maker do you want to leave behind?

On another, and totally unrelated note, today marks the 500th post in the Carpentry Way! It's a bit hard to believe actually. Thanks for your support!

Friday, February 17, 2012

Cap and Boots (VI)

So far in this look at some of the challenges facing buyers and owners of older homes we have looked at the roof and foundation, the plumbing and wiring, and then a couple of toxins commonly found, lead and asbestos. Both of those hazards are natural materials which, because of certain desirable qualities, have been utilized by industry to create a 'fantastic' range of products, and as a result are found in larger-than natural concentrations in many homes. There are more hazards yet however, and in today's post I wanted to look at another potential toxin that has little to do with industrially-produced materials - this one is entirely natural.
  
Mold.

If the house has a primitive foundation, and moisture in the soil, it is very likely that mold will also be present. If a house has a leaky roof, or blocked gutters, and/or suffers from ice-damming, the space under and around the roof deck will tend to have a significantly higher moisture level than normal, and that can promote the growth of mold. Some houses have poorly installed bathroom fan duct work putting moist bathroom air directly into the unconditioned roof space, and you can be sure to see mold sooner or later. Faulty plumbing is another major culprit. If air circulation in damp areas is lacking, then it is even more likely that the house will suffer from mold problems. With all things being equal, cooler temperatures will lead to a higher relative humidity percentage, since cooler air is able to hold less water before condensation occurs. Of course condensation means moisture. Finally, a lot of modern houses are so well sealed with plastic vapor barriers and caulking that interior sources of moisture and humidity can lead to some fairly grievous problems

Molds are parts of the natural environment and serve an utterly critical role in the breakdown of organic matter, such as fallen leaves and dead trees, etc. Inside the home however, molds are not so welcome or helpful. Taken right from the EPA:

"Molds are usually not a problem indoors, unless mold spores land on a wet or damp spot and begin growing.  Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins).  Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.  Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common.  They can be immediate or delayed.  Molds can also cause asthma attacks in people with asthma who are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people.  Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold."

Mold commonly propagates in a hidden manner and it may be quite a while before problems are detected. A first sign would be mildewy smells or a rise in allergic reactions among house dwellers. According to a 1999 Mayo Clinic study, nearly all chronic sinus infections (afflicting about 37 million Americans each year) are a result of mold.

In some houses the mold problems can reach epic levels and become a deadly hazard to the inhabitants. One account I read of involved a house in South Carolina in which one particular mold Stachybotrys, the so-called Toxic Black Mold," had taken over:


The mold had built up to such levels that the owners abandoned the house, fearing for their daughter's safety:

"Leventis and his family were the first to discover the horrible secret of Number 6 Whitten Street. There is no indication the previous owner was aware of any mold.
"I've never seen my kids that sick. And it was scary," Tricia Leventis said in tears. According to Tricia, she and their two young daughters became desperately ill, and said doctors told them to leave the home immediately."It was adamant. Absolutely, get out," Leventis said. "It was to the point where my youngest was so sick, she was unable to hold any nutrition, nothing was working, she couldn't breathe."The Leventises did the only thing they believed they could do, with no money in savings to have the mold removed. They stopped paying their mortgage and let the home go into foreclosure."

The foreclosed house was later re-sold to another couple, the Brown's who eventually discovered the house's secret.  A lawsuit followed.

If you look around the wwweb you can find some truly horrific pictures of household mold problems, especially from companies offering mold remediation services, like this one:


The toxic black mold Stachybotrys chartarum may associate to childhood respiratory distress, though a link remains to be proven apparently. Evidence does appear to be mounting however, according to one paper I read by University of North Dakota Professor of Plant Pathology, Berlin Nelson, in a February 1999 article entitled Stachybotrys chartarum: The Toxic Indoor Mold. Another site with a wealth of information on this topic is mold-help.org.

If the house does have mold, the immediate action to be taken is to reduce humidity levels, eliminate the causes of higher moisture in the home, and remove all affected materials. This can get quite expensive, and in the case of many houses, it may well be cheaper to bulldoze and start again. A few molds can be killed by cleaning the moldy surface with chlorine, however this is ineffective against the worst forms of mold. According to the site mold-help.org,

"...stachybotrys often has a germ mycelium that is buried inside the water damaged surface that is often inaccessible to chlorine. In fact, bleach often does not kill Stachybotrys entirely when directly applied to it. Changing the humidity may lead to limited death of the stachybotrys colony. However, changing the humidity may also induce heavy sporulation. Burning the building that has undergone stachybotrys contamination has been an idea of many people but some experts state that not even a fire of 500 degrees could destroy the spores of this deadly enemy. If anything, it could spread it and worsen the condition. The ground around these buildings can also become heavily contaminated with stachybotrys from a sick building. It is recommended that the ground (dirt) be removed at least one meter prior to rebuilding any new foundation."

Imagine that - you can burn the house down and still not get rid of this fungi! It's tenacious.

Bandaid solutions of spraying anti-fungal chemicals and using 'anti-mildew' paint over affected areas are largely doomed to failure though it is not an altogether uncommon strategy by those seeking to sell a diseased house. It definitely pays to have a detailed home inspection done, with a check specifically for mold. For those owning an older home, to avoid mold problems before a potential catastrophe occurs, the building should undergo scheduled maintenance that includes inspection for water leaks, problem seals around windows and doors, as well as checks for visible mold in moist or damp parts of the building.

Perhaps I am overly cautious, but when I see stuff like this...


...I'm not thinking 'fixer-upper'. I'm thinking, 'run'. And I've been looking at a lot of real estate listings over past months and there is no shortage of houses on the market with mold problems or houses which have had 'mold-abatement'. I'm not optimistic that the abatement will be anything other than a stop-gap measure in the majority of cases, as it simply costs, for many home owners, far too much money to fix the problem when foundations and roofs are involved. There are also a huge number of homes on the market right now which have been foreclosed upon and then sit empty for months and even years. Once a house rides through the winter with no central heating, things inside take a turn towards dampness, and I can't help but suspect a large number of homes will transition from 'inhabitable' to 'scraper' just from sitting unoccupied.

Next time I'll conclude my look at old house ailments with another entirely natural and common pathogen. Thanks for coming by the Carpentry Way. Comments always welcome, and here's hoping you have mold-free weekend.

Wednesday, February 15, 2012

Chinese Connection, Part II (III)

Somewhat absurdly, this it the third part of a part two, a continuing look at traditional Chinese timber framing details. We have so far looked at pavilions, models, and bridges, following up with a post yesterday showing a few examples of architectural carving. In today's post, we crane our heads up to take in the marvelous sights to behold. Believe it or not, there are alternatives to ceilings of white plastered sheet rock.

Chinese Temple Ceilings.

One Chinese term for temple ceilings is zǎojǐng (藻井) a pair of characters which means the well 
'' of the floating aquatic plants ''. The first character, '', is a rather complex little gem, consisting of '' (a depiction of chicks in a nest in a tree - the connotation is of activity happening above) plus an abbreviated form of water, '' to the left. Water plus activity happening above gives the character '' which means float on the surface of the water. On top of that piece, an abbreviated form of '' referring to grass/plants, is added to give '', and that is how we arrive at the meaning of plants which float on the surface of the water. Neat!

A curious term it would seem, to have this aquatic plant well placed up in the ceiling. Apparently there was constant worry about fire destroying temple buildings, and the placement of a symbolic water feature in the middle of the structure, usually directly above the main throne, seat, or religious figure, was believed to guard against the spirits which brought fire. 

The form of this ceiling is of a sunken coffer bordered in a square, a polygon or a circle, decorated with elaborately carved or painted designs - what would be termed in English a caisson ceiling. 'Caisson', a term relating to the word coffer, refers only to this type of Chinese ceiling.

There is even a Chinese knot named after this form - in English termed a plafond knot, the word 'plafond' being French for - can you guess? - ceiling:


For more on Chinese knotting, there is a site dedicated to the topic: www.chineseknotting.org, and that is where I found the above image. The classic text in the field of knotting is Ashley's Book of Knots, which features several Chinese knots in a section titled 'decorative knots'.

Anyway, let's take a look at some of these aquatic plant wells:


I find this one particularly stunning:


Baoguo Temple in southern China has some incredible ceilings:


Note the lobate posts as well:


A couple more examples:




A large circular hall with a richly decorated ceiling:


A variant on the aquatic plant well is the octagonal heavenly aquatic plant well (八角穹藻井) - notice the scale of the work and the small 'button' in the center:


That 'button' is actually richly detailed - here's a closer look:


The center of most of these caisson ceilings feature a more or less flat panel decorated with carving or painting. A pair of dragons circling around chasing a pearl is a common motif, as seen above. This iconography and the theories regarding it is a fascinating area in itself - for more, check out a page in wikianswers (⇐ link). Also, an interesting discussion can be found here (⇐ link).

Another one:


And one more:


Whew! My had is spinning. I hope you enjoyed the brief tour of Chinese timber frame delights and thanks for dropping by the Carpentry Way. Will there be a part 4 of this series, I wonder?

Tuesday, February 14, 2012

Chinese Connection, Part II (II)

Heh-  a part 2 of a part 2. There was no part 1, and maybe there will be a part 3 of a part 2, too! Hopefully I'll be able to muddle through somehow. I continue a look at Chinese timber frame detailing from the golden era of traditional Chinese carpentry.

Carving.

Many temples and upper class homes feature extensive carving. I present a few examples, the pictures largely speaking for themselves:





The following shots are from a Ming-era house in Taiwan, the Lin An Tai Ancestral House (林安泰古厝):


I love the carving of the bird on the right of this picture especially:


Awesome decorative pendants on the hanging posts:


I imagine that the bottle neck struts in this roof structure could only be attached by being slid onto the beam sideways:


No expense was spared on this house:




I've never seen a carved 'shrimp' beam in the form of a zither - beautiful!:


The bright red eave ceiling paneling is also very nice.

Another structure, and one needing some work, but it must have been really stunning at one time:



The roof edge is a bit thin, but I could live with it:



A few 'simple' carved panels:



And another pendant:


Next time, we'll look at Chinese temple ceilings. Thanks for coming by the Carpentry Way and comments are always welcome.