A few weeks ago when I began exploring the world of framing it (and I) was dominated by a fairly straightforward technique of wood-framing – using standard 2×4 lumber with nails and metal connectors to construct a home frame. But then I came across a blog where someone spoke of another building method – one that relies on creating elegant joints between wood joints that are fastened together with wooden pins (kind of like huge nails) – an all wood structure.
I encountered all kind of terms I didn’t know like dovetails and tenon joints. So I did some more searching and came across this abundant resource that had way more information then I could possible want about techniques for joining together pieces of wood. I discovered an entire art of wood-joints … which actually blew the wind out of my sails. I thought that was just too much to attempt to muster on a project with limited time and resources. So I set it aside.
I am now entering a second round of inquiry into wood framing – the straightforward “nail and connecing plates” kind this time going into more detail. Then, a few days ago I came across Northern Lights Timber Framing and a single image on their home page blew my mind. This is what timber-framing looks like:
Most of the structure (except for some of the supports) is made from massive timber beams that are crafted into a carefully planned puzzle. There is an entire carving process that takes place away from the building site during which all the pieces are meticulously crafted and tested. Then they are brought to the building site site and with the help of cranes, assembled into a monolithic structure. It is an artful process shimmering with quality and inspiration. It is very different then wood-framing. Here’s another images from Northern Lights – this time an indoors view of a timber-framed house:
The Northern Lights site listed a link to the Post n Beams blog, written by a student that trained with the folks of Northern Lights. It is a great and informational blog to read with excellent, detailed and informative images. This images from the blog further demonstrates the elaborate art of Timber Framing:
This is very different from wood-framing:
We Will Probably Build with Wood Framing
From where I stand now I am somewhat sad to say that we will be building our house with wood-framing and not with timber framing. There are a few reasons for this:
- The overall framing process, as I understand it, seems to be more complicated and longer then wood-framing.
- It seems like a more expensive building method (tools, materials).
- It requires refined skills and workmashinp – making it less relevant as a do-it-yourself project.
- Most of our wall-framing will remain hidden from sight as it will be emdedded inside the hemp-lime walls.
- Hemp-lime masonry needs studs to support it.
- Except for a living-kitchen space, energy concerns are leading us to smaller more heat-efficient spaces – so the benefit of an open-floor structure are marginal.
- Most of the roof will also be highly insulated with hemp and other materials.
I would love to incorporate into our building process some of the qualities of timber-framing. There is more to it then meets the eye. I wonder if, for example, similar joint techniques can be employed when framing with 2×4 lumber?
I am no expert but my instincts tell me that timber-framing delivers a superior structure (to that of wood-framing) and the fact that it is all-wood (no chemical interactions with metallic parts) give it a better shot at longevity (though in our case this may be mitigated by the hemp-lime encasing).
A part of me hopes that we come across a magical local timber-frame builder that will change my mind 🙂 I would love to live in a structure that was built with such masterful craftsmanship.
Passivhaus is one of the terms out there in eco-green-sustaintable building land. It may look like its spelled wrong but that’s because its originally from Germany. It represents a very strict and high standard of energy efficiency in a building. It isn’t (yet) an official requirement or standard but it is gathering momentum as an unspoken standard.
There are three complementary core ideas behind the idea of a Passivhaus:
- Complete and thorough thermal insulation of the house which prevents conductivity of heat from the inside-out or the outside-in.
- Complete air-tightness which prevents exchange of heat through air leaks (windows, doors, pipes, chimneys … every opening needs to be sealed!).
- An efficient ventilation system that both exchanges air (from the outside and the otherwise airtight house) and does so without losing heat.
This is one of those images that is better then a thousand words. The apartment building on the left is standard/traditional building while the apartment building on the right is built according to the Passivhaus standard. That’s the bottom line of Passivhaus – keeping the heat from escaping means you need to expend less energy to heat the inside.
I have come across Passivhaus numerous times in recent weeks and my recurring personal impression is that it is too extreme:
- It seems like more of an academic indulgence then a practical construction practice.
- It’s objective and success is measured in a single number – the amount of energy needed to heat a square-meter of space.
- It demands rigorous builing disciplines which require uncompromised excellence in construction.
- It demands the use of specialized insulation materials which can be expensive (especially if you consider the ecological foot-print involved in manufacturing them).
- It creates a house that demands constant attention, maintenance and proper use by its residents (every window opened and every hole drilled in the wall is a potential energy hazard).
All of which results in a delicately balanced system: if it isn’t absolutely sealed, perfectly ventilated by a carefully installed system and properly used it just won’t work. There is no room for error. This maybe OK in a scientific experiment but not so for life, nature and people.
In any case it doesn’t feel right for us: we have a limited budget, average construction capabilities, standard building materials, etc. We are going to do the best that we can with what we have. It’s an 80/20 kind of thing – where 20% of the effort takes you 80% of the way you need to go and it would take another 80% of effort to go the rest of the way. We’re aiming for a good middleground – pushing the limits of what we have – but that, by definition, is not enough to go for 100%. Passivhaus is uncompromising, but we live in a reality which demands compromise.
“A passivehouse is cost-effective when the combined capitalized costs (construction, including design and installed equipment, plus operating costs for 30 years) do not exceed those of an average new home.”
I am hesitant to relate to this statement as that may give it unwarranted legitimacy – cost is just too narrow a perspective to view ecological housing. But if I do meet it head on, as is, I would say that it sets its sights much too low. I hope to build a house where the combined capitalized costs are much lower then those of a new average home (whatever that is). I also hope to build a house who’s qualitative effects (both for us and others) far outway it’s economic effects.
Maybe Passivhaus is, for the time being, a high-end building experiment? Maybe in time it will spawn accessible, affordable and feasible techniques, solutions, technologies, practices … that can become a defacto standard that simply makes sense to follow? For now, it is out of touch with us and our needs.
Having said all that exploring Passivhaus has brought to my attention a factor I had not taken into consideration in all of my energy research: Indoor Air Quality. I have been following a very basic intuition: “generate heat” in trying to solve a problem we’ve been having for many winters: “being cold”. Most of my attention has been on how to preserve and generate heat (space and water) effectively.
I had not given any thought to one of the central themes of Passivhaus: quality of air. Quality of air (assuming there is good ventilation) is strongly effected by humidity … and humidity effects the overal experience of temperature … cold is much colder when humidity is too low and heat is much hotter when humidity is too high. I have experienced the effects of humidity in warm and cold temperatures in Israel and I have seen it (as accumulated moisture and mildew) in almost all Romanian homes I have visited.
I don’t know yet enough about ventillation and humidity.
One of the much praised qualities of hemp masonry is it’s breathability. It seems to have a natural tendency to absorb and expel unneeded moisture. I don’t yet have enough information on the overall effects of hemp on moisture, ventilation or quality of air indoors – but I do have a good feeling about the effects of hemp!
Following are some of the resources I came across and consumed in trying to understand Passivhaus:
- BRE – Passivehaus Primer – which I found at Passivhaus UK
- Wikipedia entry for Mechnical Ventilation Heat Recovery (MVHR) systems
- Blog post about MVHR’s by Mark Brinkley
- Forum debate about MHVR’s at Green Building Forum
- Blog post about a Passivhaus built in Cardiff at a staggering cost of £1,400 per square meter
- Wikipedia entry for Passivhaus
- Passivhaus Institue (which was quoted above)
- Some Passivhaus built houses
So pleasing to see a pleasant person who loves and believes in what he does. An interview with Ian Pritchett, Managing Director of Lime Technology:
Informative video which did a great job of putting images to words: