Monday, September 28, 2009

I See ICFs

Just a short stretch down the road from me there is a recently constructed house - well, it's now about 2 years old I guess. It has always caught my eye because it is unlike most of the buildings you see in New England, the ubiquitous white two-story Georgian-style Cape Cods or the occasional asymmetrical Saltbox house. This new house had different proportions, it was partly round and partly rectilinear, and clearly had been built, mercy-sakes, with passive solar orientation - the north wall of the place was even earth-bermed. Shocking! It was obvious to me, upon glancing at the structure, that the builder was someone who was actually thinking outside the, er, box.

I could clearly see that someone had built the house with an eye to 'green' and thus I had a certain interest in finding out a little more about the place and its builder. A few weeks ago I decided to pull in to the driveway of the place to see what was what. I met the owner, who turns out to be a local contractor, long-established, and he was quite enthused to show me his place and tell me all about it. I ended up staying for more than a couple of hours in fact.

The contractor had spent most of his career doing the regular sort of stick framing with 2x material, OSB, vinyl siding and sheet rock that you find pretty much anywhere. This building however was a point of departure from that rut, and was heralding, for the builder at least, a new approach to construction. He wasn't going back either. This approach, about which he extolled the virtues for as long as I was willing to hear, was building a house, from foundation to roof, using Insulated Concrete Form construction, ICF for short. I thought that today in my blog I'd begin to address the topic of ICF use in construction, and to relate some of the claims that are made for it and to share my opinions and conclusions, after having done some further research into the matter.

For those with a high-speed computer connection, I'll link a time lapse video showing how typical ICF construction works.

Like, ahem, all good things in life, ICF's as a system can be said to have gotten its start in Canada in the mid sixties. The first Canadian patent being issued to a German immigrant named Werner Gregori. He got an idea about changing the way people formed up concrete, which, at he time was largely by means of steel pan forms and disposable wooden forming. The disposable wooden forms are wasteful obviously. The metal pan forms are stout, however they suffer from the drawback of being heavy and cumbersome, which means that heavy machinery is needed to move them about the site and both machinery and forms take up a lot of space during that process. Further, metal pan forms are not easily adapted to designs that call for anything other than flat walls and 90˚ corners. Gregori understood these issues and set out to design a form that was lightweight, easy to manipulate and modify, and which could be used to easily form a wide variety of shapes. Thus, in short, his intention, the driving concerns, was to create a forming system that was going to improve productivity. As always in North America, the drive of innovation is almost always a drive towards increased economy.

Gregori's solution was to use a form made of expanded polystyrene - the forms are light and easy to place, and would be left in place after the concrete pour, so labour costs would be reduced. ICF's then are hollow blocks or panels made of plastic foam that can be stacked into the shapes of building walls. The center of the form is then filled with reinforced concrete. This produces a sandwich between the high strength concrete and the light insulating foam. Gregori's system was dubbed Foam Form.

Of course, like many new ideas which are introduced, traditional concrete crews ridiculed the idea of pouring straight concrete mix into anything except steel forms and Gregori had a long struggle to gain any modicum of acceptance for his concrete forming technique. In fact, he ended up going back to Europe where he found he had better success in finding people open minded about his product. Europe after all has a long tradition of building with stone and brick walls, and wood is more expensive for house framing than it is in North America, so he had an easier sell from those angles. Over time, ICF's gained a foothold in the European market, underwent many innovations in Germany and France, and eventually crossed the Atlantic once again to a somewhat warmer reception.

I say somewhat warmer as a bit of a play on words. You see, though ICFs were created as a replacement for steel forms and to increase productivity, many people with ICF basements noticed how much warmer and drier the spaces were than the conventional concrete formed basements. Further, ICF walls didn't suffer from cracking as is somewhat common in conventional concrete, nor did the ICF floor-wall systems require expansion gaps to be built in - these expansion gaps being notorious as a place for water and air infiltration in conventional concrete structures.

By the mid 1990's ICF use began to be employed for more than just foundations - entire walls, one and two story and higher, were now constructed using ICF methods. This development is that of a wall and floor system that form, literally, a continuous envelope. Today, more than 40 years on after Gregori's Canadian patent of 1966, there are dozens of manufacturers of ICF systems and ICFs are being employed for floor and even roof construction these days. Though wood-frame construction still accounts for some 90% of the N. American market, ICFs are gradually gaining a decent foothold, and have some 7% of the market at present.

During my visit with the contractor down the street, he touted many advantages to ICF-constructed homes, among them (and I'll expand somewhat upon each point):

-Higher R-value. A conventional 2x6 framed wall may have pink fiberglass insulation rated at R-19, however due to thermal bridging through the studs themselves, which are only about R-7, the net value of such a wall is typically only R-13. An ICF wall, depending upon which thickness is used, can vary from R-22 up to R-50. So, comparing apples to apples, the thinnest ICF wall outperforms a conventional stick framed wall in thermal efficiency by some 70%.

- Simplicity. A modern stick framed wall system is a complex sandwich of many parts, and in common practice these components form sub-contracted portions of the work. Thus there is a framing crew, a sheeting crew, an insulation contractor, a vinyl siding contractor, the boys with the sheet rock, the house-wrap with Tyvec® is another step, and of course the plumbing and electrical people need to get in there after the frame is up with sheeting. With a conventional concrete foundation underneath the stick framed structure, there is also a concrete forming sub-contractor involved, who needs to make two visits to the site (set up and removal of forms), along with the concrete company. With ICFs however, the forms are set up plumbed squared and braced, in very short order I might add, and the walls are poured. The forms can be placed in a day and the concrete poured on the next day. The walls are braced with steel which can be re-used on the next job. In one step the insulation and moisture barrier are complete, and each is ready to receive any finishing system, be it stucco or siding on the exterior, or sheet rock or wood paneling on the inside. Electrical and plumbing or fairly easily fitted into the foam cladding using simple methods, and modern ICF systems have pre-formed channels in the foam of floor blocks for routing electrical and plumbing circuits.

-Low sound transmission. Studies show that a conventional wood framed house dampens sound transmission by 50 times, whereas a ICF-walled house dampens sound transmission by 400 times, which is eight-fold better performance.

-Durability. A modern stick framed house is likely to be a 50-year proposal at best, then scraped off and dumped in the landfill. A concrete house will last much longer. The contractor I spoke with gushed that and ICF house would last "a million years" and said that, "you know, the ancient Romans built with concrete and that's still around..." Well, I'll take up those claims and their implications soon enough, but I think it certainly is accurate to say that an ICF house will last considerably longer than a conventional wooden stick built house.

-Mold and Insect Resistance. Mold is not uncommon in stick framed walls for there is both moisture present in the wooden components themselves, which may evaporate and then re-condense inside the wall cavity, and if the moisture barrier system is not perfectly installed, there are numerous places where moist interior air can find its way into the wall and condense. Water vapour condensing in the wall cavity can result in rot, mildew, and deterioration of the studs and wall over time. The mold which leads to wood damage then sets up an environment which is more attractive to certain insects, namely carpenter ants and termites. These insects either employ wood as a food source or as an easily-tunneled medium in which to build their nests.

ICFs, especially of the panel-formed type, have a continuous barrier of concrete which is neither a food source to insects nor can be penetrated by them. Although the EPS foam is not a vapour barrier as such, it still is a closed cell foam and thus allows for diffusion of moisture and water. The poured concrete forms an effective vapour barrier, though concrete itself can wick water very readily if it becomes in contact with water, which could happen through damage to the foam.

So, lots of pros being touted here for ICF construction. Does this mean I'm sold on the system? Is it the Holy Grail? Am I now a paid hack for the ICF industry? Well, no, I'm not quite in the employ of the ICF contingent, nor do I plan to be, and I'll get to addressing those other issues in my next post. In it, I'll take a closer look at the situation with ICF construction methods and materials, with the long-term lens in place, and with a look to environmental issues comparing ICF construction to other methods. There are pros and cons with everything of course.

Put it this way though, given the choice between a stick built house and an ICF house, I would choose the ICF house. Further, given a choice between the timber frame wrapped with structural insulated panel system (trimberframe + SIP) currently in vogue in North American timber framing practice, I would choose the ICF system over that without second thought. I do think there are yet 'better' ways to go than an ICF house though. 'Better' from my perspective at least. I'll get to some of the reasons I draw those conclusions in the next post.

I Hope to see you then - thanks for dropping by.

For part II, click > here <.

Friday, September 25, 2009

First Light L (50)

I have made a couple of small changes to the blog, as regular readers will probably notice. I've added an index of blog topics, to the right sidebar, which I think will greatly facilitate finding information and, for those new here, discovering some of the topics I have written upon over the months since this blog came into being back in January.

Also, I've added a sidebar listing the schedule of Japanese carpentry presentations I have set up for the Autumn here in the Northeast of the US. These presentations will run about 2 hours and the build of the garden lantern will be the focus. This list will be appended to as new dates are finalized over the next few weeks. Readers who might like a presentation in their area can contact me to see what we might be able to arrange.

Back to the lantern. Final assembly was proceeding well yesterday when about half-way along, wouldn't you know it, the battery in the camera gave up the ghost. My camera's power adapter was also broken, so I was left with no way to upload the pictures I had taken, and no means of snapping any more pictures. Dead in the water, so the process had to grind to a halt altogether. This morning a trip to an electronics supply store yielded a generic charger. It looks like the battery is pretty much dead, however it holds enough of a charge to allow me to continue.

So, without any further ado, on with the conclusion of the garden lantern's final assembly...

Onto the dodai went the housing posts, and the electrical were leads fished up one of the posts:

Since the relish on the post tenons was at the bare minimum (3x peg diameter), I went with Mahogany for the pegs since it is more flexible than the Bloodwood:

The posts fixed, in then could go the grill assemblies, and then I started installing the keta, or wall plate:

Here's the keta installation completed along with the sub-ridgepole, roof board pairs along with their supporting ribs, and the gegyo (gable pendants)- I've moved the lantern into another room so as to have enough ceiling height to facilitate the roof fitting:

The hafū are pre-assembled:

One of the hafū assemblies slides into place on its central pair of draw bars and the lower corner dovetailed draw bars:

That's a 16" wide slab of figured Bubinga, about 12' long, in the background, currently being used as a shelf in our cramped apartment. also visible in the above photo are sets of the Bloodwood hi-uchi-sen, opposed wedging bars that travel across the wall plate corners in a compound slope.

Next, the tapered sliding half-dovetail pins are tapped home - these ensure that the lower roof board is fixed tight to the barge board and serve to reinforce the lower cross-wedged draw bar connection:

A step back for a look at the roof after all the components except for the ridgepole are in place:

Now, the ridgepole slides down into place, simultaneously engaging with the hafū, the draw bars connecting to the sub-ridge, along with the six dovetail tenons found on the ends of the roof ribs:

The very last step of assembly is to tap in the two Bloodwood pegs that fix the upper ridgepole, or muna-gi, in place:

A look to the other side of the muna-gi with the pegs fully in:

This was the original design:

And here is the lantern I produced, complete at long last:

The above image could use a few degrees of rotation, however it'll have to do for now as I don't have photoshop.

On with the light, the First Light:

Another view:

I think I'll play around with a few different light bulbs to see the one I like the best. The current one might be a bit too bright, though I will need to see how it looks out in a garden before deciding. Another option would be to increase the opacity of the glass.

I hope readers have enjoyed this detailed build up of a Japanese garden lantern. It was a prototype, and I feel really pleased with the way it came out. I learned a lot from the design and building process, and have some lessons to bring forward toward the next time I build a lantern like this. I was surprised at how long it took - I certainly didn't expect to run 50 posts and more than 750 photographs. I hope it hasn't been overly tedious for the reader at least, though many have expressed encouragement along the way, for which I am deeply grateful.

It occurs to me that it might feel a little weird actually to start blogging about other matters from here on out, however I've got more than a few things on my mind that seem to need outlet, so we'll see what unfolds on upcoming installments of the Carpentry Way.

As always, thanks for coming by, and your comments are always welcome.  Installation series can be found starting here.

Thursday, September 24, 2009

First Light XLIX

The 49th post - rounding the bend and entering the home stretch. Although I was thinking back at post #40 that this thread would end somewhere around #45, well, I am now going to have to revise that upward, obviously, and am quite sure that the nice round number of 50, 'L' in Roman numerals, will be the final post.

I am now entering into the final assembly process and have few remaining tasks to deal with. One was to install the glass into the grille panels:

Here are the 4 panels with glass fitted:

I then cleaned up the end grain of the Bloodwood opposed wedge pairs which lock the four post sections together:

I later did a bit more trimming and have made these wedges all exactly the same length now so they stick out the same amount. It looks a little tidier that way, though as I said earlier I would probably just as well trim them flush and paint the end grain white.

So, the final assembly begins - here, the lower tier of hijiki are in, along with the central and perimeter draw bars, along with most of the pillow blocks:

Next, all the pillow blocks with their central pins installed, along with the Goncalo Alves cap with the electrical cable routed through at the side position:

Then the upper tier of support beams (hijiki) are installed, and the electrical cable now routed through one of the diagonal hijiki:

Ever upward, now two of the dodai are positioned, and the black wire is woven through the end of the half lap on one piece:

Another view:

The remaining two dodai dropped into place along with the floor panel of the lantern housing, the white wire fed through the joint, and the slots of the cross wedges in the central draw bars are front and center:

Another view from a pace back:

Next, the wedges themselves, which I made out of Ebony:

The Ebony actually crushes a bit against the Lignum Vitae mortise walls when driven in, so I'm thinking I might remake the wedges also in Lignum Vitae.

That left the insertion of the sliding cross bars, in Bloodwood, which lock up the central pins at each sill piece, the making of which I described in the previous post:

With all the pins and wedges in place, I was pleased to find the entire top assembly was very rigidly attached to the post - even with some firm attempts to twist the bracket assembly, or kumimono, off of the post top, it didn't budge or creak at all. I can tell that could even lift the entire piece, including the foundation stone, up by the sills alone, though I felt no need to actually do that. No need for senseless lifting if one can avoid it (that's not something I would have said in my twenties - hah!). So, Mission Accomplished in terms of that design goal! Ultimately, the in-service durability and repairability of the piece, over the long term, will really determine the soundness of my design choices.

In the next and final post in this design/build thread of a Japanese garden lantern, I will attach the lantern housing to the sill, install the grilles, and cap it all off with the roof assembly. I'm really looking forward to powering up the light and seeing how the lantern works in the dark.

Thanks for dropping by today. Next post, the big 5-0, will be coming up soon, so please don't go to far away.

Tuesday, September 22, 2009

First Light XLVIII

Post number 48. Previous posts in this thread, along with other topics, are archived in the sidebar to the right of the page.

I recently joined Facebook, so those readers who frequent that site can connect with me there.

Today I will show the final joinery task with this lantern project, namely the locking pins which tie together the lower level of hijiki, through the pillow blocks, and into the sills of the lantern housing, or dodai.

To connect the central Lignum Vitae draw bar, which ties the parts, to the lower tier of hijiki, I decided that I could employ what I will call an interference pin, rather than a conventional peg through the pin. Given that the pin is only .375" in size, an appropriately-sized peg would be too small to mortise, with my tools, and given the awesome strength of the Lignum Vitae, the toughest wood on the planet, I thought I could get away with it. Time will tell of course.

First I mortised for the interference pegs, which will also be made out of Lignum Vitae:

As you can see, these peg mortises are rectangular, rather than square, only 0.1875" x 0.25" in size.

The completed mortises, all four of them, in the two hijiki parts involved here:

Here's a pin slid into place, showing the near half-interference of the pin in the mortise - well, about 0.125" actually:

I used a chisel to mark out the mortise walls on the pin, then sawed and chopped the waste material out from the pin, leaving a 0.1875" wide trench through the pin. There was about 0.375" of relish on the pin below the trench cut, which I estimate to be adequate.

Here is a look at after the peg is installed though the central pin, but before the dodai is slid and pressed down on top of the pillow block:

Normally I try to avoid displaying too much of the joinery mechanism, and given that these hijiki are somewhat buried and obscured by the 45˚ oriented hijiki adjacent to them, the peg is fairly discreet -I cut them flush for that very reason.

Now then, here comes the tricky bit: the connection at the top of the pin, at the dodai level. At this location, the lantern housing grills sit, and again, given the small size of the through pin, pegging is not really an option. I decided to adapt a type of joint used in high class Japanese residential construction - a joint that connects a sliding door upper track to a stub post. This is a variant on a cross-sliding lock dovetail, shino sashi ari tsugi, a joint not found in Western carpentry as far as I can tell.

This joint is better explained in pictures. First I made a jig in MDF, from which I would reference my router:

The result of the initial cut-out is a crosswise trench, cutting partially across the Lignum Vitae pin, and angled at 14˚:

This cut creates a half dovetail on top of the Lignum Vitae pin.

All four locations now mortised:

Then I used a 6mm chisel to square up the oblique trenches:

Then it was time to take the dodai off of the supporting parts as I needed to deal with both the pins and their slot mortises separately:

For the dodai slots, I adjusted the router fence to cut the slot 0.01" wider, in towards the direction of the pin:

And for the pins, I deepened the shoulder cut a little with a chisel:

Here then are the sliding fixing pins, shachi-sen, which I made out of Bloodwood - they have a 14˚slope machined into their upper surface and are precisely sized for thickness to the slots in which they fit:

So how does this joint work? Well, first I reassembled the parts, and placed the shachi-sen into their respective slots in the dodai:

Then I use a drift to push the shachi-sen sideways, where they run into the half dovetail on the top of the Lignum Vitae through-pin -- given that there is some 0.01" of interference at that meeting point, the pressure of the sliding pin causes the dovetail to lock up and draw upward slightly:

The sliding pin fully into position -I leave a little room on the opposite side of the trench so that the sliding pin can be drifted back out when necessary:

All four locations now complete:

I designed this joint so that with the lantern grilles in place, the mechanism of the sliding pin is completely covered over and hence protected from the weather:

All that remains now is to fit the glass into the grilles, and chamfer/finish plane a few parts, followed by final assembly. That will form the subject of the last two posts in this build thread. The end is nigh! Stay tuned for post 49

Thursday, September 17, 2009

First Light XLVII

This is the 47th post in a build thread about a Japanese freestanding garden lantern of my own design - previous post installments are linked in the 'Blog Archive' to the right of the page, so visitors new to this blog may wish to look there before proceeding - if so, you'll need to set aside a little reading time.

Continuing on then with the fitting of the main post to the foundation stone. When I left off yesterday, I had scribed the line, knifed it, and then completed the rough cut of the base of the post with saw and chisel. The next step was to trim right to my line using a bench chisel with a convex bottom, or o-ire soto maru nomi (追入外丸鑿) as it is referred to in Japanese:

I carefully worked around the knifed line along the perimeter of the post with the chisel.

Now, the stone is convex and the underside of the post must be hollowed to fit it. In the past I would gouge out the post bottom with a chisel, however the resulting surface wasn't especially clean as I don't actually have the ideal curved gouge for that task. These days in fact I prefer a more expeditious solution: my Metabo 4.5" angle grinder with a 60 grit flap wheel, normally reserved for working on metal:

The aim is to hollow the post in the middle ever so slightly greater than the surface of the stone, so that the post will fit tightly along it's perimeter and not wick water into the core region. In the past I also used a circular saw to do this task, brushing sideways with the exposed blade, guard retracted- not the safest practice, with the femoral artery rather close to the action. I virtually never grind wood with abrasives, however this task is one exception.

After a few seconds swabbing with the grinder, the post base looked like this:

A clear example here folks of the difference in surface finish between rough grinding and rough cutting. Even with using fine sanding grits though, there is still a different surface left behind whether using abrasive cloth or a blade, one scratched, the other sliced. I avoid taking to grinder to the edge of the post, as it is all too easy to go too far too fast, so I prefer to make the final fit adjustments with the refinement a chisel allows.

So, after all that, it was time for the first trial fit:

Obviously, a little material in the center is still keeping the surfaces from meeting at the perimeter. It's hard to know exactly where the high spots are by looking, so I use something to transfer the marks within the space between post and stone - carbon paper:

Carbon paper is getting hard to find at stationer's these days - this time I had a 'choice', if you can call it that, between a pack of 100 sheets or to buy a ledger book with two added carbon sheets in it. I bought the ledger book.

The paper in place, carbon-coated side up, the post is placed back in position:

The key thing with this process is to make sure the post goes back to the exact same position each time - otherwise you will find yourself going around in circles and a good fit becomes quite elusive (ask me how I know!). I've used chalk for this task in the past but I find that kind of messy and vastly prefer the results from the carbon paper method. Speaking of results here's what I found after giving the post a little to and fro rub on the stone:

So, the black-marked high spots are worked down, and then a refit is tried:

A lot better after round two. The procedure is repeated until the fit is satisfactory - here's the fit after round three:

The other side:

At this point was very close and needed only to do one more round to get a nice fit.

Stepping back a few paces, here is the look of the post now fitted to the stone:

The next step was to paint the end grain on the bottom of the post with a couple of rounds of latex paint. Between coats, I then fitted the plastic liners for the threaded rod holes:

The little mark is for orienting the oblique cut on the end of the plastic with the hole correctly - it orients to the text printed on the pvc tubing.

Well, the post fitting is another tick off the list of tasks to complete. This list is getting awfully short now:

Another coat of paint on that puppy and the post is ready for installation.

Next up: the wedges for locking the post sections together. Like most of the other pegs in this lantern, the wedges are in Bloodwood. They are to be left long for the time-being:

At final install, I will trim the wedges flush with one another, slightly proud of the post face, and paint the end grain of the wedges white.

A look from up on high at the post on the stone with the locking wedges installed:

Well just one more joinery task remains on this project - that will be the subject of the next blog entry on this thread. Stay tuned.