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EcoMotive

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Reply with quote  #1 
This thread will showcase (in as much detail as I possibly can) the design features and construction of my new super-insulated passive solar house. After many, many hours of meticulous research and with the help of Google SketchUp I have planned the house down to the finest detail.

My goal is to build a house that is healthy, comfortable, efficient, environmentally friendly and durable. Some of these five traits are complementary to one another while some are mutually exclusive. As such, I've spent countless minutes carefully weighing the pros and cons of each design decision to strike the best balance between these five principles.




[LARGE]
Here is the front of the house. It's a two storey structure with a slab-on-grade foundation and attached garage. The garage sits with it's front face parallel to the road (as per town regulations) while the rest of the house is angled back by 30 degrees in order to face south.



[LARGE]
The house is situated on a 1 acre lot in the small town of Flatrock, NL, Canada. The lot is almost perfectly flat and is covered in a mature closed canopy Balsam Fir forest. The property borders a fairly expansive wilderness area with opportunities for hunting, fishing, hiking and other outdoor activities. My plan is to develop a somewhat self-sufficient lifestyle by utilizing the land to provide my own food and fuel.



  [LARGE]
The rear of the house faces south. The windows, doors and daytime living space are concentrated to this side in order to make the most of passive solar heat gain. A generous eave overhang over all the windows provides passive shading in the summer and includes a unique solution to getting the geometry just right for maximum benefit (more on this later).



[LARGE]   
The house will be built using a unique framing scheme known as a "modified Larsen Truss" or "Riversong Truss". The exterior wall system consists of two parallel chords that are offset by a continuous gap. The roof and second floor are supported by the inside chord while the outside chord extends uninterrupted from foundation to roof. This creates a thick, high R value wall system that has almost no thermal bridging; even around the band joists. Combining this framing system with some careful planning and placement of window and door openings ensures that only a small amount of extra wood is required over a typical 2x6 stud wall.

This system is probably the most cost effective way to build a super-insulated wall. It's also a sustainable way to build since it only requires natural and renewable materials such as locally harvested lumber and straw bale insulation. Most other super-insulation schemes rely on petroleum based foams for their efficiency.



[LARGE]
A 3D model of the Riversong Truss system illustrates how framing efficiencies can be achieved by placing window and door openings within the natural stud pattern and aligning them vertically. It takes some meticulous planning but it's not technically difficult. Not only does it cut down on studs but only one header is required for each pair of windows.



[LARGE]
The first floor plan is typical of passive solar design principles. Daytime living space is wide open and concentrated to the south side. A very large effort was put into squeezing as much functional, modern living space out of a small square footage. In some cases, walls, windows and doors were placed where they are based on requirements of a few millimeters.



[LARGE]
Again, the second floor is made to fit a big house into a small space. In several rooms we will require the use of custom made built-in furniture and fixtures as well as creative layering of multi-use areas to make the most of our space; both horizontally and vertically.

[LARGE] 
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More information regarding the fine details of the house are coming soon.

Lance in Newfoundland

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 “Only primitives & barbarians lack knowledge of houses turned to face the winter sun.” 
Greek philosopher Aeschylus


EcoMotive

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Reply with quote  #2 
These photos were taken about 6 weeks ago on the day before the contractor was scheduled to start the house. I spent some time during the previous winter clearing the trees from the building site. The surveyor had been there a few days prior to stake out the corners of the house for the excavator. I ran some jute twine between the stakes for clarity.

[Perspective%20Insert_zpstmt6bcug]This is a simplified image of the floor plan that appears as an insert in some of the following photographs. For clarity, the position of the camera is indicated by a red dot and the direction is shown with a red line.



[IMG_0111_zpsqlqd8spx]Here's a photograph taken from the road. I have a narrow driveway leading up to the house. I wanted to leave as many trees intact in front of the house as possible for privacy and shelter from Northerly winds.



[IMG_0090_zpsce1ydc3o]Here we're looking at the front of the garage. The face of the garage is parallel to the road while the house is "tilted" back at 30 degrees to face South on the back.



[IMG_0092_zps67emirgp]Now we're standing on the back of the garage looking into the sunspace. The corners of the sunspace were not staked by the surveyor.



[IMG_0101_zpsexxjoiij]This is the East side of the house looking West.



[IMG_0104_zpsa5n2ldzy]And another view of the sunspace. This time we're inside the living room looking outside. As time goes on I will clear the trees on the South side of the house, using them as firewood and opening up the Southern sky for solar gain.



[IMG_0088_zpsre2oyxhz]As I cleared the land for the house I harvested and stacked the firewood. I plan on using a small wood stove as backup heat and I'm hoping these two chords of wood will last me a couple of years.

Lance in Newfoundland

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 “Only primitives & barbarians lack knowledge of houses turned to face the winter sun.” 
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EcoMotive

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Reply with quote  #3 
The clapboard was the first tangible part of the house that I had - all 980 pieces of it. The boards were harvested locally and milled at a lumber yard just a few minutes away. Good ol' Newfoundland Black Spruce. I helped my father in law install clapboard on his house a couple of years ago and it was love at first sight. Despite being a little bit more expensive and A LOT more work, I highly prefer clapboards over vinyl siding. It's much more solid and it makes an eco-friendly and healthy alternative to siding.

[IMG_0203_zpsk9yjwtmj]
Here we have an excited little girl sitting atop our new arrival. Being a local and rough sawn product, all of the ends are live and need to be measured and cut square. That was the first step of the process. The smell that this wood gives off is wonderful.



[IMG_0332_zpsgdgix4q5]
Most of the boards were stained in the basement as our fall weather tends to be too wet for staining outside. I used the service cart as a table for de-burring and brushing the sawdust off each one. Any boards that were damp were stood up along the wall to dry in the breeze coming in through the door.



[IMG_0331_zpszuzzuvjz]
After de-burring and dusting the clapboard is placed on this table in stacks of fifteen waiting to be stained. To the left and right are racks holding completed boards, bundled in twelves. The rack on the right is holding 324 boards... almost one third of the lot.



[IMG_0334_zpsaozjksbb]
The boards were stained 30 at a time on the front and back. Staining on both sides before installation prevents the boards from warping and splitting while on the wall. They will be given another coat after installation. The rough texture causes the boards to really soak up the stain and hold on to it, giving them a durable finish.

Lance in Newfoundland

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 “Only primitives & barbarians lack knowledge of houses turned to face the winter sun.” 
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EcoMotive

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Reply with quote  #4 
Another thing I've been doing while waiting to start construction is pre-fabricating the plywood gussets that tie together the two parallel walls that make up the Modified Larsen Truss system. I originally planned to make the gussets out of scraps from the framing and sheathing materials but in the interest of being productive I opted to buy new materials.




[Gusset%20Illustration_zpsb1atozu1]
Here is an illustration of how the gussets attach to each of the parallel 2x4 studded walls and hold them at an offset. The entire wall cavity is 11.25" deep (the thickness of a 2x12). The 4.25" gap in between the two walls is maintained by a small block of 2X4 attached to the plywood. The inside chord is the principal load bearing member while the outside one holds the exterior sheathing. The outside chord should be able to transfer a heavy wind load to the inside via these gussets.




[IMG_0360_zps7hmjvkuy]
Here you have the workspace complete with the jig for fabricating the gussets as well as a good stock of precut 2x4's and 3/4" plywood. The plywood is first ripped into 3.5" strips and then cut to lengths of 11.25" on a mitre saw with a stop clamped to the fence for quick repetitive cuts. The 2x4's are cut to a length of 4.25" on the mitre saw in the same manner.




[IMG_0361_zpsu0abrybc]
This is the jig up close. It holds the two components of the gusset in place until they can be mechanically fastened.



[IMG_0367_zpsebvi7i79]
First the small 4.25" block of 2x4 is placed in the jig and a small bead of low VOC construction adhesive is applied.



[IMG_0368_zpsdejwbmd5]
Next, the 3.5" by 11.25" piece of 3/4" plywood is laid in place on top of the block of 2x4.



[IMG_0369_zpsa5tlofcu]
A stamp is laid over the plywood and given a couple of taps with a hammer.



[IMG_0370_zpsvzjmtiys]
The stamp indents small holes into the wood to mark out the locations for the nails. It also mashes the construction adhesive into the two pieces, forming a good bond.



[IMG_0371_zpshmduflv7]
The two pieces are then nailed together using 2" hot dipped galvanized spiral nails. The other eight holes will be used for nailing the gusset to each of the two parallel studs it will be connecting together. The gusset is now finished.



[IMG_0372_zpsk7jcwrez]
Before you know it, you have a dozen or so made. I haven't counted exactly how many I will need yet but I figure it will be in the neighborhood of 600.

Lance in Newfoundland

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 “Only primitives & barbarians lack knowledge of houses turned to face the winter sun.” 
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Bert

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Reply with quote  #5 
Impressive. You are blessed to have the resources to do this project. Looks great.
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EcoMotive

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Reply with quote  #6 
Moving along with the design process. I have most of the groundwork laid and I've finished modeling the first storey framing. I recently switched my wall framing scheme from 24" On Center stud spacing to 16" centers. This was for a couple of reasons...

The first was because local building codes require a wall supporting a roof and one storey to be 2x6's if 24" O.C. while a 16" spacing will allow me to use 2x4's. Both schemes use roughly the same amount of framing material, but since this house is a unique case where the total thickness of the wall cavity has nothing to do with the size of each individual stud it makes more sense to go with 2x4's 16" O.C.

The increased lateral strength of a 2x6 over a 2x4 is of no issue in this house either since the exterior wall is actually a system of two parallel chords that together are almost a foot thick. Furthermore, the narrower stud spacing means smaller spans for my exterior sheathing, cladding, drywall and consequently more nails holding everything together... which brings me to my second reason for reducing my stud spacing...

Although traditional "green" building philosophy would have you frame on 24" centers in order to save [a marginal amount of] wood, there's nothing green about a rickety, scantily framed house that needs to be rebuilt after every decent storm either.



[LARGE]
Here's the front of the house. The main living area is the rectangle shaped area on the left while the double garage is on the left.



[LARGE]
This is the back (South facing) side of the house. The sunspace is the small bordered-in area on the left but I haven't decided exactly how I'm going to build it yet.



[LARGE]
Most of the window and door openings fit within the natural stud spacing pattern. This makes the framing more efficient but more importantly, it ensures that I don't have to add in any extra jack studs which would have to extend all the way from the foundation to the roof. The interior wall of the building envelope is pictured here but only the bottom plate is shown for the exterior wall. You can see how each stud from both walls are in perfect alignment.



[LARGE]
The wife wants a year 'round heated garage and even though I think it's totally impractical given the apparent thermal and air sealing weaknesses of garage doors I figured I'd give it a shot. Since a full 2x12 thickness wall would be excessive in an otherwise poorly insulated and leaky area I figured I'd try another approach. This staggered stud wall has 2x8's for the top and bottom plates and 2x4 16" O.C. studs. The outside studs are positioned for exterior sheathing installation and the interior studs are positioned for drywall installation. Both stud spacing arrangements are optimized for each side and minimize wastage and installation labour of their respective materials.



[LARGE]Because this wall is only one storey high there's no need to align each pair of studs and tie them together. This wall could be made thicker with just the extra costs of bigger top and bottom plates and more insulation. I think this would make a great system for single storey houses or even multiple storey platform framed houses where the builders are unfamiliar with Larsen Truss construction.


Lance in Newfoundland

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 “Only primitives & barbarians lack knowledge of houses turned to face the winter sun.” 
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gbwillson

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Reply with quote  #7 
Lance-

Have you considered structural insulated wall panels for your build? Unlike traditional stud walls that suffer from thermal bridging, you get a thermal break across the entire surface of the wall. You also get a much higher R-value per inch of wall thickness and far less air infiltration.

Greg in MN



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  r-values1-500x314.gif 

EcoMotive

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Reply with quote  #8 
I didn't actually look into it but I doubt that SIP's are even available here and doubt even more that there would be anybody around to install them.

I want to build a house that's more healthy and environmentally friendly than it is energy efficient. Although SIP's are very efficient they are made mostly out of petroleum products and glue which are eco harmful and create a toxic indoor air environment. I also wouldn't want to live in the hermetically sealed environment that SIP's will create.

Instead I chose a system that can be built from all natural materials, namely [real] wood, recycled paper (or hay) and earthen plaster.

Lance in Newfoundland

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 “Only primitives & barbarians lack knowledge of houses turned to face the winter sun.” 
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gbwillson

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Reply with quote  #9 
Good points on the potential hazards. Oh, and I gotta go with your wife on the heated garage. Mine is detached and uninsulated. Brrrrrrr! It's nice to come out to a truck not covered in ice and snow in the morning, which mine does unheated. But if I had the money, I'd eliminate my basement workshop(750SF) and build me a proper garage/workshop/man-cave. Could the garage be solar water heated beneath the slab?

I didn't see any mention of what you will be using to insulate the exterior wall cavities. Cellulose, polyiso, hay, or something else? I lived in a house that had crumpled newspaper inside the walls. The newspapers were from 1910, so I had fun reading the old news and ads during a couple of projects. I can't imagine what a fire hazard that was with the old knob wire system.[biggrin] One project was to replace the medicine cabinet. Inside the wall cavity was a gas line from the old gas lamps for the bathroom. They were still live with gas! The ends of the tubes were folded over and crimped with a pliers![eek][eek][eek] I about messed myself when I found that. Oh, how I love old houses!!!

Greg in MN
EcoMotive

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Reply with quote  #10 
The other things I don't like about SIP's are their apparent structural weakness when it comes to high wind loads, the difficulty in running electrical and plumbing lines, the OSB's tendency to crumble when wet and the inability to get a good thermal envelope around the rim joist for the second floor.

I'm still on the fence about building a solar thermal system for the house. I'm going to give it some deep thought in the next couple of weeks and make the decision since I would have to start building the collectors pretty soon in order to have them ready in time for installation. Even if I did have a hydronic solar thermal system, I'm not going to install radiant tubing in any of the floors around the house. The thermal lag time for the floors would be too long for the thermostat to respond properly to changing passive solar input. Plus, you wouldn't get that "warm toe" feeling in a superinsulated house since the design temperature for the floor would be too low. I'm going to try out radiant walls instead.

I was planning on editing the first post in this thread to provide an overview of the construction details including insulation, heating system, windows, etc. but haven't found the time yet. But since you asked, I'm going to be insulating the walls and attic with blown in cellulose. Cellulose is recycled material with a low embodied energy, provides for a healthy indoor environment, is very hydroscopic, is breathable but still does good with stopping air infiltration, is incredibly fire resistant (it is an approved firestop between the two floors) and has a pretty high R-value per inch of thickness.

Dense pack cellulose has a R-value of 4 per inch of thickness which would bring my wall cavity to an R-value of 45. Even the stud locations would have an R-value of 17.

Lance in Newfoundland

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 “Only primitives & barbarians lack knowledge of houses turned to face the winter sun.” 
Greek philosopher Aeschylus


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