Gravitas Blog

SIP roofs and SIP walls in the building industry are short hand for Structurally Insulated Panels. Basically a layer rigid foam sandwiched between two layers of plywood (typically oriented strand board, or OSB) with integral structural members (2×6, 2×10, etc.). Some companies adhere the finished ceiling material like tongue and groove pine on the inside face as shown below. These panels are made to the specific structural and insulating requirements of your home, the thicker the panel, the greater the R Value. The construction time can be reduced because the panels arrive ready to tilt up or fly in on a crane and are pre-cut to fit.

Photo: Eagle PanelPhoto: Precision Panel

The Following is a discussion on the Pros and Cons of Structurally Insulated Panels (SIPS) by Steve Hancock at The Log Connection up in beautiful BC, Canada. It’s a good summary of some of the SIPS applications and benefits. Thanks Steve for sharing your insights. We specify SIPS on many of our projects and have used Precision Panel locally, Eagle Panel in Illinois, and Enercept in South Dakota.

The Log Connection takes great care to ensure that our homes are handcrafted with the best techniques for ensuring a weather tight seal. The SIP panel (Structural Insulated Panel) system works in very will in some applications and for some people…. but not everyone. A large part of the decision is understanding all of the pros vrs. cons of the product and making sure they work for your design. We have outlined a number of areas that we review and discuss with our clients when making the decision of conventional framing vrs SIP panels.
ROOF PROS:
It’s our opinion that the the use of the SIP panels on the roof system is an efficient way to install a roof system quickly. The more simple the roof line, the more practical the application. In most situations, the panels can be made to easily span between our roof logs and be completely roofed in a just days. The thicker the panel the higher the R-value. If made the same thickness as a conventional roof the rating is about 30% and higher depending on the manufacture. The panels are pre-cut at the assembly plant so the on site waste and clean up is lower with the use of the SIPs

Photo: Precision Panel
ROOF CONS:
Most of our home owners are as interested in the look of their home as they are in the efficiency of the products. On of the largest issues our home owners have is the accent lighing you see in the ceiling of nearly all our homes. It is not yet possible to install a recessed or pot light into a SIP panel. In areas with heavy snow loads the design of long overhangs are be limited to that of the panel.
WALL PROS:
The wall systems stand and install quickly on our post and beam homes and the upper gable ends of the stacked log packages. The pre-cut panels* are ready to install when delivered to job site.
Openings are pre-cut for window and doors, minimal framing or trim work should be required. The on site waste and clean up is lower with the use of the SIPs

Photo: Enercept
WALL CONS:
The largest issue we have with the wall panels is that the exterior sheathing of the the panel is cut flush to the edge. We have a system that allows the exterior sheathing and interior drywall to EXTEND INTO the posts. This creates an impenetrable weather seal and no drafts at the joint. When butting a SIP up against the post there will eventually need to be a weather block/ trim installed to stop the draft. Hanging small pictures will be fine but without heavy artwork and shelving should may not be possible due to no solid stud to fasten. Installing unplanned electrical boxes is a huge hassle and requires cutting and patching of the panels. Pre-plan and you will be fine.
* Rarely will the SIP manufactures visit the job site to acquire and verify the as build measurements. Therefore they will not assume any responsibility if the as built conditions are not 100% CADD prefect.
To sum it all up, the SIP panel it’s a great product when used with the right conditions with reasonable expectations. We encourage the conventional stick build system for our stacked log, and the post & beam homes. The SIP panel is recommended with our timber frame homes.
Steve

Solimpeks Corp has unveiled a hybrid solar panel, Volther hybrid photovoltaic-solar thermal collector, that incorporates both Photovoltaic technology, as well as providing domestic hot water.

Typically, one of the larger impediments to efficient energy harnessing from a PV system, is the fact that as the panel heats up, the efficiency drops off.  By tying the two systems together, the domestic hot water collector acts as a cooling device for the PV portion of the panel, not only limiting the footprint of a dual system, but also improving the performance of the PV portion.

Traditional PV systems loose efficiency at the rate of 1/2% per degree of temperature increase.  Research and Develompent at Solimpeks claims that PV efficiency has been tested as high as 28%, while producing 104-160 degree water.  By stabilizing the panel at 113 degrees, approximately 20% more electrical output is produced, as when compared to a traditional PV system with the same peak output.

According to the company, tests by independent organizations have shown that an average single family residence in Northern Europe would need 270 square feet to meet their hot water and electrical demands.

Solimpeks Volther offers two different models, emphasizing either hot water collection, or electrical energy production.  The PV utilizes monocrystalline silicon cells, and the hot water portion uses copper tubing.

The first system was installed in May, 2010 in England, and the company sells directly to the US market from Turkey.

MarkWagner<>Gravitas

We recently had the pleasure of visiting one of our smaller structures as it is going through its final steps before completion.  Derek Hurd of Gravitas worked with a couple from Texas that were permanently relocating to Boise, Idaho.  They asked Derek to design for them a small accessory dwelling unit (ADU), behind the home they had owned for a few years, but rented out.  They had decided to move permanently to Boise, and the small building would serve as a writing loft for the couple.  They gave Derek a little direction to go by asking him to be inspired by Japanese Tea houses.  The couple referred to the ADU as the “Writing Shed”.  At Gravitas, we called it a “Zen-in-Law”.  Either way, it got the point across, a small out-building, dedicated to the more contemplative things.

The owners came across our company through a mutual friend.  We’re always appreciative when past clients, and future friends can pass along our name to those in need of thoughtful design.  After the owners diligently investigated us, and our web presence, they called, and discussed their needs with Derek.  What ensued was the typical package of sketches being sent, and descriptions of likes, and dislikes.  Derek then integrated all of the ideas, and came up with a  contemporary little writing studio.

We are only a few days away from the final punch list, and we hope to get photographs of the finished work in a few weeks.  Good timing to enjoy the cool Boise evenings.  I’ll be sure to include them in a future post.

Here we can see the little house in all of its glory.  One of Derek’s soft spots is for the faithful ‘butterfly roof’.  It’s simplicity in design ins contrasted with its complexity of construction.  We were treated to some interesting stories of its construction by the crew from Green Remodeling, who did a terrific job helping to realize the owner’s dreams, and Derek’s vision.  One of the wonderful things about this sort of roof, is the fact that all of the wall studs, and all of the roof rafters are unique in length.  This, in addition to the compound angle makes a standard out of the box approach to construction unsuccessful.  Thankfully, Kenji Wright, John King, and Josh Bogle were able to accommodate the design, and deal with the mathematics of the framing.

As with any remodel, or addition, staging the construction of the project can present some challenges.  The site is located at the back of the lot, perched 30 feet above the road.  Luckily there was a vacant lot behind the building (behind the fencing we see to the right).  Through this lot, they were able to bring in the concrete for the foundation, and the floor, as well as the other building materials.  Utilities had to be trenched out to the front of the house.

Siding is T-111 no groove panel, with 1×2” cedar battens at 16” on center.  All earth tones on the finishes help to reinforce the timber feeling, and blend in with the surrounding landscape.  One of the not so surprising ramifications of a ‘butterfly roof’ is the tremendous water collection that it affords.  In this case, the runoff is channeled to a small spillway, that deflects the force of the water as it hits the ground.  The rain is then allowed to gently seep into the soil.  That’s the theory at least.  I’ll check in next spring, and see how things are going.

A fish-eye perspective of Kenji finishing taping before the final finish is put on the loft floor.  The open loft looks down into the common area, with a kitchenette, and writing bench below the window.

Family friend “Woody” stands at the ready to greet any new arrivals.   The owners’ other pooch, a Corgi, is behind the scenes, making sure that everything is built according to plan.  The deck makes a nice perch to view the rest of the yard, and the use of canted beams eliminates the columns breaking up the natural flow, and the site lines.

The landscape walls are made of lava rock, and they turned an aggressively sloping back yard into a series of terraces.  This created much more usable space for the family to enjoy the Boise summers on, and it helps mitigate the runoff, allowing it to soak into the soil, and not run unhindered towards the house, and deck below.  Again, this will be interesting to revisit, after the owner has had an opportunity to enjoy the home for a season or two.

The Laramie

We could tell that this was a special little home from the beginning.  We’ve adopted it into our “Plan of the Month” series that we offer.  We have renamed it to protect the innocent to the “Laramie”.  We haven’t updated our plans list on the site yet, but if you are interested, here is a link to the plan information. We are currently working on the animation for the building, so check back with us next week, and it should be wrapped up.

–Click on the image to download additional content–

I think Derek did an outstanding job on this little home.  It provides the owners with a little get-away retreat, as well as a working office to write from.  It has a sleeping loft, kitchen, full bath, and an area to stretch out in.  There is not much more you can ask for.

Mark Wagner<>Gravitas

The Clearwater will be built in Lenore, Idaho, overlooking the Clearwater River.  At three levels, with 2,681 SF, it can accommodate a growing family, or the empty nester.  The view of the river from the rear is accentuated with a full height gable, and two, wide porches.  The upper level has a small loft area that will be used as an office.

The plan utilizes wide plank siding to take advantage of high R-value insulation, and a tight building envelope.  Hand stacked trusses on the wings, and parallel chord trusses over the central portion help to create a vaulted affect on the interior, while keeping costs under control.  Timber accents throughout the home help tie it all together.

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In our relentless pursuit for the best (relative) green (relative) options for specifications in our home designs I was tracking down more info on soy based spray foam for a home we are designing for the North End in Boise, Idaho. There are as many “best” ways to super insulate a house as there are builders. What follows is an informative article that I found in my search by John Wagner that was published in Residential Design & Build magazine. John is a regular contributor to many industry magazines and a national speaker. You can learn more about him on his site John Wagner.   Below is the article which does a good job of explaining the difference between open cell and closed cell and the applications for both.

By John Wagner

When I was a working contractor, I remember how daunting it was to walk into a large project, bare studs for walls, knowing that I had to work (with a crew of course) to stuff each bay with fiberglass batts. I remember thinking — like a boy wishing he could fly — if we could only liquefy the insulation and spray it in place the job would go much faster. It would also get the insulation into every nook and cranny and save me from using duct tape in an attempt to remove the itchy glass from my arms and neck.

That was in the 1970s, and little did I know that by the time I got out of the blue collar side of building, just such a thing would be invented in the form of spray foam. I mean, let’s face it, you couldn’t design a better dream product. The stuff flows on as a liquid, fills up every crack and what’s best, teams of guys in white jumpsuits apply it in one day’s time. Heaven.

It’s also very green. The problems with propellants have been largely worked out, and there now are water- and soy-based products as well as isocyanate-free, formaldehyde-free alternatives to suit the greenest customer. Once in place it doesn’t leak or off-gas harmful emissions, and all foams are good at reducing noise transfer and sound penetration. What’s not to like?

Here’s how you differentiate among the two different types of foam, and the attributes for each product category.

OC-SPF. Open-cell spray polyurethane foam cures in place, stays soft and is designed to slow convection (the transfer of heat through the movement of warm matter like air) by leaving irregular bubbles that fill with trapped, ambient air. Weighing in at 0.5 lb. per cu. ft. and scoring around R-3.5 per in., the foam tends to have an R-value close to captured, still air. Although it has less mass (and is therefore less expensive) OC-SPF isn’t a good vapor barrier, and it gets knocked for this.

CC-SPF. Closed-cell spray polyurethane foam cures in place and stays rigid. But unlike open-cell products, its bubbles aren’t irregular or open. The bubbles form by trapping “reaction gas,” which offers insulation properties. With the higher-density foam you get higher R-value around 7 per inch. CC-SPF weighs in at 2.0 lb. per cu. ft. and partially because of its greater mass, it costs more per R than open-cell foam. Unlike its open-cell cousin, CC-SPF is a good vapor barrier and is often code-approved as such. What’s more, CC-SPF can add to the sheer strength of a wall, and in recent tests when sprayed under a roof decking it can help defeat roof uplift (Google search University of Florida, Dr. Prevatt, foam).

By the way, the polyurethane foams you see in molding are of even higher density than CC-SPF, weighing 30 to 40 lb. per cu. ft.

Even after you compare cost and vapor barrier performance, note that some foams are inappropriate in certain applications. Open-cell foam should not be used below grade because it can absorb water. Since water is a poor insulator (relative to air), foam that is soaking wet has dramatically compromised thermal performance. You’ll also want to spec closed-cell foam in tight areas or around utilities where you can’t get the bulk and thickness required by an open-cell product to achieve the designed R-value.

I was in communication with John Wagner a couple months ago about an article he wrote that was published in Residential Design/Build Magazine on Foam Insulation.  I will get to that next week, but first lets talk about wood preservatives, something that comes up every time we design the deck. At Gravitas we have always discuss what is the most responsible way to specify the treatment of wood in decks and porches. Code says “rot resistant” and we take that to mean that you could use sustainably harvested rot resistant species of wood such as redwood or cedar. Unfortunately these species have a decreased structural capacity and thus you need more tightly spaced joists, and/or more girders to shorten the spans of the joists. This always pushes us in the search for the greenest wood treatment options. In the article below John Wagner has outlined some good options, at least the best of the worst so to speak. John, thanks for sharing your knowledge again.

Wood Treatment Basics

By John Wagner

We are seeing some real innovation with wood treatments these days; whether it’s wood for decking, siding, or part of the structural frame. At the root of this topic is the fact that, when left untreated or when unprotected, wood can rot. Even premium species like cedar and redwood—which are naturally decay- and rot-resistant—require treatment to extend their useful lives.

Today’s wood treatments range widely from chemical treatments to heat treatments (a.k.a. “thermally modified wood”). And if you are looking for the green angle here, the simple fact that wood treatments can dramatically extend the life of the wood is a very “green” attribute indeed—in a life cycle analysis, it lowers the environmental costs of re-harvesting (and re-treating, and re-shipping and re-installing) replacement wood products. However, each wood treatment method has its merits, and each one has features that can make it more or less green. Let’s take a closer look by first reviewing a brief history of wood treatment.

Chromated Copper Arsenate (CCA)
For a long time, Chromated Copper Arsenate, or “CCA” was the formula for treating lumber. For decades, it was common to see “green” CCA decks – the green was the color of the oxidized copper. And CCA-treated wood was also commonly used in most ground-contact situations. In the ‘90’s new alternatives to CCA were introduced. None took meaningful market share from CCA because none could match its performance and value. As the millennium approached, there was increased scrutiny regarding the perceived safety of CCA as reported by various “consumer advocate” reporters and environmental organizations. In 2003, treaters voluntarily stopped using CCA for residential applications and newer, more expensive formulations replaced CCA. One bright spot that emerged from the demise of CCA was that the pace of innovation in preservative development quickened.

Alkaline Copper (ACQ) & Copper Azole (CA-B)
The replacement wood preservative treatments were ACQ and CA-B. Let’s first look at ACQ.  ACQ is a treatment consisting of alkaline copper, a fungicide, and quaternary ammonia (sometimes called quat), which serves as an insecticide. On the other hand, CA-B is a treatment containing mostly copper and azole; the azole is a fungicide that appears in various chemical forms. If you step back and take notice, there are two consistent elements in these approaches to wood treatment. One, they all are aimed at stopping rot, decay, fungus, and insects from getting to the wood.  And two, they all overwhelmingly contain copper, a natural, harmless wood preservative. As wood treatments have evolved, some wood treaters (and the chemical companies that license their formulas to these wood treaters) have stayed with copper. But they have eliminated other chemicals in their wood preservative formulations.

Micronized Copper (MCQ)
Among the most positive result was the recent introduction of a new micronized copper wood preservative. Developed by Osmose, Inc., and marketed as ProWood Micro (MCQ Treated Wood), the new process bonds microscopic copper particles to the wood cells. Because of this there is no need for a solvent (which is still used in most other non-micronized formulations) . These attributes have earned the ProWood Micro formulation Environmentally Preferrable Product (EPP) status from Scientific Certification Systems, a leading third party certification firm. This is the first and only such preservative to earn this recognition. To earn EPP certification, a product must demonstrate reduced impact on human health and the environment when compared to other products that serve the same purpose as measured by guidelines published by the U.S. Environmental Protection Agency.

Non-metallic
There is another relatively new product out today that is offered by Arch Wood Protection. The treatment is Wolmanized L³ Outdoor wood. It contains no copper as part of the preservative and uses a proprietary non-metallic preservative.

Boric Acid
Yet another class of wood treatment is focused on boric acid, as well as its oxides and salts which are called borates. Boric acid is a very-effective wood preservative. Conveniently, it is toxic to insects, but it has low toxicity with humans. That said, the problem with boric acid has always been that it is water-soluble. That means it can be floated into wood with water-based pressure treatments or applied with surface applications. But the boric acid will eventually leach out of the wood. That leaching process is dramatically accelerated if the wood is exposed to the elements. All of this means that wood treated with borates isn’t generally good for ground contact, and in any application, it has to be re-treated repeatedly with borate applications to ensure that the wood is preserved. Now, because borates have gotten another look from consumers, due to the perceived toxicity of alternative wood treatments, borates have seen some innovative uses. One company floats borate deep into wood fiber by mixing it with glycol, a kind of alcohol. The glycol flashes off, leaving the borate behind, and until the borate leaches out, it is a good termiticide, insecticide, and wood preservative. But here too, the wood has to be re-treated regularly.

Thermally-Modified Wood (TMW)
Another kind of wood treatment that you see gaining wider acceptance is heat treatment. Wood that is treated with heat is generally referred to as thermally-modified wood or TMW. This treatment process contains no chemicals or additives at all.  Like its name says, the thermally-modified process uses high heat and steam to change the very nature of the wood. In fact, the thermal process removes the aspects of the wood that serve as food. With no insects, fungus, or mold attacking the wood, the thermally-modified process can prevent for rot and decay. Specifically, the process removes or de-natures the sugars in the wood, leaving behind aspects of the wood that cannot be digested by insects or eaten by fungus and mold. After the wood is thermally treated, it can be stained, sealed, joined, and glued like regular wood.

No matter what type of treated wood you seek, you should be aware of its code acceptance. Some treatments are not code compliant, even though they have been around for a number of years. To get code approval, preservative companies can either work with the American Wood Protection Association (AWPA) to have their treated wood listed in the AWPA Standards. Or the preservative company will work with the International Code Council (ICC) Evaluation Service to earn an Evaluation Service Report (ESR). Without the support of either an AWPA listing or an ESR, there is no guarantee that a local code will allow a product on the job where treated wood is required. So, check the fact sheet from the wood provider or the wood treater to see if the wood is approved for use.

A home we designed for a homeowner in Park City. The site was located in a equestrian development so the home was designed to fit in as if it were part of a larger barn complex. There is an indoor endless pool and a large guest suite over the garage. This home is within sight of the ski runs so of course there is a large ski prep area in the back of the garage to keep the skis in shape for the slopes.

Log Home Design For Park City, UtahLog Home Plan for Park City, Utah

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I just returned from a pleasant trip to the east coast to attend the Log & Timber Home Show in Chantilly, Virginia. We were invited to the show by Chad Clark of Handcrafted Log Homes and met a lot of great log and timber frame suppliers as well as individual clients. There was a lot of positive energy, and it seems that the worst is behind us economically.

The latest in the Gravitas Design Series: The Cache B

 The Cache B makes a cute little get away cabin or an efficient retirement home. This home has just the right amount of room in a compact design.  This is a modification of The Cache plan which didn’t have dormers or the upper bedroom, just an open loft but it did have a full daylight basement that added about 1200 SF. An example of how we work with clients through changes of existing plans to better suit their unique requremens and site conditions.  If you want to use this, or any of our plans free of copyright infringement, we have affordable and easy licensing options whether or not you use our full design services.

Many of you save out these floor plans for use with clients or they go in the “someday dream home” folder. Here is a link to our Gravitas Plan Book that we update about quarterly with the new “plan of the month” plans. Please honor copyright ownership and contact us about licensing and use if you move forward in design with another designer or if you want to discuss their use for marketing or on your website. This link is “live” so to get the most current plans you will want to download from the same link every 3-4 months.

The Cache B - Dovetail Log Home by Gravitas

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The latest in the Gravitas Design Series: The Santee

The Santee is a custom home we designed for a couple about to retire to the Owyhee Desert for some quiet and peaceful living. This home has a open floor plan with a Main Level Owner’s Suite. The Upper Level accomodates the guests and open area for a home office. Sunsets from the lookout will be unbeatable over the desert. This space will also be a fun hideout for the Grandkids. If you want to use this, or any of our plans free of copyright infringement, we have affordable and easy licensing options whether or not you use our full design services.

The Santee - Modern Home Plan by Gravitas

The Santee - Modern Home Plan by Gravitas

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The latest in the Gravitas Design Series: The Carson

The Carson is a hybrid log home that has a dovetail core with interior log walls and standard framed wings. The integration of multiple materials using the dovetail log, board & batten, and  shake shingle siding adds to the rustic charm of this home. This home has a formal Living Room off of a grand Entry and an informal Living Room near the Kitchen/Dining and Family Entry. The Owner’s Suite has a unique stepped storage hall that gives access to a private loft that would serve as a retreat or home office. The Upper Level features two bedrooms with built in beds in the dormers and full bath. This home would be easily adaptable to have more bedrooms on the Lower Level with an appropriately sloping site. If you want to use this, or any of our plans free of copyright infringement, we have affordable and easy licensing options whether or not you use our full design services.

The Carson Log Home Plan by Gravitas

The Carson Log Home Plan by Gravitas

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