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Top 10 Important Things to Know for SIPs

Dean Dalvit — Thu, 19 Jan 2012 21:00:49 +0000

With the growing popularity of SIP designed homes, it is important to know some critical details that are different than traditional stick frame design. Below is a list of what I have developed as important details to consider as early as the pre-design stage as well as tips during construction as well:

1.) The thickness of the SIP wall is a critical factor in determining your layout geometry. Most SIP manufacturers provide panels in both 2x4 and 2x6 varieties, however, bear in mind that those sizes predicate that the 2x4 or 2x6 is sandwiched between the panels. Therefore, your wall thickness to rough structural frame will be 4-1/2" and 6-1/2" respectively. Including the OSB skin is very important to the structure.

2.) The entire sip wall must be supported by the structure below. In frame construction, you typically run the studs to the outside face of the floor deck or foundation, then sheath beyond that. In SIP design, the OSB skin bust be supported and therefore will cause the layout to be shifted by about 1/2".

3.) SIPs panels must never be in direct contact with concrete. No untreated wood should ever come into direct contact with concrete because the caustic nature of the materials in concrete will cause rapid and premature decay in the wood fibers. SIPs panels are no different. In special circumstances, you can have a SIPs panel manufactured with treated skin.

4.) Do not add additional plates above the panel that are less than the full panel width of the SIP wall itself. This is tied to the structural implications in item 1 above, but the entire SIP wall (skin-to-skin) is the structural member, and therefore should be loaded continuously across the full thickness of the panel.

5.) Don't design unsupported horizontal joints in the wall. This is also true with stud framing. You should not introduce hinge points within walls of any height. Instead, in stud framing, you would balloon frame the wall, or in SIPs detailing, you would run the SIP wall full height. Special care must be taken because there are practical limits to the sizes of SIPs panels. The manufacturer should make special recommendations for cases where the walls in the design exceed these limits.

6.) Plan for only continuous 2x's or i-beams for SIP spline connections. Using spliced lumber for these splines will significantly reduce the structural integrity of the wall system.

7.) Provide access holes in the sill plate to allow for electrical wire chase access. Often forgotten, these access points are critical for your electrician. The SIP wall design specific you your building will have more information about the sizes and locations of wiring chases and a little preplanning goes a long way down the road. As a result, it is always a good idea to develop the electrical plans before the SIP wall manufacturing.

8.) Avoid plumbing runs in the SIP wall. This means supply lines, vent stacks etc.. There are special details for these conditions that allow this to happen without impacting the thermal or structural performance, and they must be addressed on a case-by-case basis. Again, planning in the design phase helps to circumvent potential conflicts during construction.

9.) Never overcut the skins for field cut openings and don't cut the skins for electrical chases. These cuts impact the structural ability of the wall to carry the design loads. Wherever possible, have all openings and chases provided in the SIP core by the factory.

10.) Handle SIPs with care!! Protect them on the jobsite from the weather. Provide adequate supprt when storing them flat to avoid deflection. Never lift them by the top skin only. Don't drop them on their corners as they will easily damage.

SIPs offer a great option for many building types and the more you know about how to design with them as well as what to look out for during construction will help to make the design and construction process much more seamless (not to mention painless).

I've also written a post comparing and contrasting Insulated Concrete Forms vs SIPs.

Originally posted 2008-12-15 10:35:09.

ICF vs. SIP…The Debate Continues

The Easiest Place to Find Fire Rated Assemblies is the Gypsum Association Manual

Sean O'Hara — Thu, 19 Jan 2012 21:00:47 +0000

After several projects of fighting with the UL Manual (Underwriters Laboratories) and the International Building Code I discovered that there is a much easier visual way to find fire rated assemblies.

I use the Gypsum Association Fire Resistance Design Manual. Everything is visual and it is generally acceptable to building departments. It contains the most used gypsum fire rated designs and it also contains information on sound ratings for most of the assemblies. Plus it is a free download which the others are not.

The main note is that you need to read the ratings carefully where some of them are proprietary and designed for one manufacturer's gypsum product. In many cases there will be another number for the same assembly from a different manufacturer or a generic product. You can list them as alternates.

In addition you should read the general notes at the front, they tell you about ways that you can modify the assemblies and still maintain something acceptable for the rating. This is important for adding insulation, adding other layers to the assembly or changing the size of framing members.

Finally, if you need a rating that doesn't involve gypsum board then your best bet is probably Chapter 7 of the IBC. That's where I go for concrete and other assembly materials.

Originally posted 2008-10-27 22:27:18.

Types and Design of Wood Trusses

Jim Houlette — Thu, 19 Jan 2012 21:00:42 +0000

Here are some great resources about the different types of wood trusses and how they are designed. If you have any questions about roof or floor trusses please let us know.

Alpine Engineered Products – Builder’s Guide

SBCA – Structural Building Components Association – Truss Configurations

Originally posted 2009-08-16 00:01:36.

Effect of Overdriven Fasteners on Shear Wall Capacity

Jim Houlette — Thu, 19 Jan 2012 21:00:34 +0000

APA Technical Topics - Form No. TT-012A

With the use of nail guns set too high and the speed of construction, many nails are over driven. Most building officials don't seem to notice or comment on this error. But, if they do you might have a lot of work ahead of you to add correctly placed nails or staples when the nailing is too close for additional nails. Before you start adding nails or staples consider that additional nails may cause more harm than good. If the specified nailing is at 4"o.c. or less, adding more nails can damage the sheathing and studs, reducing the shear wall capacity more than if the additional fasteners were not used. APA addressed this problem and issued a simple breakdown on when you need additional fasteners or not.

Please visit www.apawood.org for additional information and other useful technical bulletins.

Originally posted 2009-08-08 22:27:19.

Architecture School on Sundance

Sean O'Hara — Thu, 19 Jan 2012 21:00:33 +0000

The Sundance Channel has a show called Architecture School. It follows the work of a studio at Tulane focused on designing and building a house in some of the more difficult neighborhoods in New Orleans.

Chris and Elicia and I have been watching it and I think it is well done. The project involves real clients and real construction so it is a more interesting show that it might be if it focused more on the traditional studio project. Of course my perspective favors the architecture school experience.

Originally posted 2008-09-12 20:35:47.

Caribbean School of Architecture

Consider Closed Cell Spray Foam for your Thermal Envelope

Dean Dalvit — Thu, 19 Jan 2012 21:00:32 +0000

Our projects range across commercial and residential building types and climates from cold and dry high alpine environments above 10,000 feet to hot and humid sites below 1,000 feet. One very important element to consider in every design is the thermal envelope. This is composed of the floors, walls and roofs, and all of the insulation therein designed to maintain consistent comfort within the building regardless of outdoor temperatures and large swings in those temperatures.

Spray Foam Installation

Advances in spray foam technology is making closed cell foam more affordable for projects of all kinds, and the advantages over traditional batt and cellulose insulation methods are staggering.

Insulation Comparison Chart

As you can see from the above comparison chart, not only does closed cell spray foam significantly outperform other methods in R-value, but it also contributes substantially to moisture control, reductions in air infiltration and even structural frame rigidity. Not shown in the chart are also the superior acoustic advantages to closed cell foam in the walls.

Typical solid foam installation assemblies are below:

Walls: 2×6 with 3″ of Closed Cell Foam = Approx. R21
Walls: 2×6 with 5-1/2″ of Closed Cell Foam = Approx. R38.5
Walls: 2×4 with 3″ of Closed Cell Foam = Efficiency Equiv. R21
Walls: 2×4 with 3-1/2″ of Closed Cell Foam = Approx. R24
Ceilings: 7″ Closed Cell Foam = Approx. R47.5
Ceilings: 10″ Closed Cell Foam = Approx. R68

All of this performance does come at a premium, however, and one way to cut down on installation costs, while also maintaining a sound thermal envelope is the "Flash and Batt" method. This method combines the advantages of closed cell foam with a thinner layer, and making up the balance in the wall or ceiling with traditional, lower cost batt insulation.

Typical "Flash and Batt" assemblies are as follows:

Walls: 2×6 with 1″ of Closed Cell Foam and R15 Batt = Approx. R22
Walls: 2×6 with 2″ of Closed Cell Foam and R15 Batt = Approx. R28.5
Ceilings: 1″ Closed Cell Foam and R30 Batt (for cathedral roofs)= Approx. R37
Ceilings: 1″ Closed Cell Foam and R38 Batt (N/A cathedral roofs)= Approx. R45
Ceilings: 2″ Closed Cell Foam and R38 Batt (N/A cathedral roofs)= Approx. R51.5
Ceilings: 3″ Closed Cell Foam and R38 Batt (N/A cathedral roofs)= Approx. R58.5

Originally posted 2011-01-01 00:01:37.

The Front Porch and What Makes it Functional?

John Olson — Thu, 19 Jan 2012 21:00:21 +0000

Front Porch: “an exterior appendage to a building, forming a covered approach or vestibule to a doorway.” (Definition from Dictionary.com)
Front porches are often installed on homes, but many are not used. Some porches are simply appendages of a home to give the traditional appearance to a home, but virtually unusable if a homeowner had the desire to use it. I have lived in multiple homes in my life and have always had the desire to use my porch. However every home I have lived in, aside from my current townhome, did not have a porch that was functional. I would like to discuss what components of a porch are key to make it functional.

Overhead Structure or Roof:
A porch without a roof is not considered a porch. The roof defines the porch and gives it the “covered approach” in the definition. Regardless of the size of the porch I have had, with every porch I had the desire to be on it when it was raining or when a storm was passing through. I do not think I am in the minority because in all neighborhoods I have lived, I would see others on the porch during storms. The roof provides the shelter and the depth of the shelter is critical in a rain storm. If a porch is too shallow, the rain can easily make contact with you.

The porches on these townhomes appear nice along the sidewalk, but the depth is limiting to the function.

Porch Depth:
To this day, I have not lived in a home with enough depth to the porch to utilize its full potential. I feel that a minimum of 6-feet is necessary for optimum use of a porch. I currently have a porch in a neo-traditional neighborhood and the depth of it is generous in comparison with CSD (conventional suburban developments) porches, but still inadequate for optimum use. The depth of my current porch is about 5-feet, on which I have a porch swing turned perpendicular to the street (though towards Pikes Peak). With an extra foot, I calculated that I could have comfortably positioned chairs and a small table between them and still leave room for leg room and passage by. With three extra feet, I could have turned the porch swing toward the street without risking rocking into the house.

Porch is sited for privacy and interaction.

Porch Height:
Another important consideration of the porch is the height of the foundation and its proximity to the sidewalk. Height is important for the feeling of privacy and use of the porch. Aside from ADA exceptions, a porch should be no less than 18” above the sidewalk height. Steve Mouzon, of the New Urban Guild, put together a great chart which can be seen in his book, A Living Tradition: Architecture of the Bahamas and also New Urbanism: Best Practices Guide which illustrates a ratio of height to setback from the sidewalk to allow for optimum privacy, yet interaction with passersby.

Adaptability and Flexibility:
A porch should not be considered any differently than anything designed. It should be adaptable and flexible for several uses. Some may wish to have their porch be purely decorative, with nice yet uncomfortable furniture. Some may desire a place to rest and read a book. Others may desire a place to drink their morning coffee or evening glass of wine. My porch is used most often for kids playing and sidewalk chalk but the point is that it must be flexible for all of these uses. In a home, we must adapt and change the functions of a lot of the rooms, bedrooms to offices, to playrooms, etc. The same is true for the porch, after all with the frequency of changing residences that our country has grown accustomed to, we can not anticipate remaining in the same house our entire lives like our ancestors once did.

The details of this porch provide the authenticity of a porch in South Main.

Architectural Details and Vernacular:
I have listed the details and vernacular last because they have the least to do with the function of the porch (at least with today’s technology), yet they have the most to do with the appearance of the porch. Have you ever looked at a house and thought “Something is just not right with it?” As a non-architect, I felt this way about houses and structures for a long time and could not peg what the problem was. This was true until I discovered new urbanism and its many facets including traditional architectural detail. The reason that we (as non-architects) have this sensation is because we have seen enough beautiful architecture to know what is right and what is not.
I am always reminded of a professor of mine at Kansas State who explained to us that when designing a raised deck, or similar raised structure, that we could structurally support a large mass with very little. He was referencing utilizing very small lumber and very little lumber for support. However, if we did use something so small, it would not appear or feel safe (modern architecture or modernism is notorious for this factor). Therefore many will not use it. Much of today’s home building provides a good illustration of this. Homes are built with the minimum amount of supports or columns that take the authenticity away. On a porch as an example, columns are spaced to a maximum. This maximum is not equal to the maximum that homes used to have because we did not have the technology. For a home with a porch frontage of 30-feet, historically we may have had six columns, whereas today there are typically no greater than three. There are many other details not mentioned that should be carefully analyzed when designing your porch.

Originally posted 2010-04-29 02:50:42.

Why Hire an Architect When a Contractor Offers to Design-Build

Sean O'Hara — Thu, 19 Jan 2012 21:00:15 +0000

Design-build is a common delivery method in construction and a popular buzz word in the industry. What it generally means is that you hire a single person or company who both designs your project and builds your project. Design-build can be great and it can be a real mistake. What is important is to know who the players are behind the design-build label.

Just to admit bias to new readers, EVstudio is an architecture and engineering company, we participate in many projects titled "design-build".

Design-build can be a great setup where you have a company that has experts and licensed professionals working on both the architecture and construction portions of the project. They can typically deliver a project on budget and they may be able to reduce your upfront design fees because they bury them in your total project cost.

Unfortunately, what often happens is that the design-build team is an outgrowth of only one profession. You frequently have a general contractor who has decided that they can do the design work as well. Suddenly you are hiring someone to design your home who is only marginally qualified and yet you are paying enough for the service to hire a full time architect. With this approach you are also hiring someone to design the project who is often most concerned about the simplest details and is likely to give you reasons that you can't have something more complex.

What I would advise all clients entering a design-build setup to do is make sure that you know who is actually doing the designing on the project. You should be meeting with the architect directly and be pleased with the design work that you are receiving. When we participate in design-build we meet with clients directly for the design and the contractor meets directly for the build. They only pay one bill but it is distributed according to the work involved. The architect is your advocate and more able to provide solutions based on years of full time design experience rather than excuses.

Another solution that works well for the client is hiring an architect and a contractor at the same time and working as a team throughout the project. We do this with many of our favorite contractors and it is a rewarding way to bring experienced professionals and still give the client an integrated project. While it is not truly design-build it offers many of the advantages.

There are a large number of project delivery methods in architecture and construction, please ask questions or give us a call.

Originally posted 2010-01-20 00:01:06.

Agreements, Proposals and Contracts Used by Architects, Engineers and Contractors

Sean O'Hara — Thu, 19 Jan 2012 21:00:12 +0000

There are no shortage of different forms for agreements, proposals and contracts in the design and construction industry.

The base contracts of the design and construction industry are the contracts produced by the American Institute of Architects. These contracts have been in place for more than 120 years and they are the standard. They cover all of the relationships in the process not just those involving the Architect, a common example is the Owner/Contractor agreements.

The primary reasons for choosing an AIA contract is that the contracts are generally fair and balanced and they have been through legal proceedings enough that their definitions are well established. They aren't very open for interpretation. The contract document software also has a feature that tracks changes so if you know the usual contract it is very easy to understand the changes. In addition the various agreements all tie together create a comprehensive set. What this means is that the obligations in the Owner/Architect agreement match up with the obligations in the Owner/Contractor agreement and the Architect/Consultant agreements.

The primary reasons that people choose to avoid AIA contracts tend to be complexity of the contract, scope that is very unique and attempts to produce contracts that are tilted towards one party.

At EVstudio we emply a variety of contracts. Where owners have their own contracts we will review them to verify that they are workable. When we propose on most smaller residential and commercial work we have a 4-5 page agreement that is much less intimidating than the 20+ pages in an AIA contract. We also enter into a number of different AIA contracts depending on scope and coordination with other agreements. We also suggest contract forms for owners to use with other parties. We've put together enough to guide you through your choices.

Originally posted 2009-02-16 23:16:22.

Who Does Truss Drawings?

Sean O'Hara — Thu, 19 Jan 2012 21:00:09 +0000

Most residential projects and wood framed commercial projects utilize roof trusses. A roof truss is generally cheaper and less time consuming than a roof framed with rafters. It has these advantages because it is created from smaller pieces of lumber and it is fabricated in a shop and then only has to be set up in the field.

When we design a house we do a truss layout where we show where we anticipate each truss going and give information on what the shape of the top and bottom of the truss is, what the plate heights are and what the loading criteria is for the trusses. We also call out if the truss is a flat bottom truss, a scissor truss or an attic truss. Then the contractor gives our layout to their truss supplier. The truss supplier does the actual design of each individual truss based on our roof design. The reason for this is that each truss supplier may have a slightly different preference for how they construct the truss and they use their own proprietary software for the design. When the truss drawings are complete the contractor sends them to the Architect for review. Usually the drawings are right on when we review them.

The wrinkle that we are starting to see more of is municipalities requiring the submittal of truss drawings to their building department prior to the issue of the building permit. This can cost some time because typically the truss supplier doesn't do their design until after they are selected as the winning bid. In other words the truss supplier has to be selected prior to the completion of architectural drawings, otherwise expect another week or two added to the schedule. Oftentimes in a bid situation the contractor hasn't been selected at this point.

I've recently run into this new policy in Jefferson County and Commerce City, Colorado. I'd urge municipalities to look at this policy and consider going back to not requiring truss drawings to be submitted as part of the permitting process.

Originally posted 2008-10-05 16:57:45.