There are a variety of different methods for framing, insulating and finishing interior walls in homes. Normally in conventional stick frame construction these trades are separated and the work is accomplished by different trades at different times in the project. In SIP construction these functions are merged in one step where exterior sheathing and interior drywall sandwiches an internal insulation to speed construction in a variety of building types.
Initially SIPs were designed for timber frame construction. In timber frame construction the skeletal frame of the home is built first and then the walls are fitted to the frame. With SIP construction large sections of walls such as for vaulted ceilings can be installed in one step and then anchored to the frame. It is not uncommon to install all the exterior walls, including the roof, of a Timber Frame home with SIPS in one or two days. Final finishing and exterior siding is still required but normally for an average 2000sqft home a few weeks of work can turn into a day or two at most.
SIPs Construction Materials
SIP Panels are normally constructed of OSB wood exteriors, Polystyrene Insulation for a core and Drywall as the interior surface however they can also be made with Metal surfaces on either or both sides of the panel and OSB on both sides of the panel when drywall is not desired. Concrete is also available but in the industry OSB makes up about 80% of installed panels with Metal making up about 15% and the remaining are specialized materials.
Interior to the SIP panel there is stud lumber that frames out openings for windows and doors and joints between panels are often accomplished with a spline and the panel is attached to the framing with long hardened screws.
SIPs can be but are normally not used for floors. This is because the OSB material used in the SIP can become degraded due to moisture. Moisture problems can be due to rain during the install process or ongoing problems with water due to moisture below the building in a home with a crawlspace or moisture from above due to leaks from plumbing or the exterior of the home.
The SIPs And The Home Design Process
Your home must be designed to work with the SIPs Process however most frames can be modified to meet the needs for SIPs use. CAD designs are used to guide the layout of the panels and then CNC machines are used for cutouts. It is also important to layout your electrical and other needs for voids in the material prior to construction.
Panels can be manufactured in common lengths of 8 feet x 24 feet but a variety of shapes and sizes can be made and they are not constrained by normal construction grade OSB sizes. This allows architects to design rooms with a much more freedom than conventional construction allows.
There are some things that you should account for such as the fire resistance of the materials Urethane Foams are good at resisting fires. Other materials will pass standards. You should understand how these structures resist fires as a component and not as the individual material. Always look at the actual fire rating tests of the SIPs Panel.
Thickness of the panels are also a factor in building including insulation factors. Polyurethane is sprayed and expanded in place within the panel and can only expand so far. Other materials can be laminated but this will require more gluing and other panel buildup requirements. If you need panels that are thicker you should understand how the panel is built and what your limitations are before completing your design stage.
All of your door and window openings must be completed before you order your SIPs. Although you can make modifications to SIPs in the field you really want to limit field modification to a minimum. The only SIPs panels that are not easily modifiable in the field are ones with a cement surface.
SIPS are not a finished surface material and must be protected in all environments. The exception is metal which is used in panels for refrigeration.
Like building with Trusses or Glue Laminated Materials in our designs it is important to know a lot about the materials used and their limitations. This means that a professional designer must be used during the planing stage. You might want to have your own designs reviewed by a Structural Engineer and many manufacturers do offer this service as a double check of plans that are submitted for ordering.
In future how tos we will look deeper into the design stage and installing the panels.