Limiting air infiltration is one the most important aspects of creating an energy efficient house. Leaky houses use more energy to re-heat or cool the lost air. Air infiltration is often measured as Air Changes per Hour (ACH) SIP Homes are extremely tight.
Proper sealing of your enclosure system is very important. Expanding foam is meant to eliminate Air Infiltration and prevent Moisture Migration. Air Infiltration refers to outside cold air seeping into your house. Moisture Migration refers to water in gas form escaping to the outside.
Foard Panel uses three methods for applying foam sealant: “Drill and Fill”, “Gapping” and “Foam-As-You-Go”. Each method is meant to achieve the best seal for a particular situation. What we, and most other panel installers like about these methods is that the panels are put up “dry” with foaming done as a separate step. This makes the process cleaner, quicker, and allows for undivided attention to be given to this important job. Below is a list of eight key situations that require foam sealing and the appropriate method to use.
|1||Where wall panels meet the deck||foam-as-you-go|
|2||Spline and butt joints on wall and roof panels||drill and fill|
|3||Panel to panel connections @ corners||gap|
|4||At intersection of wall and roof along eaves and rakes||gap|
|5||At roof ridge hips and valleys||gap or foam-as-you-go|
|6||Behind rough opening framing||foam-as-you-go|
|7||After window/door installation between jamb and r.o. blocking*||gap|
|8||At any penetrations such as vent stacks**||gap|
*When foaming around installed windows/doors, use low expanding urethane foam – not the foam supplied by Foard Panel. It is possible to “blow-out” the jambs with the triple expanding foam Foard uses.
** Standard chimney openings that require clearance should not be foamed.
Foam As You Go
Foam As You Go is used behind blocking at window and door openings and corner blocking. Apply foam to the panel or the blocking before installing the blocking at the rough openings. We also use this term to describe the application of a bead of mastic along sill plates or top plates as directed. The use of foam or mastic is labeled in our details.
Gapping allows you to seal the most critical joints in the house. In order to completely seal these joints, we intentionally leave a gap between panels large enough to get a spray foam nozzle into. When filling a Foam Gap, be sure to get the spray foam deep into the space so that you’re sealing on the “warm side” of the insulation. Fill the gap entirely as you work your way toward the outside.
Drill and Fill
Drill and Fill is performed from the exterior of the house. All interior splines must be fastened before foaming begins. At the panel joint, drill holes approximately 10”o.c. for walls, 6”o.c. for roof, to the depth of the spray foam channel and inject foam using two to four second blasts. Push the nozzle as far into the joint as you can, ideally until contacting the back of the interior spline. Begin foaming there and slowly pull out, pausing at the spray foam channel to allow foam to travel in the channel. Blast duration varies depending on temperature and humidity and how much pressure is left in the can. Enough foam must be injected so that ping-pong sized balls of foam protrude from the drilled holes after the foam has cured. The balls can be easily scraped off after the foam has cured. Do not disturb the foam until it has completely cured, generally 24 hours.
Start foaming from the bottom and work your way up. This will keep the uncured foam from falling on you while you work. Fasten exterior splines as you go instead of going over the same area later. First timers should experiment with scrap material to get a feel for the proper amount of foam needed. Cut a cross-section out of practice pieces to evaluate the technique.