Interior Spray Foam
Spray foam insulation, for buildings, eliminates drafts and makes a structure highly energy efficient which makes it more comfortable to be in all year. This type of spray on insulation is considered to be the best, home, wall insulation or attic insulation by far.
The first thing you need to know about spray foam insulation, or commonly called wall foam, is there are two main types:
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Open-cell and Closed-cell
When it comes time to actually put the spray on insulation, like spray foam, in your home or commercial building structure, you must know if you are buying 0.5 lb./cu. ft. (open cell) or 2.0 lb./cu. ft. (closed cell). This makes a big difference in cost and performance. The lb./cu. ft. refers to density. The less dense the spray foam insulation is, the softer it makes it. This affects R-value and insulation performance.
Open-cell spray foam insulation is where tiny cells of the spray foam are open. These half open cells have air in them instead of trapped gas. This makes the spray foam insulation weaker or softer feeling than closed-cell foam. Open cell spray foam insulation typically weighs in at 0.4 to 0.5 lb./cu. ft.
Closed-cell spray foam insulation is formed with small and tiny cells of the spray foam that are closed. They are filled with a gas that helps the spray foam insulation rise and expand. This forms a better insulator; about twice that of open cell. Close cell spray foam insulation densities are greater which means they are heavier and resistant to puncture. Closed cell spray foam insulation densities range from 1.7 lb./cu. ft. to 2.0 lb./cu. ft. This is commonly used for wall insulation in homes and buildings. Roofing spray foam applications typically use a 2.8 to 3.0+ lb./cu. ft. to support traffic and loads better. The higher the density of the spray foam, the heavier or stronger it becomes.
The advantages of closed-cell spray foam insulation:
- Greater compressive strength (denser)
- Higher R-value
- Air barrier with less thickness applied
- Vapor retarder at 2″ thick
The advantages of open-cell spray foam insulation:
- Requires less material and therefore less expensive
What open cell and close cell spray foam insulation have in common:
- Both can be an air barrier
The choice of spray on insulation can also be based on applications and performance requirements, such as strength, vapor control, available space, etc… Example: Open-cell spray foam insulation has an R-value around 3.5 per inch, typically, and close cell spray on insulation has an R-value of around 7 per inch. If you have a 2 x 4 wall, you can only get R-12 with open cell spray foam, but you can achieve an R-21 with closed-cell spray foam.
Both types of spray on insulation are used in building applications and the choice can depend on many factors. Some spray on insulation is not to be used in certain applications. For example, you wouldn’t use open-cell spray foam insulation in basements or below grade where spray on insulation could absorb water. This would make its thermal performance drop and become zero; because water is a poor insulator.
Spray foam insulation improves the building envelope
The building envelope contains several construction systems, materials and design components that control the temperature, movement of air, and moisture both into and out of the building. A building’s insulation, air barrier and vapor barrier all need to work together to achieve a stable environment.
Build it Tight, Ventilate Right.
Ventilating the attic and crawl spaces has been the requirement of a traditional code method. Ventilation of these spaces was required because standard materials and building design were not capable of addressing radiant heat transfer, condensation, and the results of “stack-effect issues.” Therefore, the answer to address heat transfer, the formation of moisture from condensation and air infiltration, was to ventilate these attics and crawl spaces.
A problem with ventilating in these spaces is that air brings moisture, pollution and other adverse problems. Also, vents allow places where insects and rodents can enter, and conditioned air can escape from the living space.
Most of the time, our heating/cooling utility ducts are located in the attic and/or crawl spaces. The temperature of attic and crawl spaces make ducts lose up to 10% or more of the hot or cold air flowing through them, due to radiant transfer. Worse yet, moisture and mold can also form within these ducts, due to certain temperatures. This can cause adverse health effects to those who reside inside the buildings.
Traditional attic ventilation was used during the hot summer months, heat from the sun builds on the roof and radiates into the attic space. Temperatures of 130 to 150 degrees, or more, can easily be seen. These extreme temperatures can cause condensation and the potential for mold. Air conditioning systems will also need to work harder, which consumes more energy.
Most builders and design professionals are not familiar with modern materials and progressive building science techniques that can virtually eliminate all of these problems that force the traditional, less effective requirement for ventilation in these building spaces. Builders and design professionals will also make the argument that your home needs to breathe. Well, they are absolutely correct. But, why rely on cracks, gaps and holes in your building for passive ventilation, when you can build your home tight, healthy and energy efficient, and let the mechanical ventilation systems due the job properly.
Spray foam insulation can still provide benefits far greater than traditional materials, such as fiberglass and cellulose, regardless of whether you decide to ventilate these spaces or not. By using spray foam insulation you can increase your home’s energy performance, structural integrity and air quality.
Spray foam insulation for wall insulation can strengthen your home or building
The walls in your home are the main structural component of the building. In wood frame construction, the weight of the roof, shingles, standing water, and snow add weight that makes downward forces on the walls called compressive force. Strong winds and gusts also impose lateral forces onto your buildings walls. These forces can distort walls which is called “shearing force”. However, when walls are built with minimum standards, movement can cause cracks and other structural problems.
Closed cell spray foam for wall insulation has a higher density, adheres to studs and exterior sheathing, which strengthens both. This added strength makes wall movement less; due to winds and other forces. This makes the walls “racking events” strong enough to meet codes for hurricanes or other strong winds. Spray foam insulation for wall insulation adds structural strength to walls when filled. This can add 75% to 200% racking strength according to NAHB Research; demonstrated with OSB, plywood, light gauge metal, vinyl siding or gypsum board.
Spray foam insulation for attic or vented spaces
Today attics are vented through gable, soffit, and ridge vents in the roof. Using spray on insulation in attics with design principles from architect or builders using traditional vented attics insulation. Here Insulation is laid on attic floor to insulate the ceiling from heat or cold. In spray on insulation, like spray foam insulation, we simply replace traditional fiberglass batts, or cellulose, with spray foam. This vented system is the most common in the US, but may not be the most effective. A vented attic will become approximately 130-degrees in the summer. This makes air-conditioning have to work harder and, also can create moisture and mold problems. Spray foam insulation creates a thermal barrier between the attic and the temperature controlled living or working spaces below.