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:
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 vs. open-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 vs. closed-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 insulations are used in building applications
and the choice can depend on many factors. Some spray on insulations are 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 Spaces
Spray Foam Insulation in Attics (Vented Spaces) Traditional method
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.
