Building Science

Superior Continuous Insulation Performance of Bautex Wall Systems

Wrapping a building’s envelope with a con­tin­u­ous layer of insu­la­tion (CI) saves money and energy. It also increases the effective R‑value of the structure, elim­i­nates con­den­sa­tion, and creates a com­fort­able space for the building’s occupants. Con­tin­u­ous insu­la­tion is required by the American Society of Heating, Refrig­er­at­ing and Air-Con­di­tion­ing Engineers (ASHRAE 90.1) and the Inter­na­tion­al Energy Con­ser­va­tion Code (2015 IECC). Also, under the 2015 IECC, Section C103.2.1, a build­ing’s thermal envelope must be rep­re­sent­ed in the con­struc­tion drawings. The building envelope com­po­nents must meet the minimum thermal require­ments of envelopes for different climates as defined by ASHRAE.

Five Ways to Continuous Insulation

There are several methods of applying con­tin­u­ous insulation.

  1. Expanded poly­styrene (EPS) rigid foam insulation
  2. Extruded poly­styrene (XPS) rigid foam insulation
  3. Poly­iso­cya­nu­rate (ISO) rigid foam insulation
  4. Insulated concrete forms (ICF)
  5. Insulated concrete blocks (ICB)

These methods are all designed to seal a build­ing’s envelope and prevent the flow of heat and energy through the wall assembly. Ulti­mate­ly these methods should save money, reduce energy con­sump­tion, and make buildings more com­fort­able for occupants. When selecting a method of CI, builders and designers should evaluate the CI’s thermal per­for­mance, fire, ultra­vi­o­let (UV) and moisture resis­tance, the ver­sa­til­i­ty of use, and the cost. Regard­less of the method of CI instal­la­tion, the result should create a com­fort­able, healthy, and energy efficient structure.

EPS, XPS, and ISO Rigid Foam Continuous Insulation

Appli­ca­tion of rigid foam insu­la­tion to walls, roofs, and foun­da­tions can reduce thermal bridging, raise the R‑value, and reduce air leaks. Tightly fitted wall cavities and properly taped joints between the sheets and boards are essential to pre­vent­ing air flow problems within rigid foam insu­la­tion. Another potential problem is that sunlight and UV rays can damage rigid foam. The most common types of rigid foam insu­la­tion used for CI are EPS, XPS, and ISO. All provide CI but vary on R‑value per inch, com­pres­sive strength, per­me­abil­i­ty to water vapor, and cost.

Expanded Poly­styrene (EPS) Rigid Foam Insu­la­tion (beadboard)

  • EPS provides an R‑value of 3.6 to 4.2 per inch of thickness
  • EPS is fragile and therefore rarely used for wall sheathing
  • EPS is semi-permeable with a permeance (water vapor trans­mis­sion) of 2.0 to 5.8 perm). It is too permeable for below-grade; however, applying high-density EPS below-grade is acceptable
  • The air bubbles inside EPS prevent heat transfer and may collect moisture, which makes it ineffective.
  • EPS is the least costly of the rigid foam insulations

Extruded Poly­styrene (XPS) Rigid Foam Insulation

  • XPS provides an R‑value of 5 per inch of thickness
  • XPS a semi-imper­me­able. One inch of XPS has a permeance of 1.1 perm. Two inches of XPS has a permeance of 0.55 perm
  • XPS has high com­pres­sive strength and water resis­tance and is mainly used in walls and below grade
  • The cost of XPS is between EPS and ISO
  • XPS uses HCFCs in its pro­duc­tion, which depletes the ozone layer

Poly­iso­cya­nu­rate (ISO) Rigid Foam Insulation

  • Uti­liza­tion of ISO is mostly on roof assemblies
  • At warm tem­per­a­tures, ISO has higher insu­lat­ing values (R‑6 to R‑6.5 per inch) than XPS or EPS; however, when tem­per­a­tures drop, the per­for­mance of ISO worsens
  • ISO’s R‑value starts at R‑7 per inch of thickness but decreases to R‑6.5 over time as the thermal-enhancing blowing agents used to make ISOs diffuse out of the material
  • ISO is the most expensive of the rigid foam insulation
  • Because ISO absorbs water, it should not be used under slabs or on the exterior of a foun­da­tion wall

Insulated Concrete Forms (ICF) Continuous Insulation

Insu­lat­ing concrete forms (ICF) are hollow panels or blocks made of expanded poly­styrene insu­la­tion (EPS) or other insu­lat­ing foam. Insu­lat­ing concrete forms are stacked to form the shape of the walls of a building. Steel rebar rein­forces the hollow centers which are filled with rein­forced concrete to create a layer of con­tin­u­ous insu­la­tion; sub­stan­tial­ly elim­i­nat­ing thermal bridging through the wall.

  • ICF walls are energy efficient with whole wall R‑values of 20
  • ICF buildings are com­fort­able, quiet and pest proof
  • ICF walls contain no organic materials and won’t support the growth of mold, mildew and other poten­tial­ly harmful microorganisms
  • ICF concrete walls can withstand con­tin­u­ous exposure to intense flames and flying debris with wind speeds of up to 250 mph
  • The dis­ad­van­tage of ICF is the walls can be thick, which reduces the interior space. The structure plus interior finish and exterior cladding can be 14 inches thick
  • The extra weight of ICF adds cost to the foun­da­tion design and expenses for engi­neer­ing and materials

Bautex Insulated Concrete Blocks (ICB)

Bautex Block Wall Systems™ are insulated concrete blocks that meet and surpass rec­om­men­da­tions for best practices for con­tin­u­ous insu­la­tion in exterior walls. The Bautex Block is a light­weight (45 pounds), stay-in-place concrete form that measures 16 inches by 32 inches on the face and 10 inches through the wall. Com­po­nents of the Bautex Block include custom engi­neered expanded poly­styrene (EPS), region­al­ly sourced Portland cement and region­al­ly sourced recycled cemen­ti­tious material. Com­mer­cial and res­i­den­tial buildings can use Bautex Blocks.

  • The Bautex Block Wall System provides a con­tin­u­ous insu­la­tion R‑value of 14; far exceeding 2015 IECC recommendations.The Blocks stop thermal bridging and create an insulated and energy efficient building envelope that is compliant with the latest building codes
  • The Bautex Air and Moisture Barrier limits thermal con­vec­tion and thermal radiation by pre­vent­ing air, moisture and ultra­vi­o­let infil­tra­tion to the interior of the structure
  • The unfin­ished Bautex Wall System has an ASTM E119 fire rating of four hours, and ASTM E84 values for flame speed of zero and smoke devel­op­ment of twenty. Since the Blocks meet the ASTM E84 and NFPA 286 standards, they meet the NFPA 101 code
  • The Bautex Wall System is easy to install, noise reducing and storm-resistant
  • Bautex Blocks are lighter than both concrete block (CMU) and ICF. An 8‑inch concrete block (CMU) wall weighs roughly 50 percent more than the Bautex Wall System. A poured tra­di­tion­al ICF wall weighs about 100 percent more than the Bautex Wall Systems
  • Bautex Wall System does not move during the pour; unlike ICF that requires extensive and expensive bracing systems

The con­tin­u­ous insu­la­tion design of a building should stop the flow of heat, energy, pollution, noise, and moisture through the wall assembly. The method used must take into account the CI’s thermal per­for­mance, fire, UV and moisture resis­tance, along with the type of con­struc­tion, climate zone, and the wind loads. Regard­less of the method of CI instal­la­tion, the result should create a com­fort­able, healthy, and energy efficient structure. For more infor­ma­tion on con­tin­u­ous insu­la­tion, visit Bautex Systems.

The effective R‑value includes all the materials used in its con­struc­tion: the drywall, studs, fiber­glass batts, plywood or OSB sheathing, water control plane, and siding. The larger the R‑value, the lower the con­duc­tiv­i­ties of the wall assembly.

The IECC is a model code which is part of the family of Inter­na­tion­al Codes (I‑Codes) first published by the Inter­na­tion­al Code Council, Inc (ICC) in 2000. The ASHTAE 90.1 is the ICC ref­er­enced standard for the IECC. Their purpose of the IECC is to establish codes and standards for the minimum design and con­struc­tion require­ments for energy effi­cien­cy, for both new and renovated buildings. The IECC has separate codes for com­mer­cial buildings and low-rise res­i­den­tial buildings (three stories or less in height above grade). Revision of the Inter­na­tion­al Energy Con­ser­va­tion Code occurs every three years. The most recent 2015 IECC improves energy effi­cien­cy and saves building expenses.