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.