Wall Materials for 2015 Energy Code Compliance

There are a few prod­ucts and meth­ods avail­able for achiev­ing con­tin­u­ous insu­la­tion.

Under­stand­ing what each of these prod­ucts offers can help guide how you choose wall con­struc­tion solu­tions in your projects.

Let’s take a look at the most com­mon kinds of con­tin­u­ous insu­la­tion mate­ri­als.


1. Polyisocyanurate (Polyiso or ISO)

Poly­iso pan­els are rigid foam pan­els fab­ri­cat­ed from liq­uid foam. Poly­iso rigid foam pan­els pro­vide an R‑value of about 6.0 per inch, although insu­lat­ing val­ues can degrade slight­ly over time. Due to the liq­uid foam fab­ri­ca­tion tech­nique and the need for addi­tion­al dimen­sion­al sta­bil­i­ty , poly­iso pan­els must be faced with a sec­ondary lin­er mate­r­i­al.

These pan­els are not vapor per­me­able — one man­u­fac­tur­er states its prod­uct has a 0.05 perm rat­ing. If the breatha­bil­i­ty of the wall cav­i­ty is an issue, poly­iso sheath­ing should be used with cau­tion. These pan­els are often con­sid­ered less green” than some oth­er exte­ri­or sheath­ing options. They are used more often in roof con­struc­tion than wall con­struc­tion.

2. Extruded Polystyrene (XPS)

XPS pan­els are quite notice­able because they are usu­al­ly green, pink or blue in col­or. XPS offers an R‑value of about 5.0 per inch.

XPS is a semi-per­me­able sheath­ing with a perm rat­ing of approx­i­mate­ly 1.0. As such, even unfaced XPS is more of a vapor retarder than a vapor bar­ri­er. In some instances, XPS can absorb mois­ture over time, which low­ers its R‑value.

The man­u­fac­tur­er of one XPS prod­uct cal­cu­lates poten­tial shrink­age of as much as two per­cent. Undue con­trac­tion can leave gaps and put stress on tape along seams, which impacts its effec­tive­ness as an air/​moisture bar­ri­er.


3. Expanded Polystyrene (EPS)

EPS pan­els are con­sid­ered a ver­sa­tile solu­tion for insu­la­tion. With an R‑value of approx­i­mate­ly 4.0 per inch, it often out­per­forms XPS and Poly­iso in terms of cost-effi­cien­cy, and tends to retain its R‑value over time.

EPS rigid foam pan­els are usu­al­ly applied over house wrap or a suit­able alter­na­tive. EPS is typ­i­cal­ly the foam of choice for use in struc­tur­al insu­lat­ed pan­els (SIP) and insu­lat­ed con­crete forms (ICF). EPS can also be used for below grade appli­ca­tions and can be treat­ed to resist insects.

EPS is avail­able faced or unfaced. Faced EPS is con­sid­ered a vapor retar­dant, and some spe­cial­ty prod­ucts are con­sid­ered vapor bar­ri­ers.


4. Mineral or Rock Wool

You can also design walls with a lay­er of min­er­al wool, also referred to as rock wool and stone wool.

Rox­ul® is a rock wool insu­la­tion pan­el fab­ri­cat­ed from basalt, an igneous rock. In both com­mer­cial and res­i­den­tial con­struc­tion, Rox­ul is used in a vari­ety of ways, includ­ing as exte­ri­or wall insu­la­tion.

Since it is a stone-based prod­uct, Rox­ul is very fire-resis­tant. In fact, it can with­stand tem­per­a­tures up to 1,177 degrees C or 2,150 degrees F. It inhibits the spread of fire, and it does not release tox­ic gas­es. More­over, the non-direc­tion­al nature of the rock wool fibers effec­tive­ly absorbs acoustic waves, so it reduces noise and dis­rup­tive echo.

Min­er­al wool is high­ly water repel­lent, so the risk of mold, mildew and bac­te­ria growth is effec­tive­ly elim­i­nat­ed. And Roxul’s vapor-per­me­abil­i­ty allows water vapor trapped inside a wall cav­i­ty to escape.

Unlike some types of rigid foam pan­els, Rox­ul retains its essen­tial char­ac­ter­is­tics over time. It’s not as prone to expan­sion and con­trac­tion when there are local shifts in tem­per­a­ture and humid­i­ty.

5. Spray Foam

Spray foam insu­la­tion pro­vides an R‑value of 6.0 per inch while both act­ing as a vapor retarder and offer­ing an air/​water bar­ri­er. What makes it stand out from oth­er insu­la­tion prod­ucts is the flex­i­bil­i­ty afford­ed by its sprayable form.

The spray appli­ca­tion is far sim­pler than con­ven­tion­al con­tin­u­ous insu­la­tion meth­ods and entire­ly elim­i­nates the need for met­al fas­ten­ing. With few­er steps and easy appli­ca­tion, spray foam reduces labor costs. This is espe­cial­ly true for curved walls and oth­er sim­i­lar designs, which are oth­er­wise dif­fi­cult to achieve and require addi­tion­al labor hours.


6. Bautex Wall System

For both com­mer­cial and res­i­den­tial struc­tures, a wall sys­tem with built-in con­tin­u­ous insu­la­tion is an effec­tive solu­tion to ther­mal bridg­ing. The Bau­tex Wall Sys­tem, for exam­ple, is a four-hour fire rat­ed load-bear­ing sys­tem that includes the con­tin­u­ous insu­la­tion required by mod­ern, updat­ed build­ing codes, so no addi­tion­al sheath­ing or insu­la­tion is required.

Sin­gle-con­trac­tor instal­la­tion reduces the chance of work­er errors that can com­pro­mise wall integri­ty. The ther­mal mass of the wall helps exceed ener­gy code require­ments in Texas and cli­mate zones in near­by states. More­over, with the appli­ca­tion of a liq­uid-applied air and mois­ture bar­ri­er, Bau­tex exceeds both above-grade mois­ture pro­tec­tion require­ments and air tight­ness stan­dards.