South Florida Insulation Guidance- How to create a value engineered insulation system for your new home.

There are certainly certain items I would suspect are considered standard and then other areas where it becomes an owner’s preference choice.

 

Obviously minimum “Thermal Requirements” standard.

Roof Unvented over AC – R20

Exterior Wall – R5

Garage common Wall – R11

Basic sound attenuation at laundry, baths and mechanical closets where applicable.

 

Upgradable Options include interior sound walls, between floor sound solutions and insulating non conditioned areas such as garages, porches and loggias.

 

Choices:

Exterior wall:

Rigid Board – R5 - I only consider this a viable choice if glued to wall prior to framing and seams taped to provide continuous envelope.  Generally, $1.00+.

 

               Options: Because air space provides improved R-Value a chase wall 1 5/8” offer an R5 with basic AA2 foil or R7 with VR-Plus foil.  These choices are approximately only 35% and 55% respectively of the price of Rigid Board with same or better result.

 

               There are two other options: Core Foam 500 (CBS block fill injection) – I’m not a super fan but paperwork claims an R9+.  The Ultimate choice is use of Closed cell foam.  Expensive but advantage beyond R-Value includes an absolute continuous air barrier, flood control, exterior sound.  Expensive choice and requires proper care by framers to add clips or cross bars to stabilize framing.

 

Interior walls: Sound reduction and prevention is very much an assembly consideration.  For our purpose we will presume interior walls with only one 3 5/8 metal stud.

               Options:

               Standard Batt – better than nothing, carries a tested result of STC in high forties. .47

               Mineral Wool – (Roxul brand is the crème de la crème) doubles the STC values.  Recommended for certain around theatres.  An optionable upgrade for any walls, such as bedrooms, baths and others.  2x price of Sound Batt.  When working with multimillion-dollar projects, this tends to be considered a low-cost improvement no customer has regretted.  These owners have always been pleased they did not overlook this upgrade.  Open Cell foam is a comparable choice, but the testing reports do not exceed the Roxul and this requires added coordination.

 

Between Floors Sound: A real conundrum as I like to claim, “Sound is in the ear of the beholder”.  No customer guarantee offered. 😊

              

Options: These can be used in conjunction or singularly.

               Icynene – a fantastic choice to encapsulate interior sound a prevent resonance. If lots of stone and tile being used and music speakers throughout the home, I believe this should be considered.  This is NOT considered a great solution to prevent thumping or walking from above.

              

Sound Batt or Roxul – same discussion from above but note the assembly of floor system (recommend a rubber matting above), air space, these products and drywall is likely as good as one can do in thumping prevention.

 

 

Unconditioned spaces: (exterior porch, unconditioned garage …)

               Whether foam or batt makes no difference.  Both slow down some heat transfer but space will be nominal to the outside conditions.  Foam is cleaner and allows no to interfere with lights or speakers installed as bottom chord.  Doing nothing is standard.

 

We have all passed the Introductory 2^nd level course Insulation 202 by Therma Seal University.  😊

 

Send questions or comments if presentation has been less than clear.  Happy Memorial Weekend!

Finding a performance sweet spot with Icynene spray foam and R-Values

Please refer to the attached Law of Diminishing returns chart. As you can see, from the R-20 point on the graph, you already have 96% conductive heat flow resistance. By adding additional R-value to get to a prescriptive level of R-38(typically for batt insulation) for Zone 2, you are only gaining less than 2% of additional heat flow resistance. So you are not getting much for the money invested in the increased R-value. With Icynene open cell spray foam insulation, you have the advantages of the air barrier component coupled with the conductive heat flow resistance, ultimately making the home more energy efficient, so there is no need to increase the R-value beyond R-20.

There are several ways to meet building code when it comes to residential insulation requirements. One of the more popular ways is the Performance method in which, rather than simply supplying the prescriptive insulation values, an energy analysis is done on the home.

Spray foam insulation, being an excellent air barrier material, helps create a tighter home that does not leak interior conditioned air uncontrolled. This allows for the home to perform better and for a lesser R-value of insulation and still comply with building code.

These advantages have allowed homes all over Florida utilizing spray foam insulation at an R-value of R-20 and still perform better than traditional insulating materials. 

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