Is extra Insulation worth the cost

[SGBJ]

I'm building a new home in Florida. The exterior walls are CMU and I'm trying determine if it is worth the extra cost to use 2" Insulation board (r10) in place of 3/4" Insulation board (r4). The former cost about 3 times as much as the later and wondering if it will really save me more in term of utility cost in the future. Any thought would be appreciated.

 

[Badbird2000]

Not sure what your utility rates are, but if you are almost tripling the r-value of the wall, go for it. Escpecially in Florida where the cooling season is the longest.

 

[tys90]

Is there a residential building code you have to follow? I ask because, for example, if they adopted ASHRAE 90.1 for residential buildings, in your climate zone you would need a minimum R-value of 5.7 continuous insulation.

 

[mauricestoker]

Don't know about State codes for Florida, but I would hazard to say that the ASHRAE 90.1-2007 would be useful. If in Florida, you are probably in Zone 2. For zone 2, continuous insulation at 7.6 is recommended, which is for energy savings. I'd recommend looking at the EnergyStar page and considering whether the available 30% up to $1500 tax credit would make a difference. I live in a different climate, but I'm definitely spending on insulation and doors while the credit lasts.

 

[willard3]

The next question to answer is whether to put the insulation on the outside or inside the wall....there are advantages to both.

Economic insulation of thickness is moot as energy costs are sure to rise. Put on the thicker/better insulation.