Thinking about a new roof

[CptnRn]

Originally Posted by G Grasshopper

I went up into the attic and noted a few things. There was both batting and blown in isulation, but some of the batts have peeled away from the sides ofthe skylight well, so there are areas that aren't insulated at all. Also, the area above the garage isnt insulated. I know it isn't an air conditioned space, but wouldn't the garage be more comfortable in the summer if it had some insulation from the attic heat?

The vertical insulation batts around the sides of the skylight can be held in place with wires between nails at each stud, to keep them from drifting loose again. An insulation contractor or any handyman can install those for you.

Most people don't insulate the garage ceiling, but you are right that doing so would probably keep it cooler during the worst summer heat when the attic air temperature is significantly higher than the outside air temperature. Insulating the ceiling will keep the garage temperature closer to the outdoor temperature. That can also result in some energy savings as the insulated walls between the garage and interior of the house will have a lower temperature differential.

An 18 year old HVAC unit is definitely getting up there and is due to be replaced. When we replaced our 18 year old HVAC with higher efficiency SEER 16 equipment and added R30 insulation our annual electricity usage dropped from around 17,000 kwh per year to around 11,000 kwh/yr. I have since increased the insulation to R-38. You will probably need to stay with fiberglass insulation as it is lighter weight on the ceiling drywall, which limits how much you can add.

[Restrain]

If you replace the AC unit, have dampers installed in the ducts to direct the air flow. Wrong air flow through the home can cause the unit not to function as well. Very inexpensive in the grand scheme of things.

As to radiant barrier, we had a wood shingle roof with comp over it (1970's home). Thanks to a hail storm, we had the entire thing redone, including decking with radiant barrier. 40% drop in energy cost, attic temp dropped big time. We then blew in another 8" of insulation ($350 from the BigBox store and they threw in the blower rent). Another big cut in energy cost. If your decking is good, often the roofer will have a subcontractor that can spray in the barrier on the UNDERSIDE of the decking. That is where you want it, not on top. It reflects the heat back out. I highly recommend getting it. Also, get hail-resistant comp shingles. A bit more, but we have a LOT of hail storms.

Long term, look at replacing your older metal insulated windows with newer vinyl high-R windows. An average window will cost about $350 installed, but makes a big difference as well. You can actually buy replacement windows from the BigBox store and remove the tab, install them yourself for about $175 a window.