Our roof tile is installed on top of galvanized iron sheets. We do not have any toher form of insulation. The roof tile or tegula is quite thick.
Absolutely. You will find in the summer that your tiles will heat up from the sun and will stay hot even after dark (the steel sheets don't exactly help either). Your energy bills will go down about 60% in the summer and 20% in the winter by just installing a cheap fiberglass filling. A good example of how these tiles are effecting you house would be a stoneware cup. Pour hot water into it and place it in the microwave until it boils. Feel that the side are very hot, too hot to hold (this represents the sun heating up the tiles). Now pour out that cup and fill it with cold water (which would represent AC in your home). In about 2 or three minutes, place your finger in the stoneware cup. The water will be warm. The tiles do the same thing. The absorb and distribute heat into your home during the warm months, and will rob your home of it's heat during the winter and cool months. Just by placing insulation in your home, you stop that unwanted heat exchange with your home and the outside world.
You can never have too much insulation, esp. in a roof. Heat rises, and a well-insulated roof helps with energy savings.
Yes, you do need other insulation. If you are on a budget, check craigslist, often people have leftovers from a project., frequently for free! You can mix and match, blown, fiberglass, whatever! Just one note of caution, however: If you have electrical boxes sticking up into the attic space, for recessed lights, make SURE they are rated for contact with insulation, or leave a little space around them.
Oh yeah. You need insulation. Think of it this way. If you turned a stove top burner on medium-low and placed one of those roof tiles on it, it would be too hot to pick up. If you put down a small piece of insulation first, you'd be able to pick up the tile with no problem.
. Insulation does a bunch of things; it hinders heat transfer and also Noise transfer. If the pitter-patter of rain doesn't bother you, you're ok. This tile is popular in California where the temperature is often mild. Of course people living in the Sierra Nevada Mts. wouldn't agree, but installation might NOT be necessary for you. Stick a 'remote thermometer' up there to monitor the temp. See the comfortHouse link below >>> .
