I was curious about the use of the Grace Ice and Water Shield you guys are talking about. From what Pete said, I wouldn't want that in my truck/car on the walls or the floor boards when it gets hot, so I did some searches. I ran across this write up on the differences in products used for sound deadening or primary sound deadening products, it mentions the use of roofing products.
http://www.dctra.org/files/1974_TR6_...r_Showdown.pdf
Quote from the above link:
"I looked at the specifications for products developed for roofing, which many of the products in this
category began life as, I saw the problem. Roofing materials are designed to withstand temperatures
of 158°F for two weeks without melting. Manufacturers supply butyl products for situations that will
either exceed this temperature or duration. Extend the time and the maximum sustainable
temperature falls. This explains why some people have had success with asphalt mats for a few
years, only to have them fail in a subsequent year. Failure can be disastrous. If you're lucky, the mat
will just fall off. If you're not, it will melt - pools of asphalt in your carpet or upholstery or window
mechanism.
Another problem with asphalt mats is the smell. You should be fine during cool weather, but on a hot
day, they tend to smell like, well asphalt."
category began life as, I saw the problem. Roofing materials are designed to withstand temperatures
of 158°F for two weeks without melting. Manufacturers supply butyl products for situations that will
either exceed this temperature or duration. Extend the time and the maximum sustainable
temperature falls. This explains why some people have had success with asphalt mats for a few
years, only to have them fail in a subsequent year. Failure can be disastrous. If you're lucky, the mat
will just fall off. If you're not, it will melt - pools of asphalt in your carpet or upholstery or window
mechanism.
Another problem with asphalt mats is the smell. You should be fine during cool weather, but on a hot
day, they tend to smell like, well asphalt."
If it were me I think I would be looking at something else.