Older houses tend to fare better in a fire than newer ones. This is due in part to the building materials used. Vinyl siding is a lot more flammable than steel, stucco and brick.
Another consideration, though, is the advent of attached garages. As early as the early 1940’s, home designers began incorporating the garage into the home design. Homeowners wanted an easy way to move from the garage to the living quarters.
Sounds good, but hold on.
With all of the flammable items, such as gasoline, solvents and the car itself, a garage fire is the hottest and most deadly.
For that reason, fire-resistant material such as sheetrock is used when building the house.
Sheetrock (also called gypsum board or GB), is a code-required building product that helps to create an effective barrier when used correctly. But then a handyman comes along and inadvertently creates a void in the wall. The most common mistake is a PVC pipe from a whole house vacuum or a radon vent. Although Polyvinyl chloride (PVC) burns at a very high temp of 734F, it begins to melt at a mere 200F, and the opening into the house can be like a blowtorch.
And that’s why I recommend installing intumescent firestop collars where a pipe or vent penetrates the space between the house and garage.
Intumescent material expands (a lot!) when it gets hot. The collar holding it expands and crushes the PVC pipe, blocking gasses and flames from entering the home. They come in an assortment of sizes and range in price from $11.00 to $30.00.
The collars are easy to get online and at home centers, and are very easy to install.