As a Lubbock home inspector I see lots of strange things. In just the past one week I've conducted two Lubbock home inspections and found houses that have suffered attic fires at some point in the past. In both cases extensive rebuilding and enormous expense was necessary to restore the houses to a functional condition. In the first house, the fire started with a pan full of food that caught fire on the cooktop. The range exhaust vent was turned on to remove the smoke that was gathering in the kitchen. (Big mistake. More on that later).The purpose of the range exhaust vent fan is to remove moisture and grease laden air rising from the food at the stove top and send it outside. This is desirable to prevent both a build up of moisture in the house, as well as grease from being deposited on interior surfaces all around the house. There are two types of range exhaust vents. One type pulls the air through a vent pipe up through the attic, and on through the roof, to vent the air outside. The other type is a recirculating type, which uses one or two metal filters to collect the grease. (It doesn't remove the humidity). In both types, a build up of grease can occur. In the first type, the grease can build up in the vent pipe that runs from above the cooktop up through the roof. In the recirculating type, the metal filters will become coated with grease over time. If something you are cooking at your stove top catches fire, it can catch the grease filters or vent piping on fire as well. This is one good reason why these filters should be cleaned occasionally if you have the recirculating type.
As for the first house, once the exhaust fan was turned on, it also pulled the flames into the vent pipe and caught the grease on fire that had built up there. This may have been ok, because the vent pipe through attics is required to be metal and would normally contain the hot gases and vent them safely through the roof to the outside. But a vent pipe connection in the attic had come completely loose and was venting directly into the attic. You can see where this is going! With the flames from the burning food being pulled into the vent by the fan, and the flames from the grease fire in the vent pipe being pushed by the fan into the attic; it was like taking a blow torch to the attic.
This is a picture of the attic. The new looking wood at the top half of the picture is just that- the new rebuilt area. The lower half of the picture shows the older wood that wasn't burnt badly enough to replace. It has been sprayed with a white colored odor blocker. And, even though you can't see it in the picture, the area that had to be completely replaced was very large.
In the second house, a barbeque grill had been used with a lawnmower and gas can nearby. Both were right next to a wood fence which ran up to the house. Again, you can see where this is going. The owners aren't sure exactly how it happened but at some point I'm sure the gasoline got involved, then the fence, and finally the underside of the eave and up into the attic.
When we at Lubbock Inspections inspect a house, we look for problems like the ones I've described here. If you ever get a home inspection and your inspector says the range exhaust vent pipe is disconnected in the attic, be sure and get it fixed! Same thing if he says your recirculating type range exhaust filters are very dirty. Put them in the sink (they are removable) and clean them with a good degreaser spray. And of course, we all need to be very careful with gasoline. Be safe --- Kim Christensen