Hello, I'm Darren and I am trying desperately to find an answer to just one question that no one seems able to answer at the hardware stores. I need a whole house fan and it is wider than my trusses in the attic. I do not have the old joist and rafter so I don't know if I can cut into a truss and box in the fan or do I need to search for a smaller fan?

Thanks so much
Darren

Hello Darren

Can you please describe precisely the entire system you envisage ?

Note : just cutting into a truss is in general never a good idea.

See this You Tube video on an Airscape Whole House Fan system installation

And

Here is another link to an installation movie at wholehousefan.com

Most whole house fans sit on top of the joists or trusses, you do not cut them or remove them. They give you options for boxing in the cavity below so the truss of joist is actually part of a enclosed box below the fan. Open one of the boxes and read the installation manuals before you buy. You also raise the fan into the attic by removing the drywall only giving you the hole size for the fan. The joists still run through this opening and you lift the box up between the joists.