Is it possible to accommodate a cassette fan coil in the ceiling when the joists are too close?

Or maybe I should ask: are there ways to reinforce around a cut in the joists?


I'm trying to retrofit my home with a heat pump which requires a registered installer so I've been asking a few contractors and have been getting a wide range of answers. Some say they can do it, others say my joists are probably too close to install something like this.

This is the type of 9 kBTU sized cassette like I want installed:

enter image description here

I live in a town house, and the cassettes would be for the top floor, where there is sufficient attic space for the height of the unit.

This is what my attic looks like:

enter image description here

  • Is your roof a truss system (lots of interconnected struts with metal plates at the joints) or traditional rafters? Jul 16 at 3:27
  • Good question @AloysiusDefenestrate it looks like a truss system to me? I've just attached an image of my attic space.
    – Daniel
    Jul 16 at 3:36
  • 2
    Measurements would be a good first step, before asking. Measure the size of the fan and the space between joists/trusses. Most buildings have standard spacing and imagine those fans are made for it. Off hand from the picture(bad to guess from) maybe 24 inch OC which should give you about 22 1/2 free space between
    – crip659
    Jul 16 at 11:32
  • 1
    The fan measurements should be listed on the web page, if you do not have it yet.
    – crip659
    Jul 16 at 13:14
  • 1
    For up to removing 1/2 inch(1/4 inch on two joists) should not be problem. For removing about half the joists then need extra support by sistering more wood to the joists. Removing a whole section of joist, will probably want an engineer. Should probably have an engineer for sistering also, to be safe.
    – crip659
    Jul 16 at 18:04


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