I just installed a heater in the ceiling of my bathroom and am trying to decide how to insulate around it. The insulation in my attic is blown-in.

It seems like it might be a fire hazard to put it right up against the heater. Is it ok to put this insulation right up against the heater or should I get some sort of thermal insulation? Or should I just give it some space?

  • 2
    Since the manual says nothing, I would CALL the manufacturer and verify insulation is not an issue. Not worth the risk to not be certain.
    – topshot
    Commented Sep 26, 2016 at 13:10
  • What is the heater make and model?
    – wallyk
    Commented Nov 27, 2016 at 17:38
  • @wallyk It's a Nutone 665RP. Here's a copy of the manual -- All I found was "follow fire codes" and "don't block the vents".
    – Gary
    Commented Dec 17, 2016 at 23:08

2 Answers 2


The manual and device specifications—oddly—do not use any of the words which mean the appliance is zero clearance. Though it is meant to be installed through sheetrock or other fire dampening materials. It is an odd situation.

There have been several fires reported caused by the Nutone 559R:

Presumably, thousands and thousands of these units are in use daily, so the few incidents reported actually seem to indicate a really good safety record. Note that one of the six reports was from a modified unit which bypassed the thermal protection.

Given the possibilities, I would—if reasonably simple:

  • Install with metallic brackets so that no wood touches the box.
  • Keep all flammables away from the box exterior.
  • Don't worry about insulating around it.

In this case, i would read the manual carefully; usually the housing provides a buffer for heat dissipation, but some heaters may specify no flammable materials within x inches, or nothing on top. And make sure the air intake is unobstructed or the heater may pull insulation fragments in to the housing.

  • It does mention specifically about the air intake, but it says absolutely nothing about insulating. Maybe that implies that I don't need to worry about it?
    – Gary
    Commented Sep 25, 2016 at 23:31
  • 1
    with no guidance from the manufacturer, I would not worry, but if it were me, I wouldn't put anything on top since it would tend to trap heat.
    – SqlACID
    Commented Sep 25, 2016 at 23:36
  • But that could either way, right? Minimizing heat loss into the attic would put more heat out the bottom.
    – Gary
    Commented Sep 25, 2016 at 23:53
  • If it's unheated space above I could see that.
    – SqlACID
    Commented Sep 26, 2016 at 0:30

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