Furnace on Bricks

I posted in the emergency forum but did not get a response so I am posting here. Is a horizontal gas furnace allowed to be mounted on bricks in an attic?

You not going to find a specific code that address your furnace. I personally would write up what you found based on MFG installation procedures . Brick would add some extra weight to the ceiling joist and would be an easy transmitter of vibration noise to the ceiling joist and into the living area. It’s basically a dumb installation. I am also an old HVAC person

To be sure, you would need to refer to the specific mfg installation instructions as Charley suggests. There you might or might not find something like this Bryant furnace installation manual snippet:

Bryant Furnace Install.JPG

Bryant Furnace Install.JPG

Almost every attic-mounted furnace I have seen (I’m in Texas) was suspended from the roof rafters. I will assume that that is the practice because it is preferable to resting them on the ceiling joists, which are typically not designed to act as a floor system. What does the attic floor (ceiling joists for the room below, typically) look like? If they are 2x8’s on 1’ centers, you are almost certainly fine, but the width of the span comes into play as well.

Suspended or resting on the ceiling joists, the main question is whether that structure is designed to bear the weight. I would not take a HVAC installers word on it.

First break down the word “assume” and you will understand why you never “assume” anything!

Re the HVAC installers word then whose word would you take on it? Would you take the word of the manufacturer as asked in this thread https://www.nachi.org/forum/f79/furnace-mounted-bricks-122296/ and an example of one manufacturer pointed out by Mike both in that thread and in this one? As for Charley’s word I would have a tendency to believe him as he has been around the block with this more than a few hundred times! Of course, no offense to Charley, I would still look up the manufacturer installation requirements to verify it. Did you obtain the data plate information from the unit so you could do this?

You discuss loading on the ceiling joists, are you a licensed Engineer that can perform this function? Are the framing members exposed to the point (no insulation covering them) that you can see the interconnection between them which would come into play to determine loading ability? If not you should be very careful about discussing that which may be under the purview of a licensed Engineer and that which you can not see!

Hey Mike!

The weight of the HVAC system is nothing compared to the weight of the two 50 gallon water heaters up there. Your ceiling joists are more than adequate to support the weight of an HVAC system. Hanging the HVAC from the rafters may help reduce transmission of vibration and noise through the ceiling, but not necessary to relieve the attic floor of the weight of the system.

Topics on this forum routinely run into areas that are the “purview” of any number of licensed professionals. Plumbing, electrical, framing, grading, soils, the list goes on. Are you going to come out and wag your finger at us every time such topics come up? If so, you will be a busy man indeed.

I went back through both threads on this topic and at no point found any mention of two 50-gallon water heaters. Did I overlook that? If there are 2 50-gallon water heaters up there, I would be even more hesitant to place an additional load on the attic floor.

In most cases, typical ceiling joists would probably be up to handling the load, but I have seen ceiling joists that were nothing more than the bottom chord of a 2x4 truss system on 2’ centers. Without any information about the ceiling joist dimensions, their span, how closely they are spaced, and the weight of the load being placed on them, I would not venture an opinion. But that’s just me.

I would expect by now you would learn that attempts at twisting around another persons words are not the answer to any situation as displayed in this post https://www.nachi.org/forum/f2/suggestions-truly-useful-pool-spa-inspection-course-122166/index2.html.

To help keep the conversation straight I have answered your blue wording above with red wording as replies to it.

So who mentioned trusses? What is the point of your rampant assumptions about an installation that you know nothing about. Are your inspections full of all this same B.S. and made up nonsense “almost every”, “I will assume”, “typically”. You’re way the hell out on a limb that you don’t belong on.

“I would not venture an opinion. But that’s just me.” The issue is that you have ventured an opinion. An ill-informed one at that.

Charleys answer:
“would be an easy transmitter of vibration noise to the ceiling joist and into the living area. It’s basically a dumb installation.”

@Manny and Chuck

I will go back to what I said before:

“the main question is whether that structure is designed to bear the weight.”

I honestly don’t see what the problem with that statement might be.

“I would not take a HVAC installers word on it.”

Because there is NO WAY the HVAC installer knows the details of the construction at the point of installation. Now, if the installation instructions were available and went into specific detail about structural requirements to support that specific unit, then I would be more inclined to take their word as long as those conditions were met at the point of installation. Keep in mind that in this example the weight of the bricks come into play as well, which again, the manufacturer cannot possibly know.

Answers to your question in blue and red above.

I think you really should stop as the hole just keeps getting bigger for you. If you wish to speak about this it is better for you to use the thread started in the MO section of the BB.

Chuck provided a very good point in an earlier response about the pair of 50 Gallon water heaters mounted in an attic. I’ve run into my share of this very installation. His example no doubt was to display how a properly installed joist system, and platform, has the capability of handling an approximately 1000 Lb load in what is typically no more than a 4’ X 4’ area. Do you believe that an HVAC system typically spread out across an approximate 5’ - 6’ line would not be handled properly including with any “bricks”?

As I said before there is certainly nothing wrong with any Inspector trying to learn and think of how a piece of equipment might be loading the framing. However don’t leave consumers with a wrong impression that Inspectors should all be calculating and verifying loading when they can not since we can not see all conditions needed to do that. Also there is no reason to even try if the installation is not displaying signs of stress on the structure!

Well, bless your heart. You just go right ahead and write up every attic floor installed HVAC system that you encounter as a possible structural defect in need of a full engineering evaluation in your reports to your clients. Best wishes to you in your new career. Please don’t advise other inspector to do so though. There’s no need for them to ruin their reputations too.

Mr. Ogletree,
Like Mr. Scanlan said it is good you formed the question; the answers have been provided by the dynamic duo from Texas. They are both quite knowledgeable. If you were to pick up and move a furnace, you might find it is not that heavy, lighter than a lot of furniture. Many roof trusses are designed with snow loads in mind, as they are based on national standards. The areas without snow are sometimes subject to hurricanes. Either way, they are shored up. I forget the terms, dead load plus live load 10 lb.s plus 40 lb.s per square foot? I should look it up, or ask my father who is an engineer.

I would not take the word of the HVAC installer regarding structural load(s), but it is a relatively common practice. Like mentioned previously the HVAC tradesmen are likely the most informed of the individual trades.

Chuck, thanks for mentioning the 2? WH up there. Never seen even one here. I could never move a filled 50 gallon tank, 400 lbs. Kind of hard to believe, but if you have seen it, you have seen it.

And for those times when two, just won’t do…


The original question was, is it OK to install an furnace on bricks. No details were given as to what everything was resting on. Should I have assumed it was standard 2x8 joist floor? Of course not. So, I continue to maintain that the main question is whether that structure is designed to bear the weight.

If I saw a furnace installed on an attic floor supported by 2x8 ceiling joists on 16" centers, I would not need an installation manual, load tables, an engineer’s opinion, or anything else to be comfortable with it. I have enough real world experience as a home builder and re-modeler, and have dealt with load distribution and re-distribution enough to know this. I am not uninformed on the issue.

If, on the other hand, it was installed on a platform set on the bottom chords of a 2x4 truss on 2’ centers, and I know many homes in my area with exactly that configuration, I would have to take a good hard look at it before I could comfortably say that it was a safe installation.

My point is this: It is the inspector’s observations in the field - not the generic instructions in manufacturer’s literature which have no insight into the facts on the ground (or in the attic as the case may be) - that informs the inspector’s opinion.

I have a tremendous amount of respect for Manny, as he obviously has loads of experience and technical knowledge. Likewise with Mr. Evans.

That being said, I will always use my training, past experience, guidance from code, and common sense when I evaluate whether any installation is proper or safe. Taking someone else’s word for it - especially when they are not privy to the specifics of the location - seems to me the easy (and risky) way out, and not what I was hired to do.

Awesome!! I’ve done some doubles, quite a few singles but I don’t ever remember a triple! Thanks for the pic as well. I was trying to find a double but it has been a while and that means looking through a lot of picture files.

BTW that’s over 1200 Lbs of water alone and must have topped close to 1500 Lbs. total. Did you calculate the loading to ensure the installation was properly performed? :wink:

Answers in blue above.

As I stated you are best served starting a new thread in the MO section or continuing the existing thread in the MO section of the BB!