Do you have a back guard on the range so it can go against a wall?

We will have island trim.

Not rated for up against a wall- that’s what the back guard is for. Anything else is not tested but I mean it’s probably fine. What’s the worst that happens?

The pvc softens or melts behind the wall?

According to Bluestar, island trim is fine if cement board is used.

Call Blue Star and talk it through. Probably fine to do whatever their installation manual says. But sometimes you'll get a great person who answers the phone and gives practical advice beyond their manuals. I had a Blue Star. It kicked off serious heat. It was not as well insulated as I had expected.

Use the backguard. Cement board wont burn, but it sure transmits heat through it. Just like the pan on the range doesn’t burn. But it sure transmits the heat to the bacon in the pan. Plastic pipe is the bacon in the pan. So is the wood in the studs.

I’m more worried about the ovens than the burners, given how much I bake (bakery biz). The backguard is irrelevant for that. Even with the backguard, wouldn’t the oven temp still affect the pvc pipe in the wall?

I have a Bluestar 48 inch. The range vents the oven heat out the top back. The back guard directs the heat out the front of the back guard.

Zumi what i dont get is the stainless steel backguard condiccts heat as well… so from a fire resistsnce perspective i get it, but it is not exactly a heat barrier

The heat coming out the top back vent from the ovens is hot enough to scorch quartz. So think how hot the tile will get. The purpose of the backguard is to help vent the heat toward the front and not up on the wall. Here are some photos of people who did not use the backguard and what the heat from the ovens vented out the top back did to their quartz. No they are not Bluestar ranges but it is the same concept.

^^*^ and they probably aren’t running a bakery business.

I think those burns happen when roasting at high temps or using the cleaning cycle, and not with standard baking.

Even if I did get a backguard (we had one pre renovation, which scorched behind a burner fwiw), it’s not protecting the pvc/wall below the 6” below the top of the range, ie behind the ovens. Im still not understanding how the backguard helps with heat transfer in the wall to the pvc since the metal of the backguard conducts heat. How is it helping beyond cement board for heat transfer? If I installed stainless steel sheet metal inside the wall would it have some additional affect? Likely not.

Is there any code rule about having pvc behind a range generally?

Here is the BS installation manual on clearances, distinguishing btwn horizontal and vertical clearance.

It looks like they changed the installation specs. Mine stated that all ranges require a back guard but that was almost 7 years ago.

Your manual states you do not have to extend the non combustible material horizontally so you should be ok with what you had planned.

You aren't understanding the function of a back guard. Or NFPA definitions of combustible. A backguard provides an air gap to the wall, and protects the wall that way. It doesn't touch the wall, to transmit any heat to the wall. You could do the same thing with a stainless sheet and stainless standoffs about 1" from the wall. The backguard just does it much more attractively.

Minardi, what do you mean by stainless sheets and stainless standoffs?

A big ugly restaurant looking stainless sheet mounted on multiple washers or sleeves, to achieve 1" air clearance from the wall. The backguard does this. And yes, ANY surface, including the backguard, right behind the range is going to get scorched. Because it would in any restaurant setting too. If it gets used, it is going to look like it gets used. Stainless is NSF rated for a sanitary backsplash, which is why restaurants use it, either in a manufacturer's backguard, or in a separate application.

If you want a commercial enterprise in your home, you are going to need some basic restaurant sanitization and housekeeping knowledge. You need to be taking a class from your local health department. Otherwise, you can get shut down.

I interpret the blue highlighted material to mean that with island trim, the wall has to be non-combustible (includes sheetrock and studs) for six inches back. This might include wood-framed grandma's portrait on the other side of the wall.

I interpret the blue highlighted material to mean that with a riser/back-guard, you only need the wall surface to be made from non-combustible material.

The general spec comes from the International Machinery Code (IMC) referenced by the International Residential Code (IRC). The section is 308.4.2. The relevant table is inserted below.

I believe the process is that the manufacturer has the appliance tested, e.g. by UL, with and without back-guards to determine what degree of wall protection is required to be equivalent to the requirements of the IMC.

And I think PVC qualifies as combustible, so I would install the back-guard and put in place the cement board/tile above and below the cooktop surface.

I would add that in many if not most commercial kitchens, the cooking apparatus is free standing and not mounted to walls. Here is a relevant description from the commercial kitchen oriented "Greenheck Guide." https://www.tagengineering.ca/wp-content/uploads/2015/02/KVSApplDesign_catalog.pdf [Click to enlarge.]

I called Bluestar again today and they explained that the interior wall components need not be non combustible as long as there is a non combustible surface right behind the range (eg tile). They said cement board would be a good idea behind the tile but is not required, and PVC and wood studs are definitely fine. (This is in line with their installation manual).

Thanks for the help all.

Bluestar does not get to define what a non combustible wall assembly is. That is the National Fire Protection Association. If you do not have a non combustible assembly, you are risking combustibles behind the wall becoming damaged by heat.

Thanks for providing their clarification. I would argue that the last (fifth) bullet of their clearance instructions is in conflict with the second sentence of their third bullet. Some rewording seems necessary to bring them into alignment.

I don’t think they’re in conflict? It’s saying that if island trim has no clearance with the wall, it must be up against non-combustible material which extends up the vertical plane at the specified distance but need not extend horizontally thru the wall.

Kimberly I don’t think they’re defining what a non combustible wall assembly is; they’re saying a non combustible wall structure is unnecessary, and that just non combustible material up against the range is required for their range.

The second sentence should include the phrase "wall surface" in some form. A reader familiar with IMC 308.4.2 would assume that it includes 6 inches into the wall. The third sentence does not clearly exclude the interior of the wall. I spent much of my life writing requirements documents, and quickly learned that it is important to avoid any ambiguity.

The question about PVC may not be an issue anyway, because the purpose of this code is to keep wood studs and such from deteriorating from long-term heat exposure such that they give up some of their fire resistance.

I hear you, as a lawyer who also tries to steer clear of verbal ambiguities. The fifth bullet clarifies the horizontal plane issue though.

What’s your opinion on the pvc issue, @kaseki - non-issue? I’m surprised code doesn’t deal with this, since pvc has such a low softening/melting point…

Is this a large air vent PVC pipe that goes to the roof, connected to a bathroom closet drain, or ???. What is the diameter vs. stud depth? Can you insert a section of copper, stainless, or other material pipe? Can you space out the wall an inch (not an idea I would embrace unless there are no doors or windows in it).

I don't think the PVC (max temp 140F) will deteriorate over time in the manner of wood, but as you point out, wood can withstand brief hot temperatures and PVC can't. If the PVC is air-gapped from the wall board, and at best can only touch a stud, I would be surprised if it was ever overheated if the wall cavity is fairly large. But I haven't any experience with your baking process.

The advantage of the back guard is not only that it diverts the rising heat from the wall, it usually provides some temperature dilution by entraining cooler air into the flow. But I haven't seen any BlueStar back-guards to know about theirs.

Another factor is that actual drain/vent pipes are open from sewer to roof, and when there is no water flow down them, sewer air will tend to rise up and provide some flow to the roof. The cooling effect of this would be hard to model.

Similarly, fire stopped (baffled) and screened vents at the stud section bottom and top could provide cooling air in the cavity.

None of these ideas, of course, are covered by the Code. NFPA 70 (NEC) allows for engineered solutions in many cases (that is, calculated proof of safety), but I am not familiar enough with the IMC to know if air-gapping/non-combustibility rules can be "re-engineered."