Rangetops

Page 12 of the Installation Guide is clear. You need a backguard. And the distance between the appliance and the rear wall determines whether or not the rear wall must be non-combustible.

The Cafe spec sheet has a similar requirement.

And there's Miele:

• Please observe safe distances to rear combustible surfaces of 12" (305 mm) clearance. For zero clearance installation the Miele Backguards will satisfy the required distance to combustible surfaces. The Miele Backguard is available in 12" (305 mm) or 20" (508 mm) heights.

Tile is a protective surface but tile over drywall does not create a non-combustible wall.

My take…better to be safe, than sorry, especially with a powerful Bluestar. Just install steel studs and the fireproof cement board. End of.

In most instances, the concern is with heat coming through the rear vent of a range/ stove…especially when quartz is used as the backsplash. Rangetops, don’t have the rear vent, so there’s not usually a concern. However, I imagine there might be a concern if you use the rear burners on a high BTU Bluestar.

Even though my rangetop is a lesser BTU Thermador…and, I was putting in a ceramic tile backsplash, my contractor still installed steel studs and fireproof cement board in the wall behind the rangetop. I’m grateful for his cautionary approach.

I've got the 30" 6 burner Cafe range arriving tomorrow. From my read, it comes with a 7/8" spacer that's required to be installed behind the oven vents, but that's the only restriction on putting it against a combustible wall. In my case, the wall it's going against is tiled for 20" above counter height and 3" below in the range cutout (but I assume it's just drywall and wood studs behind the tile, I didn't put this wall in).

The most powerful individual rear burner on the Cafe is only 12k BTU, compared to 15k for the Bluestar ranges. And the Cafe has more distance between the rear burners and the back wall, as the front to rear burner spacing is a little closer.

Plus the oven vents are done differently. It's hard to tell in pictures where the oven vents exhaust on the Bluestar without one of the taller backguards.

On the Cafe, the oven vents are right behind the burner grates pointed upward (and likely part of the reason for the extra trim spacer to keep them further from the wall, plus the spacer is slotted so some cooler air will likely be drawn up through it via stack effect to cool the air flowing up the wall).

Most likely it's some combination of the burner to wall distance, more powerful rear burner on one side and oven venting considerations that drive the Bluestar requirements.

EDIT: The 36" Cafe rangetop that was mentioned to have a similar clearance requirement to the Bluestar is one of the Cafe commercial style units. 2 of the 3 rear burners on it are 18k BTU, plus it's a rangetop, so no oven vents behind the burners (leaving the burners a bit closer to the wall). Those differences adding the clearance requirement seem to support that it's a combination of higher heat from a single point, and heat sources too close to the rear wall that are driving the requirement.

The requirement that the code enforcement officer will want to see complied with is the one in the installation guide. Why do some guides allow lesser installation conditions than the IMC implies are needed? Presumably because the manufacturer had UL or equivalent test the unit under various conditions and evaluate the resulting wall temperatures. Most codes allow for engineering evaluation to supersede general requirements. But the code enforcement officer has the last word.

@kaseki - except the installation guide doesn't say what some here seem to think it says.

I read it many times (having also written & reviewed very large, complex contracts for a living & dealing as a result with precision of language), and it CLEARLY says to me that ceramic tile 6'' above the plane of the cooktop and 6'' below DOES MEET install requirements.

Here's the relevant language from the Install Doc:

"The non-combustible material need not extend horizontally past the initial barriers thickness. The initial barrier should consist of materials such as ceramic tile, cement backer board, stainless steel (.032” Thick) or other non-combustible material" .

Emphasis: NEED NOT EXTEND HORIZONTALLY PAST THE INITIAL BARRIERS THICKNESS (where the initial barrier can be ceramic tile). Ergo, the composition of the wall (which for most people will be drywall and wood studs) beyond a layer of ceramic tile is not relevant.

I suspect this language has been clarified in recent years and that the opinions of some who believe you need a minimum 6'' steel back guard or steel stud / cement backer board walls was formed prior to the Install Docs being made more clear.

I have a call into BlueStar to confirm, but as many of you know, they're not really setup to answer pre-sales questions and it's been like pulling teeth to get confirmation.

That wording from Bluestar makes me think their concern is more about short-term high heat events (like a pan fire) that might rapidly set a combustible surface on fire. And not so much about long term heating (like from the oven vents) getting things too hot and damaging the structure of the wall.

As a reference point, I just ran the oven break in on my new 30" Cafe range. The range is pushed back against the tile backsplash with the provided 7/8" trim piece installed behind the oven vents. After 45 minutes at 400* the tile right above the oven vents was just barely warm to the touch, I'd say not over 100* F.

I don't know what you are reading or why you are calling Bluestar. Page 12 of the Installation Manual for Bluestar Rangetops is clear:

• All rangetops require a backguard. Most models have the option of using: grate height trim; island trim; 6” inch standard; 17” inch hi-back; 24” inch high shelf.
• If you are using an island trim or grate height trim, a six inch clearance between the back of the rangetop and a combustible surface is required. If an island trim is to be used without this six inch clearance, the back wall must be constructed using non-combustible and heat resistant materials that extend below the top surface of the range a minimum of six inches.

You want to use the grate height trim because, you wrote, "the 6 [inch] backguard is ugly and would cover a good amount of a backsplash design we currently have, and look ridiculous. So for that reason, I strongly want to avoid it"

Therefore you either need (a) the six-inch clearance or (b) a "back wall...constructed using non-combustible and heat resistant materials".

Ceramic tile over drywall is NOT "non-combustible and heat resistant".

@wdccruise did you read my reply to @kaseki?

The install doc for the Range (not Rangetop) clearly says on page 8 that the Range can be installed in a zero clearance if non-combustible/heat resistant materials are used in a VERTICAL PLANE for a min of 6'' below and 6'' above cooktop surface.

Then goes on to say..

THE NON-COMBUSTIBLE MATERIAL NEED NOT EXTEND HORIZONTALLY ***PAST THE BARRIERS THICKNESS**. The initial barrier should consist of materials such as CERAMIC TILE, ...

Since the non-combustible material can be ceramic tile and NEED NOT EXTEND horizontally past the barrier's thickness, the construction of the wall is not relevant.

THAT is why I am reaching out to Bluestar.

Because I have a completely different read on this than you do.

And ceramic tile IS non-combustible and heat resistant (not that it matters as the BlueStar docs specifically list it as an acceptable material) that does NOT need to extend "horizontally pasty the barrier's thickness".

Yes, ceramic tile is considered fireproof, non-combustible, and highly heat-resistant, as it is made from natural clays and minerals fired at high temperatures. They will not burn, melt, or release toxic fumes, making them ideal for kitchen backsplashes and fireplace surrounds.

@retiredinmi I think what is going on here is that there are different installation manuals. I bought a Bluestar Platinum range 8 years ago and it appears the installation instructions have changed.

First link does not say anything about extending horizontally. This is the installation manual that was around when I purchased my range. Second link must be what you are referring to and the newer manual.

https://www.bluestarcooking.com/wp-content/uploads/2016/02/FreeStanding-Range-Installation-Manual-750163-1.28.18.pdf

https://www.bluestarcooking.com/wp-content/uploads/2019/03/BlueStar-FreeStanding-Range-Installation-Manual-750163-Rev3.28.19.pdf?utm_source=chatgpt.com

@retiredinmi

I think your point made after my last message is consistent with what I wrote; if the testing has been performed and the implications of the results allow a lesser wall construction to meet safety requirements vis-a-vis wood degradation due to heat, inter alia, then the manufacturer can write requirements such as tile is good enough.

Conceivably, an oven could be so well insulated that hot air rising up the back was tepid and no special precautions would be needed, other than for resisting pan flambès.

@retiredinmi Yes there is contradicting language. From reading the new manual clearance section it appears you are correct. If you used island trim as long as the back of the wall is covered in non combustible tile 6 inches below horizontal plane and 6 inches above you should be ok.

Reading the newer manual my range installation would not be correct. It was at the time.

When a unit is installed with any other back guard in a zero clearance condition, noncombustible/heat resistant materials are to be used in a vertical plane for a minimum distance of 6” below the top horizontal plane of the unit and at least equal in height to the back guard being used.

I have the 24 inch backguard with shelf. My back wall is log as it is a log cabin. It is not noncombustible. Although my range is not directly against the wall. There is about a 2 inch gap(long story). The place hasn't burned down so I guess we are good.

I am not even sure what the point of a backguard is because the newer instructions say you still need non combustible materials 6 inches below and atleast equal in height of backguard above. So according to those instructions I would need a 24 inch high non combustible surface behind my range which is more than what it says for island trim. So island trim 0 clearance only needs 6 inch high noncombustible surface but a 24 inch high backguard would need a 24 inch non combustible surface. I don't get it unless I am reading it wrong.

What we are trying to avoid with wall studs (and I suppose where applicable sheet rock paper) is long term pyrolysis that leads to potential combustion. The temperature that can induce this is believed to be well below that which causes wood to rapidly char. It seems to be a combination of temperature and time, and may be as low as 170F for a large number of hours (need not be continuous). Reviewing the document in the link below may help. If one's tile only reaches hot house water temperature of 120F, then I think you would be safe. Note that the temperature behind the tile may well be close to that on the exposed surface. Even 1.25-inch soapstone (rock) has fairly high thermal conductivity, so would need to be air gapped from wood if subject to high heat on one side.

https://www.warrenforensics.com/wp-content/uploads/2016/06/PUBLICATION-Low_Temperature_Ignition_Wood-.pdf

As @kaseki said, temperature the wall reaches and sustains in normal use is what would determine if the wall needs to be non-combustible or protected by an air gap.

If normal operating temperatures aren't high enough to be an issue then the only concern is protection from transient events like a pan flare up. In that case a protective surface over a combustible wall is fine, as the high heat event isn't expected to last long enough to overheat the wall.

You wrote initially, " Hi, all..considering the Blue Star Range (or more likely, Range Top)". I thought that is what you were installing a rangetop and all my comments were about that.

EOM.

If you e-mail Bluestar, they get back to you pretty quick. I just purchased the 30" open burner range, its an awesome cooktop! If you cook with a wok, just remove the grate and the wok sits right in the well directly on top of the burner! No need for a wok ring! The Garland open burners are in a class of their own! I know a range top is different, but Bluestar told me they want the range as close to the back wall as possible.

If the current BlueStar manual says 6 inches of noncombustible material like tile is acceptable for zero clearance, then that’s what counts. Installers and inspectors go by the manufacturer’s latest specs, not old forum posts. Just double check with your local inspector to be safe, but if you’re following the current manual you should be fine without the backguard