Both firebrick and decorative front arches needed?

[Audionatic]

I'm back to working on my oven as much as possible again, and have reached the point where I'm trying to finish off the front vent area, so I can start using this thing. I should have built this from front to back, so I would have been assured of enough room to support my front arches and a cantilevered front stone shelf. Instead, I worked from the rear oven wall to the front, and now find myself a little short on space to finish the front vent entry with fire brick sides, and firebrick front entry arch, then also a front decorative arch. My thinking was that the firebrick arch was needed to protect the decorative arch from the heat of the hot gases on the back side within the gallery. Now, as I finish up the brick work on my base, I've found I'm a little short on room, but can create a bit more with the last several courses of brick on the base facade if I have to. My question is this: Can I get away with building only a single front arch, out of my new decorative brick, and save the depth of that 4" wide firebrick arch? My decorative brick is solid and heavy. My gallery is 25" wide x 9" (length of a full firebrick). If I build above that decorative arch with old used brick, as I have with my base, will that type brick likely hold up to the heat on the inside? Eliminating the planned firebrick arch will save me space, and time, but I'll go with whatever the consensus is here. See attached photos where Im showing the mock-up of the depth of the two arches on the left, and the decorative brick only on the right.

[NCMan]

Firebrick are only necessary where fire will or might be in direct contact w/them. There is no real need to use them anywhere else, unless that's just what you want to do. I'm not sure if that's what you are asking, but hope it helps.

[Gulf]

I like having both arches. Aside from not having the worry of mixing different materials, there are a couple more pluses gained by including both. The decorative face (if it is separated from the firebrick) will make it more comfortable for you to work the oven on a hot day. It also allows for a reveal in which to easily place a storm door. You could gain an inch and a half by cutting the outside firebrick arch down to 3". You could gain anther inch or two on the decorative face. If you haven't seen it, check this post and discussion out.

[Audionatic]

To be clear:
Do you think the backside of the outer arch bricks will get too hot, to use anything other than firebrick, at 9" depth? Where the smoke leaves the oven the opening at top is 25" wide x 9" depth forward to the inside of the outer arch. I've tried to over-build where possible, but am trying to get this thing ready for winter. Thanks, and let me know what you think.

[deejayoh]

My $0.02 is that you don't want the firebrick to be exposed to weather. Soaks up water like a sponge. that''s why I put a decorative arch in front of the firebrick.

[Audionatic]

Ok. Consensus is clear that I'll need both arches right at the landing. Thanks all for the opinions.
I'll create some extra space with my brickwork.

[fornax hominus]

I used the two arch method , but I used red common brick , as I figured it was not a super hot face , [all the extra air cooling it off ] and 7 years later no problems !