Clearance to non-combustables

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New Member
Dec 20, 2021
I've just moved into a new home and removed an old cast iron fire back and opened up the builders opening in the hope to install a wood stove. The opening turned out to be quite small ( 580 wide 350 deep 800 high mm). The lintel is a throat forming lintel which is moulded to the chimney stack and the jams are only 330 mm so I'm not confident to start widening the opening as I don't think I can get away with removing any masonry without making the breast unstable.

from the research I've done most stoves recommend a minimum air gap to non combustables at the side of at least 150mm for optimal heat output and maintainance. I can't achieve this clearance with the opening I've got and am struggling to find much information regarding just how badly a smaller gap will effect output. I'm hoping for the stove to be my main source of heating in the living room so would be gutted if it effected it a lot.

From what I've read you can counter the problem by having the stove sit proud of the opening to allow better air flow which I'm considering but I'm concerned that when I get building control to sign off my work they may want to see manufacturers recommendations and see I hadn't allowed the correct clearances and potentially not certify.

Any help would be much appreciated, would it be worth it to get a builder in to see if they can safely widen the gap?
Should I go for a stove that recommends less clearance to non coms. (For example ACR woodpecker wp5 recommends minimum 50 mm)
Or go for a stove that will sit proud of my opening and fit a rear flue?

Many thanks
The UK has many more stove options than we have here in the states. As long as the rear-vent flue exit is below lintel and a proper hearthpad sits under the stove, that plan should work. However, if there is a combustible mantel those clearances also need to be honored. Another option would be to put in a narrow box-style stove like a Morso 2B in with a vertical flue outlet, so that the only the front of the stove is projecting into the room.