Hi Jim,
You can find a full downloadable installation manual on Gazco's product page:
https://www.stovax.com/stove-fire/inset-gas-fires/designio2-steel/
This is a conventional flue gas fire so would require either a class 1 brick chimney flue or a class 2 pre-fabricated flue of sufficient depth for installation,
The installation manual does not specify fire rated boarding but the manufacturer does heavily recommend fire board or preferably a back panel of natural material (e.g. granite, limestone, slate, etc.) to help avoid cracking over time.
Whether metal studwork would be required, such as in the event of a partial false chimney breast to bring the fire forward, is likely going to be dependent upon the thickness of boarding and the distance of the fire from any combustible material. We would heavily recommend speaking to your Gas Safe engineer to confirm in either event, as they will be able to advise in terms of designing this to meet Document J regulations,
Please feel free to contact our Sales team via 0161 376 4181 or
[email protected] if you need any further advice