I'm thinking of installing a woodstove in my cabin. How far away must I install it from the walls (which are surfaced with wood planks)? Should I cover the nearby walls with bricks? Is there any other surface which would be better (I have seen sheet metal used in some places)?
In the US, there should be a 36" clearance between any point on the stove and any point on a combustible wall. Shielding should be mounted on non-combustible spacers which allow air circulation behind the shield. UL-listed stoves with attached heat shields may be installed with less clearance according to manufacturer's specifications (you should consult their documentation before purchase).
I would suggest getting a piece of fiber cement board and covering it in a heat resistant clay wall tile. You can screw the fiber board to the wall prior to tiling so there are no obvious fixings.