Width of heat shield behind woo stove?

[frenchy85]

If you guys (and gals) could give me some some help I would greatly appreciate it. We're putting a heat shield behind our wood burner at camp. We're going to use 1" emt conduit to space the 1/2" cement board off the wall. I've found all the clearances that I need except for one. How wide does the heat shield need to be? I've spent the last hour trying to find something. The wood stove is 20" wide. Will a 4' wide heat shield be sufficient and safe? We will go wider if necessary but 4' would work a lot better. Thanks

 

[Fred Wright]

The following link is from Delaware but it may help: http://nasdonline.org/1248/d001052/wood-stove-installation-and-operation.html