Fixes several wall issues.

code/game/turfs/simulated/wall_icon.dm

@@ -69,6 +69,7 @@
 /turf/simulated/wall/proc/set_material(var/material/newmaterial, var/material/newrmaterial)
 	material = newmaterial
 	reinf_material = newrmaterial
+	update_material()
 	check_relatives()
 	check_relatives(1)
 
@@ -85,7 +86,10 @@
 	else
 		set_wall_state("[material.icon_base]fwall_open")
 
-	var/overlay = round(damage / material.integrity * damage_overlays.len) + 1
+	var/dmg_amt = material.integrity
+	if(reinf_material)
+		dmg_amt += reinf_material.integrity
+	var/overlay = round(damage / dmg_amt * damage_overlays.len) + 1
 	if(overlay > damage_overlays.len)
 		overlay = damage_overlays.len
 	if(density)
@@ -115,11 +119,11 @@
 		var/turf/simulated/wall/T = get_step(src, checkdir)
 		if(!istype(T) || !T.material)
 			continue
-		if(T.material && can_join_with(T))
-			if(update_self)
+		if(update_self)
+			if(can_join_with(T))
 				junction |= get_dir(src,T) //Not too sure why, but using checkdir just breaks walls.
-			else
-				T.check_relatives(1)
+		else
+			T.check_relatives(1)
 	if(!isnull(junction))
 		set_wall_state("[material.icon_base][junction]")
 	return

code/game/turfs/simulated/walls.dm

@@ -144,15 +144,15 @@ var/list/global/wall_cache = list()
 
 	return ..()
 
-/turf/simulated/wall/proc/dismantle_wall(devastated=0, explode=0)
+/turf/simulated/wall/proc/dismantle_wall(var/devastated, var/explode, var/no_product)
 
 	playsound(src, 'sound/items/Welder.ogg', 100, 1)
-	if(reinf_material)
-		reinf_material.place_dismantled_girder(src, reinf_material)
-		reinf_material.place_dismantled_product(src,devastated)
-	else
-		material.place_dismantled_girder(src)
-	material.place_dismantled_product(src,devastated)
+	if(!no_product)
+		if(reinf_material)
+			reinf_material.place_dismantled_girder(src, reinf_material)
+		else
+			material.place_dismantled_girder(src)
+		material.place_dismantled_product(src,devastated)
 
 	for(var/obj/O in src.contents) //Eject contents!
 		if(istype(O,/obj/structure/sign/poster))
@@ -161,6 +161,11 @@ var/list/global/wall_cache = list()
 		else
 			O.loc = src
 
+	clear_plants()
+	material = name_to_material["placeholder"]
+	reinf_material = null
+	check_relatives()
+
 	ChangeTurf(/turf/simulated/floor/plating)
 
 /turf/simulated/wall/ex_act(severity)
@@ -275,6 +280,5 @@ var/list/global/wall_cache = list()
 	..()
 
 /turf/simulated/wall/Destroy()
-	clear_plants()
-	check_relatives()
+	dismantle_wall(null,null,1)
 	..()

code/modules/materials/materials.dm

@@ -40,6 +40,9 @@ var/list/name_to_material
 	if(!display_name)
 		display_name = name
 
+/material/placeholder
+	name = "placeholder"
+
 /material/proc/place_dismantled_girder(var/turf/target, var/material/reinf_material)
 	var/obj/structure/girder/G = new(target)
 	if(reinf_material)