Index: src/industrytype.h
===================================================================
--- src/industrytype.h	(revision 19053)
+++ src/industrytype.h	(working copy)
@@ -84,6 +84,7 @@
 enum IndustryTileSpecialFlags {
 	INDTILE_SPECIAL_NONE                  = 0,
 	INDTILE_SPECIAL_NEXTFRAME_RANDOMBITS  = 1 << 0, ///< Callback 0x26 needs random bits
+	INDTILE_SPECIAL_DONT_BUILD            = 1 << 1, ///< Tile is not actually built (intended for checking clearance on layouts)
 };
 DECLARE_ENUM_AS_BIT_SET(IndustryTileSpecialFlags);
 
Index: src/industry_cmd.cpp
===================================================================
--- src/industry_cmd.cpp	(revision 19053)
+++ src/industry_cmd.cpp	(working copy)
@@ -1598,8 +1598,9 @@
 
 	do {
 		TileIndex cur_tile = tile + ToTileIndexDiff(it->ti);
+		const IndustryTileSpec *itspec = GetIndustryTileSpec(it->gfx);
 
-		if (it->gfx != GFX_WATERTILE_SPECIALCHECK) {
+		if (it->gfx != GFX_WATERTILE_SPECIALCHECK  && !(itspec->special_flags & INDTILE_SPECIAL_DONT_BUILD)) {
 			i->location.Add(cur_tile);
 
 			WaterClass wc = (IsWaterTile(cur_tile) ? GetWaterClass(cur_tile) : WATER_CLASS_INVALID);