Twelve of the fourteen BL Mk XII guns were mounted in casemates along the broadside of the vessel amidships; the remaining pair were mounted on the forecastle deck near the aft funnel and were protected by gun shields. The anti-aircraft (AA) armament were composed of two quick-firing (QF) 20 cwt Mk I guns. The ships were fitted with four submerged 21-inch (533 mm) torpedo tubes, two on each broadside. "Barham" was completed with two fire-control directors fitted with rangefinders. One was mounted above the conning tower, protected by an armoured hood, and the other was in the spotting top above the tripod mast. Each turret was also fitted with a 15-foot rangefinder. The main armament could be controlled by 'B' turret as well. The secondary armament was primarily controlled by directors mounted on each side of the compass platform on the foremast once they were fitted in July 1917. The waterline belt of the "Queen Elizabeth" class consisted of Krupp cemented armour (KC) that was thick over the ships' vitals. The gun turrets were protected by of KC armour and were supported by barbettes thick. The ships had multiple armoured decks that ranged from in thickness. The main conning tower was protected by 13 inches of armour. After the Battle of Jutland, 1 inch of high-tensile steel was added to the main deck over the magazines and additional anti-flash equipment was added in the magazines. The ship was fitted with flying-off platforms mounted on the roofs of 'B' and 'X' turrets in 1918, from which fighters and reconnaissance aircraft could launch. During her early-1930s refit, the platforms were removed from the turrets and an retractable Type EIT catapult was installed on the roof of 'X' turret, along with a crane to recover a floatplane. This was initially a Fairey IIIF until it was replaced by a Fairey Swordfish in 1938. "Barham" received a series of minor refits during the 1920s. In 1921–1922, rangefinders replaced the smaller ones in 'B' and 'X' turrets. Two years later, her anti-aircraft defences were upgraded when the original three-inch AA guns were replaced with a pair of QF Mk V AA guns between November 1924 and January 1925 and another pair of four-inch AA guns were added from October to November later that year.