「とすると石造り？」「一般的なＲＣ造よ」

「？」「」

'So then, is it stone construction?' 'It's ordinary RC construction.'

Literal

''If-so, stone-made?'' ''Ordinary [possessive-の] RC-made is [feminine-よ].''

Architecture/construction shoptalk. 石造り ('stone construction'), RC造 (RC construction — 鉄筋コンクリート造, 'reinforced concrete construction') are standard construction-industry shorthand. 造り ('make, build, construction type') is a suffix for describing how something is built: 石造り, 木造, 煉瓦造. とすると ('if that's the case, then...') is a conditional connector.