I bought this 3 bedroom duplex with I sitting room since 2019 ,but the upper part is opened which means they didn’t deck the upper part . And we are a family of 5 (3 children) . So I am thinking of covering the upper part (deck it ) and make it a sitting room to create more space for the family . The present design of the interior is a mordern style which allows the upper part to be a total waste of space and I am thinking of turning the space to a parlor probably for the children . I want to know how much it will cost me to deck base on the present cost of building materials and is it advisable to convert the empty space to a sitting room or I should just leave it the way it is .

Please my fellow NLanders help me push this to the FP Your advises & suggestions is urgently needed