This Lancaster bungalow has a low-profile roof and shed dormer with deep overhangs and brackets. It has an enclosed, full-width porch, wood shingle siding and a brick chimney. It was built circa 1925.

If you want to boost your home’s usable square meterage, using the space underneath the roof is a great way to do so – and dormer windows could make a conversion feasible. And it’s these projecting ...