CHARLOTTE, North Carolina — As investigators work to uncover the cause of last week’s deadly construction fire in SouthPark, new details are emerging about the type of construction used at the site. The 239-unit luxury apartment building had a wood-frame construction, an increasingly common style over the past decade. …Two construction workers died and 15 others had to be rescued. …While international building codes adopted by North Carolina allow for wood-frame buildings, some fire science experts worry about the style’s prevalence. …Glenn Corbett, at John Jay College in New York… said “The more wood on a project, the harder it is for firefighters to put flames out because the framing contributes to the fire. …Other experts expressed confidence in the safety of wood-frame buildings when complete, saying wood is not the enemy. They pointed, though, to the need for more early-warning notification systems to workers and first responders when fires start in buildings that are under construction.