Recently, with the situation in Gaza worsening again and many buildings being destroyed, the lack of construction material to aid in rebuilding has been brought up again.
The IDF claims, on their official site (published 2018, according to the page source):
In addition, lack of necessary resources continues to have a detrimental effect on the population. Although a large amount of building materials enters Gaza from Israel (more than 3.5 million tons of construction material in 2016 alone), a significant portion does not reach construction companies, and is instead diverted to Hamas' [sic] tunnel building activities.
A Google search doesn't really turn up any results on this past 2015, though, and the IDF isn't exactly an impartial source here.
Are there other sources that corroborate this claim? Is Hamas exacerbating the scarcity of construction materials in Gaza by seizing materials?