They were skimping on building materials to save money, and the house developed problems quickly.

skimping 是动词 skimp 的现在分词形式。skimp 的意思是"节省、吝啬"，常带有贬义，指为了省钱而减少必要的开支或降低质量。skimping 在这里表示"偷工减料"的行为。