However, the reconstructed roof was not a perfect copy of the original Madison-era roof.  Because 19th century terras roofs were known to leak, the architects wanted to ensure that the new roof would be watertight.  To solve the problem a modern rubber membrane was inserted between the wooden sheathing boards and the metal plates that covered the top of the roofs' ridges and furrows.  To further ensure that the roof would last, the architects also upgraded the iron sheets that had originally covered the roofs with stainless steel.  While President Madison had used iron sheets that were left over from the construction of the original Capitol building in Washington, DC for his roofs, stainless steel sheeting was selected for the reconstructed roofs because it was almost identical to the original iron sheets but will last for many, many more years.