Single or bulk services order

Hi guys,

My partner has recently got property maintenance contract for 22 old houses, which are in different states of bad health.

I wanted to know if it makes a big difference in costs go get repairs done one by one or giving bulk orders. e.g for Roofing : How much cost savings there would be if we give order to one company for 20 roofs instead of 1?

If we can standardize all materials and take personal choice and guesswork out of the equation.

What about other essential repairs like driveway repair, lawn work?

Does the cost have significant impact for bulk orders? If it does, we can pick up more properties quickly.

Please share your thoughts.

Thanks.