If the building is brick bring a good mason who can point out possible pointing issues, pushing walls, failed lintels, etc.If you have a flat roof or even a normal roof have a good roofer check it out. 

I have a trusted roofer if you need a referral.

Roofer is neighbors son, genuinely nice guy, want to trust him.

I have also had a couple of roofers ask for all at completion of the job and nothing upfront.

Also I need a good carpenter , plumber , roofer etc any references would be great.

I've flipped a dozen houses but no longer have my original go to roofer.

Roofers price their work by the square. 

We are purchasing a 3 family in Belmont, NH. (South end of lake Winnisquam) and it needs a new roof.Reaching out here to see if anyone has a recommendation?Thank you-Donna

Talk to a few roofers I would sheath over. i wouldnt put a second layer of shingles on over the old roof but we're in snow country and i knew the roof was old...

Check with your roofer to find out if the premises need to be vacated.