I agree very much with @Brian Pulaski, creating your own scope as detailed as possible will ensure that they are quoting the same thing. With lack of experience, it may be difficult for you, and that’s ok, it’s how we learn. When you leave something out, and the cost increases, it’s the lesson that you won’t forget. But after you write your scope, I’d be happy to review it for you and see if anything is blatantly missing.
I managed constructuring for years before investing or becoming an agent, and can attest to how detailed you need to be until you know the person you hire well, so well that you feel confident they can read your mind. Otherwise it’s a shot in the dark and you can’t build a business on that. Here’s an analogy, if you go to an upscale restaurant that was recommended by a friend because they had wonderful porterhouse steak and say, I’ve got $100 to spend and I want meat for dinner, with a starch and a veggie, and I’m thirsty, so add some fluid, thinking the chef will take care of you. What comes out is a glass of red koolaid with no ice, a dry piece of boneless chicken breast, grilled and slightly burnt, with white rice and a Brussel sprouts. When you wanted a medium rare Filet minion, with garlic mashed potatoes and grilled zucchini, with a glass of red wine from NAPA. Those are two COMPLETELY different meals, that both meet the same description given above, and one main difference is the restaurant will make a whole lot more giving you the first one, and they really met the demands. Whatever your vision is for your project, you have to describe it as clear as possible for your contractor. If you hire an architect, it’s your job to let them know what you want and they will spell it out as clear as possible for the contractors. The better the architect the better and clearer the description. If the fireplace mantel is supposed to have two hooks integrated and perfectly spaced evenly, side to side for Christmas stalkings, and painted the same color so they blend in, and only 1” tall, the contractor needs to know that upfront, so they can plan to do it, and know what to charge you for that. Otherwise if you just say you want to rebuild the fireplace mantel when you walk by with one contractor, and they envision a wooden mantel without any decorative detail, and the next contractor is thinking brick surround, and bluestone in front, and a metal mantel above, and powdercoated, that’s going to take more time, cost more money and you said the same thing to both of them but they have different experiences and vision. You need to focus their vision and see if they are comfortable creating it.
Then once they are on the same page, and if their numbers come back similar, that probably means it’s somewhat accurate, but the only way to know if get as many quotes as possible, if 5 quotes are within $5k and one is $20k cheaper, it probably means the low guy missed something and will try to get it back later through an argument, or just leave it out because it was missed and may not get discovered, or he underbid the job just to get it, and either won’t have enough money to pay his crew and finish, will finish but will try to get more money out of you through change orders, or just may not make any money, which is bad for him and you because he won’t be in business much longer!
Ask your agent if they have a good contractor they trust. And make sure you and them have really looked through comps for the ARV (after repair value) and really know how much room you have to play with.
It’s hard to say what a roof will cost without seeing it, if the house is only 1400sf, it may be a ranch, without dormers or charges in roof line. Does the sheathing need to be replaced or is it in good condition? Have you seen what it looks like from the attic space? If it’s just removal of shingles and replacement and there is just a single ridge, it may only be a few thousand. If there are a bunch of dormers, different sections, needs full plywood replacement, it may be over 10-15k. That’s where the detailed scope comes into play! Are you buying materials for the roof, or in the contractor supposed to provide everything they need to get the job done, the prices will be very different for each of those options.
Long story short, I would write down a thorough scope, and give it to the contractors that have given you the prices, see if they need to change anything in their quote, and also get 2 more contractors in there, using that new scope you just created.
Where is the property, I want to see if anyone I know would work in that area. Keep us posted!