What to Look For When One Bid Is $15,000 and Another Is $20,000

Why is one roofing bid $15,000 and another $25,000 for what looks like the exact same roof? Because they are not the same roof. They just might look the same on paper. And once you see the differences, you cannot unsee them.

I get questions about roofing estimates constantly, and they almost always come down to three: why are the prices so different, how do I compare the bids, and is going with the lowest bid really risky? After 15 years as a roofing contractor in Colorado, here is how I would walk a homeowner through all three, so you can ask better questions of whoever you are considering.

Why Are Roofing Estimates So Different?

When you have three or four bids in front of you that all say "new roof" and list a bunch of materials, but the prices are thousands of dollars apart, that is frustrating. But that spread is the truth telling you something. They are almost never the same scope of work.

A price by itself does not mean anything. A lot of what you find online for typical roofing prices is just national-average junk that has nothing to do with your specific area, and we are in Colorado, where the climate and code drive real differences. Or it is a website trying to grab your phone number. Neither one tells you what your roof should cost.

Even three real, local bids will spread out. And when they do, that spread is usually three different scopes of work, all hiding behind the same generic roofing-bid language. The cheapest one is usually not the smart deal. It tends to be the smallest scope of work.

So the move is not to ask why one bid is cheaper. The move is to ask what is actually in each estimate. That is what the rest of this guide is about.

How Do You Compare Roofing Bids?

It is easy to say just go line by line between the estimates. But I have found that when I write really detailed bids like that, they can actually create even more confusion. You end up with 313-page estimates and a ton of detail, and it does not help you decide.

Instead, for an asphalt shingle roof replacement, think about it in four categories. If you understand these four, you can read almost any roofing bid.

1. Underlayment

Are they using paper felt, or a new synthetic underlayment? I recommend the synthetics. There can be real differences between types, so if one contractor is using a higher-grade underlayment, they may have good reasons for it. This is the first place two bids quietly diverge.

2. Leak barrier (ice and water shield)

This is a big price mover. Most professional roofing contractors, if you ask them what they would put on their own house, will insist on leak barrier, also called ice and water shield, in the valleys and on the eaves. It is expensive material, but in my mind it is completely worth it in Colorado. If one estimate includes it and another does not, those two bids could already be thousands of dollars apart right there.

3. Ventilation

The easy question is: are you replacing the vents that are up there? A lot of contractors will say yes, we are replacing the slant-back or turtle vents on the roof. But are they also replacing the bathroom vents and the laundry vents? A better question is whether you even have the right quantity and layout of vents. Sometimes replacing what is already there is not right, and a contractor should be adding to it or changing the design. This matters beyond price: proper ventilation is often what keeps your shingle manufacturer warranty valid.

4. Detail flashings

Two things live here, and both get skipped on cheap bids.

Step flashing is the flashing at roof-to-wall junctions. The material itself is not that expensive, but there is real labor in installing it or replacing what is there. A cheaper bid might just leave the old step flashing and interlace the new shingles between it, which is not something I recommend. On a home with a lot of roof-to-wall junctions, doing it right can move the price by hundreds or thousands of dollars.

Drip edge is the metal flashing that goes around the entire perimeter of the roof. Definitely look for this on your estimate. Where we work in Colorado, it is required by building code for the entire perimeter. There are cheaper versions, and the profile changes how well it performs. We like a 2 inch by 4 inch drip edge because it gets much better results and much less risk of water getting to the homeowner. One estimate might include a cheap, small 2 inch by 1 inch drip edge, and another a 2 inch by 4 inch, and that alone is a price difference of a couple hundred dollars.

Add up all four categories and you can very quickly find $5,000, $6,000, even $10,000 in price differences, even on an average-sized roof replacement. That is where your "same roof" bids actually separate.

Is Going With the Cheapest Bid Risky?

It certainly can be. I would just go into it with your eyes open, because I have watched the cheapest roof turn into the most expensive one a homeowner ever bought.

When a bid comes in thousands of dollars under everybody else's good, reputable bid, it is almost never that that roofing company found some magic savings nobody else knows about. They probably left something out. It might be tear-off details, the flashing, a higher-quality shingle, ventilation, or even something like worker's compensation insurance. That last one matters more than people realize: if a roofing crew is on your roof with no worker's comp insurance and someone gets hurt, you, the homeowner, can be on the hook for it. There is real liability there.

Then add the potential callbacks, and the leak that shows up two winters later when those guys are nowhere to be found.

Now, sometimes a smaller, cheaper scope genuinely is the right call for your budget, and that is fine. Maybe everyone else overbid it, and the cheaper contractor is the right decision. But it should be a decision you make on purpose, knowing exactly what you are getting and what you are not, not a surprise you find out about when it is raining in your living room.

So when you see a huge range of estimates, do not anchor yourself to the lowest number and then compare everything against that really low price. That might be a bid you want to throw out entirely. Start asking roofing contractors why they are doing it a certain way. If they cannot give you a good answer, that is a red flag.

The Bottom Line

The prices are different because the roofs are different, even when the bids look the same. Compare scope, not just the bottom-line number. Look at the underlayment, the leak barrier, the ventilation, and the flashings, and ask what each contractor is actually including in those four categories. Do that, and a confusing stack of bids turns into a clear decision you can make on purpose.

Frequently Asked Questions

Why are roofing estimates so different for the same roof?

Because they are usually not the same scope of work. Two bids can both say "new roof" while including different underlayment, leak barrier, ventilation, and flashing details. Those differences can add up to $5,000 to $10,000 on an average roof.

What should I compare when looking at roofing bids?

Compare scope, not just the total price. Look at four categories: the underlayment (paper felt vs synthetic), whether leak barrier or ice and water shield is included, the ventilation plan, and the detail flashings (step flashing and drip edge).

Is leak barrier or ice and water shield worth it in Colorado?

In our view, yes. Most professional contractors would insist on it in the valleys and on the eaves of their own home. It is expensive material, and whether a bid includes it is one of the biggest reasons two estimates differ by thousands of dollars.

Is drip edge required in Colorado?

Where we work in Colorado, drip edge is required by building code around the entire perimeter of the roof. The profile matters too. A 2 inch by 4 inch drip edge performs better than a cheaper 2 inch by 1 inch version.

Is it risky to go with the cheapest roofing bid?

It can be. A bid far below everyone else usually left something out, tear-off details, flashing, shingle quality, ventilation, or even worker's comp insurance. Going cheap can be the right call for your budget, but only as a decision you make on purpose, knowing what is and is not included.