What Chicago Requires When You Re-Roof: Layers and Insulation

If you are looking up re-roof insulation requirements in Chicago, the short version is that two rules do the heavy lifting: a rule about how many layers are already up there, and a rule about insulation minimums in the energy code. Both come from the City's own Express reroofing page. Neither is the same as the permit question (the full picture is in the Chicago roofing guide), which we cover in the Chicago roof permit guide. This article is about what the City checks once you are re-roofing.

What does "re-roof" mean to the City?

The City's Express reroofing page sorts reroofing into three kinds of work it will review through Express: roof repair limited to 25 percent of the roof area, a roof recover over one existing layer, and a roof replacement with no structural work.

A recover means the new roof goes on top of the old one. A replacement means the old roof comes off. Which one is right for your building depends on what is under the old roof, and a roofer cannot know that from the street. The Express program was set up in November 2023 to replace the old paper Easy Permit process (City of Chicago), so older advice about "easy permit reroofs" is out of date.

How many layers can a Chicago roof have?

Here is what the City says, and only what it says. Express covers a recover over one existing layer. If the new work would add a layer over two or more existing layers, the City requires drawings from an Illinois-licensed architect or structural engineer (City of Chicago). Structural repairs to the roof structure also need those drawings (City of Chicago).

What we cannot tell you is whether the Chicago code sets an absolute cap, such as "never more than two layers." We have not found that in the sources we could open, and you will see roofers and websites state a cap as fact. Do not take it at face value, and do not take "you can always add one more" at face value either. The City's wording is about what gets drawings, and the Department of Buildings is the place to confirm the rest for your roof.

If you have a pitched shingle roof and are wondering about roofing over what is there, we have a separate answer in can you roof over old shingles in Chicago.

What do the insulation rules say?

The City's page says reroofing must meet the Chicago Energy Transformation Code insulation minimums, and that Express reroofing is not available for work that does not comply (City of Chicago). The page points to the energy code sections that apply: one for commercial roof replacement, and one residential section with an exception for reroofing.

We are not quoting R-values, reflectance numbers or "cool roof" requirements. We could not confirm current figures from a primary source, and the energy code has been updated more than once. What you can do with this rule:

• Ask your roofer, in writing, what insulation the new roof will have and which code section they are meeting.
• Ask whether the old insulation stays, gets added to, or comes out. That answer often follows from the layers question above.
• If the answer is vague, call the Department of Buildings. A roofer who says "that's not a thing in Chicago" is wrong, because the City lists it as a condition of Express reroofing.

When do you need drawings, and who draws them?

Express handles the simple cases. Two roofing jobs fall out of it and need drawings by an Illinois architect or structural engineer: adding a layer over two or more existing layers, and structural repairs to the roof structure (City of Chicago). The City says an architect or structural engineer is needed for any plan-based permit, while most Express-eligible repair work needs none (City of Chicago).

This matters for timing and for cost. A roof that turns out to be structurally soft once the old layers come off can change the type of permit mid-job. Ask your roofer how they handle that before you sign: who finds out, who tells you, and what changes in the contract.

What else can make a re-roof ineligible for Express?

The City lists several reasons a reroofing job cannot go through Express (City of Chicago):

• the work is done by someone without a valid Illinois roofing contractor license,
• the building has an unpermitted rooftop feature (the City's example is an unpermitted roof deck),
• the materials or methods do not meet Building Code minimums, or
• the work does not meet the Energy Transformation Code insulation minimums.

The rooftop feature rule surprises owners. If a previous owner built a deck, a shed or a mounted unit on the roof without a permit, that can block a clean Express reroof. See what to check before putting a deck on a flat roof for the other side of that problem.

Who has to hold which license?

Roofing in Illinois is licensed by the state: roofing and waterproofing work may be done only by a licensed roofing contractor or qualifying party (Illinois law). The City's Express page adds that a Chicago-licensed general contractor (Class A to E by project cost) is required unless the owner qualifies as an owner-contractor, and that the general contractor or the roofing subcontractor must hold a valid Illinois roofing license (City of Chicago). Check both before you pay a deposit.

What to ask before you sign a re-roof contract

1. How many layers are on my roof now, and how do you know?
2. Is this a recover or a replacement, and why?
3. What insulation will the new roof have, and which energy code section does it meet?
4. Does anything on my roof need a permit of its own, such as a deck?
5. Who pulls the permit, and what is the number?
6. If you open the roof and find a structural problem, what happens to the permit and the price?

Water that stays on the roof also shapes the insulation choice, since tapered insulation is one way to build slope. See flat roof drainage in Chicago. When you want a straight read on your roof, our roofing crew will look at it and tell you what the City is likely to ask for.

Common questions

This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.