Illinois Roofing License IDFPR #19HC00108700 · GAF Certified Contractor
Gutters and roofs are different products installed at different times by different contractors. But they work together as a single water-management system – and when one fails, it often takes the other with it. This guide explains how the roof and gutter system interact, when to replace them together vs separately, and the drip edge details that determine whether the system actually works.
How the roof-and-gutter system works together
Picture a heavy rainstorm. Water hits the roof, runs down the slope to the eave, and needs to be captured by the gutter rather than running behind it onto the fascia, soffit, and wall. This handoff between roof and gutter is where most failure happens. The components that make it work:
- Drip edge at the eave – bends water out and over the gutter lip instead of letting it wick back behind
- Properly sized and positioned gutter – wide enough to capture flow, hung at the right angle and depth relative to the roof edge
- Adequate downspouts – enough capacity to carry the gutter’s water away
- Clean gutter – debris-free so water actually flows to the downspouts
When all of these work, water from the roof leaves the property quickly. When any one fails, water finds the fascia, soffit, foundation, or basement.
The drip edge + gutter relationship
Drip edge is the L-shaped metal trim at the eave (covered in detail in our drip edge installation guide). For drip edge to work with a gutter:
- The drip edge has to extend over the back edge of the gutter, not just to the fascia
- The vertical leg of the drip edge has to drop into the gutter trough, not stop short of it
- The gutter has to be hung at a height that aligns with the drip edge extension
When the gutter is installed first and the drip edge later (during a roof re-do), this alignment often gets missed. The contractor focuses on the roof and the drip edge sits flush with the fascia instead of extending into the gutter. Water then misses the gutter and runs behind it.
This is why pairing gutter and roof replacement makes sense: the gutter gets hung after the drip edge is in place, with the alignment correct from the start.
When to replace gutters with the roof
Strong reasons to replace gutters when re-roofing:
- Gutters are 20+ years old – original aluminum gutters typically last 20-30 years; brackets fail, seams leak, sections sag
- Gutters are pulling away from the fascia – sign of bracket failure or rotted fascia
- Gutters back up regularly – even with cleaning, the gutter may be undersized or positioned wrong
- You’re adding gutter guards – installing guards is easier on new gutters than retrofitting old ones
- The roof scope includes fascia replacement – gutters mount to fascia, so fascia work means gutters come down anyway
Reasons to keep existing gutters:
- Gutters are recent (under 10 years old) and in good condition
- Brackets are sound and aluminum is straight
- Drainage pattern is working – no chronic overflow or backup
If you’re keeping existing gutters, plan to take them off and reinstall during the roof job. Most roof crews need them off to install drip edge correctly anyway. Reinstall labor is a small line item.
Gutter sizing and downspout capacity
Most Illinois homes have 5-inch K-style gutters and 2×3 inch downspouts. This is fine for moderate-sized homes with normal rainfall. Heavier requirements:
- Larger roof areas (2,500+ sq ft) – consider 6-inch gutters and 3×4 inch downspouts
- Steep-pitch roofs (8/12+) – water flows faster off steep roofs; larger gutter handles the higher peak flow
- Roof valleys flowing into a single gutter run – the gutter section that takes valley discharge needs more capacity than a straight slope; sometimes a 6-inch section makes sense even on a smaller home
- Long roof slopes – slopes over 30 feet long can outpace 5-inch capacity in heavy rain
Trill Roofing checks gutter sizing during the inspection and recommends upgrades when warranted. The cost difference between 5-inch and 6-inch is small (~$1-$2 per linear foot installed).
Gutter guards
Gutter guards prevent leaves and debris from accumulating in the gutter. Several technologies:
- Foam inserts – cheapest, fastest install. 5-7 year lifespan. Acceptable for moderate debris.
- Mesh / screen guards – fine mesh sits over the gutter. Stops most debris but small particles can still pass through.
- Surface tension (reverse curve) guards – water adheres to a curved surface and flows into the gutter; debris falls off. Brand names: LeafGuard, Gutter Helmet. Expensive but most effective.
- Micro-mesh stainless steel – premium product with the smallest mesh openings. Brand names: LeafFilter, GutterShutter. Very effective but high cost.
For Illinois homes in heavy tree-canopy neighborhoods (most of Godfrey, Edwardsville, parts of Alton), gutter guards pay back in reduced cleaning labor and reduced ice dam frequency.
What Trill Roofing does
Our standard roof replacement scope includes:
- Removal of existing gutters as needed for drip edge installation
- Inspection of gutter condition with recommendation to replace or reinstall
- Reinstallation of existing gutters (if kept) with proper alignment to new drip edge
- Gutter replacement (if approved) using K-style aluminum or larger sizes as recommended
We don’t push gutter replacement when existing gutters are fine. We do recommend it when the inspection identifies real failure points.
Schedule a roof + gutter inspection at /free-inspection/.
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No-pressure, written estimate. Family-owned. IL-licensed. Serving Godfrey and the Riverbend.