Shingle Small Flat Roof Areas

When a homeowner asks me to “just shingle that little flat spot over the bay window,” I already know what’s going to happen: within eighteen months, the edge shingles will curl backward, water will track sideways under the tabs, and a brown stain will appear on the bedroom ceiling below. I’ve seen it on at least twenty tiny Brooklyn flat roofs. The mistake isn’t the size-it’s treating a flat or near-flat surface like a slope, because shingles don’t shed water when they’re laying almost horizontal. The short answer: you can shingle a small flat roof area only if you bring it up to proper slope and back it with a flat-roof underlayment system, or you risk a slow, persistent leak that ruins insulation and ceilings.

Small ‘Flat’ Roofs and Shingles: What You’re Really Asking

Around Brooklyn-Greenpoint, Sunset Park, Bay Ridge, Crown Heights-most of these “small flat roof” spots are over bay windows, front or rear bump-outs, entry porches, or at the base of shed dormers. Homeowners see asphalt shingles running up the main pitched roof, and they notice that same shingle pattern continuing right onto a nearly horizontal section below. It looks normal. Sometimes it’s been there for decades without obvious leaks. So the question forms: can you safely use shingles on low-slope or flat-ish areas, and if not, how do you cover them without starting over?

Shingles are designed to shed water downhill, not hold it. They have minimum slope requirements written into every manufacturer’s installation manual, and below that cutoff even a “small” ten-square-foot patch will leak. The gap between what looks fine from the sidewalk and what actually keeps water out is where most small-roof problems live.

First Check: Is Your ‘Flat’ Area Actually Flat or Just Low-Slope?

Before you decide whether shingles belong, you need to know if your roof is truly dead-flat or just shallow-pitched. Many “flat” roofs in Brooklyn rowhouses and small multifamilies have a slight slope-maybe 1:12 or 1.5:12-built in from old framing. Code and manufacturer instructions use slope ratios like 2:12 (two inches of rise for every twelve inches of run), and knowing whether you’re above or below those cutoffs tells you immediately if shingles are even on the table.

How to Get a Rough Sense of Slope (Without Fancy Tools)

• From inside, look at framing directions: if the ceiling is level and the roof is tiny, it may truly be dead flat above.
• From outside, see if you can spot water sitting for days after rain-persistent puddles usually mean too flat for shingles.
• Ask a roofer to measure slope during a visit; they’ll use a level or digital inclinometer and compare it to shingle manufacturer minimums.

Most asphalt shingle manufacturers don’t allow standard installations below about 2:12 to 3:12 slope. Below that, you need a flat-roof material, even on small areas.

Can You Shingle a Small Flat Roof Area? (Short Answer: Rarely, and Only If…)

Here’s the direct answer: yes, you can sometimes use shingles on small low-slope areas if they’re brought up to minimum slope and treated almost like a tiny pitched roof, but shingling a truly flat or near-flat surface is asking for leaks. I’ve shingled small sections over bays in Bensonhurst and Flatbush where we built proper slope into the framing first and used upgraded underlayment rated for low-slope installations beneath the shingles. But when clients push me to lay shingles on a surface that’s less than 2:12, I walk away-it’s just not going to work in Brooklyn’s snow, ice, and driving rain.

Minimum Conditions Before Shingles Are Even Considered

• Slope meets or exceeds manufacturer’s minimum for the specific shingle.
• Deck is smooth and solid, with proper underlayment (often an upgraded, low-slope-rated membrane) beneath the shingles.
• Water has a clear path off the small area with no parapets or dead-end corners.
• The small area ties into a larger pitched roof, not into another flat roof edge that traps water.

If water ever sits or ponds on the surface, shingles are the wrong material, no matter how small the area is.

Better Options for Small Flat or Nearly-Flat Roof Spots

For genuinely flat or very low-slope areas, you’re generally better off using a compatible flat-roof system with good detailing, then managing how it looks from the street or upper windows with trim, color, and edge metal. On a little twenty-square-foot roof over a front bay in Dyker Heights, we installed a single-ply EPDM membrane with custom brown metal edge trim that matched the shingles on the main roof above. From the sidewalk, the transition looked clean, and inside, the homeowner stopped seeing ceiling stains. That’s the trade-off: you give up the exact shingle appearance on the flat spot to gain a roof that actually works.

When Shingles and Flat Roof Materials Have to Meet

One of the most common Brooklyn details I work on is a small flat section at the bottom of a pitched, shingled roof-or a bay roof that blends into a main roof slope above. The materials change right where water changes direction, and if the junction between shingles and flat-roof membrane isn’t well designed, that’s where leaks show up in ceilings below. On a recent Park Slope rowhouse, the original roofer ran shingles right over the bay, and the bay’s flat section had no real membrane underneath-just felt paper. Every spring thaw, water backed up under the shingles at the transition line and dripped into the living room. We stripped the bay to deck, installed a full EPDM membrane with upstands at the back wall, then shingled the main roof slope and lapped those shingles over a metal drip edge that capped the membrane. That detail has held through three winters now.

Key Principles for Shingle-to-Flat Transitions

• Always lap shingle courses over upstand flashings coming from the flat-roof system, not the other way around.
• Raise the flat-roof membrane up under the shingle field to a safe height before exposing it.
• Use compatible metals and flashings between systems to avoid chemical or movement conflicts.
• Avoid “dead valleys” where two shingled slopes dump water onto a tiny flat patch; use crickets or redesign flows if possible.

Small Flat Areas You Should Almost Never Shingle

Certain small roof areas are notorious leak points when shingled, even if they look similar to a main roof. The combination of low slope, trapped edges, and heavy water flow makes them poor candidates for shingles. I’ve refused to shingle these spots outright, because I know I’ll be back in a year doing warranty work or watching the homeowner hire someone else to rip it all out and start over with a membrane.

Brooklyn-Specific Challenges With Shingling Small Flat Areas

A typical Brooklyn rowhouse or small multifamily has small “flat” sections at front bays, rear extensions, and shed dormers-all of which started life as low-slope or flat roofs before someone added shingles in a past re-roof. Some older buildings already have shingled patches that pre-date modern codes, and simply copying those details today causes problems with heavier rains, changed insulation patterns that slow drying, and stricter warranty rules from shingle manufacturers. On a Sunset Park three-story, the original flat bay roof from 1920 had wood shingles on tapered sleepers; a 1980s re-roof covered it with asphalt shingles on felt; by 2022, water was tracking under both layers and rotting the deck. We stripped to framing, rebuilt the slope to 3:12 with new joists, installed ice & water shield over the entire bay, and then shingled it to match the main roof-but that rebuild cost $4,800 for an eighty-square-foot area, because we treated it like structural work, not a patch job.

Local Factors to Consider Before Using Shingles

• Snow drifting from taller neighboring buildings onto small, flat-ish areas.
• Historic district / Landmark rules that shape visible edge details, pushing some owners to hide membranes under shingle-like trims instead.
• Multiple past re-roofs raising small flat areas higher than adjacent shingles, changing how water flows.
• Shared party walls and parapets that trap water on one side if details aren’t coordinated.
• Harsh sun and freeze-thaw cycles that punish marginal slopes more than in milder climates.

If You Decide to Rebuild Slope and Shingle a Small Area

If you’re going to use shingles on a small roof area, it should be treated like a mini pitched roof, not a flat pad. That usually means rebuilding the surface to proper slope and layering it correctly over flat-roof components. I’ve done this on a handful of jobs where the homeowner wanted shingles for aesthetic reasons and was willing to pay for the structural work underneath to support them.

Conceptual Steps (For a Pro to Implement)

1. Strip the small area to deck and verify or repair structural framing.
2. Add tapered framing or boards to create consistent code- and manufacturer-compliant slope (typically 3:12 minimum for standard shingles).
3. Install appropriate underlayment or self-adhered membrane designed for low-slope beneath shingles (many manufacturers require full ice & water shield coverage below 4:12).
4. Shingle according to manufacturer directions, integrating upper courses with adjacent pitched roof and lower edge with gutters/drip edges.
5. Detail any sidewalls or terminations with kick-out flashings, step flashings, and counter-flashings tied into wall systems.

This kind of rebuild should be engineered and installed by licensed pros, especially in NYC where codes and warranties are strict.

Common Mistakes When Shingling Small Flat Roof Areas

Many leaks in Brooklyn start where someone thought, “It’s just a little area, it’ll be fine,” and broke every low-slope rule in the book.

1. Laying shingles directly on a truly flat surface with no internal membrane or underlayment upgrade.
2. Running shingles up against side walls or parapets with no proper step flashing or counter-flashing.
3. Letting a whole valley’s worth of water discharge onto a tiny, under-sloped shingled pad.
4. Ignoring manufacturer minimum-slope requirements and still expecting warranty coverage.
5. Mixing patched flat-roof materials and shingles without a clear, designed transition detail.
6. Using small areas as dump zones for snow and debris from upper roofs, dramatically overloading and soaking the shingles.

FAQ: Small Flat Roof Shingle Installation in Brooklyn

My neighbor has shingles on a small flat section and it seems fine. Why can’t I just copy that?

Older installs may pre-date current codes or may leak without the neighbor realizing yet-sometimes ceiling stains take years to develop, or the leak shows up in a wall cavity instead of on a visible ceiling. Each building’s slope, framing, exposure, and snow load differ; copying a visually similar detail can still be technically wrong for your specific structure. I’ve seen identical-looking brownstone bays on the same block where one leaks every spring and the other doesn’t, purely because of a half-inch difference in slope and how the upstairs gutter overflows.

Are there shingles made for low-slope roofs?

Some manufacturers allow shingles on marginal slopes (down to 2:12) with enhanced underlayment systems-typically full coverage of self-adhered ice & water shield-but they still require that minimum slope. Below 2:12, they recommend flat-roof membranes or roll-roofing systems, not standard asphalt shingles alone, because the shingle tabs can’t seal properly when water sits on them.

What if I just want the look of shingles from the street?

Use flat-roof materials on the surface, then use metal trims, parapet caps, or a short, properly sloped shingle “skirt” above the flat section to mimic the look without shingling the actual flat area. On a Clinton Hill townhouse, we installed a TPO membrane on the flat bay roof and ran a steep 5:12 shingled slope just above it as a visual transition; from the sidewalk, it looked like one continuous shingled roof, but the flat section underneath was fully waterproofed with membrane.

Can I put a membrane over existing shingles on a small flat area?

Overlaying membranes onto old shingles is sometimes done, but substrate irregularities, fasteners poking up, and trapped moisture between layers must be addressed. Best practice is usually to strip to deck and rebuild with a single, compatible system-otherwise you’re sealing problems underneath and guessing whether the new membrane will adhere well enough to shingle granules and old tar.

Does NYC code say anything specific about shingles on flat roofs?

The code leans on manufacturer instructions for slope and application, so inspectors expect low-slope areas to use appropriate systems that match product specs. A local roofer or architect should match details to current NYC building code and manufacturer warranties; if you submit plans for a shingle install on a 1:12 slope, the plan examiner will likely reject it or require engineered drawings showing how you’re meeting code.

Get the Right Covering for Your Small Flat Roof Area

The “best” way to shingle a small flat roof area in Brooklyn is often not to use shingles at all, but to design a small, robust flat-roof system with smart transitions to any nearby shingle fields. Thoughtful detailing-metal edges, proper laps, upstands at walls-matters more than squeezing a pitched-roof material onto a flat plane. When you treat these little roofs like the hybrid details they are, they stop leaking, stop needing annual patches, and stop showing up as brown stains on your bedroom ceiling.