Green Roofing FAQ

A green roof is a roof partially or fully covered with living vegetation planted over a waterproofing membrane and supporting layers. Chatfield Green Roofing supplies extensive green roofs built with pre-vegetated XeroFlor sedum mats — a lightweight, low-maintenance system that delivers immediate green coverage as soon as it's installed.

An extensive green roof is a lightweight, low-profile system with a shallow growing layer, typically planted with hardy, drought-tolerant sedums. It's the most common and economical type because it's light enough for most existing roof structures and needs very little maintenance.

An intensive green roof uses deeper soil to support shrubs, lawns, and even trees — essentially a rooftop garden or park. It's far heavier and needs more structure, irrigation, and upkeep. Chatfield specializes in extensive XeroFlor systems.

Green roofs deliver value on several fronts at once:

• Reduce stormwater runoff volume and peak flow
• Lower rooftop temperatures and the urban heat-island effect
• Improve building energy efficiency
• Protect the waterproofing membrane and extend roof life
• Add biodiversity, habitat, and usable green space
• Support sustainability codes, ESG goals, and LEED credits

Learn more on our Benefits of Green Roofing page.

Yes — it's one of their most valuable functions. Green roofs absorb and slow rainfall, reducing the volume and peak rate of stormwater runoff that reaches drains and sewers. In dense urban areas this is a key reason cities encourage, incentivize, or require green roofs on certain projects.

XeroFlor is a pre-vegetated sedum-mat green roof system. Chatfield grows the XeroFlor XF 300 vegetation mats in Central New York and delivers them as fully grown rolls or flats for direct installation — so the roof is green on day one, not after a season of growing in.

The mats are non-biodegradable, lightweight, and removable: sections can be lifted years later for roof repairs and then reinstalled, which protects the long-term investment. XeroFlor is approved by most major roof manufacturers for single-source warranties.

Yes. XeroFlor green roof assemblies work on flat roofs and on slopes up to 45 degrees, using different system configurations and slope-stabilization measures for steeper pitches. That flexibility makes them suitable for both retrofits and new construction across a wide range of roof geometries.

A properly designed and installed green roof protects the roof rather than harming it. The vegetation and growing layers shield the waterproofing membrane from UV, temperature swings, and physical wear, which typically extends membrane life.

XeroFlor is approved by most major roof manufacturers for single-source warranties, and its removable mats let you lift sections for inspection or repair and reinstall them afterward.

The cost of a green roof depends on the system you choose, the size and slope of the roof, site access, and your project goals — so the best way to get an accurate number is to request a quote.

A green roof typically costs more up front than a conventional roof, but that difference is often offset over time: by protecting and extending the life of the waterproofing membrane, reducing energy costs, and helping manage stormwater. Chatfield can help you choose the right system for your budget and provide project-specific pricing.

Often, yes. Many municipalities offer green-roof incentives, and New York City's Green Roof Tax Abatement has been extended through June 20, 2027. Green roofs can also contribute toward LEED certification credits.

See our Funding page, and our team can help identify programs that may apply to your project. Always confirm current eligibility and deadlines with the relevant agencies.

XeroFlor extensive systems are lightweight — typically 8 to 12 pounds per square foot for the thinnest built-up assemblies, up to about 31 pounds per square foot for heavier applications. A few examples:

• XF + Fleece — about 11 lbs/sq ft (the lightest, thinnest build-up)
• XF + Bio-Retention — about 15 lbs/sq ft
• XF + Tray — about 17 lbs/sq ft
• XF + Growth Media — about 24 lbs/sq ft
• XF + Mineral Wool — about 28 lbs/sq ft

Because they're so light, XeroFlor systems can often be added to existing roofs — but a structural engineer should always confirm your roof's load capacity for your specific building.

Many can, precisely because extensive XeroFlor systems are so light. The deciding factor is your roof's structural load capacity, which a structural engineer or design professional should verify. Chatfield can provide weight calculations and specifications to support that review — and our team can help you select the lightest system that meets your goals.

Extensive sedum green roofs are designed to be low-maintenance and largely self-sustaining. Once the plants are established, typical upkeep is just a couple of visits per year:

• Clearing debris from roof drains
• Occasional weeding
• A general inspection
• Sometimes a slow-release fertilizer application

There's no mowing, and little to no irrigation is needed once the mats are established.

Green roofs are long-lived. By shielding the waterproofing membrane from sun, weather, and wear, a green roof commonly helps the roof last 40 years or more — often well beyond the lifespan of a conventional roof. Some European green roofs have performed for over 50 years.

XeroFlor's removable-mat design adds another advantage: when the membrane eventually needs work, mats can be lifted, the roof re-done, and the same mats reinstalled.

No. XeroFlor systems use hardy, drought-tolerant sedum species selected to thrive on rooftops with minimal water. New installations may need some watering while the plants establish, but once established an extensive sedum roof generally relies on natural rainfall.

Local Laws 92 and 94 (adopted in 2019) require many new roofs and full roof replacements in New York City to include a sustainable roofing zone — a green roof, solar PV, or a combination of both.

Local Law 97 sets carbon-emissions limits on most buildings over 25,000 square feet, with limits tightening in 2030. Green roofs can help satisfy LL92/94 requirements and support a building's broader LL97 performance strategy. See our NYC Local Laws page for a full walk-through.

Often, yes. Where Local Laws 92 and 94 apply, a green roof is one of the qualifying ways to cover the required sustainable roofing zone — and it can be combined with solar. Green roofs also support broader Local Law 97 goals through reduced rooftop heat gain and stormwater benefits.

Chatfield helps architects, contractors, and owners evaluate compliant green-roof options. This is general information, not legal or code advice — always confirm requirements with the NYC Department of Buildings.

Chatfield Green Roofing supplies XeroFlor green roof mats throughout the Northeast United States — including New York, Philadelphia, Boston, Washington D.C., and surrounding areas. The mats are grown by Chatfield in Central New York.

Our largest project to date is the Javits Center in New York City, with roughly 297,000 square feet of XeroFlor product.

Reach out through our Request a Quote or Contact pages, or call (315) 466-2162. Share your project location, roof size, slope, and timeline, and the Chatfield team will help with system selection, budgeting, and design coordination.