Tree-Heavy Lots, Moss and Your Reston Roof

Why trees matter so much here

Reston's planners worked with the land rather than clearing it. Waterview Cluster's handbook, for example, says architect Chloethiel Smith prioritized saving as many trees as possible when she designed the cluster in the 1960s. Decades later, those trees are tall, and many roofs sit partly or fully under canopy. Shade, falling leaves and needles, and the occasional limb shape how those roofs age.

What shade and debris do to a roof

• Moisture lingers. Shaded slopes dry slowly after rain and dew, which favors moss and algae.
• Debris dams water. Leaves and needles collect in valleys, behind chimneys and on the uphill side of skylights, slowing water right where flashing is most vulnerable.
• Gutters clog. Overflowing gutters push water behind the drip edge and onto fascia boards.
• Branches abrade. Limbs that brush the roof wear away the shingle surface in wind.
• Limbs fall. A storm can drop a branch through shingles and decking.

Moss and algae: what's what

Dark streaks running down a shingle roof are usually algae. They look bad but are mostly cosmetic. Moss is different: it's a plant with real thickness that grows between and under shingle edges, holds water against the roof, and can lift tabs as it grows. Moss on a shaded north slope is a common sign that the roof stays damp too long.

Algae-resistant shingles are one tool when you re-roof. Reston Association records show them in use here: February 2024 DRB minutes record an approved replacement roof in an algae-resistant version of GAF Timberline HDZ. Ask your roofer which algae-resistant options exist in the product lines your standard allows.

Removing moss without damaging the roof

• Don't pressure wash shingles. High pressure strips granules and drives water under the laps.
• Don't scrape aggressively or pry at shingle edges.
• Clear loose debris gently, and only if you can do it safely; otherwise have a roofer do it.
• If moss has lifted shingles or the roof is near the end of its life, moss removal may simply expose wear. Have it inspected.

Gutters and gutter guards

On wooded lots, gutters often fill faster than owners clean them. Roofing Roughnecks installs Leaf Relief gutter guards, which keep leaves and debris out of the gutter while letting water through. If you add them with a re-roof, include them in your Reston Association application; RA's roofing checklist asks you to indicate any addition of gutter guards.

Trees and Reston Association

RA's Member Guide to Covenants lists tree removal among the exterior changes that need DRB or covenants staff approval, and RA's FAQ says owners may not undertake construction, including tree removal, until they have the final written decision. DRB decisions on projects routinely include the condition that no trees may be removed without prior DRB approval. If a tree is the root cause of your roof problems, talk to your covenants advisor about it as its own item, and ask whether the pruning you have in mind needs approval too.

Protecting trees during roof work matters as well. In a February 2024 decision on a deck project, the DRB strongly recommended tree protection fencing for trees near the construction zone and said excess soil, fill, liquids or construction debris shouldn't be placed within the critical root zone of trees to be preserved. A re-roof doesn't dig, but dumpster placement, material staging and debris drop zones can still land on roots, so plan them with the trees in mind.

A tree-heavy lot at re-roof time

1. Have the roof inspected for moss damage, worn shaded slopes and debris-related leaks.
2. Decide what tree work, if any, you want, and raise it with your covenants advisor early.
3. Consider algae-resistant shingles and gutter guards, and include them in your application.
4. Plan dumpster and material placement away from tree roots where you can.
5. After the new roof, keep valleys, skylight curbs and gutters clear each fall.

Tear-off on one of our Reston re-roofs, with debris caught on a tarp below rather than dropped into the landscaping.