The paperwork you signed when you purchased your home in Original Northwood included the original deed, which places some restrictions on the sorts of changes you are permitted to make to your property (and, just as importantly, that your neighbor can make to her property). These covenants are held and enforced by the GNCA, but are primarily handled by the Covenant Committee, which is part of the ONA. For a quick overview of the covenants, see the document "A Layman Looks at the Covenants", which was included in GNCA Articles of Incorporation in 1972.
Practically, this means that all alterations to the exterior of Original Northwood properties require prior approval from the Covenant Committee. Please refer to the Architectural Guidelines for more detailed information.
Once an application is submitted, the homeowner will receive confirmation via e-mail or telephone. This typically occurs within 3 days. The application will then be reviewed by the Covenant Chair and committee, possibly with additional information requested from the homeowner. After discussion, the committee makes a recommendation to the ONA board for a vote. This vote can occur at the monthly board meeting or through e-mail. The result of this vote will then be conveyed to the homeowner. This typically occurs within 3 weeks, depending on the complexity of the project and the responsiveness of the homeowner. Approvals are valid for 6 months from the date of the ONA board vote.