You can obtain a Certificate of Appropriateness Application at http://www.houstontx.gov/planning/Forms/hist/coaap.pdf. This form is dated 08/01/07 so I expect an updated form to be uploaded in the future as this one does not address new requirements from the Historic Preservation Ordinance that changed on October 13, 2010. Now there are design guidelines to be taken into consideration, but these have not been developed yet for all historic districts.
The application states that it must be turned in at least 21 days prior to the next HAHC meeting which occurs monthly, but on the monthly calendar for the HAHC, it states something different. You might want to call and see which is correct..
For application, you will need the following documentation:
For new construction, additions, relocation of structures, demolition or mandatory repair, you will need the above documentation except replace (2) above with the applicable paragraph below:
For completeness, I included the following from the HPO as it pertains to the COA application:
HISTORIC PRESERVATION ORDINANCE AS AMENDED 10/13/2010
Pages 23-24
Sec. 33-238. Application.
An application for a certificate of appropriateness may be filed before, at the same time as or after the filing of an application for a building permit, but the 90-day period provided for in section 33-250 of this Code shall not begin until a completed application for a certificate of appropriateness is filed with the director. An applicant for a building permit may request the building official to review and process the application for a building permit during the 90-day period provided for in section 33-250 of this Code, but no building permit shall be issued until the applicant for the building permit presents a certificate of appropriateness or a 90-day waiver certificate issued pursuant to section 33-250 of this Code.
Application for a certificate of appropriateness shall be made by the owner of the property for which the application is requested or by the owner's agent. When necessary for the city to enforce the provisions of article IX of chapter 10 of this Code, the neighborhood protection official shall apply for any necessary certificate of appropriateness. Applications shall be filed with the director and shall contain the following information:
(1) The name, address and daytime telephone number of the owner and the applicant, if different from the owner;
(2) The address and general description of the property that is the subject of the application;
(3) A statement of whether the intended action by the applicant is:
a. Demolition;
b. Relocation;
c. Alteration;
d. Restoration;
e. Rehabilitation;
f. New construction;
g. Excavation; or
h. Mandatory repair;
(4) A current photograph of the subject of the application; and
(5) Either:
a. A rendering of the exterior of the subject of the application as it will appear upon completion of the proposed activity; or
b. A description of the work intended to be done, the materials to be used and the changes to be made.
If any plans and specification are required to secure a building permit, a copy of the plans and specifications shall be submitted with the application for certificate of appropriateness. There shall be no fee for the filing of an application for a certificate of appropriateness.