Unique Housing Types
In the appraisal and appraisal report review processes, special consideration must be given to properties that represent unique housing for the subject neighborhood. Mortgages secured by unique or nontraditional types of housing, including, but not limited to, earth houses, geodesic domes, and log houses, are eligible for sale to Fannie Mae provided the appraiser has adequate information to develop a reliable opinion of market value. It is not necessary for one or more of the comparable sales to be of the same design and appeal as the property that is being appraised, although appraisal accuracy is enhanced by using comparable sales that are the most similar to the subject property. On a case-by-case basis, both the appraiser and the underwriter must independently determine whether there is sufficient information available to develop a reliable opinion of market value. This will depend on the extent of the differences between the special or unique property and the more traditional types of houses in the neighborhood and the number of such properties that have already been sold in the neighborhood.
A 3D printed home with a traditional design and constructed using conventional building materials is not considered a unique or nontraditional housing type. Lenders should follow the standard eligibility and comparable sales selection requirements for site-built housing. See B4-1.3-08, Comparable Sales and B4-1.3-09, Adjustments to Comparable Sales, for additional information. To identify this construction method, the appraiser must enter "3D Printed Home" in the bottom free-form description field of the Sales Comparison Approach grid in the appraisal for the subject property and comparable sales (if applicable).
When appraising unique properties,
- if the appraiser cannot locate recent comparable sales of the same design and appeal, but is able to determine sound adjustments for the differences between the comparables that are available and the subject property and demonstrate the marketability of the property based on older comparable sales, comparable sales in competing neighborhoods, the existence of similar properties in the market area, and any other reliable market data, the property is acceptable as security for a mortgage deliverable to Fannie Mae;
- if the appraiser is not able to find any evidence of market acceptance, and the characteristics of the property are so significantly different that they cannot establish a reliable opinion of market value, the property is not acceptable as security for a mortgage deliverable to Fannie Mae.
Fannie Mae does not specify minimum size or living area requirements for properties with the exception of manufactured housing (see B4-1.4-01, Factory-Built Housing: Manufactured Housing). There should be comparables of similar size to the subject property to support the general acceptability of a particular property type.
For additional information, see B4-1.3-05, Improvements Section of the Appraisal Report.