Trained appraisers can spot poor construction and structural issues. A required house inspection should uncover necessary building and infrastructure problems needing correction before selling a house, but an appraiser may go beyond the necessary upgrades to recommend cosmetic fixes on top of these.
Appraisal checklists include materials and wear-and-tear sections, and whether your home is brick or wood-sided figures into valuation. Brick is valued highly for its insulation and long-term wear, but areas of worn inter-brick mortar and gaps between the foundation and outside walls may bring recommendations for patching to improve appearance. Replacing worn wood with siding is another area that can increase value but is certainly not required for safety reasons. Adding insulation between the outer and inner walls of an older home is another update that can add value, as is painting the exterior if siding is weather-worn.
Power-washing the outside of any home is recommended before showing, as it is a relatively low-cost project that can significantly improve the look of a home by clearing accumulated dirt from cracks and crevices. Replacing old windows is highly advisable if seals and framing are worn, but it's one of the more expensive home improvement projects. However, potential buyers place good window condition high on their lists of wants.