It depends on what is going up and how it prices against your home. For an apartment building, two things matter: - Caliber of the project. Higher-end rentals with professionally employed tenants tend to have little negative effect. Lower-end rentals can weigh on nearby values. - Setting. In a dense or urban area, new apartments are expected and barely register. In an established all-single-family suburban pocket, an apartment building next door is more likely to drag on value. For new homes going up beside you, relative price does most of the work. New construction that is nicer and sells for more than your home tends to support or lift your value. New homes that come in cheaper than yours can pull you down, at least at first. We have seen neighboring new builds undercut an existing home's value early on and then even out over a few years as the area matured, so a short-term dip is not necessarily permanent. One appraisal wrinkle: because of the age difference, brand-new homes may not be treated as direct comparables to an older home, so they might move your appraised value less than you would expect in either direction. If you want a read on your specific street, a local agent who knows the submarket can give you a grounded opinion.