Does it work on masonry? Detection distance it can be used on item?

Yes this can be used on masonry, reflective surfaces or especially bright ones may interfere with an accurate reading. No set max distance, however at 8:1 distance to spot ratio, if you want to measure a 1 foot diameter area, you would need to measure from 8 feet back. If you want to scan a 1 inch diameter area you would need to measure from 8 inches back.