What is ordinance or law cover on a rental?
It pays the extra cost of rebuilding to current code rather than to how the property was originally built, including demolition the code requires. On anything other than a recent build it is worth having, and it is typically sold as a percentage of the dwelling limit for a modest premium.
Does it apply if the damage is only partial?
Frequently yes. Many jurisdictions require full compliance once repairs exceed a proportion of the structure, so a serious but partial loss can trigger upgrades across the building. That is exactly where owners discover whether they have this cover.
Does a code rebuild take longer?
Usually, which is why loss of rent should be sized with it in mind. Permitting and additional work extend the timeline, and the rent stops for the whole of it rather than for the original estimate.