Inner city areas have more limitations with site access, deliveries and traffic issues. The builder will have to assess your build location to determine if there are any issues that will arise during construction and there may be extra costs involved, especially if permits are required.
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In estate areas there's likely to be multiple builds and trades in the same area so they can easily go from one job to another. This can reduce the time for multiple jobs to be finished and having local trades is a big advantage. Although a builder may travel to your location it's best to use a builder that is frequently building in your area.
Difficult soil conditions, drainage issues, and any slope on the site can all affect the overall site cost. Majority of land estates are prepared so there are minimal site costs involved. There are some exceptions, especially with estates in sloping areas.
Source: Building on sloping block
Most estate blocks suit standard size plans. If a standard plan doesn't fit then a custom plan needs to be designed.
There are less builders competing in the inner-city suburbs to have the 'cheapest' pricing. With more competition in land estates, builders frequently offer specials to stand out from the crowd.
Source: Sherridon Homes