This document should be read along with the explanatory document which provides information on how the statistics are collected and how they should be interpreted are provided below.
Starts and completions
New build information is provided for starts (when the foundations are begun) and completions (when a building inspector deems the property complete). In general, the number of starts will be a strong indicator of the likely trend in completions over the longer term, but there may well be differences over the short and medium term depending on factors such as the housing market, economic climate, access to finance, and speed of construction. A wide range of factors can influence the length of time it takes for a new private dwelling to be constructed, including the type of property (house, flat etc.), and the overall size of the site. Depending on the size of the site, the average time from start to completion of the entire site can range from anywhere between around 1.5 years to 2.75 years. Individual homes, or blocks of homes, might be completed in shorter timescales if parts of the site are completed in advance of the rest.
Comparing over time
New build figures are not seasonally adjusted and so it's not always appropriate to compare the latest quarter's figure with the previous one. In particular Housing Association approvals tend to peak in Quarter 1 of each year due to the way in which funding is allocated to these projects. This document generally compares the latest quarter's figures with those for the equivalent quarter in previous years or it compares the latest 12 month period with the previous one. For series where there is no obvious seasonal pattern it may also compare with the average quarterly figure over a period of time.