Brisbane is set to see the biggest uplift in multi-unit construction over the next two years, followed by Melbourne - and both cities are "clearly more immature unit markets" that carry "a risk" for buyers and their financiers,  argued Cameron Kusher, head of research at CoreLogic, in a commentary over the weekend.Kusher used as a starting point the commentary by the Reserve Bank of Australia in its Financial Stability Review a week ago."In all cities except for Hobart, house values have risen by a greater amount than units," Kusher wrote."In fact, in all of the remaining capital cities except for Sydney unit values have increased by less than half the rate of houses.  This highlights that, despite the shift to more unit living, there appears to be a healthier relationship between supply and demand for houses compared with units.?"As a result, house values have increased at a faster rate than units.Sydney's median unit price at A$675,000 is more expensive than the median house price in the second most expensive capital city, Melbourne ($641,500), Kusher said."Looking at the differential between selling prices of houses and units, the difference is $115,000 in Brisbane, $156,400 in Melbourne and a much greater $215,000 in Sydney.  In fact, Canberra is the only other capital city in which the gap between house and unit prices even comes close to the Sydney gap; it is recorded at $204,000. "Urbis recently published data in their 2nd quarter Sydney Apartment Essential Report which showed that the weighted average sale price of off-the-plan units was $1,150,266 which is significantly higher than the median unit price across all stock."In Melbourne, "it has only been since August 2012 that the city has approved more units than houses and in Brisbane more units have been approved consistently since July 2013," Kusher said."Clearly the higher density living phenomena is much more ingrained in Sydney than it is in Melbourne and Brisbane.  "At the end of the June 2016 quarter, there were 55,682 units under construction across New South Wales, 46,676 under construction in Victoria and 31,070 under construction in Queensland.  "If you look at the long-run averages you can see that the current unit construction boom is unlike anything we've ever seen before.  "The long-run averages for units under construction are: 16,194 in New South Wales, 10,139 in Victoria and 7,429 in Queensland.  While each state has seen a substantial surge in units under construction, the magnitude of the increase relative to the long-run averages is much greater in Victoria and Queensland than in New South Wales," Kusher said.