He said: "There is quite a lot of potential to talk up a slowdown or recession because a lot of the construction and property business is about feel.
"This is not a recession; it's a slowdown compared with the level of growth last year. There's still growth but not as fast."
Lett made the comments despite the fact that Aukett, Taylor Woodrow and materials firm BPB have warned that the US slowdown was beginning to hit demand for buildings and materials.
Aukett's pre-tax profit plummeted 52% for the six months to 31 March relative to the same period a year earlier. Aukett posted pre-tax profit of £460,000, compared with £950,000 then.
UK profit dropped 75% to £180,000. Lett said this was a direct result of the weakening US economy and its impact on IT-related projects in the UK.
The architecture, design and engineering group had warned in March that its profit would be hit by the slowdown, which it said was affecting clients' expansion plans.
IT-related projects, such as internet farms, account for about 12% of Aukett's orders.
Lett said several such projects had been put on hold, which had hurt Aukett's margins, even though turnover increased 22% to £11.2m over the six months.
He said: "The growth that we had planned for, and still think will come eventually, hasn't come through as quickly as expected."
Meanwhile, Taywood said demand from US high-tech giants for commercial properties in the Thames Valley had cooled.
BPB said it expected market conditions in the USA and Germany to remain difficult. The firm added that there were growing concerns about a weakening in the worldwide economy.
Construction analyst Stephen Rawlinson said it was not just the USA that was causing concern. Many firms operating in Germany were pessimistic and Italy showed signs of slowing.