A UK vote to leave the EU would disrupt imports of bricks, timber and kitchens from continental Europe, the boss of the housebuilding firm Crest Nicholson has said.

Stephen Stone, the company’s chief executive, said ceramic tiles from Spain or a Bosch washing machine would be harder and more expensive to obtain.

By harming imports of building materials and ending the flow of foreign workers, a UK exit from the EU would slow down construction, worsening the housing crisis.

“As a business, we’d be disappointed if Brexit were to happen,” he said. “This is a period where we are growing as an industry, and it would be a shame to put that at risk.”

During the financial crisis and recession, Crest halved its 800-strong workforce, but it now employs 850 people, including 90 apprentices. Stone said leaving the EU would put the apprenticeship programme at risk because “we would stop recruitment”.

He noted that a lot of building materials were imported: bricks and blocks from Belgium; ceramic tiles, bathrooms and kitchen components from Spain; and white goods come from Spain and Germany.

“We have strong relationships with our European suppliers,” Stone said. “Belgium and Spain would still be keen to trade, but clearly Brexit is going to take a few years to negotiate.”

The pound is expected to fall sharply if next week’s referendum results in a leave vote. This would increase the cost of building materials, bathrooms and kitchens, according to Crest’s finance director, Patrick Bergin. But he highlighted the “disturbance factor” as the main risk.

Crest’s comments came as opinion polls continued to shift towards a leave vote. Economists at Berenberg Bank rate the probability of an exit at 42%, compared with 20% in late May.

Stone said: “As a prudent business we would probably pause. It means restricting investment in land and in people. We would review it in three or six months’ time.”

Like others in the industry, Crest warned of shortages of construction workers if the leave campaign prevailed. The industry has always relied on foreign workers to plug skill gaps – from Irish labourers to Polish plumbers. In some areas, such as concrete frame construction in Suffolk and Norfolk, an estimated 40% of workers come from eastern Europe.

Crest reported a 25% rise in profit before tax to £72.6m in the six months to 30 April. Revenues increased 22% to £408.1m. Crest built 1,206 homes, 7% more than a year earlier. It raised its half-year dividend by 42% to 9.1p a share.

However, Stone said the company was having to work much harder to sell homes priced between £750,000 and £1.5m in central London, blaming Brexit fears and affordability issues. Prices have been stagnating for a year after a period of rapid growth.

Jefferies analyst Sam Cullen said: “Crest Nicholson has become the first UK housebuilder to voice concerns and to disclose facts suggesting a London slowdown. Overall trading (the walk) remains robust, but the talk was weighted towards London, possible Brexit and bends in the road.

“In the event of a leave vote they may stop buying land for three months and then re-assess. If the ‘bend’ in the road is more severe than they currently think they will push the brake pedal somewhat harder.”

Crest, like others, is pushing into the “build to rent” market. The company won planning permission for its first purpose-designed, suburban private rental sector scheme. It is building 227 homes in partnership with fund manager M&G at Faygate near Gatwick airport. Stone said the project was inspired by the American family housing model and that the company was considering a similar scheme in Bristol.