English Heritage and the National Trust ordered contractors working on their properties to stop work or take precautions until further notice.
Both organisations have closed all their rural properties and land. A National Trust spokeswoman said decisions on whether to close sites were taken locally on a case-by-case basis. She added that contractors on sites remaining open were urged to take precautions to avoid spreading the disease.
The National Federation of Builders said it had heard reports of equipment put in quarantine and had received an increasing number of calls from members worried about the closure of sites.
Chief executive Tony Maynard said: "The longer it takes to remedy the situation, the more serious the consequences become." The National Trust's Northumbrian region building manager Nev Kirby confirmed that work had ceased on up to 30 projects. He said: "We are talking to contractors regularly. They have been very understanding but it is going to have an effect. This is uncharted territory." National Trust sites are scheduled to open at the end of this month but concern is growing that building work will still be going on at the start of the tourist season.
English Heritage said it was possible that projects would overrun but emphasised that containing the disease was its priority.
Elsewhere, work on roads has been disrupted. Work on the £56m A43 to M40 junction at Towcester, Northamptonshire, has been halted in parts considered at risk.
Steve Draper, WS Atkins operations director for trunk road and motorway maintenance in the East Midlands, said the Highways Agency had advised it to suspend routine maintenance near fence lines. The agency and Railtrack have issued guidelines for contractors.