Amec revealed this week that it is in talks with Centex Corporation to agree a deal that would give the US giant an important foothold in the UK housing market.
In a statement, Amec said: "The discussions are at an early stage and remain subject to due diligence and contractual negotiations.
"The possible disposal would be in line with Amec's stated strategy to focus on the group's capital projects and services businesses and related investments." Fairclough's book value is estimated at about £90m, but analysts believe the company could be sold for up to £120m in the current buoyant housing market.
Its landbank in the North-west and South-east is thought to be worth at least £100m.
The housebuilder is expected to announce a pre-tax profit of about £16m on a turnover of £180m this week. It is expected to have built about 1800 homes last year.
Centex, which opened an office in the UK last year, has been looking at the market for some time. In 1995, the company formed a joint venture with Surrey housebuilder Charles Church, which later sold out to Beazer.
Amec must think quite seriously about returning some of the cash to shareholders, or look at expanding into the services side
Mike Betts, Analyst, JP Morgan
The move immediately got the thumbs-up from the City, with Amec's shares jumping 7.5p to 207.5p, a 3.75% rise.
JP Morgan analyst Mike Betts would not hazard a guess at the value of the company but said: "I think it's an excellent time to sell, given the string of good results coming out of the housebuilding sector. The question the Americans should be asking is whether it's a good time to buy. It is not yet clear what stage the UK cycle is at."
He said investors were likely to welcome Amec's move away from housebuilding. "History shows that combining contracting with housebuilding is not successful."
Betts said the City would be interested to see what Amec did with the cash. "They must think quite seriously about returning some of it to shareholders, or look at expanding the business more into the services side."
Leslie Kent, analyst at Seymour Pierce, welcomed the deal. "Fairclough has been fairly disappointing for Amec, and the extent to which it has affected its core business has never been clear.
"It will be interesting to see whether it can do a lot better in the hands of a pure housebuilder." Kent believes Centex will use Fairclough as a foothold in the UK, but that the Texan firm's ambitions are likely to be bigger.