It's a sort of flint, containing voids. Very hard. In English we'd talk about flint house, flint-walled house, etc
The remains of a flint house, perhaps built by Jurnet the Jew
in 1175, now forms part of Wensum Lodge in King Street. ...
www.norfolkesinet.org.uk/pages/viewpage.asp?uniqid=3356

As the road starts to climb turn right along a lane and past a large flint-walled
house that contrasts sharply with its thatched neighbours. ...
www.nqsouthern.com/digitalpublication/ digitalpublications/index.cfm?dpid=133§ion_id=1072

Property Details. Superb garden flat (ground floor) with own front and rear entrances,
set in beautiful flint walled house near the sea at Totland Bay on the ...
www.findproperties.co.uk/ propertiesforsale.php?view_id=1270 -

<<silex [flint] - Agglomérat compact de quartz amorphe plus ou moins mêlé d'impuretés, dont il existe de nombreuses variétés ; les silex constituent de bons agrégats pour les bétons. La pierre dite "meulière" est un silex caverneux en éléments atteignant de grandes dimensions>>
[Dicobat]