Villagers in Carmarthenshire say they fear restoration work is being damaged by drivers using satellite navigation.
This office in Llangadog has been struck three times
Residents in Llangadog said trucks and lorries were smashing into buildings that have already had thousands of pounds spent on them.
One property, once thought to have been a toll house, has been hit three times.
The Townscape Heritage Initiative, which oversees the restoration work, said there was growing concern over the rise in traffic through the village.
Around £1.5m is being spent restoring landmark properties in Llangadog and Llandovery.
The Townscape officer for Carmarthenshire Council, Roger Morgan, said Llangadog residents were convinced that satellite navigation was to blame for the damage.
"It's a very small narrow road and these large lorries are coming through the village and causing problems for everyone," he said.
An office used by an architectural consultant in the village has taken the brunt of the damage.
"Since the lime rendering has been applied to the front of the building it has been damaged at least three times," said Mr Morgan.
In August, the Vale of Glamorgan council became so concerned over lorries being sent along narrow roads near St Hilary it began trials of a sign warning drivers to ignore sat-nav directions.
In the same month, a Polish lorry driver became trapped for three hours at Ty Croes in Carmarthenshire after following sat-nav directions.
Roger Morgan said there was "mounting concern" in Llangadog at the number of heavy vehicles using routes to cross from the Black Mountain in the Brecon Beacons through the Llangadog area.
"There has been a tremendous increase in traffic and there's no reason for it to come over the Black Mountain unless they have been directed that way," he said.
"I think the thing is to stop them coming over the mountain by telling them not to use the route from a sat-nav point of view."