People were seen on CCTV near Cruck Cottage at Torthorwald shortly before fire ripped through the building.
And the Cruck Cottage Heritage Association which operates the site as a museum is now looking at a massive repairs bill.
Rhys Jones takes cuttings and, right, an old cruck
barn made using black poplar
Another is that every building shown within was constructed using a modified cruck
A PS13,000 re-thatching of Dumfriesshire's historic Cruck Cottage is to be marked with a free Christmas celebration on Sunday.
Christmas at the Cruck is open to the public from 1pm to 4pm and there will be live music, carol singing, mulled wine and mince pies in the unique building in Torthorald near Dumfries which is the only remaining example of its kind in the area.
The tuneful couple turned the 15th Century cruck
house into their home and created a mini studio under its 500-year-old oak beams.
In the other two bays the oak crucks
curved over the single-storey hall, 20 feet wide and spacious enough to prevent the occupants from choking on the smoke from the fire.
I have witnessed the destruction of beautiful 17th Century wallpaintings because ``the wall leaned,'' the demolition of a cruck
cottage to allow for an extra parking space on a bungalow plot, and a beautiful oak inglenook ripped out because the owner ``banged her head on it.
Cottage, Upton Magna, nr Shrewsbury, Shropshire, is for sale at pounds 290,000.
The original oak crucks
and roof was raised and the roof re-thatched in wheat straw with gorse underthatch.
Surprisingly each of the crucks
and roof timbers carried carved letters and numbers, a sort of 18th century DIY instructions kit.