What wood is the floor made from and how old is it?
Clue (1): an extra pair of joists made of ash, not the usual oak, have been inserted crudely either side of the central beam, with notches and wedges instead of a mortice and tenon.
The ash is easily recognisable because it still has a lot of bark on it. It is between much older worm-eaten oak joists. The boards are all half the length of the room and meet and are nailed at the ‘new’ joists. This suggests the farmer had a job lot of new or second-hand planks already cut to one size and needed to insert the new joists to avoid cutting again to make the planks fit on the old ones. Conclusion – this is a replacement floor. It never did seem very likely that a 16th century floor could survive in a utility building.
Clue (2): The wood is a dark brown, almost black, right through. The dark colour suggests lots of tannin, which points to oak.
Clue (3): The wood is riddled with worm holes in many places. Where a particularly bad piece had to be cut out, the wood was so aerated by holes it was surprisingly light.
Even that piece is strong, and there are only two or three places in the entire floor where the strength is suspect – they have been reinforced from below with new oak. The worm holes suggest either a lot of soft oak sapwood – heart of oak tends to be too hard for worms (there is much evidence of this elsewhere in the building in timbers that are part sapwood, part heart wood); or it might be some other softer wood.
Clue (4): The boards vary in width, but not greatly – perhaps by 15cm. The saw marks are regular, which to me as a non-expert suggests mechanical sawing. Could it mean a Victorian saw mill? Or did they have mechanical sawing in the 18th century? To check.
Clue (5): The wood is long grained and has very few knots. The longitudinal patterns look similar to those in new oak planks. It seems that the best way to identify wood is by the detail of the grain patterns, but end on under magnification, which is beyond my competence. See this very useful article.
Clue (6): The same Building Conservation article gives the periods in which different woods were most commonly used. If oak, then it is less likely to be Victorian, when high quality pine was predominant. Oak is more likely to have been 18th century or earlier. Elm is another very plausible answer to the question. In fact our next door neighbour has a number of very old worm-riddled elm boards in store.
I think it is oak or elm and if pressed would guess oak because of the dark tannin colour. I suspect it is earlier than Victorian, because there’s an old floor in rather better – but still battered – condition in the next room which is definitely pine. That has the look of the well-used early and mid-19th century floors I was familiar with in previous homes.