Blackened timbers

bouicca21

My garage roof leaks - badly.  It’s felted (or whatever the standard flat roof stuff is) and according to my neighbour originally had some sort of covering between the felt and the timbers. If so it’s perished.  The timbers are pine, some are now black but not soft as far as I can tell from looking at the underside.  Does this mean they are likely rotten and need replacing?

The garage was built in the mid 1960s. I doubt anything has been done to it since.  There’s a bit of repointing needed - the mortar is very sandy so I assume lime rather than cement (?).  I think there was a sort of bitumen damp course between the concrete floor and the eastern brick wall but I think that’s gone too.  Not sure whether it’s possible or worth it to replace it.  

Probably should add that it’s en bloc and is the end garage.

Bendy_House

Photos?

Black doesn't usually suggest 'rot', afaIk. Perhaps it's been treated with a Creosote-type preservative?

It doesn't 'feel' soft, but what if you stab it with a sharp screwdriver? Esp near the ends?

stuart45

The mortar is probably sand/cement mix. Possibly a weak mix, or over time the weather has eroded it. Repointing will probably sort it.

bouicca21

Thé screwdriver test was somewhat inconclusive - the surface seems very slightly softer than the non black bits but there’s hardly anything in it.  Photos attached.  Plus some of both sides of the outside wall where it meets the ground.  I’m not too bothered about damp coming through there (unless I ought to be), it’s the prospect of the roof falling in and the puddles that bother me.