Loft Condensation, or not condensation (Ed.)

[WD40solvesall]

I normally do all my DIY, but this was beyond me, so I had to get a professional in....which is way it's driving me mad not knowing what's wrong!
I had a leak from an unknown place, and all the roofers I consulted said: need a new roof! had a 1930s roof with tiles straight on the rafters and nothing but (now crumbling) cement to stop any issues. I picked a roofer, had the tiles off, membrane on, tiles back on again (couldn't afford new), and all done, BUT.....
There was a leak. I'd already paid, the roof was convinced that it was just condensation, but I persuaded him to come around and he realised that he hadn't done the flashing proper;y on the attic windows. So, pretty pleased he addressed the problem promptly. However, since then my beams have still been damp. This is driving me bonkers - is it just the beams being slow drying out from the leak? Is there still a leak? Either way, when I've mentioned it to the roofer he keeps coming back to it being condensation again. TBF to him, this IS thing, and I know nothing about attics.
My question is, if this IS condensation, should I be concerned about the level of dampness of the beams? I have a Dryzone moisture meter. The wood on the hatch to the eaves reads 15%, as does the bottom half of the length of the beams. However the top half of the length of the beams, which touch the membrane read 21%. This has gone down since the leak was fixed, it was 26% touching the membrane. If this stays at 21% is this going to be damaging to the beams? Does condensation normally create moisture to this level? The roofer has ventilated properly.

 

[JohnD]

You can see it, I can't, so how would I know?

Post some photos.

 

[JohnD]

Try this

CONDENSATION IN LOFT (ANSWERS)

This seems to be the time of year for condensation in lofts, so instead of replying to lots of queries I though I would write this "one-size-fits-all" post. Please also see //www.diynot.com/wiki/Building%3ACondensation-in-Houses Condensation in lofts occurs when the amount of water...

www.diynot.com

 

[WD40solvesall]

Thanks John, that's quite helpful. No photos as nothing to see - the beams that are water stained are reading the same as those that aren't. Main question is me trying to figure out if condensation can cause this level of dampness (sounds like it might), and is this level of dampness likely to cause problems with my beams.

 

[Harry Bloomfield]

Is the inside surface of the membrane moist during cold weather, if it is - you need to improve on the ventilation. Eaves ventilation, or vents in the membrane, or both. You can buy cheap plastic vents, to slip in the membrane overlaps to hold them a little way apart, but not to difficult to just concoct something similar, with wood laths.