shed wall leaking through knots

[Ouch77]

I've just re-assembled a largish shed at the top of my garden. The shed itself is probably over 10 years old, yet is still sound. I want to start filling it with bits of car (long term project) however after some recent driven rain I noticed that despite having 3 coats of Cuprinol Ducksback, there is rainwater coming in through several knot-holes in the timber.

The shed construction is T&G, and I've been pretty thorough with the paint.

I've since given the weather-facing sides another generous coat of the same paint, and also marked the offending holes and touched them in with yet more paint.

Is there anything else I can do to stop the water getting in? Is it worth painting the insides? Is there some sort of filler I can apply over the paint, and also paint over?

 

[JohnD]

T&G (and even shiplap) expand and contract and warp, so will never be totally weathertight. I'd suggest putting a lining of roofing felt (or breathable membrane would be better) as a lining for the shed. Fold the bottom so that any water running down it can escape outside.

 

[big-all]

when was the ducks back applied ??
on my shed loose or damaged knots removed and filled
my shed is 10 years old it had 3 coats off ducks back when new 2 more coats year 3
2 more coats year six due another 2 coats due this year and no penetration

 

[Ouch77]

Ducksback went on 2 weeks ago. Prior to that it was originally blue stained (from factory), and then about 5 years ago previous owner hosed it (badly) with some horrible shade of brown, slightly waxy paint of some sort.

None of the knot holes are loose, some have split slightly, but you can only see daylight through one or two, and then only a glimmer.

What did you fill the holes with?

 

[big-all]

ronseal high performance woodfiller
you can use car body filler or even smear silicon over the back off the knot and half an inch beyond