Tongue and groove shed problems

[atomic7431]

I had a family member build me a shed extension to my brick shed, which had the back brick wall knocked out before we moved in a few years ago.
They had built a very poor small shed on the back and it just fell to bits etc.

The new extension has tongue and groove sides with heavy duty frame and flat roof with 15 year guaranteed felt on top. The roof doesn't leak at all.

To start with the shed used to poor water in through the side which was figured out to be blowing in from the corners at the rear of the shed which were not covered at all and were exposed to the elements.
This has been since covered with sealant and timber joists to cover the exposed area and stop the rain just blowing in through the corners.

Now the timber was bought as pressure treated but leaks through the sides, im not talking rivers but enough to cause some small `puddles` at the bottom on the floor in some places. Elsewhere it leaks down the wood and leaves the water trail on the tongue and groove.
Most of the leaks come in through the knots in the wood or the rear back corner where it takes the brunt of the rain/wind etc.

Will coating the shed in say some ducks back cuprinol stop the leaks via the knots etc?
What if any advice can people give as i dont want to put card board boxes from gpus or motherboards in there and they get ruined.

Thanks for looking.

 

[billybob89]

With all of the driving rain we have had I guess it's to be expected somewhat. I certainly know many homes will have been affected. I would certainly give the shed a couple coats of paint and top it off with timer/water proof sealer. Possibly as well you could install internally and damp proof membrane which is breathable.