My shed is 15' x 7' and built on brick base 18" high. The outside slats are rotting and have been letting in water for the past three years. Consequently the inside wooden struts of the shed frame rotted.
The struts inside have now been replaced, the gaps between filled with loft insulation, then the whole covered by plywood to make a smooth insulated surface. However, the outside still needs to be fixed and there are also a lot of gaps, both big and small on the inside that need to be filled to make the whole waterproof/draughtproof - especially around the window frames.
Please can you advise :
+ what filler I should use for gaps around wood (I normally use caulk for filling every other gap - is this suitable?) both inside and out?
+ whether the outside wood needs to be 'lapped' or could it just be a flat type of boarding and, if so, which wood is suitable - I presume plywood isn't strong enough, even when it's painted with wood preserver? I'm trying to do this as cheaply as possible (pension very tight).
Many thanks if you can help