How can I fill the gaps between barn wood siding boards?

Question

I want to better weatherproof an old shed that has barn wood siding. Most of the boards have a gap between them, and these gaps can be as wide as 3/8" although most are more like 1/4". The boards are about 3/4" thick and are run vertically. and they constitute entire wall structure (i.e. there is no internal finishing, it's just sided and that's what you see both inside and out).

I would like to seal this thing against Ohio weather. What sort of filler or caulk (or ?) should I be looking for to fill that kind of gap? And how do you go about applying it when you can't get at both sides of the board at once? As in, if I apply caulk, what's to keep that caulk from just pushing through the gap and out the other side?

Answer 1

Do not try to use caulk between all the boards. It will look like crap and on top of that, like you already indicated, it will be hard to put in there in the first place.

The proper approach to this is to install vertical strips of wood over the cracks from the outside. You can choose to use something like 1x2 inch cedar strips. Or if your shed looks like it is 100 years old and you want to maintain that look you can search out a source of recycled barn boards and rip them into strips to use on your shed.

The vertical strips are called batten strips. Often folks use even wider strips that may be 1x3". Here is how a typical structure might look: