I've got some leaks in my garden shed. There seem to be some small gaps along the the edge of the T & G at the corners. I'm thinking of using an external window & door frame sealant to fill the gaps and then use a good preservative to paint the whole shed. Can I use a spirit based preservative, will it ruin the sealant and if so, what type of preservative can I use. Or is there a better method ??