I am transforming a garden shed in to a playroom for my grandchildren. In one corner some of the wood has rotted (about 10" square). Is there any form of sealant that I can use to pour into this area to harden the timber and stop the rot before I fill the hole with filler.
Ask for wood hardener at your local DIY store, they should supply you with a tin of clear, highly flammable liquid which will strenghen the rotten timber.
If you want to stop the rot you will have to use a liquid with nasty chemicals in it - I would not recommend it for a playroom.