I have a leak in my garage roof, the water is coming through and slowly rotting one of the main beams. I can't afford a professional fix and I'm utterly useless at DIY, so advice appreciated. I think the water is getting in via a hole where a pin/big screw goes through to hold that part of the roof on. What I'm thinking as a first attempt is to get on a stepladder, then putting some of that expanding gunge stuff through/around the hole and hope that stops water coming in. Then get the bad wood off the beam and treat the remainder with something suitable which stops/prevents rot.