Hi, my son is remodeling a old house and he purchased some pressure treaded tongue and groove flooring and put it down. After about six months the flooring started coming up so he went back and screwed each on but it left cracks. He started putting down some vinyl putty but it is cracking and coming out since it rained before he could get it sealed. Do anyone have a solution to his problem? He has spent a lots of money on this porch. It is a rap around porch on the second floor and is wanting it to water tight from the rain that might get on it and not leak to the lower porch.

He laid the floor when it was wet, it should have been dry. No quick fix here as your boards shrink to a size they like. You can remove every board, dry and reinstall in a tighter pattern.

If that is treated yellow pine he isn't done with his problems. Often that material is not quartersawn, to get a "vertical grain", which is what you need for a good tight floor. If it was flat sawn, the wood will expand and contract with the seasons and if you add screws through the face you will just create more cracks when it moves. Yellow pine is not a good material for a floor like you describe.

T&G fir porch flooring would be a better choice. You have to paint it correctly and keep after it, but if installed and maintained correctly it can be kept watertight. I have given it one thin coat of paint (back in the days of oil base paints) on all sides before installation and then two coats after, and it held up VERY well for many years. Even with kids, bikes, trikes, wagons, wood for the stove, what have you.

EP, I agree. Folks like to use PT but that stuff can be so wet that when you drive a nail you get spashed with your last stroke. Kiln dried lumber is the best and can be sealed and/or colored with stuff like Thompsons wood protector plus tint or their Advacnced.