Grade slopes toward foundation under sloping deck

Question

I have a two-part problem.

Problem #1: The grade under my deck has developed a slope towards the foundation of the house. I have begun to get water seeping onto the floor of my finished basement. The deck is about 3 feet above the ground at the house and about feet above ground 14 feet away from the house. I've crawled under to check it out (there's just enough room to crawl around) and sure enough, the four feet closest to the house (the old back fill) has sunk about a foot, and in places there are bigger sink holes leading right to the basement wall.

Problem #2: The deck itself now slopes back toward the house. I built the deck (14'x24") 23 years ago. Three years after the house was built. I decided NOT to attach the deck to ledger board (BIG MISTAKE!) and build it "free standing" right up the house with access to a kitchen door. I dug (4)post holes about 2' from the basement wall, and filled them with concrete. They were inspected to be sure they were deep enough and below the frost line. The back fill has sunk, pulling the deck down with it.

Question: Should I just tear the whole thing apart, fix the grade, and build a new deck? Or is it possible to dismantle the deck, fix the grade, install a ledger board, and rebuild the deck saving as much material as possible? I need to address the water problem ASAP before I have Problem #3: Mold in my basement!

The deck boards are installed perpendicular to the house, so I cant just remove some of the boards. They must all go!

Answer 1

You did not say what kind of the wood the deck is made of and the condition (other than old). I have completely rebuilt some 30+ year old redwood decks in the past that were nailed with a nail jack like this. The boards bay be able to be turned over and an almost new surface is possible after a little sanding. if the surface has been well maintained and the nails are pulled without damaging the surface of the wood screws could be used to replace the boards in the original positions. this will take more time than replacing the decking but can save thousands. You will also find material cost has dramatically increased and the quality of the lumber is lower today than it was 20+ years ago. it all depends on if there is any rotten ares with the decking if it can be reused redwood and cedar have very long lives compared to other soft woods.

Answer 2

I've been there. If your deck is nailed together, it'll be a real pain to dismantle and save the boards (so much denailing!).

You may be able to more easily save the joists if they are in good shape, but at 23 years, this is not a young deck (on East Coast anyway).

Your instincts are right about what could happen if you leave this as-is. In my case it was rotten sill plates and rim joists... no fun at all.

TL;DR - tear it down, regrade and build a new deck; treat salvaged material as a bonus. It's not worth the hassle.

Answer 3

To correct the settling would entail elevating the sunken deck to its original position and re-grading the earth under it. That would be labor intensive with the limited headspace. Considering that the deck is 23 years old, I would remove & rebuild. Then the work area would be accessible for the landscaping work. And you could put in a new deck with the benefit of your experience.

I saw a homeowner deal with the same issue a different way. He screwed long sheets of plastic corrugated roofing to the joist's under his deck. He must have sloped the roof panels because rain pours out one end of the deck. I've never talked to him, so I can't give any of his feedback.