The unfinished basement gets water which is pumped out with a sump pump. (Water from heavy rains percolates into the basement.)

Company A gave me an estimate to insulate the attic. So did Company B, but B said I need to do some landscape architecture first to eliminate the basement moisture, because otherwise, tightening up the house would make it much more likely that mold will grow, and therefore I should solve the humidity problem first, prior to adding insulation. Does this make sense? Note: I use a dehumidifer as needed.

  • If landscape problem is that the ground slopes toward house or is level near the house , it should be corrected. The ground should slope away from the house to reduce water at the foundation. Dec 22, 2018 at 17:55
  • @blacksmith37 - I'm a bit stymied on how to remediate the drainage problem, given that the property is quite flat. Run-off from uphill pools in the neighbor's back yard and then spills over into mine. Dec 23, 2018 at 3:34

2 Answers 2


The advice to remove water before it comes in is sound but if you run a dehumidifier and the rest of the house isn't extremely tight, it seems unlikely that insulating the attic is going to cause a major difference overall.

It really isn't a problem that your land is flat. The grade required is very sight because the actual drainage will be to a pipe. If you live on a street with a storm sewer, it will drain to that which will be below your yard regardless of how flat it is.

The biggest source of water is likely your roof, not the neighbors pool. If you have old clay drainage, it's probably clogged and cracked and mostly non-functional. And it's probably installed right up against the foundation. This means water comes from the drain spouts, goes into the clay pipe and then (because it is porous) bleeds out around your foundation because it has no where else to go.

Contemporary drainage is completely different. It takes the water direct from the downspout to non-porous PVC and takes it away from the house, typically to a storm sewer. You can also add drains to other areas of the yard where water pools. All of this may be subject to code.

  • That is very interesting. It helps me understand the strange paving stones I found placed at the edges of the house, all the way around. // We have just put in a modified French drain along the worst edge, where the run-off from the neighbor was spilling over. // I'm still confused about the water welling up through a hole in the thin basement rat slab. Do you think it's OK to patch a hole in that slab? I patched one such spot already but water has found a way to seep through one edge of the patch. Maybe that's a good thing? It's a foot from the sump pail. I could poke some holes in Jan 9, 2019 at 20:52
  • the new patch before the mortar sets. (I want to patch that hole because water collects in it and I don't like having to step around it.) Jan 9, 2019 at 20:53
  • YMMV but I don't think trying to seal the inside of the basement from water is an effective strategy. I know of people in my area who do this and end up with issues like water spurting out of the walls from pin holes. If you are really successful at making it watertight, it's possible that the foundation would be buoyant enough to make it unstable. The real solution is to get the water away from the house. Waterproofing from the inside is basically just covering up the problem.
    – JimmyJames
    Jan 9, 2019 at 21:20

adding an attic vent as well as attic vent fan similar to a bathroom fan that operates on a timer should reduce the amount of moister that is rising up through your walls due to evaporization

  • There is already a ridge vent. Dec 23, 2018 at 3:34

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