I have a new construction home that leaks in the basement near where the frame meets the foundation. The house is on a slope, so the rear has above ground windows.

An attempted solution by the builder was to caulk the inside and foam the outside. The foam wasn't done on the outside between the siding properly, as most of the foam wasn't anywhere near where it needed to be.

The inside regular caulk was used but I think due to the house settling and it not being silicon it's no longer holding up.

Could the bolts holding the frame to cement need to be tightened?

What are the proper steps to take to correct this? It was really windy and rainy last night so I snapped pictures of the action.. also, the insulation on the adjacent walls I can see moving back and forth, like air pressure sucking it in, is this normal too?

My furnace draws return air in from the outside but I am not sure what it's using for combustion, if the basement gets a good seal from the outside, do I need to worry about carbon monoxide? Or is that more for older houses.. house is equipped with detectors.

The grade seems okay outside as it's about 6 inches below the window and is flat away from house. But i am not sure. Warranty is almost up, so I want to make sure this next fix is the last.

leaking at frame and cement

leaking hire up


  • 1
    If it is not puddling over the concrete level it sounds like they did not install flashing properly. Caulking is not a real solution for that.
    – Trevor_G
    Commented Mar 7, 2017 at 18:33
  • 1
    That looks like they flashed it right... there anyway.
    – Trevor_G
    Commented Mar 7, 2017 at 21:50
  • 2
    I'd be alarmed by the fact that anyone tried to solve this issue by caulking the inside of the wall. Talk about missing the boat. If the water is in the wall, there's a problem. Stopping it from entering the room doesn't solve it.
    – isherwood
    Commented Mar 7, 2017 at 21:59
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    Right to left.. ok @eaglei22, then at least the installed the siding the right way round. (common mistake..there is a right way and a wrong way :) )
    – Trevor_G
    Commented Mar 8, 2017 at 15:41
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    Ya I did that, it has a "clear" plastic cover over it so yes I was assuming its electrical, but even zoomed in you can't really tell. Either way. because the backing plate on those is flat, and the siding isn't, they tend to be a source of leakage.
    – Trevor_G
    Commented Mar 8, 2017 at 15:55

1 Answer 1


You said, "The warranty is almost up." First, I'd get their contractor's license number (CCB number) and notify your state's Construction Contractors Board. (If they won't give it to you or you can't find it, call your local building code office.) The CCB can help you file a claim against the contractor and attach his bond, if necessary. They've had at least one chance to fix the problem and I'm not sure you want them back to try again and again... (By the way, that feeble attempt to fix the problem by caulking the interior face of the framing, is also warranted. So, technically, you have a warranty period for that work too, but I'd make sure all the paperwork was turned in before the original warranty expires.) Also, you need "the repair" fixed now too, because they have created a moisture problem by trapping moisture in the wall (between the sill plates) which will lead to mold and dryrot.

Now the leak: 1) water on concrete mudsill means water is either splashing UP from surface water on exterior, or running DOWN from the window. I doubt if it's splashing up, because the leak occurs at just the window location. If water was splashing up, you'd see wet spots all along the mudsill. 2) water seems pretty evenly distributed under the window...maybe even a little more in the middle of the sill. Usually, when water gets in at the head or jambs, we find water has run down the jambs and is concentrated at the bottom of the jambs on each side of the window. 3) windows are made with grooves along the sill for window panels to slide in. These grooves have "weep holes" that allow water to escape. If the weeps are plugged (or damaged) the sill could leak. OR, if the contractor screwed or nailed down through the vinyl window sill it could leak around the screw hole. Also, there are "stops" (small notches) cut into the window frame that allow the sliding pane to lock into a partial open position. If that notch is cut wrong, water could leak through the frame. Also, check the window frame joint where the jamb meets the sill. It is suppose to be "welded" closed, but sometimes the window is dropped and it could crack loose. You're looking for a "hairline" crack.

I recommend you do a water test. Turn your water hose on and hold it in one place for about 10-15 minutes. See if it leaks, if not, move to a new spot. Start with bottom and work up. So, start with sill, then center of fixed pane, then center of sliding pane, then jambs, then head. (Just because some siding is removed doesn't mean you can't do the hose test.)

So here's some bad news...if this window leaks, others probably do too. Just because you don't have water running down the inside of your house under other windows don't mean they aren't leaking. Is there another window with the same wind exposure that you could "pop" the interior sill trim off and check for moisture?

By the way, why did he caulk between all the sill plates? Was there water coming out from between each sill plate, or did he return on a sunny day and didn't see any standing water so he tried to seal everything?

  • Great information Lee. I had the same concerns about moisture being trapped between the frame and the foundation when it was caulked from the inside. I was thinking if anything it should have been caulked/foamed from outside and leave inside an escape for moisture to evaporate. The original intent was to foam the outside and caulk the inside. there were gaps at the sill so bad that I was getting crickets in my basement... Well, the guy who attempted to foam outside missed the target entirely.
    – eaglei22
    Commented Mar 8, 2017 at 15:20
  • Should I remove the caulk from inside at the sill? I will see how the next meeting goes for the fix but I will defentially keep in mind everything you have said. The only other windows are the living area windows, and those seem okay. But you said I can take the window out and pop the seal to look underneath? Also, if things start getting air tight from sealing up the outside, do I have to worry about carbon monoxide? The furnace draws return air from the outside, and exhausts to the roof, hot water tank exhausts out..
    – eaglei22
    Commented Mar 8, 2017 at 15:23
  • I was going to caulk the perimeter, but I worry about carbon monoxide, as I was watching the insulation foil was being sucked in and out when it was real windy, so I know drafts are definitely coming in. I just worry about sealing the basement off too much with gas hot water tank and furnace.
    – eaglei22
    Commented Mar 8, 2017 at 15:25
  • The furnace you don't have to worry about since it's a closed loop and, as long as the furnace/flu is not leaking will not present any problems with a 100% sealed house. The water heater on the other hand could prove problematic. It's good to provide a fresh air source to the furnace room / area, probably via a pipe to the attic or garage if you have one. Right now it sounds like your house is so leaky, that's the last of your worries though.
    – Trevor_G
    Commented Mar 8, 2017 at 15:51
  • I was going to suggest the hose thing too... though I would add, run it for like 5m with someone watching inside then leave the hose off for like 15-20m to see if it takes time for the water to dribble out to where you can see it.
    – Trevor_G
    Commented Mar 8, 2017 at 15:53

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