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Main Problem

Camel crickets are getting inside house and the entry point appears to be a gap between foundations.

Background

Occasionally, we see camel (spider) crickets in the bathroom of our addition. An exterminator identified a potential entry point as a ground level hole where the foundation of the house and the foundation of the addition meet. This appears promising because this is only 3 feet from the bathroom where we normally see the crickets.

We have found camel crickets in other places of the house but finding and patching small holes in crawl space vents appears to be limiting their access. Now we are seeing them in only the addition.

The Foundations

The addition was added about 25 years ago and the house is 50 years old. The house foundation goes at least a few feet down. We do not have a basement but the floor of the lowest level is a little below ground level. The addition's foundation is higher than the main house. We live on a hill with the ground rising behind the house.

The Hole

The hole is at ground level where the original foundation and the addition's foundation meet. It is about 3" wide and 3" tall and very deep (maybe length of the addition). If I send a endoscope in the hole, I can see the flat vertical face of the original foundation (on the left), dirt and large rocks below, and a rough concert surface that looks like the bottom of the additions foundation above. To the right, the top and bottom of the hole taper off together.

Possible Solution: Patch the Hole

I would like to patch/fill/seal this hole. But it is at ground level where the foundations meet, the surfaces are all very rough, and I am not what is safe for the foundation.

I have scheduled some contractors to come out and look at this but I know nothing about foundations so they could tell me just about anything and are likely not to explain things nearly as well as SE.

Questions

Is it typical for there to be a gap underneath the edge where one foundation meets another? Is it a problem?

How can I fill/seal this void to keep critters out? Is it safe for the foundation?

Suggestions for troubleshooting this would be welcomed too.

Update

Spoke with contractor who does foundation repair and he will be looking at it on 8/29/2016. Over the phone, he said that the open space under the addition's foundation could have been caused by the settling of dirt. He also proposed packing additional dirt in to make up for the settling.

Diagram of Layout

Diagram of layout

Exterior wall with hole at bottom

image of hole

Close up of hole in exterior wall

close up of hole

|improve this question
  • Do you mean to say there is a gap between the new addition's foundation and the original home's foundation? Or the new addition's foundation is actually above the original foundation? Sorry, I'm not envisioning a great picture of it from your description. Could you provide a quick sketch of what the situation looks like? – tbox Aug 23 '16 at 21:34
  • I suppose if the bugs are entering there must be a gap between the foundations (if possible) but I can't see that. I can just see a hole underneath the foundation of the addition. Does the sketch help? If not, I can tweak it. – LasersMatter Aug 23 '16 at 21:50
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    Ahh perfect. I think that will help a lot in getting an answer. I was going to suggest simply filling it with spray foam but that might not cut it if the crack goes back really far. You might find a long pole/rod/stick/measuring tape to poke back there to see how deep it is. – tbox Aug 23 '16 at 21:55
  • Thanks for the suggestion. I thought about spray foam. The depth is one issue and the second is that the "floor" of the hole is dirt and rock. I am not sure what could provide a "seal" as the dirt can just move. I suppose as long as the gap between the foundations is filled then I may not care that there are critter below? – LasersMatter Aug 23 '16 at 22:00
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    Right--if the bugs are getting in, there's got to be some kind of larger gap in, through the foundation, from the unconditioned -> conditioned side of the house. Spray foam would seal that up good. (also, don't spend extra money on the "pest" version of spray foam... it's almost literally the same exact thing as the cheaper non-pest stuff). I would say if you can't determine how deep the hole goes to maybe pass on the foam option. You wouldn't want to accidentally block up the hole and prevent yourself from getting to the actual problem spot. – tbox Aug 23 '16 at 22:04
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You can get two pack pouring foam which is the same but on a larger scale and that stuff will fill any gaps regardless of their size, i would be be more concerned about it expanding into your bathroom, Also you may want to extend that down pipe away from your house looks like a lot of water has been running under your foundation, Which may cause you bigger problems in the future than insects in the house.

|improve this answer
  • Thanks. I'll look into the two part pouring foam. This may sound dumb but could the foam lift the foundation? – LasersMatter Sep 27 '16 at 15:12
  • I removed the downspout so that the hole would be clearly visible. It normally runs into the underground drain. – LasersMatter Sep 27 '16 at 15:12

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