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Community and Q&A

Termites – adding shields to existing house on old stone walls and missing(?) foundation anchors

Calloused_Thumb | Posted in Energy Efficiency and Durability on

I’m prepping to dense pack empty cavities on an existing home, and am working from ground up.

Without replacing the sills, how would one go about inserting termite shields on an existing balloon-framed home with a stone foundation?

Why I care – The easier approach is to let the pest control guy do full perimeter treatments with termidor on a regular basis, but researchers say termidor contributes to colony collapse disorder. To reduce the pesticides to bare minimum I’d like to monitor for the little buggers crossing visible shields, and since I’m already committed to rebuilding 40 feet of the 100 ft foundation wall anyway, I may just bite the bullet to add shields on the other 60 feet if it isn’t absurdly expensive.

Description of house – The stonework is pretty thick, with lime mortar inside/out, and heaps of loose rubble and air pockets in the middle. A local builder told me houses of my vintage were often perched on their stone walls without any anchors at all, but it was a short conversation and he wasn’t entirely convincing. On my hillside we’re regularly getting pretty strong sustained winds and higher gusts, but the place still stands. No bolts? Really? The sills are 6×6(true) with 2×4(true) studs bearing directly on the sills (balloon framing). .

So questions are….

1. What’s the basic approach to adding termite shields to this sort of existing home?

2. If I try it and run into anchors, how do you add shields with them in the way? Cut ’em out and replace? (if so, see 3)

3. If I open up a wall and find no anchors, how would one add them given the way the stone wall was constructed?

Yes, before I get crazy I’ll have my engineer weigh in. He’s coming out anyway to decide which sills should go, and which can stay.

Links to recommended ref material in lieu of long reply welcome


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  1. Calloused_Thumb | | #1

    PS The house is 1920's, central Pennsylvania

  2. GBA Editor
    Martin Holladay | | #2

    I can't answer all of your questions, but I can answer some.

    It's certainly true that most buildings sat on their foundations by gravity alone until after World War II, when anchor bolts came into common use. Buildings weigh a lot, and gravity works -- at least until there is a severe earthquake.

    If you want to jack up your building to insert a termite shield between the stone foundation wall and the sill, read this article: Rubble Foundations.


  3. Calloused_Thumb | | #3

    Thanks Martin, I'll check it out

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