GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Living without a sill gasket

timstokes81 | Posted in General Questions on

I live in a circa 1905 Toronto house and am constantly tinkering away at it. Lately I’m repairing the sill on the South side. Because there is no sill gasket, this seems to be a bandage fix to get a few more decades out of it at best.

At least in the harshness of a Toronto climate, a house without a sill gasket seems to me like a house that is forever heading toward structural failure, and I don’t think I’ll ever buy another, unless I can budget in (what in my mind is the proper fix) jacking up the house and putting one in. The same issue applies to structural brick homes with floor joists resting within the brick walls (many of these exists here in Toronto as well).

Granted I found a post by Martin about keeping the sill area as dry as possible (ventilation, lack of bushes, grading) but this seems more like mitigation than a solution.

My wife and I are hoping to move within the city at some point in the next 5 years, and I’m wondering if it’s an overreaction to write off most of the historic homes in the city due to lack of sill gaskets (of course there are other “old house issues” but this one bothers me the most), or other members would agree?

Thanks, Tim

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member


    A couple of thoughts;

    - If the sill-plate hasn't experienced significant deterioration over the long life of the house, chances are that unless you alter the conditions around that sill, it will continue on as it has for some appreciable time.

    - You don't need to jack the house up to replace the sills. You can piece them out and replace them in sections, although in some areas point loads may have to be temporarily supported.

  2. jackofalltrades777 | | #2

    How bad is the sill plate rot? If it lasted 115 years, I would not waste my time replacing it. Wood sitting on top of concrete can last 100's or 1,000's of years. A lot of factors at play. How much moisture is actually mitigating through the concrete onto the wood?

  3. Expert Member
    Dana Dorsett | | #3

    The lack of a sill gasket is usually only a problem when there isn't sufficient exterior above grade exposure to dry into, the interior of the foundation is insulated (= colder, damper sill with no drying path to the interior) and the roof overhangs are short/or the soil has poor drainage.

    Brick, fieldstone, and rubble foundations usually don't have anywhere near the capillary draw of poured concrete, cinder block or CMU foundations.

    With brick-embedded joists it can often last pretty much forever if there are decent roof overhangs limiting direct wetting of the walls and no insulation installed within 4" of the joist. In a full-gut rehab (or in unfinished basement) there's usually a way to fully insulate the walls, supporting the joists with a ledger beam that is on the conditioned space side of the insulation, with a bit of design work.

    Of course putting all the insulation on the exterior side of the brick works too, but might not be allowed in historical districts.

  4. walta100 | | #4

    I agree it lasted 115 years as is it is likely to be fine unless something changes like covering the sill in spray foam.


  5. vap0rtranz | | #5

    >I live in a circa 1905 Toronto house and am constantly tinkering away at it.

    I hear ya! 1930s house here.

    >write off most of the historic homes in the city due to lack of sill gaskets


    I thought Candian homes mastered foundations, no? No freeze/thaw buckling, etc.

    Our house here (in Wisconsin) also doesn't have a sill gasket. 2'f thick field stone encased in mortar with, what I would guess we would now call, "untreated" sill plate & rim joist sitting on top. No rot. And we do battle with our damp/wet basement on a regular basis, but that has not affected the wood components.

    Our sill plate / rim joist starts at a good 1.5' above grade, the cedar siding overhangs a good 2" below, and we have 1' overhangs from the roof sofits. So perhaps this has nothing to do with historic homes in Canada or wherever but how each house protects components. Maybe the grading and other factors really are at play with your historic house?

  6. Jon_R | | #6

    If you want to know how your house is doing in terms of sill moisture, start measuring it.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |