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What is the best non-cracking interior caulking

Cgalgowski | Posted in Green Products and Materials on

I am in climate zone 5.
What is the best interior non-cracking caulk?

In years past I have used DAP and pretty sure it was DAP 230.
After 2 to 3 years much of it is cracked and leaking air.
I intend to fix those areas and caulk new areas brought to light by a blower door test using  smoke.  Blower door results were 6.5 ACHr50.

If I cannot find a good interior caulk, I am considering using an outdoor silicone like window and storm door caulk on the interior.  Apply it in August or early September and keep the windows open for a few weeks.  Then close up windows in late Sept at least at night.  Would this cause long term undesirable interior air quality?

One room has vertical interior 5″ tongue and groove light mahogany.  The expansion contraction in each joint is as great as 3/16 inch per  year.  These joints need a caulk with very great adhesion to the painted wood and the ability to stretch and not crack.

Thanks in advance for any good ideas,
Charlie Galgowski

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  1. Expert Member
  2. ERIC WHETZEL | | #2

    I've had good luck with this M-1 caulk from Green Building Supply (order online and they ship from Iowa).

    I used the white for my interior wood trim and haven't seen any cracking. I used a similar product in my last home, which was leaky and saw much wider swings in humidity, and still no cracking. I also used it on some areas for my siding and it's holding up well outside as well. My guess is it's the high solids content that allows it to avoid cracking over time.

    It's low VOC, although there is an initial smell for a couple of hours. Paintable after 24 hours, which a professional painter probably wouldn't like.

    The hardest thing to get used to is it cleans up with rubbing alcohol, not water like the latex/acrylic caulks at a big box store. I kept a rag soaked in rubbing alcohol in a cut bucket for smoothing and positioning the caulk where I wanted it. It took some getting used to, but very happy with the results.

  3. FluxCapacitor | | #3

    Eric and Malcom’s suggestions look good.

    Be advised latex paint will not stick to silicone unless it specifically states “paintable silicone”.

    I have used GE “paintable” silicone (available at Home Depot) and it works well as a caulk IMO.

  4. brianvarick | | #4

    What are people using for indoor air sealing?

    1. ERIC WHETZEL | | #5

      For exposed framing I used HF Sealant from

      I also used Prosoco's Air Dam around my basement windows, painting over the Air Dam without any issues.

      Neither of these is immediately easy to use if you're expecting them to act like traditional latex caulk. The HF Sealant is super sticky and will get all over everything if you're not careful. The Air Dam is thicker, and it too takes some getting used to in terms of applying it neatly.

      Or you could use the Big Stretch suggested by Malcolm above.

      I've never had much luck with caulks/sealants from big box stores, or even the paint stores. They all seem to crack or fail much sooner than you'd expect.

      The products I've mentioned should last a long time.

      1. brianvarick | | #6

        Thanks Eric, after I posted I went back over to your blog to see what you used. I figure you probably did more research than I before you selected a product.

  5. GBA Editor
    Brian Pontolilo | | #7

    I add a vote of confidence in Sashco products. Both inside and outside. I've used Big Stretch inside where it has held up well and I've used clear Lexel to seal between dissimilar materials outside and it held up beautifully too.

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