The Right Way to Caulk a Window

Caulking is nothing less than an art.

Hello again this is John Whalen and in this article I wanted to explain about some of the right ways and the wrong ways to caulk a window.

I can remember when the only type of caulking was in 5 gallon buckets, back then we had to use a metal tub caulking gun and actually fill the gun with caulking.   I would remove the end of the gun by unscrewing it, depress the plunger arm and place in the caulking and pull up on the plunger to fill the tube with the thick sealant.  The guns held the equivalent of maybe four tubes that we use today, not to mention being about 8 times heavier.  I think the guns are still in use today?  But all in all, the tubes used today are more efficient and less messy.

Anyways enough reminiscing… those were the days.

The caulking products today are much easier to work with than those used back when I started, in 1969.  Some notable improvements are that they are much more workable and smoother.  The latex type is probably the easiest to work with.  Latex is water soluble and for many dry areas,  is a good choice.  On windows, I would recommend latex only for interior  appearance type sealing, not for exterior.   One reason is that latex is a light base caulking (even the silicone latex) and light base caulking does not provide good adhesion nor does it expand and/or contract as well… not to mention they don’t keep air and water out over the loooong term.  If you were to caulk a window with a silicone based caulking, you could go back to that window in about a year and pull the caulking off in one piece, with your bare hands.  Perhaps you have had this experience.

At JWS, we use a multi-polymer formula sealant that I believe is the best on the market today.  This heavier based product is designed to adhere to many types of surfaces — from vinyl to brick.  This advanced sealant is specifically designed for use on windows, doors and siding and has many applications for roofing.   It adheres to surfaces without priming and creates a water/air-proof bond, stays flexible in extreme heat and extreme cold for 10+ years and still counting.  This is a definite requirement when it comes to windows.  Some 20 years ago… before the multi-polymere series caulking was available, we used a professional grade Styrene Butylene sealant called SBR.  This was a mid-weight sealant that was very workable and designed for window exteriors.  The problem that we ran into using this series of sealant was that after 5 to 8 years, the sealant would fade in color and dry-out, causing cracking in the bond.  Even though 5-8 years was a superior lifespan for caulking then, we were not satisfied.  We revisited a lot of customers and re-caulked the SBR sealant… ouch.   We decided at that time that we  wanted to find something that was as close to “maintenance-free” as we could find.  Since switching to our current multi-polymere sealant, we have revisited jobs at the 5 – 10 year level and inspected all condition of the sealants (color, bond, flexibility) and I am happy to report that they remain in excellent condition.

So, we have solved a major problem that exist in window and door installation; the sealant.  While it may seem insignificant in the function and performance of a window or door, in reality, it is one of the most important elements in keeping your home more energy efficient.  Poor sealants are responsible for air infiltration, water infiltration, bug infestation, formation of oxides (rot), and even worse — MOLD.  Many companies use a lesser quality caulking on their installs, leaving the customer to deal with its inadequacies.  You won’t get that here.  At JWS, we’ve learned from the school of hard knocks that it’s better to invest more upfront in the proper sealants, supplies and materials than to pay later with a mountain of service calls and unhappy customers.  We supply all of our installers with the best sealants,  products and materials used on your home and make it policy that they are used.  Just one of the many reasons why dealing with an installation-based company like JWS is better than dealing with a sales-based company.  They might have great marketing and hype to sell windows and doors, but lack experience in proper installation and superior product and material knowledge.  These are things we learned over 40+ years of seeking installation perfection effort.

We at JWS offer craftsmanship, generations of experience, understanding of proper installation, superior knowledge in durable materials, and products that meet our 48 point quality checks.  As part of the 48 point inspection we look for and do things like … securely fasten all trim using trim-slots to insure water and air tight connections from the new window to the homes surface, flashing properly and making sure everything is even and square before caulking.  These few procedures alone adds many years to each window we install.  It’s worth repeating this will ensure a water and air tight exterior on your new windows.  I personally have performed countless service calls from installations done by other companies and exterior trim installed incorrectly is the main reason for water and air leak problems.  Some problems I inspected were “Severe” to say the least and required wood replacement and total re-installation.

Don’t be a victim of sales hype and poor installation… Let the installation experts install your new windows… There is a better way.

I hope this article was helpful in understanding a few of the many caulking’s available in the market today.  Mostly though, I hope you can see more clearly “The Right Way to Caulk a Window”.

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8 Responses to “The Right Way to Caulk a Window”

  1. tom warren says:

    I just had all new e windows installed in our home now that it is cold they have two to three inches of water build up on them on them every morning. What is causing this to happen?

  2. tom warren says:

    the water is on the inside

  3. John says:

    Hi Tom,
    This condition is related to the rating on the window called the CRF (Condensation Resistance Factor). Basically, without getting into too technical of an explanation, this determines what temperature of the inside glass (I state glass because it is the coldest surface on your window) is under certain weather conditions outside versus inside temperature. There are other factors such as inside humidity and such, but the bottom line is; that if the CRF rating on a window is in the upper range of the CRF scale of 30-80 or as with our Vanguard window is 70 CRF. The inside temperature of the glass is higher and it takes a much lower exterior temperature to bring the inside glass temperature below the dew point or the condensation point. On many windows you can realize undesirable sweating or condensation at exterior temperature of +25F degrees. With a Vanguard 70 CRF you might not realize sweat until a temperature around -20F or -30F degrees. So in summary think about how many winter days are at +25F range versus how many are at -20F or -30F range and you can begin to appreciate the higher CRF rating on your window.

    Another big factor in sweating or condensation would be how well the window is installed. If the window is installed improperly and all the seals of the window are not working as they should… it will leak air. This condition will further reduce the inside temperature of the glass lowering the CRF rating on the window well below those stated on the window.
    One way you can possibly improve your condition of sweating is to:
    1. Check to make sure the window has no obstructions, dirt or debris keeping it from locking down tight. Then lock it down tight. You would be surprised how many times this problem exists.
    2. Do not block the inside warm air of the house from getting to the window with say heavy curtains or blinds, keeping the inside temperature of the glass warm is important.
    3. Lower the humidity level in the house. You can do that by lowering the humidity on your furnace, after boiling water in the kitchen vent the humidity with a vent fan or opening a window, vent humidity out after a shower, etc.
    4. Check the seals around the interior and exterior of the window. This means visually inspect that caulking around window is complete and has no gaps. Then check the fiber weather-stripping of the window and make sure it comes in contact with the surfaces of the window where they seat and that they appear to be tight. Our Vanguard window has 3 layers of this weather-stripping to add triple defense, protecting your windows from air leak.
    These remedies are not all inclusive of what can be done to control humidity, but it should address some of the most common problems.
    I hope this article was helpful.
    John Whalen

  4. Susan says:

    Is OSI Quad caulk in the category of caulks that you recommend for interior window caulking?

  5. John says:

    Hi Susan,
    Interior caulking is where I say caulking is an art. Neatness and a good smooth surface are what most people are trying to achieve with the interior caulking. You don’t want to have ugly rough caulk lines on the inside or the out side for that matter, but exterior can have a heavier bead. That said, yes I do use quad for interior. I do use a *smaller bead size (*the hole you cut in the cauking tube) and when required smoothing and cleaning up the surface with mineral spirits. Like I mentioned in my article Quad is a heavier base caulking compared to say latex, but for seals that have to stand the test of time and are required to seal out air or water its a good choice. It just takes more skill and care to use on interior surfaces.
    I hope this answers your question.
    John Whalen

  6. Rich Bole says:

    John –

    First I’d just like to say that I used to live in SE Michigan and I have the following story to relate:

    My neighbor and I were both looking for new windows at the same time in 2006. I went with another company (just a tiny amount cheaper), and he went with JWS. Ultimately my job came out poorly with some of the windows moving side to side as they raised and others bowing and being too tight to raise easily. Most importantly mine were caulked with some budget caulk that failed after just a few months of winter. JWS fit all his perfectly and caulked them with a thick bead of QUAD caulk. I ultimately went back and had to do the same on mine at considerable expense (time and money).

    Anyhow, now I’m living out of state (better job offer) and looking to replace more old windows. The bid that I am considering is from a company that is planning to use “Anvil” caulk, which they say is equivalent to Quad. John – can you give me a brief list of brands that you would use besides QUAD? Is Anvil good? Thanks for the help. I’ll keep recommending you to my buddies up there.


  7. P. Ma says:

    Hi. Is OSI Quad a heavy multipolymer caulk? What are the names of (others of) the best of that type?

  8. John says:

    Hello and thank you for leaving a comment. In answer to your question, yes, the heavier based caulks of this brand are best for adherence to a variety of surfaces, from vinyl to brick. OSI Quad is an elastomeric polymer, unmatched by others of its kind, making it the caulk of choice for the installation that we perform here at JWS. It is designed to resist weather-related elements like water, ozone, heat and UV light. The surface, once cured (up to a week), exhibits a sheen comparable to the silicone sealants. If given the option, I would choose this brand.

    For your convenience, here is the website to OSI where you’ll find a variety of caulks for various home improvement projects. But should you have additional questions, please do not hesitate to ask! We’re here to help.

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