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Seal the Seam between your Garage Floor and Your Asphalt Driveway

(Use this method to seal cracks in your driveway, too, if you want the longest lasting repair!!)

Why should I seal the seam between my garage floor (or concrete foundation) and driveway? Come on, NH... I've got a toaster to clean!!

Blackjack Speed-Fill asphalt crack filler caulk tubeI'm not one to do (or ask anyone else to do) unnecessary work!  Lord knows, we have enough to do!  But because they are dissimilar materials, asphalt driveways and concrete foundations or garage floors often do not meet tightly, leading to the possibility of:

  • Water infiltration
  • Insect infestation
  • Weed growth

Depending on where you live and how active the local flora and fauna are, you may want to consider this little project.  You should be able to do this in an hour or so and for under $20.00 materials cost.

Lets take these potential problems one at a time:

Water infiltration can lead to heaving and breakage in concrete and asphalt...

When water enters the seam or crack between an asphalt driveway and a concrete garage floor or foundation, it isn't a big deal in warmer climates for the most part.  But in colder climates this water can cause damage to both the driveway and the concrete when it freezes. 

Most people who live in climates subject to months of freezing weather are aware of tire and car suspension-destroying "frost heaves".   Frost heaves are raised bumps in the road surface caused by the expansion of frozen water underneath the road surface.  Frost heaves are like a progressive disease... small cracks in the road surface allow water to collect underneath the road surface.  When the water freezes, the road surface is forced upwards leading to more cracks which lead to more water infiltration leading to more heaving... get the point?

Also, heaving that occurs in the asphalt driveway can produce enough force to, over time, break the edge of the concrete garage floor... especially if it wasn't an especially strong pour... leading to more repairs.  And we all love unnecessary repairs, don't we?  Sealing the seam eliminates this problem since it eliminates the water! 

Insects love to make their home in nice moist little cracks!

Ants are fun!  They like to make these cute little piles of sand and dirt outside their nests as they add room after room for their growing families.  The problem is that this sand and dirt is never replaced, so over time hollows develop underneath driveway surface leading to 1) more water accumulation leading to 2) heaving due to freezing or even sagging.  Keeping the ants out is easy... a good crack sealant will be impassible to the little buggers!

What about insecticides?  They work for a short period of time, but the ants are persistent and before you know it they will be back!

Plants are amazingly strong, plenty strong enough to break up asphalt and concrete!

Widen asphalt/concrete seam with toolThough we all know the power of tree roots, even smaller plants can cause pressure damage to the asphalt/concrete seam... not so much to break up your entire driveway but enough to make inviting holes for (you guessed it) water infiltration and insects.  Ah... the Great Mandala goes round and round and round!

Seam after widened with Fein MultimasterThe solution is simple... seal the seam with a flexible asphalt crack filler such as Blackjack Speed-Seal Blacktop Filler.  It's not hard to do and will last for many years with proper preparation.

How to seal your concrete/asphalt seams...

The first step is to, if necessary, open up the crack so it is at least 1/4" wide and at least an inch or so deep.  The crack filler is less likely to fail if it is firmly seated in the crack, as opposed to simply putting it over the surface as you would apply tub caulk!  I used a Fein Multimaster with a carbide grout removal blade, which does a good job on both the driveway and the concrete and isn't dulled by the dirt!  You can also use a grinder if you're careful.  If the crack is already wide enough but just messy, you can use pretty much any tool that will fit into the crack to scrape out loose material... old screwdriver, prybar, chisel, "goth" fingernails, etc.

Apply crack sealer with caulking gunUse a vacuum and thoroughly clean out all loose debris. 

 It isn't necessary to wash the surface and a little remaining dust isn't a problem.  Also vacuum around the crack so the filler stays clean while it dries.  Leaves and twigs will stick to it till it skins over... take a little care and you'll have a neater looking job!  Promise.

You have a choice of asphalt fillers in caulking-type tubes or in plastic jugs that are pourable.  For this repair, I prefer the thicker filler in caulkiSmooth asphalt crack filler with gloved handng tubes.  It shrinks less and (in my personal opinion) will last longer that the watery liquid.  But you know about opinions, so it's your choice!  On the plus side, the liquid form is easier to use, cheaper and doesn't require a caulking gun.

Use a caulking gun to apply the asphalt filler. 

I chose Blackjack Speed-Fill because it will fill cracks up to an inch wide.  Some brands cannot bridge a gap that wide because they shrink too much and will pull away from the edges, breaking the seal!  Cut a 1/4" opening in the end of the tube to give you good volume.  You'll want to pump the caulk as deeply as possible into the widened seam so work slowly and deliberately to allow the thick filler to push into the crack.  It is not necessary to fill the seam level to the surface.  In fact, you will find it neater to have the caulk a slightly lower than the surface during this initial application.

Filled driveway crackOnce the crack if filled, use your finger or a tool to smooth and press the caulk into the seam. 

Since the driveway is rough, don't expect a bathroom caulk-level of smoothness.  As it dries, the flat-black appearance makes it look quite natural, especially if you've sealed the entire driveway since the filler is a nearly exact color match to asphalt driveway sealers.  (Yes, you can apply the crack filler before or after you seal the driveway... your choice!)

As you see from the photo, I prefer to wear a chemical-resistant "throw away" latex or nitrile glove for this work, tossing it in the trash when I'm done.  You can get these gloves in bulk very cheaply from places like Northern Tool and even some home and hardware stores for as little as $.15 a piece! 

Allow the asphalt filler to dry at least an hour or two before you touch it, and usually overnight before heavy water contact.  After that, you're good to go!!