Not Sexy, but Good Nickel Knowledge About Asphalt Paving…
Since most of us don’t install or redo our driveways very often, we probably don’t know much about asphalt. Asphalt is a material that is made of a semi-solid form of petroleum that binds aggregate particles together to create asphalt concrete.
We rely on Gordon Miller owner of GPM (General Pavement Management) as our “asphalt expert” (Full disclosure – Gordon does all our work including our Patterson Self-Storage Properties, and soon will start work at Via Laguna). As we mentioned in the last article, asphalt is less expensive than concrete to install. Depending on the size of the job it can be 40-50% less expensive on larger jobs (like a parking lot), and 15-20% less expensive for smaller jobs (like a driveway) than concrete. However, you must also take into consideration maintenance costs, as over time there will be less maintenance needed with concrete compared to asphalt.
Depending on what your goal is, there are many different asphalt updates available to you besides replacement if you are thinking about repairing your driveway. First, think about the reason for your repair or replacement. If you are preparing to sell, you might install brand new black asphalt, or you may decide on an asphalt overlay to get the dark black look and fill in existing cracks. If you’re just sprucing up around the house, you might also think about a ‘seal coat’. This is a very thin layer (10 mils almost paint thin) which dries and shrinks and just seals the surface to give you a fresh black look – however, it will not fill cracks. There is also an option of colored asphalt now, which is a bit more expensive to install and maintain than regular black asphalt.
Another option is a gravel or “chip seal” drive. We see on many high-end homes. First, an emulsion is poured over the road base then covered in rock. People either love this look and feel or hate it. Pros include: it sounds great – like pulling up to a fancy estate (think Downton Abbey), it comes in different rock colors, and it has the same basic maintenance cycle as asphalt but it won’t crack. Cons include: getting rock dust on your shoes (and tracking it into the house if not careful), rocks getting in your tire treads, gravel flying off your tires (possibly damaging nearby items), raking may be required to keep a uniform look in locations where you frequently turn your tires or drive a lot, and dust may get in the air, in your car and even under the eaves of your home.
Pervious Asphalt is also an alternative – this kind of asphalt allows water through, to percolate back into the ground. It breaks down more quickly than regular asphalt and needs to be vacuumed often or it gets slippery and the pores that let the water through will become clogged. Most engineers will specify interlocking pavers when a pervious surface is needed. Gordon shared that in his experience he thinks having a civil engineer design your drainage so that excess water runs off to a bioswale (dirt or rock-lined ditch) is much better than fussing with permeable asphalt or pavers (and this is from a person that sells both!).
Drainage Considerations: Locating drains in asphalt should be avoided if possible, to prevent settlement around the drain per Gordon. If you have to install a drain, make sure it is set in an 18” concrete vault with a band of concrete surrounding it in the asphalt. Some contractors do not include raising up utility boxes or drains to the full thickness of the new asphalt in their bids. If you have bids that are far apart in pricing, check to be sure all bids include this.
Other Considerations: Gordon suggests staying away from decorative items in asphalt, as they will take extensive maintenance and they are very hard to work with when recoating. He believes your money is better spent on gorgeous landscape or hardscape embellishments and not on concrete or asphalt.
Straight asphalt curbs, which may be lining your driveway or planters, take a special machine for big jobs and there aren’t many in the area so they can be quite expensive. Curved asphalt curbs are much more expensive as they must be formed by hand. Gordon recommends using concrete curbs if you need them as it will be cheaper, more durable, and aesthetically more pleasing in the long run.
One last thing, if the trash truck comes in and out each week through a specific driveway, concrete may be a better choice for that area as heavy trucks are tough on residential asphalt.
If you’d like to call Gordon for advice, his office number is (805) 688-9501. I hope this helps take a little mystery out of asphalt!
Trudi
