Although most people do not have the tools or equipment to actually install an asphalt driveway there are many things you can do to prepare the drive for paving work. The driveway without exception must have a solid base underneath to pave upon. Soft or wet spots are the most common reason for failure of the pavement itself. Cracking or alligatoring means the ground is unable to carry the weight of the vehicles driven over it. Severe wet spots will cause the pavement to fail totally and breakup into large chunks and cause the entire driveway to fail.
There are available today ground stabilization fabric materials that can be laid under stone sub base materials in wet areas to help solidify the sub base itself. The material is fairly expensive but may allow installation of a driveway where it would not be possible other wise. If placed directly on the earth below the sub base and over the wet area, once the sub base material is properly compacted the ground will support a great deal more weight without and shifting or movement. Many masonry supply stores carry these materials. It will take two people to roll out and handle the fabric as it generally comes in twelve foot wide rolls. A local excavating contractor may have some smaller rolls to sell. Give them a try as well.
Our first job is assure there are no wet spots either by installing some under drains, ditching along the edges to carry away surface water or actually replacing some of the wet earth with stone or other suitable materials. Sub base materials could be small and large stones, DOT item 4 materials, crushed gravel or bank run sand and gravel perhaps. The material needs to drain well and can be compacted with mechanical compactors. Drainage piping could be twelve inch corrugated piping which when installed will help water quickly pass under a drive or smaller four inch perforated piping run under the driveway areas encased in stone to provide constant pathways for water drainage without soaking the soils themselves. Water will always take the path of least resistance so any drainage piping installed will help the ground to dry much more quickly than nature would allow by itself.
Once you have solved any current or potential water problems you can move on to the actual asphalt sub base itself. Most homeowner driveways have a four inch base of gravel shale or item 4 installed when the home was built. Over the passing years, car tires break the shale down into very small pieces which will not provide a great sub base material. Adding new shale or stone can become a yearly maintenance project to maintain a smooth driving surface. As the stone or shale is pressed into the earth you are creating a thicker and thicker sub base. Depending upon whether you want your new drive to finish up higher or perhaps level than the adjoining lawns or gardens is how much sub base you want to have in the end. A typical residential driveway is ten feet wide with an actual driving surface area of about eight feet wide. For paving, you will need a solid ten foot surface to get a nine foot drive. Ten foot drive, eleven foot surface and so on. You need to have at least six inches of sub base beyond the actual finished paved width on both sides. The extra flat area is used to backup the asphalt and prevent the edges from crumbling. Remember also that asphalt and sub base may be as much as six inches thick and will require extra topsoil to backup the edge of the sub base and asphalt.
By adding sub base material and keeping the surface as level as possible, you will already have the sub base built for the paving man. In many areas of the US a material called blue stone screenings is available. This material is actually finely crushed granite and comes in three colors. Blue which will turn a darker blue when wet as time passes. Red that will also turn a lighter blue over time and yellow which stays yellow tinted forever. Once graded, this material becomes as hard as concrete on a driveway. I have seen blue stone screening surfaces snow plowed winter after winter without any plowing damage. A new dusting every few years maintains the crisp color and in-fills any depressions that may have developed. This makes a super sub-base for finished asphalt.
Well ahead of the time to have the driveway paved you should also install several conduits under the driveway for future landscape lighting. Depending upon the length of the drive, a crossing conduit every fifty feet or so should suffice. If an area is very rocky or wet, add additional conduits now before paving. Adding them later will require cutting and patching the asphalt and will not only destroy the driveways appearance but will provide a potential area for surface water infiltration. Conduit is cheap and if you never use it, it is better safe than sorry. Plastic (PVC) conduit is better than metal as it will last underground forever. Put caps on both ends to avoid any nasty surprises later on when you uncover them. Clearly mark the ends with stakes but also draw a little map and take measurements to each end from permanent objects in the yard. Once the grass grows back you will have no idea where the conduit ends are located. If you do this far ahead of the actual paving, your car traffic will compact the sub-base and will prevent any future sinking under the asphalt and thereby causing the asphalt to crack. You do not want to have to cross the new asphalt with anything later on..
Call several paving contractors for prices. The nicest guy may not do the nicest job. Make sure you tell each one exactly the same things you want. If you change the description of the work, you will not get comparable prices. Write down what you want done and then give them a copy. Ask for a written quote to make sure they included everything on your lists. Will they pickup all spillage? Are they insured against yard damages to flowers or trees or your house? How long is driveway guaranteed? How thick with the rolled asphalt be when done? Loose rolled asphalt 3 inches thick will be only 1 1/2 to 2 inches thick when rolled. Ask questions before they do the work. Get a written signed contract and a copy of their insurance policy. Be very careful with down payments. If they insist on one, make sure it is not a major portion of the contract value. Many times a down payment is paid and the contractor never shows again. Do not be suckered in by sob stories. Reputable contractors have open accounts at asphalt plants and do not need your money to buy the asphalt. If you sense something is awry move on to someone else. Ask neighbors about his work or stop at someone’s house who he has just paved their driveway. Most people are proud of their new yard and will glad to talk to you. Call the Better Business Bureau and check on the contractor as well. It may sound like you are a bit over cautious but after all it is your hard earned money.
Once you have selected a contractor ask him/her if there is anything else you can do to save a few bucks on the price. Maybe removing a pre-installed asphalt driveway apron or removing adjacent features such as signs or statues or whatever else that he figured on doing for you. If you save fifty bucks on the price, that is fifty dollars towards your next project.
Pete
Your Friendly Building Inspector
http://www.Wagsys.com
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