Jul 14, 2016

What goes under your pavement makes a big difference

In our previous post we discussed the design considerations and planning that should be done prior to paving your driveway. One thing that needs to be considered is if the paving is a new installation or is replacing an old and worn out driveway that is no longer suited to your needs or simply has aged beyond a repairable state.

In either case, for a new installation, or after the old driveway has been removed, the next step is to prepare the base for the new driveway. Setting the right foundation in place is key to a making sure the new driveway works well and lasts a long time. Making sure that there are no hidden problems buried in the ground and preparing proper drainage are essential and not steps you want to skimp on.

First though let’s look at the case where you need to remove an existing driveway. Here are some things you will need to think about.

Removal of an existing driveway

If you have determined that an entirely new driveway is the best option, removal of the existing surface is the first step. Whether it’s old asphalt, concrete or paving stones the removal process typically starts the same way.  First it needs to be broken up into manageable sized pieces that can be fitted in a truck. Then a skid steer or bobcat is used to remove the old surface material. These versatile machines make quick work of loading the old material into a dump truck to be recycled or sent to a fill site.

It’s a good idea to find out what kind of machinery and man power your selected paving contractor is going to show up with. Be cautious of fly by night contractors that sub-contract part or all of the work to others. This can lead to many problems such as work delays, additional costs and liability issues just to name a few.

Preparing the gravel base before paving– check for surprises!

Once the old material has been removed it’s time to assess the gravel base, unless of course you run into something unexpected underneath the existing driveway. Over the years we have discovered some pretty remarkable things underneath old driveways.

Some of the things we have discovered underneath existing driveways are: Tree Stumps, Waterlines, Roots, and sometimes old layers of driveways from the past. Although most of the time when removing an old driveway you will run into some kind of old gravel base that was laid underneath the original driveway, the odd time you will run into a surprise and that’s why it’s called an “estimate”. In the event you do run into a surprise your trusted contractor should explain the situation and then make recommendations to determine the most cost effective solution, to get your project back on track.

If the old driveway is removed and your gravel base is relatively intact, then you may only need to add a couple inches of road base gravel to solidify your base and bring it up to the recommended 4 inches.

Note: This is the optimum situation and the one a professional paving contractor will base their estimate on in order to keep their price competitive. Beware of the estimators that do not inform you of the challenges and additional costs that may incur if there is something other than existing gravel under your current driveway.

For example, your selected contractor removes your existing driveway and discovers that the main reason your existing driveway was in such bad shape is because there is nothing but dirt and clay underneath it. Although this only happens 10% – 20% of the time, it can raise the costs of your project dramatically because of all the additional work required to complete the project properly. Additional machine costs, man power, trucking and material costs will all likely need to be adjusted.

Gravel Base Preparation

The next step is the preparing the gravel base. Make sure you know what kind of gravel base is going to be used on your specific project. Believe it or not, even gravel comes in different levels of quality. Your contractor should at least specify that they are using ¾ inch road base gravel. It is possible to use other forms of base such as recycled gravel, recycled asphalt or recycled concrete however ¾ inch gravel road base right from the local gravel quarry is usually your best option. Beware of any contractor using clear crush gravel as a base. This type of gravel is best for drainage, not compaction and could lead to premature deterioration of your new driveway.

Grading & Compacting the Gravel Base

 Once the gravel base has been installed it is time to for grading. Grading is extremely important because it will determine which way the water will flow once the asphalt surface is installed over top. Unlike its cousin concrete, the grading for asphalt must be close to perfect before installing the asphalt because asphalt is usually installed on residential projects at a compacted depth of approximately 2 inches. This leaves very little room for error when determining which way the water will flow when your project is completed.

Once the grade has been set it’s important to make sure your gravel base is properly compacted. There are a few different tools that a professional paving contractor should have when compacting. The majority of the compaction on residential paving projects will be done with a 5000 LB double drum vibratory roller. This roller combines weight and vibration to create maximum density in the gravel base so it can support your new driveway.

The other main tool is the plate compactor. This is a small walk behind vibrating compactor that is used along the edges and other confined areas where a larger roller may not be able reach. A small hand held compactor may also be used in very tight or hard to reach areas.

Note: If the gravel is especially dry and the weather is hot, it’s important to spray some water during the compaction process, to allow the gravel to reach maximum density and compaction.

Once the gravel base is in place and graded and compacted properly it’s time for paving! Next post we will detail all these steps so check it out!

In the meantime if you have any questions or would like a quote on having your driveway paved, please call us at (778) 855-0513.

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