What factors make a good blacktop (asphalt) parking lot?

Question

I want to convert a small gravel parking lot into a blacktop one. What are the features that I should seek for it to be a well designed and constructed. (I presume that one of them is enough gravel underneath, right? If so how much? Are there different asphalts that allow water to seep through so there is not so much dependence on one drain by the building to handle all the water runoff?)

Answer 1

you can get a pavement that water seeps through but it is more expensive to put down and need a different base stone but a good  contractor will tell you what you need and a good base is the best thing for a good driveway/parking lot

Answer 2

Your bids should include rough grading and compaction of any existing gravel, addition of any smaller aggregate and final grading. Base should be sloped to drain water off of surface which may cause you to put in a drywell for water to run into. These drywells can cost about $2500 each.

There are many different asphalt formulas - some must meet state and federal specs - others, like your project have no specs so beware of traveling asphalt crews who buy the cheapest mix available.

Asphalt is usually laid down in 2 steps. First the base which is usually 2" and the aggregate is somewhat larger than that in the final or top coat layer. Many subdivisions,parking lots,etc. will have the 2" layer put down and then wait up to 1-2 years to have the final top layer placed.

Anyway, have the asphalt company rep come out and talk to you about the job. Ask about existing base, compaction,any additional base materials (rock) needed. Drainage.

What mix they will be using for the base layer. This includes aggregate size, the binder materials (holds everything together) asphalt percent. Make sure they haul off an little dump piles they make -(small piles of excess asphalt from cleaning out paving machine,trucks,etc.

Get a proposal and not an estimate. Do not pay all money upfront, pay a certain percentage the day they show up to do the work. Such as 35% down due on the starting date of August 15, 2008.

Good Luck

Answer 3

In my opinion only the base is the most important. If you want it to last the base is the secret. I wouldn't want any water to go through it will sit there and cause the base to give way and the next thing you know you got a pot hole. I like a hot mix. It needs to be rolled and sealed graded to go to the drain or off the edge. No water under will make it last. That is why it takes them so long to build roads. Preparing the base with lime and base material then asphalt on top.

Answer 4

Besides the proper foundation for the asphalt itself, you need good drainage. You do not want the water "seeping" through the asphalt. Waterflow should be pitched towards the drain(s). If you live in an area where freezing occurs, you don't want water sitting and puddling.

Answer 5

mmmm,several variables here.

1) shoot in your elevations,a positive drainage flow is 1" fall per 10' run.

2) once you have your elevations set they can proceed with sub grade work.Sometimes they will over excavate and bring in base.

3) good base,here we use recycled concrete (class 6 - 3/4)

4) the contractor then will roll for compaction.

5) true there are different grades of asphalt however the key to a lasting parking lot is the compacted thickness of product.Many residential contractors will sell you 4" of asphalt,before rolling and your end result will be guaranteed trouble.

For most commercial use lots,or those that heavy trucks may use 6" to 8" compacted is generally what you see.Depending on how spendy you wish to get they will offer spraying with a vegetation kill or a sub mat barrier.They can contour/crown the asphalt to assist in drainage needs.

Request your bids from reputable comm contractors,they have the knowledge.

Good Luck

PS: the contractor I use says recycled concrete by far better.Who am I to argue?.I use it as a base for my concrete jobs.I will note that different parts of the country have different soil conditions,ask the contractor.