Hardcore & Concrete depth for driveway

Wavey

Hi,

I am getting prices to lay concrete driveway over a small front lawn.

There are no issues with quality of soil.

One contractors suggests 2" compacted hardcore and 5" concrete. Another contractor suggests 5" compacted hardcore and 3" concrete. Neither propose steel mesh.

Do both of these seem like reasonable depths for material? Drive will only have a car on it.

Thanks,

Wavey.

C. Eastwood

https://www.boards.ie/discussion/2058247723/hardcore-concrete-depth-for-driveway

Wavey

Remove at least 150 topsoil.

Lay 100 mm hardcore well compacted

100 thick 30N concrete with control joints every 6 meters, with A142 mesh.

Concrete laid to falls as dry as is possible

Still stihl waters 3

https://www.boards.ie/discussion/2058247723/hardcore-concrete-depth-for-driveway

How big is the area

Wavey

https://www.boards.ie/discussion/comment/119123893#Comment_119123893

About30sqm

Still stihl waters 3

Out of the 2 I'd be happier with 5 inches of concrete especially for cars parking, 3 inches is too skimpy in my opinion, but I'd also go with 4 inches minimum of hardcore compacted, I've always done 4 and 4, 4 hardcore and 4 concrete, I'd put in the mesh also

hayse

3 inches of concrete would be ok with 5 inches of 804 under it.

standardg60

The deeper the hardcore the greater chance of subsidence and cracking, no matter how much it's compacted.

Did either party check the depth of the topsoil or ask how long the lawn was there?

I've extended plenty of driveways having just excavated a few inches and laid directly on the compacted soil and they've never gone anywhere.

The best compacter of ground is time.

Still stihl waters 3

https://www.boards.ie/discussion/comment/119127311#Comment_119127311

I'd agree, if you get a good base there's no need to go breaking it out just to put something else in

Wavey

https://www.boards.ie/discussion/comment/119127311#Comment_119127311

Neither have checked the topsoil depth but I know it is at least 12" and has been there for nearly 50 years.

So would the 2" hardcore and 5" concrete be the better solution given the depth and age of the topsoil?

C. Eastwood

https://www.boards.ie/discussion/comment/119130356#Comment_119130356

You must take out the topsoil which contain organic matter and microorganisms etc and which will decay over time and shrink and cause uneven settlement of the concrete and may cause cracking. Must remove minimum 100 mm, but ensure all above matter is removed.

The Continental Op

Another reiteration of dig out all the topsoil! Keep going down till you get to subsoil with no organic matter. Should be easy to get someone to take the topsoil. If I lived nearby I'd dig it out myself and take it away.

Last time I bought 804 is was something like €300 for 22 tonnes delivered. Easy to spread if it can be dumped straight in the hole where the topsoil came out of.

standardg60

https://www.boards.ie/discussion/comment/119130791#Comment_119130791

I'd still argue that anything below 100mm in a 50 yr old lawn has done all the decaying and settling it's ever going to do, and removing any more than that is pointless, but every contractor is going to have their own way of doing it.

The only times i've ever used hardcore in such circumstances was if i needed to build up to a higher level, just seems to me that most contractors have been taught that this is the way it's done, your 4 inches of hardcore and 4 of concrete, without anyone really questioning why it is actually necessary.