Recovering existing tarmac - Depth, type, drainage

[Dubliner]

We have an existing driveway area (about 60 sqm) that has 20+ year old tarmac. It's breaking up badly and has some small weeds and moss, plus a few potholes (none too deep). We want it replaced with something smooth and flat, primarily so our small kids can have somewhere to play and to trundle about on trikes and the like.

We've got a quote from a contractor we got a recommendation of who is proposing to chase the existing surface at the entrance and in front of the paving flags we have in front of the house and sweep up loose chippings. He's then going to recover the entire area with 50mm of 10mm wearing course macadam. Cost of EUR1900 (I'm in Ireland).

I've read through much of this very useful site and I have a few concerns and questions as this isn't exactly like any of the examples I could find.

- Does this approach appear sound given the existing surface and state? From reading the site, I can see a full dig out and replace is likely to be a lot more expensive, but I want something permanent and long-lasting.

- Is 50mm of 10mm suitable? I see a lot of talk about 6mm on the site, but in shallower depths? I don't know if there is a cost or suitability difference.

- Is the chase and recover likely to leave us with a significant slope at the edges or a drainage issue?

Any advice, thoughts, most welcome, as are recommendations of Dublin contractors.

Regards,
Dubliner

[Tony McC]

The chasing-out is basically done to tie-in to existing levels, so that makes sense. However, unless there is plenty of fall, accommodating the new and old levels can result in some ponding - it all depends on the site layout.

I can understand the use of 50mm of 10mm surface course macadam: I'm guessing that the plan is to provide a surface course that is strong enough to carry traffic without needing a new binder course. 10mm is ideally suited to this, but unless a 10mm dense macadam is used, the finished surface will have quite a coarse, open texture that is less than ideal for a residential driveway. Again, cost seems to be the determinant as 10mm is cheaper than 6mm.

No mention of a tack coat, I note. If you want the new surface to stay in place, it must be tack-coated to the existing.

30 Euro a metre sounds about right for that quantity of overlay work in Dublin. I can't help with contractors, though, as the blacktop gangs I know in the city are really not interested in anything less than 200m². As luck would have it, I have to see a blacktop contractor in Clondalkin this evening - I'll see if he knows anyone prepared to take on residential driveways.

[Dubliner]

Thanks. Very useful info. I'll discuss further with the contractor. It may be that he just didn't specify the details.

We're a bit concerned about the ponding possibility as the decorative paving slabs are a bit prone to moss in any case (northern end of the house).

I'm not sure from your reply if 6mm could be used (at some extra expense) or if 10mm dense would be better for strength reasons and still be acceptably smooth. Given the use as a play area for small kids, the finished surface texture is important to us.

Thanks for your help.

[Dubliner]

Can anyone advise on the 6mm versus 10mm dense surface texture question?

Sorry to be a pain, but I need to confirm and proceed with the contractor and I'm not sure what I should ask for.

[Tony McC]

Get the contractor to show you the diff between 6mm and 10mm surfacing. I have a "compare and contrast" photo that shows the two side-by-side, but my FTP server is playing silly buggers this evening and I can't get the image online. I'll try again later or tomorrow.

[Tony McC]

Here's the photo...

[Dubliner]

Thanks for this. I'm not sure of the scale, but the difference seems much greater than I'd expect from the measurement difference. I would have said that the pieces in our existing drive ran up to 10mm, but now I'm not so sure.

Anyway, I spoke to the contractor last week and he seems sound and explained what he's proposing. We'll see.

In summary, what he said is that he's going to use 10mm medium dense. He chose this based on the specifics of our drive. We don't have much of a slope/fall-off and if I understood correctly, he believes a denser or finer tarmac will lead to standing water problems.

On tack coats, he said he normally would, but the existing surface we have is both sound and has a lot of tooth from the disintegration (ravelling) of the existing surface, so it isn't needed.

Since he's been recommended to us and he's promised that we'll be happy with the result and it will be flat and smooth, we're going to go ahead. Hopefully it works out.

[Tony McC]

Regardless of whether the existing surface is sound and/or toothless, a tack coat should always be used.

[TarmacLady]

Yikes -- not using tack coat is like not using primer when you paint -- a first-class ticket to having to do it right the SECOND time, except this time having to clean up all the stuff that didn't stick right the first time round.