The Brew Cabin

Posted: **Tue Mar 11, 2008 9:56 am**

The two options given to us by the builder for paving our driveway (approx 7.5 x 12.5 meters): 1) Paving the traditional method i.e. Hard Core, Sand and Blocks 2) Concrete, Sand and Blocks.
We decided to choose option (2) for firm and solid floor. The concrete has been laid, sand and blocks to follow. The floor has a slope towards the building leading to water channels leading to main guttering in front of the garage. However, we now realise that the water will be trapped in the sand between the concrete and the blocks and may result in ruts etc.
We have already spent huge amount of money in skips etc for first removing the existing concreted driveway also soil and to have the new concrete floor all over. The sand and blocks have already arrived (i.e. we may not be able to reverse the decision) but we are now stuck, not sure whether to go ahead and have the sand and blocks on top.

Various suggestions have been made and it looks like we may be better off by mixing dry cement and sand, compact it and then laying blocks on top and hope the water sipping through will dry up the sand and cement and hopefully the blocks will stay on top. Not sure if this is the only solution we have? Can anyone help at all?

Posted: **Tue Mar 11, 2008 3:26 pm**

Your builder shouldn't have given you the second option, there is no real need to specify a rigid base on a domestic project, especially with a permeable surface, short of ripping it all out a concrete screed is the only option i can think of.
Is it a builder or a paving company that is doing the work ?

http://www.pavingexpert.com/rigidbpv.htm

Posted: **Tue Mar 11, 2008 5:32 pm**

Some solutions hereFin drains

Posted: **Tue Mar 11, 2008 9:43 pm**

Moodi - don't panic. There will be a solution, and your builder should be able to provide it! It should never have been concreted, but there will be a way to prevent your drive from being affected by fluidisation of the bedding layer. Without seeing the site, it's hard to point you in the right direction, but the link Pablo has given to the main site will give the options.

Posted: **Fri Mar 14, 2008 3:06 pm**

It would be a HUGE mistake to lay the blocks onto a bed of sand and cement. They are not intended to be used in that way and you'll end up with more problems than you currently have.

There's a page dealing with laying block over a rigid base, rather than a flexible sub-base, and I would urge you to read that. I'd also suggest you kick the arse of the twonk that suggested using a concrete base without thinking through the implications for laying course drainage. I doubt they are an experienced paving contractor!

Posted: **Mon Mar 17, 2008 6:15 pm**

theres a company local to me who does a lean mix base of about 3" deep. I recently saw him doing a large job of around 350 sq m and guess what ? a moth later he was there repairing it.
What annoys me is some builders/pavers will tell a customer that concrete is better than plain old hardcore and of course to the unsuspecting it does sound better. As to them when i say type 1 i,m just talking about hardcore and trying to cut corners

and someone else will be using concrete.

Posted: **Tue Mar 18, 2008 5:19 pm**

I quoted 2 jobs next door to one another. I got one and lost the other. The one I got was a back garden and the other a BP drive.

The bloke that did the BP was a builder rather than a paving contractor and I noticed a half pallet of OPC after he'd already done the kerbs. As I needed some I asked if he would sell me a few bags. He told me they were for the drive "I always use a mix because it's stronger that way" :p

Posted: **Tue Mar 18, 2008 8:51 pm**

It's not called flexible paving for nothing. When CBP is laid on a screeded sand bed, upon a concrete sub-base, the probability of having to return to rectify problems such as tracking is very high. The sand becomes saturated as it's below ground, whether permeable or not, and the water goes where? Nowhere, because there is nowhere for the water to drain to. When the sand gets saturated, the CBP will track, rut and end up looking...well, basically crap.

Even if the concrete sub-base has been pre-drilled with many holes to aid drainage, the chances of clogging at a later date are high, leading to the inevitable repair works but this time just delayed a little.

The Brew Cabin

Block paving - Driveway paving