The Brew Cabin

Hi, congratulations on a fantastic site. Please advise me regarding block paving a small drive 15ft. long by 12ft. wide. Theres a natural fall to the pavement but the pavement drops 3in. across the width of the drive. What is the best way to set out the levels to produce a neat edge where the drive meets the pavement as it is 3in. lower one side.

Best regards,
JR

Your paving doesn't have to be a flat plane: it can 'twist' to tie-in perfectly with the public pavement, no problem at all.

You state that it's 15ft long, which is roughly 4.6m (it is the 21st Century!!). So, allowing a fall of 1:60 (roughly 17mm fall per linear metre), the fall from the 'back' of the drive would be 4.6m X 1/60 = 77mm. On the drawing below, I've shown this as the high point (A) having a datum level of 10.000 and so, with 77mm fall, the level at the footpath (B) is 9.923.

Then, as you state, there is 3inches (75mm) of fall across the width of the drive (between B+C) so this gives us a level at C of 9.923-0.075 = 9.848, which, as shown on the drawing, is a crossfall of roughly 1:48.

This then means there is an increased fall from D to C of 152mm, which is about 1:30.



Lay your soldier edgings on concrete using taut string lines to guide line and level, as described on the Laying Edges page. At the threshold with the pavement, lay your soldier edges to the best line possible, disregarding any minor variation in level of the public footpath. Some contractors like to lay 50-150mm back from the edge of the public footpath and then infill the gap with repair macadam or a concrete fillet to take up any minor differences.

The back edge of the drive (A-D) is laid as required, and then the sides (A-B and C-D) can be laid to tie in as required. You then screed off your bedding layer using a notched screeder board. The plane of the bedding layer will 'twist' as it moves down the drive towards the public footpath, but block paving is more than capable of dealing with such a minor twist with no noticeable effect on the jointing. Honestly!

Once the bed is screeded, lay the blocks, cut-in, sand and wacker and then you can have a pint. :)

Hi Tony,
thanks for your prompt reply. My first instinct was to pave it in the way you outlined but when I looked at drives done by local contractors the tie-in with the pavement varied enormously. A few had layed the blocks in the same plane and then haunched the low side with concrete which I thought was not best practice. When you look at the drive your eye is drawn to the concrete haunching.

Tony, what is the maximum "twist" that can be accommodated and what software do you use for designing drives?

Best Regards,
JR

The variation in laying strategy is because there's no proper training for block laying in this country, so some contractors bodge it by relying on a concrete fillet, while the better ones roll-over the paving (twist it) to tie in with existing. The big dollop of concrete at the threshold of a driveway is always a good indicator of an eejit.

The maximum twist is phenomenol. Ony my own drive, I've incorporated a roll-over of 150mm over a distance of 500mm - imagine a 500x500mm square, with one 'corner' 150mm lower than the other 3. This was done to accommodate a 'dry area channel' near the damp proof course.

Software I use - TurboCad is my favourite for small jobs, either 3D Designer or v8, as it's simple and fast, but I use AutoCAD for the larger commercial jobs. The real power behind any cad system, though, is the 'library' that each designer develops over time to help build designs, and mine dates back over 10 years.