The Brew Cabin

Hi tony i have to block pave a drive that is 70 ft long and 20 ft wide i have the digger digging it down to 10inches as i write this however i am a little concerned as to getting the levels right with the mot and sharp sand because the drive is like a big bowl , it falls down from the pavemnet by about 3 ft over the first 15 ft then it runs flat and goes back up by 3 ft for the last 15 ft to meet the rear garden so my levels are set by the pavement and the rear garden whats more the drive runs at the side of the house and the entrance to the house is mid way along the drive so my levels are set there by the dpc and the door so i will have to stay with the bowl effect with the new drive i was thinking of using marked pegs to know exactly how much mot is going where, and am i wondering about any tips u may have for me when doing this this type of drive thx m8y :)

The easiest method of checking both depth and excavation and the level of the sub-base material is to use a set of boning rods.

Set up a back sight at, say 1200mm above dpc on the corner of the house, then position a 1200mm fore sight on the public footpath, propped up with bricks or fixed to a footplate. Then, using a traveller set to (1200+100=1300mm) you can check the level of the top of the sub-base by sighting through, positioning the traveller anywhere you like between fore- and back sights.

You can repeat this for the back section, setting a fore sight at the garden and a back sight at the house.

If you want to form a hog-back curve in the profile, then have a look at the Profiling Kerblines page for further guidance.

Once the sub-base in laid, I prefer to lay my edging courses next, on a cement-bound bed and then use them as screed guides for the rest of the paving. That way. I can play about tweaking the profiling to achieve the sweet curves I prefer, and if necssary, the sub-base can then be checked again by stretching a string line from edging to edging course and 'dipping' to check, adding or taking away from the sub-base as required. Remember, a sub-base can be +/-10mm, but the more accurate you are, the less likely is the incidence of differential settlement in later years.

If you're not familiar with these terms, just let me know. I'm guessing you're a Contractor and will be familiar with boning rods, diff. settlement and hog curves, but if it's all Greek to you, post back and I'll explain it all in Layman's terms. :)

thx tony for the answer its nice to get a bit of reasurance from an expert such as yourself, we have a laser level which i will hopefully be able to implement in this job as well :) thx again.