Wacking sub-grade? is this overkill?

[ReadingGuy]

I am constructing an area of block paving in my drive and I plan to use Terram BuildA followed by 150mm of MOT1, 40mm sharp sand and 60mm Marshall Keyblocks.

The man has just been with the digger and dug down to formation level. However the contour of the excavated area was not quite right and I have removed spoil from the edges and other high spots and used this to help level out the rest of the area.

My question is: Do I need to use a 'Wacker' on the sub-grade in the area that I have back-filled or would a general trampling over the area be sufficient prior to laying the Terram? I had not planned to hire the Wacker until I had laid and levelled the sub-base but I can higher it earlier if necessary.

I have to confess that I do not recall seeing any reference to Wacking sub-grades on either this site or in Tony's book so perhaps I am worrying over nothing.

Many thanks in anticipation.

Mike

[Rich H]

If it's soft, yes, if it feels firm then no. Caversham and Emmer Green are all chalk so very unlikely to need it. South of the river is a real mix, including some clay in places.

If you are putting down 150mm of MOT and using a wacker then do it in a couple of layers.

Whatever you choose, hiring wackers by the week is cheaper than by the day. Brandon on Richfield Avenue are very reasonably priced. Tell Tony the manager that Richard from Four Seasons recommended them and you should get a good price.

[seanandruby]

if you feel that it needs it then tramp it down with a sledge hammer or hand tamp. as long as its not to deep.

[ReadingGuy]

Thanks guys.

I am in Tilehurst and I have both sand and clay in different parts of the garden. The sub-grade on the drive looks sandy but when wet it turns very 'sticky'. God knows what it is!!

I think that I would rather be safe than sorry so I think that I will give it a wack - if it stops raining!!

Many thanks for your prompt replies and helpful advice.

Mike

[Rich H]

Was in Tilehurst doing a quote this evening, Lamorna Crescent, could have come and had a look!

After all this rain, clay will be a dead giveaway because the water will take ages to drain away or evaporate.

I've built a few patios in Tilehurst and I've always had to put in extra sub base, and occasionally dig out soft spots and fill with concrete to be sure of a firm base.

[ReadingGuy]

Hey Rich! Lamorna Close is only about half a mile from where I live!

My soil drains quite quickly so there probably is not much clay in it. The area that I am paving has been part of a drive for at least 25 years and the digger man who dug it out reckoned that it was very firm.

Geologically, Tilehurst is a problem area. Some parts are on chalk, some of which, I am told, have the load bearing capacity of toothpaste!! I think that the drive area is mainly sand plus something else which makes it sticky in the wet but it sets quite hard when dry.

Hope that you get the Lamorna Close job.

Cheers