Paving

[brianohagan]

Is it possible to lay new slabs on top of old ones that have been down for a long time. Although the old slabs are over 35 years old the are sound, level and firmly bedded in.
I don't really want to start pulling these up

[PeteHull]

You should check that they are firm and not wobbly, reasonably clean and check for the dampcourse on any adjacent buildings, there should be a minimum of 2 course of brics below the damp course, if not you could leave a 100 mm gap which can be filled with gravel.
The new slabs should be laid using a motar mix o 4:1, 4 sand to one cement. Lay the slabs evenly and level in both planes, allow to set before pointing in between slabs with a firly dry moter mix to avoid marking the face, and all should be well. Remember to pay attention with run off for drainage, it doesn't need much but needs to be away from buildings.

Hth
Pete

[magicmerlin]

If old slabs are sound level and firmly bedded in then why change them? If you must change them why not take up old slabs and sell them.

[brianohagan]

The slabs that are already down, although sound and level are pretty grotty and I have tried everything to clean them, steam clean, scrubbing the lot. I would leave them if I could get them looking reasonable

[buildersmate]

Have you tried a decent pressure-washer. Not the useless things sold in the DIY stores - a proper Karcher, with about 160 psi, hired for a day from the local hire company. Worked with some old Yorkstone slabs I had with 40 years of grime on them.