The Brew Cabin

HELP - I'm being a bit dense and need assurance. I need help on the methodolgy of laying the bedding layer for my block paving DIY patio. From the advice of the Screeding page and assuming 40mm final bedding layer and 50mm block paviour, is my interpretation of sequence correct?
1. Lay out material generously (say 70-90m) on subase;
2. Lightly compact (2 vibrating plate passes);
3. Dig out and level in screed bars at 41-43mm below FPL ;
4. Screed off;
5. Remove bars and fill in;
6. Lay blocks, brush in sand, vibrate, check FPL's.
I appreciate that my material charactersitics may not give the same performance as the dims above but is my basic method correct? Also, when ordering the sand should I request "Coarse Sharp Sand"? And finally, can I leave the levelled bed exposed until the following w/end before laying the paviours?
Thank you for you help. Your website is many a DIYer saviour. DavidH

Your synopsis is spot on, David. :)

When ordering the sand, ask for "Coarse grit sand suitable for laying block pavings" and the BM should be able to sort that out. The full name is often given as a "Zone 2 Class M washed coarse grit sand", but that would only befuddle the poor order clerks behind the desk! ;)

Once the bed is levelled and screeded, it should be paved over asap. If you leave it overnight or longer, the local cats will shit in it,and it will be disturbed by wind, rain etc., so it should be topped-up and re-screeded just before laying the blocks.

Keep me informed of how you're getting on. :)

Almost there now. Rain has severely disrupted my output. However, one, hopefully final, question!

Q. I have constructed steps to the back and patio doors. They only consist of one 75 mm riser each, but should I infill them in the same method as the rest of the block paving? What I really mean is, should I be vibrating blocks into grit sand bed? I feel that the size of the step (0.7m x 1.5m) would cause a problem for the plate compactor. i.e. by the time I have started it up and tried to keep it from vibrating off the edge Iwould be switching it off again. Also how do I compact the paviors under the door cill/threshold. Is the answer to fix them on a rigid base (mortar them in)?

Your help would be gratefully received again. David.

No - for the treads, lay the blocks on a 10:1 sand/cement mix and clonk them down to level. Dragging the wacker up there will rattle loose the risers!

Getting the levels right where the blocks lie under the cill can be a bit tricky, but if you judge the bedding right, they will go in and you should be able to tap them down enough to consolidate the bedding. Once the cement content sets, that should be adequate.

How's it all looking? Any photos?

thnx for all your help. I thought I had finished annoying you with diyer questions but just one more.

Q. I went to use Marshalls sealer on my finished paving but 'bottled it' and washed it all off before it dried? The reason - Marshalls state a mix ratio is 1part sealer to 6 parts water and a coverage of 1 litre of mixed sealer for 7.5 m2. I have approx 20m2 of paving following a line around the back of house and conservatory. I attempted to sprinkle using a rose on a watering can. I started on a 0.7m wide by 4 length of concrete block path. The coverage was not even and by the time I had gone back to ensure joints were wetted i had practically used all of 2litre mix. It looked really white and dense. Not sure how it would dry, I washed it off and booted up the PC to contact you. What am I doing wrong? Your web site details that it dries and gives a glaze to blocks, but I don't want shinny if I am laying it on too thick. Help! David.

Marshalls' sealer? Do you mean 'Keybond', David? Or is it some other product?

Yes, sorry, keybond. White, PVA looking, liquid in 5litre container. Any pointers?

Keybond isn't a sealant, but is a Joint Stabilising Fluid. It 'glues together' the jointing sand, but has no effect on the finished appearance of the paving, once it's dried. It doesn't give a glaze - you must have mis-read that section.

Dilute it, as it says on the pack, with 6 volumes of clean water, and stir it well. Douse the paving - you don't need to go to a lot of trouble making sure coverage is exactly even - spread through a rose on a watering can until the top of the blocks is wet, then move on to the next patch. Excess liquid will run off the surface of the blocks and find its way into the joints.

It takes an hour or so to dry, and you might notice a whitey-purple hue to the paving at first but, rest assured, this will disappear in the next 24 hours or so, leaving the blocks completely unaffected, but the sand jointing bonded together.

If you're still nervous, just treat an area of a couple of square metres in a discreet corner, leave it for a day or so, and see for yourself how it works out. Fret not - as long as ithe Keybond is properly diluted, it's almost impossible to balls it up. :)