The Brew Cabin

I am in the process of rebuillding a rather scruffy patio with block paviors. I have dug out, levelled the site and installed some kerb edging, of which more later.

My question relates to how to incorprate a small drain and small inspection cover for a water meter into the paving. Both the grid of the drain and the inspection cover are quite small - only 6" square and so would not merit the use of a recessed tray cover, even if they are available in such small sizes. The grid of the drain is currently 'housed' in a tatty piece of concrete which sits on an 8" square gully, the top of which is maybe a couple of inches proud of the dig level/ sub-grade. How do I mount/ connect the grid to the gully and fit it into the block paving?

As for the water meter its inspection cover sits on top of a plastic tube (height adjustable using a threaded wall - clever eh?) can I just put hardcore (Dpt2 is it) and sand around this or is it likely to collapse? Should it have protective concrete overcoat or concentric cylinder?

Finally, the edging kerbs I have laid are supported by concrete below and behind them, but not in front, in fact the front of the edgings stand a little proud of their footings. Does this matter and will the action of the wacker plate tend to push the sand up beneath them and unseat them?

I hope you manage to make some sense of the above - your advice would be gratefully received.

An excellent web site, by the way, packed full of useful information.

I'm not sure what you mean with the gully/grid problem. If it's tatty, then replace the complete unit and set it to the correct level within the paving (3-6mm below paving level). It's a nonsense to spend hundreds or thousands on block paving and then skimp on installing a new gully that costs only 30 quid.

With the water meter cover, set it to the correct height, then haunch it with concrete to hold it in place, but make sure the haunching is (thickness of paver + depth of bedding) below the top of the unit.

Finally, don't worry about the edgings. As long as they are haunched at the rear, and bedded onto concrete, they should be fine. There's absolutely no need for concrete at the front.

Tony,

Thanks for the prompt reply and for setting my mind at rest re: the edgings.

As regards the gully/grid problem closer investigation reveals that the grid should sit directly on top of the gully. Presumably, the drain was installed before my old patio went down so that when the patio was built it raised the level of the original backyard. To allow the old drain to be used the grid was elevated on what was effectively a square shaped tube of concrete bringing it level with the newly installed patio.

Is replacing the old gully the only solution? It seems a pity to break up a perfectly serviceable unit, install a new one and reconnect it to the existing drain. It's also the type of job I would prefer to leave to a professional - any idea how much this work might cost?

Another question has just occurred to me. The patio is roughly 5.6m wide x 4.3m front to back and will drain to a point midway along its width and about 1m along the shorter dimension. Initially, I had thought to feed rainwater into the drain via dished channel blocks running front to back.
It's difficult to descibe without a diagram, however, the real question is are these dished blocks necessary I have seen no mention of them on your web site and my patio may be too small to warrant their use. Secondly, I am slightly concerned that they might not fit in very well with the Regatta blocks (from Top Pave) that I am intending to use and that the dish might be a "tripping" hazard.

(Edited by Jon at 11:13 pm on July 10, 2002)

The gully/grid - you can buy raising pieces for some gullies that allow the grating to be set to a higher level, but they are not available for all types. Your local BM might know. Alternatively, you can elevate the grating yourself by building a raising piece from brick or concrete flags, or even casting one in-situ as seems to have been done before.

If you did replace the gully, then I suppose the materials might come to 50 quid, and then the labour would be perhaps 100 quid for such a small job, but, if you don't mind getting your hands dirty and enjoy a bit of a dig, it really is very, very simple for you to DIY.

Dished channels look fine with block paving. They are mentioned and illustrated on the site on the Road Kerbs page and on the Draining a Pavement page, which also shows how a channel can be formed in the blocks themselves.

There's no trip hazard with these dished channels - they are specificall designed for use on pavements and as long as they are correctly laid, they are as safe as can be.

I have managed to "raise" the mouth of the drain on which the grid sits in the manner you suggested and I think it looks OK, but then I would say that wouldn't I?

I have got the sub-base down (compacted mill waste - those wackers vibrate like hell!) and am in the process of putting the sand down ready for screeding. Of course, I now have another(!) question. I shall be using the rear wall of the house as a reference "line" laying rows of paviors parallel to it. However, there are a couple of obstacles along this wall, namely, the drain pipe and a drain for the kitchen waste. I guess I can just miss a block around the drain pipe and fill in with compacted sand or even concrete.

The kitchen waste is more of a problem as I really need a raised border around it to contain liquids. However, I can't put kerbs around it as these would interfere with the pipe coming out of the gully and into the main drain. I can't compact the hardcore around it either for fear of fracturing the drain. Is there a standard solution or product for this problem and how should I pave around it?

Once again many thanks for the advice.

If you omit blocks in the edge course to accommodate the drains, then patch-in with coloured grano or concrete, rather than with sand. Sand will just wash away and leave a hole in the pavement.

I can't quite visualise the problem with the KW - is the 'pipe' of which you speak the discharge pipe from the sink itself, or do you mean the pipe that connect the KW gully to the FW system? Any chance of a picture?

Assuming you mean the discharge pipe, then you could use paving bricks laid on edge on a bed of mortar, and omit the section where the pipe feeds in, then patch that up with coloured mortar or grano.

Compacting the sub-base around the gully is a delicate business. We normally use a punnel (see Tools page) but you could use a sledge hammer or even just a lump hammer to consolifdate the area, a bit at a time. Once the blocks are in place, you should be able to run the wacker plate over the lot, as the sand bedding will 'cushion' the buried pipework.