Re-landscaping a completely paved garden. Advice please

27 Jun 2013
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United Kingdom
Hello, new to the forum - frequent reader, but first time poster. I'd like some advice on my garden remodelling plans.

Our garden is completely slabbed with paving stones/flag stones. The garden is approx 6m x 6m, NE facing, so gets very little sun. The slabs are all on one level, except adjacent to back and side wall of the house, where 2 steps take you down to a sunken L-shaped pathway, 1 slab in width. This sunken path includes a 3 foot brick wall, which butts against the patio.

My plan is to lift half of the paving stones, and replace them with artifical grass, leaving the other half as a patio. But first I plan to 'fill-in' the sunken walk-way, to level the whole garden.

My first question is, would the base underneight the paving stones be suitable for the artifical grass? I believe the depth of the paving stones, once removed, would be perfect for the grass to sit on. My plan would be to simply lift the paving stones, fill in a small sunken area with some aggregate, compact, lay a membraine, sand, compact again, then lay the grass? Sound about right?

Secondly, and this is my main question - is it acceptable to use surpluss red chip stones and/or crushed slate stones, to fill in the sucken path? My brother has tons of these from his own garden make-over. My plan would be to remove the single L-shaped path of slabs, and break up the top layer of bricks for the smal retaining wall. I would then add the chips in layers, compacting each layer, and then top off with sand/mortar mix, and finally put the original slabs back on top.

I have checked and there are no air-bricks on the house at any point along the sunken path. And the only problem would be a down pipe from the guttering, which I can sort afterwards.

What are your thoughts?
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That's one thing I need to check. Instead of airbricks, would I have a damp proof course? I do know for sure that the house bricks change from a yellow colour, to a brown colour around the base of the wall, and where the existing patio touches the brown bricks, there is definately more than 150mm upwards.

I understand the patio needs to be 150mm below DPC to protect the house? Would I also need to put some kind of membraine agaist the wall to protect it (where it will be underground)?

I'm not even close to starting the project, so appreciate any advice you might have.
I think I will post up some photos soon. It is difficult to explain what I'm trying to do in writing.

I guess my questions are:

- can I use gravel, red chips, slate stones etc, with some kind of sharp sand, to create a subbase, instead of MOT type 1.

- can I simply lift slabs, and replace them with artificial grass, without a brand new subbase.
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Sorry to bang on about it but are you sure the DPC is where the light and dark bricks meet? I'm absolutely not any kind of expert but I thought that the DPC would always be below the internal floor level and in your pictures it looks like the light and dark meet above what would be the internal floor level.

I'm sure some of the experts will be along shortly.
I'm not exactly sure where the DCP is. I cannot see any plastic or anything in the mortar at any point, so I assume the brown bricks are treated in some way?

Are there any DP treatments I could paint on myself?

The level of the internal floor actually sits at the top of the first layer of 'sand' coloured bricks (or were the french door sill is). So where the new patio will join the wall, there will be 3 brown bricks, and 1 sand brick before the floor level.

I also should have added that I plan to leave a gap of approx 20-30cm, filled with red stones, at he base of the wall. I belive this helps to reduce splash-back from the rain.

I think I am safe to proceed with regards to the DPC issue? No?

Can anyone answer - can I use tons of red-chip stones, mixed with sharp sand, and compacted, instead of an industrial aggregate?
red chip will be fine. Don't use the slate though and don't mix sand in with it. Clean stone will not compact at all when its on a solid surface so just fill it up. You will need either a membrane or a lean mix concrete capping on the top to stop your sand bedding for the grass from perculating down through the gravel.

In theory you should dig a few test holes to ascertain if the existing sub-base is deep enough but as long as its been down a few years it should be fine if you just lift the slabs re-level and recompact as you planned. Then spread your grit and lay the turf.

Your dpc is probably level or close to level will the threshold of the doors.
Dont know if this helps but, i knocked a wall down in my house to fit french doors, my DPC was level with the internal floor (as mentioned above), my house was built in the 60s tho so they may have changed how they do things now.

It looks good what you plan on doing, just 1 question tho, why not real grass?, either way looks like you'll end up with a nice garden.
Daniel, believe me, we've debated real grass vs artificial grass for months now. The garden is NE facing, so it only get's sun until 1pm. And being Scotland, it rains a lot, and any sunny periods are shortlived. With real grass, the fear is it would not get enough sun to grow nice and green, and it would be constantly soggy. Our last house was also NE facing, and the grass was mossy and boggy all year round. Finally, we have a young daughter, who will be toddling this time next year, so artificial seems to be our best option.

Project is officially under-way. I spend sunday removing about a foot of weed-filled earth from the beds. And under the existing slabs is a good layer of compacted sand/cement, with solid earth beneigth.

I have another 2 questions if that's ok?

Would you demolish the small retaining wall completely, before filling in the gap? Or would you simply chisel off the top 2 rows of bricks until the wall is below my new patio depth, then bury the remainder of the wall?

The wall is superficially weather damaged (or it might be damp), and the bricks are pretty flaky, but it seems strong structuraly. If I leave the wall, it obviously has some structural benefits for the rest of the garden. But on the other hand, is the wall likely to crumble and sink over time, with the weight of new slabs on top of it?

Also, how would you deal with the gutter down pipe? It goes into the ground into a much thicker plastic pipe. I am worried that if I surround the standard gutter down-pipe with compacted chip stones and sand, the weight might crush and crack the pipe? I'm thinking potentially I could find some kind of stronger piping, to put around the existing gutter downpipe, before I bury it? Thoughts?
I think I've sorted the gutter issue. After some lunchtime investigating, I believe I could cut the gutter-downpipe, and slide one (or 2) of these down to ground level, and then bury them in the sub-base? Would need some kind of grating, cut to fit, to stop leaves and crud getting in. Then covered with red-chucky stones.

I assume this 'underground pipe' would withstand the surrounding sub-base, and protect the gutter pipe?

So, should I demolish the small retaining wall completely?

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