My new rear garden has had concrete slab paving for decades, resting on heavily packed and deep London Clay soil and a small amount of odd rubble. The paved area measures about 6x7m. The soil under the slabs is solid with weed roots, even where there's been no light for many years, and weeds (of all kinds) come up between the slabs continually.
I want to convert the paved area back to a nice garden and grass. The options I have heard about are:
Bulk replacement: excavate existing area some inches down, remove old rubble/soil/weeds, bring in new topsoil, compact a bit, lay new turf or seed. Concerns - Guaranteed success, straightforward, completed quickly, but probably quite costly as work on this scale probably would need mechanical hire and grabber removal.
Remove paving only (much less bulk), break up packed soil some inches down, sift manually for weeds, mix in compost/whatever, compact a bit, lay turf/seed. Concerns - no idea how much work involved and time required (might drag on a long time), soil may end up poor condition than if new good soil was introduced and need regular prevention against deteriorating, and introducing new soil implies bulk removal and cost as above so will there be any net benefit compared to the 1st solution.
I haven't had to do garden landscaping on this scale before and have no idea what I would actually have to do, nor the amount or work and cost and any practicalities involved, nor what mechanical equipment might exist could offer trade-offs between time, cost, final quality, and physical effort. I am open to hiring a contractor but will probably end up doing it myself, especially if a contractor would add a lot to the bill as expected.
I don't expect sorting it out to be cheap, but I would like to feel once it's done, it mostly stays done (other than annual maintenance) and is "low maintenance". For example, if it will help that the soil drains well, or retains water and nutrients, I'd prefer to ensure the soil the turf grows on actually has those characteristics for at least some of its depth, instead of needing to be "propped up" each year. I'd also like to ensure that any depth I work to is sufficient for the soil to retain water and nutrients enough for the grass to cope with future hot summers (ie if I only sort out the top 3 inches will there be issues with drying out/nutrients washing out). I'd like to "do it once and do it properly" as we hope to enjoy it for a long time to come.
The house is a terrace property so the only access to the garden is through or over the house itself. Large scale material movement would involve renting a conveyor, a narrow mobile digger, or at an extreme I could hire a mobile crane and hoist bulk material over the property roof (all of which could be acceptable options). Because of the residential neighbourhood and the terrace nature of the house, I'm doubtful that large scale manure and similar material (or chickens!) would be a good idea socially :-)
I need to dig up and remove about 15-18 cu.m. of packed soil and rubble and get it to the front and taken away, to get the basic ground level nearer the back of the house as I want it, so heavy bulk moving of material is already going to happen to some extent. I haven't yet decided how this will be done so that's open to being combined with the return of the paved area to turf.
Naturally I'd like to minimise effort or cost. How much work is actually involved and how deep do I have to work? What are the options I should consider and how do they stand regarding time, money, effort and final quality?
The garden is mostly exposed (a few smallish trees, no overarching shade). It's north facing but raised (the house has a cutaway as it was on a hillside) so it doesn't get much shade from being behind the house. There will be beds and planting in places, and there's a small "island" in the middle (maybe 8 ft across) which has some small shrubs/trees and that will stay, but I'd like to put the bulk of the paved area back to turf. Below the paving seems to be almost entirely compacted soil and stone, any concrete or rubble layer I do find anywhere, when I get going, I can deal with. The pics show some of the area where a little paving has been lifted.
The garden is about 3m of extension + 11m of paved area (almost all raised behind the small retaining wall). The overall plan is to level the first 2.5m of that paved area level to the back door of the house so that the when it's done, the garden is "split level" - the first 2.5m (about 1/4) of the current paved area "behind" the retaining wall" is dug away and level with the back door, the current retaining wall is removed, and a new retaining wall (or gentle grass bank) replaces it, about 2.5m down the garden. About 6m of the remaining elevated 8.5m of the paved area will be mainly grassed apart from about 2.5m at the very back which will be left as-is (shed etc). The 2.5m that is at the same level as the back door will have about 50% new paving for a small rear patio, and the other 50% grassed like the rear part. So the final garden will be about 2.5m lower level (50% grass, 50% patio) + retaining wall or grass bank + 6m elevated (grass apart from the 8ft island) + 2.5m left as-is. Plant beds and so on will largely stay where they are but might be reworked or improved later, but for now I'm hoping to sort out the turfing and landscaping, not the beds. I am reckoning I might have to lower the surface level a bit to lay more topsoil, but don't know if this is necessary or not. I'm not tied to any especial ground level so if the level rises by a few inches that's not an issue.
Photos (including 1 of the paved area with most weeds cleared-for now anyway)