Even if you go for oak/hardwood sleepers that have been treated, still pay attention to drainage. Our hardwood sleepers have rotted very badly in places after only 5 years, they are crumbling to pieces. This is worst where plants creeped over the top of them, and shaded them and created a moist environment. Where soil touched the back of the sleepers the same thing happened. You don't expect that with treated hardwood, it's not a mistake I would want to repeat, as sleepers are a very important (and visible) part of our garden.
Maybe you could build something like the photo below into the slope using gabions. By curving it you'd avoid messing about with the boundary fence and wall.
If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
If I follow you correctly then going back from the sleeper wall you intend to keep the slope for half the distance (rising approx 600mm) then create a 300mm 'ish high retaining wall (2 x 200mm sleepers for e.g), the void behind it being made up with soil cut from upper part of the slope adjacent the gabion wall. To know whether this would be possible you need to check whether you could potentially remove 300mm soil from in front of that gabion retaining wall. I would suggest that you dig a small (and I do mean small) trial pit in the centre of the largest of the gabions (As I think you are aware, gabions are there usually for a very good reason and you do not want to undermine them in any way either digging beneath them or at an edge). I would suggest a pit of about 300x300mm perhaps 500mm deep. If you find the bottom of a gabion, STOP. Second point, assuming you could safely remove 300mm soil without undermining the gabion wall, will the soil remain usable topsoil below what you intend to strip? Normally topsoil in new build would be about 150mm so stripping this to use further down the slope will leave you with poor subsoil on upper slope
I just dug a small pit next to the gabion wall and there is no further gabion block under the one visible from the image I posted originally. So as you said, it won't be possible to remove soil from the back and use it in the middle. Also there was some concrete underneath the top 100mm of soil. They must've secured the gabion base with cement.
So if I still want the 2nd terrace then I'd need to build a retaining wall to the height of the 8th brick up in the middle area? And a wall that high would then need some drainage pipe going behind it?
We converted our sloped garden into two terraces and love it. We have a trampoline and a shed on the second terrace. Definitely couldn't have put the trampoline on a slope! Mine has a brick wall retaining the bottom terrace and the builder put drainage holes in the wall. Just fyi I never see water coming out of them so not sure how necessary they are lol
@Safflower Would you mind sharing a picture of your garden showing the two terraces? Did you create the 2nd terrace yourself or got it done from a landscaper?
Sure. A landscaper did it about 12 years ago. Please ignore the state of my garden! It's a work in progress right now Lol I have to say we do love the "sunken" patio that the terrace gives us. So does our cat as you can see haha
Thanks for sharing that..it still looks good 12 years on..I guess gardens are always a work in progress 😀 The way yours is split, that's exactly how I had pictured in my mind.
Even if you go for oak/hardwood sleepers that have been treated, still pay attention to drainage. Our hardwood sleepers have rotted very badly in places after only 5 years, they are crumbling to pieces. This is worst where plants creeped over the top of them, and shaded them and created a moist environment. Where soil touched the back of the sleepers the same thing happened. You don't expect that with treated hardwood, it's not a mistake I would want to repeat, as sleepers are a very important (and visible) part of our garden.
I agree. There is a membrane behind our sleepers to avoid contact with soil, so hopefully would last longer 🤞🏼
Maybe you could build something like the photo below into the slope using gabions. By curving it you'd avoid messing about with the boundary fence and wall.
That's interesting. Or I could make sloping garden beds along the fence and wall like in the photo below?
So if I still want the 2nd terrace then I'd need to build a retaining wall to the height of the 8th brick up in the middle area? And a wall that high would then need some drainage pipe going behind it?
it's going to need to be about 600mm high in whatever you choose to construct with. Whilst drainage behind a wall is important, how significant depends on such factors as your soil. Is this clay based or free draining sand/gravel for e.g. Drainage can be achieved in different ways. If you need to install a pipe, then you need to consider where this will be discharged also. When I built patio into our sloping garden last year, I backfilled behind the rear retaining wall (700mm high) with granular fill which should prevent any subsurface water flow to build up behind the wall. I also built weep holes into the front retaining wall. All seems to be working as intended so far You should consider building your retaining wall with gabions. this will obviously match the existing rear wall, will remove any concerns about deterioration and future maintenance issues and will also obviate the need for further mechanical drainage...
So if I still want the 2nd terrace then I'd need to build a retaining wall to the height of the 8th brick up in the middle area? And a wall that high would then need some drainage pipe going behind it?
it's going to need to be about 600mm high in whatever you choose to construct with. Whilst drainage behind a wall is important, how significant depends on such factors as your soil. Is this clay based or free draining sand/gravel for e.g. Drainage can be achieved in different ways. If you need to install a pipe, then you need to consider where this will be discharged also. When I built patio into our sloping garden last year, I backfilled behind the rear retaining wall (700mm high) with granular fill which should prevent any subsurface water flow to build up behind the wall. I also built weep holes into the front retaining wall. All seems to be working as intended so far You should consider building your retaining wall with gabions. this will obviously match the existing rear wall, will remove any concerns about deterioration and future maintenance issues and will also obviate the need for further mechanical drainage...
Thanks for your suggestions. I think drainage would be required as the subsoil is heavy clay with about 100mm of topsoil. Gabion does seem a suitable option to avoid other issues but just thinking it'll be quite dangerous being in the middle of the garden especially with kids..
but just thinking it'll be quite dangerous being in the middle of the garden especially with kids..
Presumably you are concerned about creating a 2' high precipice?, but you'll have that with whatever you build with. We have an 18mth old granddaughter and when she visits we have to be diligent, it's the price you pay for gardening on an interesting sloping site.
but just thinking it'll be quite dangerous being in the middle of the garden especially with kids..
Presumably you are concerned about creating a 2' high precipice?, but you'll have that with whatever you build with. We have an 18mth old granddaughter and when she visits we have to be diligent, it's the price you pay for gardening on an interesting sloping site.
Ya you're right. I'm not much concerned about the 2ft wall in the middle but mainly the gabion as the metal cage can be quite dangerous to be placed in the centre. If I build the wall with oak sleepers, what's the cost effective way to backfill behind the wall for levelling? With drainage, I'm thinking of using french drain pipe behind the sleepers and discharging it to a border along the fence. Would that work?
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So if I still want the 2nd terrace then I'd need to build a retaining wall to the height of the 8th brick up in the middle area? And a wall that high would then need some drainage pipe going behind it?
Whilst drainage behind a wall is important, how significant depends on such factors as your soil. Is this clay based or free draining sand/gravel for e.g.
Drainage can be achieved in different ways. If you need to install a pipe, then you need to consider where this will be discharged also.
When I built patio into our sloping garden last year, I backfilled behind the rear retaining wall (700mm high) with granular fill which should prevent any subsurface water flow to build up behind the wall. I also built weep holes into the front retaining wall.
All seems to be working as intended so far
You should consider building your retaining wall with gabions. this will obviously match the existing rear wall, will remove any concerns about deterioration and future maintenance issues and will also obviate the need for further mechanical drainage...
We have an 18mth old granddaughter and when she visits we have to be diligent, it's the price you pay for gardening on an interesting sloping site.