Replacing a large retaining wall in garden - what would you do?

[KarlHungus1968]

Hi,

First time posting here looking for advice, and hopefully to learn something.

 

After 10 years in our 1930s house we are finally planning to tackle the 1960s retaining brick wall in our steeply-sloped garden before laying patio.

 

Our plot is carved into a valley; we have a small area of patio behind the house with a very steep slope held in place by the wall. It's showing cracks / spalling, plus the previous owner decided to paint it so every couple of years we have to scrape off the flaking paint and apply another tin of Sandtex. Being in a valley, with lots of big trees nearby, the area is damp in winter. We intend to replace the biggest section, 10m wide and average 1m high. Other sections aren't in such bad shape so we've just had the top courses of bricks replaced.

 

The question is, what would you do if this was yours? We want the job done properly and look good but have had different - sometimes contradictory - opinons from the four builders who have looked at it so far.

 

After discounting a few non-starters we are left with:

1. Rip out old wall, replace with blocks with a facing brick layer in front for aesthetics.
2. Rip out old wall, replace with blocks to be rendered and painted.

 

Option 1 seems straightforward, essentially 'like for like' but with added strength and the luxury of not having to paint it. It just might look a bit odd against the other - painted - sections of wall, although over time we could replace them too.

 

Option 2 was suggested by a landscaping company and is our preference. We think it would look great as we could render the other (old) areas of wall for a matching finish. However, on Sunday I had a builder tell me rendering was a bad idea as the render will deteriorate and need repainting every year. Yet another builder flatly denied this today and told me it would be fine. If we go with this, I want to be very sure it is durable and to be specific about what we need in terms of drainage, type of render etc etc. And if it's the wrong solution, fair enough, we'll cross it off.

 

Any thoughts welcome to help avoid a situation where I spend a lot of £ and then regret my decision!

 

 

[Mr Punter]

Gabions can look really good if they are faced with decent stone.  You could leave the wall and have the gabions in front.  You can get some planting in them too, as well as a flat area on the top.

[Conor]

3. Leave wall in place, build new brick wall in front with 100mm cavity. Fill cavity with concrete. Top off with new coping stones. Least disruptive, and will be more than strong enough, especially if you tie everything together with rebar and mesh. We've a 2m tall retaining wall built with that spec.

 

(Will need additional footings for the new wall)

[Bozza]

Agree with @Conor option 3 far better solution.

[KarlHungus1968]

Thanks for your input and suggestions.

 

I should have said, the option of building new brick wall in front was suggested by the first builder who looked at the job. What you can't see from the photos is our patio does not extend far from the back of the house before you get to the wall. So whilst it doesn't sound much, losing another 100mm + brick depth for a new wall would have an impact on our patio area. It's annoying as in all other respects this is a v good solution.

 

Our preference is to keep the wall in the same place or ideally push it back into the hill further to gain more patio area - accepting this will be more expensive and disruptive, but would definitely add value to the house.

 

On another note, honestly I never fail to be amazed at how many tradesmen are happy to get in touch, come to your house, discuss a job with you, mention ballpark costs and feign interest only to then go silent - no written estimates / quotes as promised, no response to messages / voicemails. Of the four we've had to look at this wall I've had radio silence from two of them, no idea why - maybe I need to change my deodorant...

[Conor]

On 20/06/2024 at 08:46, KarlHungus1968 said:

Thanks for your input and suggestions.

 

I should have said, the option of building new brick wall in front was suggested by the first builder who looked at the job. What you can't see from the photos is our patio does not extend far from the back of the house before you get to the wall. So whilst it doesn't sound much, losing another 100mm + brick depth for a new wall would have an impact on our patio area. It's annoying as in all other respects this is a v good solution.

 

Our preference is to keep the wall in the same place or ideally push it back into the hill further to gain more patio area - accepting this will be more expensive and disruptive, but would definitely add value to the house.

 

On another note, honestly I never fail to be amazed at how many tradesmen are happy to get in touch, come to your house, discuss a job with you, mention ballpark costs and feign interest only to then go silent - no written estimates / quotes as promised, no response to messages / voicemails. Of the four we've had to look at this wall I've had radio silence from two of them, no idea why - maybe I need to change my deodorant...

Fair point on the space.

 

You've a significant slope to retain, and digging back is going to be a major job, as you are then working with unknown ground conditions and even a slight increase in height of the wall could result in big design changes.

 

Whatever you do there, I'd be looking at steel reinforced concrete, definitely do not rely solely on blocks, even double thick. I'd be going for a ~200mm cast RC wall, tied in to decent footings, at least 50% as wide as the wall is high. Either that, or interlocking retaining wall blocks. Faster, cleaner, look good.

 

Re tradespeople, they are sensing that you're fishing around and aren't wasting their time and effort when there no actual defined (drawing) job to price.

[Declan52]

Leave it as it sits. To remove that wall is a massive job with that bank it's holding back. Any replacement with be either at least 200mm wide reinforced concrete with a footing off over a 1000mm wide with lots of steel or block wall 1000mm wide at the bottom and stepping up to at least 450mm at the top. Either option is going to be very expensive. 

I would use battens and clad it in something nice. You could even use thin real stone cladding that won't be much more than 50mm extra.

[Jilly]

Maybe get a view from a garden designer? They might come up with an attractive way to soften/cover the wall, eg painting it/ cladding with hurdles  it and then planting along the top with climbers which will trail down.
 

I couldn’t face a wrecked garden, mud, expense and no summer parties this year. And you’ll still need a garden design after that, with your slightly bigger patio.

 

Think how many gorgeous plants you could buy with the money. An established, clever garden will increase the value of the house also. 

To me it would be heaven to sit with the existing ‘sunken garden’ feel, and to have privacy and intimacy from the surrounding plants. 

Edited June 22 by Jilly

[SteamyTea]

Dig out as far as you can  then gabions.

 

We have a new member @Steves who does this sort of thing.

[Temp]

My choice woukd be to build a cavity wall of block and brick and no paint/render. Would specify a low efflorescence brick.

 

I wouldnt paint or render a solid retaining wall but rendering a cavity retaining wall with the correct drainage should be OK. Not all render is approved for damp conditions, most say not for use below DPC and the whole of a solid retaining wall is effectively below DPC. 

[canalsiderenovation]

Motorway barriers...... we have 90 metres of them as a retaining wall.

 

 

[oksleator]

Gabions are a good shout. Permeable to water so less likely to fall down, look cool, you could build them yourself, and you can plant ferns and heucheras etc in them. Get them in a mild steel so they rust nicely. Very on trend!