Split Level Retaining Wall in Garden brick and timber!

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Hi all,
I have been on this forum a few times but I thought it time I joined…. Of course spurred on by a project!

I am undertaking a project that will mean I have much more usable space in my garden and for this to work I need to create a new retaining wall above an existing retaining wall. For the use that I want it means I am breaking the rule that the distance the second higher wall should be from the first twice the height of the first wall. Its simply not practical.

The first wall is 3.5 feet high is brick built and built as part of the house 25 years ago. I plan on setting the second wall made from 4x4 timber posts spaced 1.2 meters apart using timber sleepers. And this will only be 1.5 to 2 feet high to allow the ground behind to be level.

wall_zpsafdc7c78.jpg

I’m confident with the drainage and the construction of the timber wall. What I am unsure of is whether I need to reinforce the first original wall as I have broken the rule of thumb. I also have a query regarding the steps too.

Dont worry the posts arent cemented in and the will be cut once I have the height of the wall and appropriate height to stop the little nipper lemming diving off the walls.....

I have dug the posts in behind the first wall, but the posts behind the wall I needed to go through just over 1 ft thick concrete to get the post 2.5 feet down. Once concretes in the post will be very secure. The level of the concrete is about 5 inches below the top of the first lower wall. My question is…. Why? And if this has been done to reinforce the first wall will I need to do anything to it at all?

My second question is relating to the steps. Currently three very steep steps that my grandparents cannot get up, and I don’t plan moving anywhere and I will struggle with these steps when getting old. So I want to take them out and have the first step as a platform with the another 7 or 8 steps going behind the existing retaining wall to make the slope far more manageable.
steps_zps2a02f04d.jpg


If I’m digging in and make the steps made of brick (not timber in this case). The retaining wall at the back of the stair case will be the combination of both walls (ie 3.5 to 4 feet!). I would plan on making like described here:
http://www.pavingexpert.com/featur03.htm
at the retaining wall section and I can only assume this is how the original wall is built. However that doesn’t explain the foot thick concrete 4 foot back from the wall! Its old ground so its possible the concrete is an old path! It says 900mm max which is obviously under 4 feet…..
Any thoughts what are my options…. A few dead mans anchors at that part of the wall?

Cheers.
Mark.
 
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The wall will be fine, and build the steps too, your plan is OK

I'm not sure what the rule is that you mentioned or where the other dimensions come from, but I can't see what effect they will have on yout project

Personally, I can't see the value in using SW timber as an earth retainer, as its' life will be relatively limited
 
Hi, and thanks fr the reply.
I've seen the rule a couple of times on the internet. its the minimum distance for the 2 walls to be considered seperate structures.
This link demonstrates it nicely:
http://www.allanblock.com/retainingwalls/Installation/Landscape/terrace/terracerule.aspx

Timber walls for 2 main reasons:
1, I think the look nice and rustic and thats a thkng I go for. I intend making furniture of the same type of thing.

2. Its within my skill set! I've put drives down, hardcore, sand little cement, but building a full blown brick retaining wall for me... Im not there yet! I may be. However if this goes wrong, timber is easy for me to fix. I'll treat it all so hopefully theres a few decades in this...

I do have a wall to build elsewhere, so I may build the wall around the stairs as I say, but a rick wall with some kind of metal fence on top have a very different look to the timber effect Im going for.
 
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Hmm, fair point. Although it might be a bit late for that as I already have most of the wood. I purchased at good prices from a reputable merchant locally, all ACQ pressure treated, I was going to coat in Cuprinol of the appropriate colour and then use bitumen paint for all the wood underground....

I was thinking that this would provide pretty long life with repeat treatments every couple of years or so for the visible wood.
It seems that most of the fencers and other people I've spoken too including the merchant seem to think these are the industry standard materials.

I guess its one of these things, If a ford fiesta is industry standard for a small car, it doesnt mean you have to like it or guarantee its reliability!
 
Found the merchants website and this blurb:

We also offer a comprehensive wood treatment service using the VACSOL Aqua trademarked process, applied in a double vacuum low-pressure plant, to provide effective protection against fungal and insect attack. VACSOL Aqua treated timber used in Hazard Classes 1 and 2 applications are treated to a desired service life of 60 years.

Means nothing to me! no mention of WPA though....
 
Is that big wall at the back leaning any?
Maybe it needs re-doing. :idea:
 
Actually its pretty straight, its been repointed in a few places and needs new coping stones, but that wall I'm led to beleive is about 100 years old and in far better condition than the retaining wall put in 25 years ago!

I will need to rebuild the bit next to the trailer at the back (you can see the green fence on top) and restore the wall to its former height. A previous owner did some work there but used the wrong sized bricks, ie modern house bricks and its awful, it slopes and bends it is generally shocking.....

Impressive wall actually it has columns either side every 8 ft or so. I intend on putting yet another 2 ft height retaining wall at the bottom of the big wall to the left side of the garden just to add that bit more support for it

The foundations are only 450mm beneath ground level. (hence Im building up to level and not leveling down as then Id have a 9ft wall at the back with very little under the ground!)
 
Found the merchants website and this blurb:

We also offer a comprehensive wood treatment service using the VACSOL Aqua trademarked process, applied in a double vacuum low-pressure plant, to provide effective protection against fungal and insect attack. VACSOL Aqua treated timber used in Hazard Classes 1 and 2 applications are treated to a desired service life of 60 years.

Means nothing to me! no mention of WPA though....

Hazard classes are now use classes (pedantic I know)

Use class....

1. internal joinery
2. Wall studs, roof members
3. external joinery (cladding)
4. ground contact
5. water

I would assume that their blurb isn't comprehensive, because VACSOL isn't suitable for ground contact, and at that treatment level it may as well be untreated.

If they have treated it with ACQ, they can treat for 15 or 30 years, ask them which schedule they have chosen (there is no option for 60 years).
 
I can ask but I bet the guy behind the desk doesnt know! I suspect it will be 15 years, basically I managed to get the sleepers (actually new 100x200mmx 2.4m) for much cheapness.
 
This bring s me to the second part of my original post
IMAG1259_zps2e63461b.jpg

IMAG1260_zps80069945.jpg



:My second question is relating to the steps. Currently three very steep steps that my grandparents cannot get up, and I don’t plan moving anywhere and I will struggle with these steps when getting old. So I want to take them out and have the first step as a platform with the another 10 steps going up to the new level. going behind the existing retaining wall to make the slope far more manageable.


If I’m digging in and make the steps made of brick (not timber in this case). The retaining wall at the back of the stair case will be the combination of both walls (ie 3.5 to 4 feet!). I would plan on making like described here:
http://www.pavingexpert.com/featur03.htm
At the highest point if I make it brick from the bottom of the first step to the height of the new higher land, thats going to be almost 5 ft high.
How do I make it strong enough to cope with that. The link in paving expert says that that is too high.
How do I make it string? A few dead mans anchors at that part of the wall? My neight suggested building it out of concrete block but side on then using facing bricks to make it look nice with appropriate drainage....
thoughts?

Cheers.
Mark.
 

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