Sleepers

Astraeus

I am planning to build a retaining wall, 9m long and 1m above ground, with sleepers on their width and slotted into universal beam (RSJ) construction.

I have had a quote for the sleepers - £725 for Canadian Oak (200x100mm) and £1,075 for French Oak (220x130mm). I've ruled out timber or reclaimed sleepers. Does anyone have experience of Canadian Oak to suggest that it should be avoided? From what I have read, it is often from slower growing trees than French Oak. The force upon the wall will not be great as it's 1m of self-supporting heavy clay.

The benefit of any experiences would be welcome please.

K67

I am struggling a bit to understand your rsj construction and how the sleepers slot into it.
Am I right that you are digging a trench and laying 9m of steel in the ground then putting in your sleepers on end cutting them to the right height?
How many sleepers are you buying?
Can you draw me a diagram please!

Astraeus

Ah, sorry. Let me try a rudimentary diagram:

I -------- I -------- I -------- I -------- I
I -------- I -------- I -------- I -------- I
I -------- I -------- I -------- I -------- I

The I is an upright RSJ, the - a horizontal sleeper. So the RSJs will be sunk into post holes and the sleepers will slot in.

Loxley

Think he means like this

K67

Doh! Obvious now.

KeenOnGreen

We have treated sleepers in our garden.  They are sunk vertically into the ground (no RSJ's), and retain clay terraces.  The biggest problem we have is rot.  If you allow any planting to grow over the top of the sleepers and to shade them from the sun, they will rot remarkably quickly.

You should put some form of membrane behind the sleepers, to prevent them coming into contact with the soil.  Ideally you should also put some drainage (i.e. gravel), so that the area behind them is as free-draining as possible.

Here's a photo showing how we lined our sleepers with membrane (they are hidden under the membrane).  We backfilled the gap below with several feet of pea gravel.  The strip in the middle of the photo is an old brick wall, we left it in situ, easier than removing it.

KT53

Irrespective of what timber you use, put a waterproof barrier behind it to keep the soil off.  We had raised beds built and they claimed to have lined them to prevent rot.  Fast forward 8 years and one bed has almost rotted away completely.  Needless to say they hadn't lined it.

I would question the statement about 'self-supporting clay'  once saturated it will slump so the wall will need to be strong with that weight behind it.  From your description I suspect it will easily be up to the job if the RSJs are set in concrete.

Astraeus

Thanks all. I've factored a French drain into the design and the membrane. @KeenOnGreen, that's an enviably tidy job.

It was really a case of me wondering about the difference between the Canadian and French Oaks and whether I would be foolish to opt for the cheaper oak.

KeenOnGreen

I've no idea about the different type of oaks @Astraeus  My gut feeling is that whatever you buy, it will last a similar length of time, given what you are using it for, so I would go for the cheaper option.  I think it's only important to know the difference if you plan to use it for furniture/flooring.

Astraeus

I'll keep it in one thread but has anyone used creocote (the creosote 'replacement'? I prefer the dark stain of reclaimed sleepers and just wondering which product is best to get that stain?

Allotment Boy

I have just used " ecosote"  a water based creosote replacement . It has a fungicide agent in it. It will  give you the colour,  can't vouch for the effectiveness yet as I have only just used it.