Existing railroad tie retaining wall under deck - Replace?


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Old 03-20-17, 08:45 AM
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Existing railroad tie retaining wall under deck - Replace?

We bought a house 2 years ago with a 12' x 20' back deck. The deck is pressure treated and almost 10 years old. Under a portion of that deck is an enclosed concrete tunnel that houses our sump pump. Its approx. 6' wide x 12' long. We've had a membrane installed which involved removing that portion of the deck which allowed us to look at the portion under the deck adjoining that tunnel.

Right next to the tunnel it is back-filled with fine gravel and is quite compacted but still friable. The front of that gravel section has stone blocks to retain the gravel back-fill. Then in front of that is a sloping perennial garden bed. Unfortunately instead of making a stone or concrete retaining wall at the very end, they put in railroad ties.

There was a (leaking) spa on a platform right next to those ties. The spa is gone and wish to keep the platform and build planters BUT:

Question: The ties are slightly crumbly in areas and appear constantly wet. What would their likely life expectancy be? Would replacing them in the near future be advisable?

Note that the painted tilted supports in front of the ties are not load bearing (obviously) and need to be removed.

I appreciate your opinions and input!




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Old 03-20-17, 08:55 AM
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It is impossible to assess the life expectancy based on the description, you have eyes on the item so your the expert!

New ties may be good for 20 years, used ties were replaced for a reason!
 
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Old 03-20-17, 10:14 AM
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I don't think there is anything in the picture that pertains directly to the problem but I am noticing a distinct issue of missing handrails.
 
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Old 03-20-17, 11:00 AM
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Thank you. The rails will be addressed once we know we can add to the deck without needing to replace these railroad ties with a sounder solution.

Here is a closer view of the state of the ties. I have nothing in my experience to compare these to so I don't know if these are rotted or still considered to be viable enough to last until the deck needs eventual replacing in hopefully many years.

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Old 03-20-17, 11:20 AM
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The best way to figure the condition of the wood is to poke it with a knife or screwdriver. Most [maybe all] RR ties used in residential are used. I have a tiered bank shored up with RR ties that were previously used on another property. I installed them over 10 yrs ago and they are still decent. They are probably 20+ yrs old. A lot depends on how long they stay wet after it rains along with how well the soil behind it drains.
 
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Old 03-20-17, 12:27 PM
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Railroads remove and sell their old ties when they are in too poor condition to be useful to them. They may be replaced because of splitting, rot or other damage but the railroads don't throw away new, prime condition ties. So, when you buy used railroad ties they are partially gone. Obviously they have some life left in them but their days are numbered.

Since each tie is different you will have to inspect each one at multiple points to see if it's still good. If it hasn't started already they will get to the point where they are rotten and spongy and no longer good for retaining wall use and the wall will need to be repaired or replaced.

I have some that are on the surface, resting on gravel and after 20 years they are still mostly OK. The freeze thaw cycles of winter are taking their toll but they probably have 5 years left in them. Others that I buried in the ground to use as posts are not fairing so well. After 10 years some have already been replaced and the remaining ones won't be around much longer.

Personally, I would not add onto your deck with that retaining wall in place. The wall will need to be repaired or replaced sometime and adding more deck will just complicate things. I would replace the retaining wall with dry stacked, engineered concrete retaining wall blocks before considering adding onto the deck.
 
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Old 03-20-17, 02:45 PM
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Is there a way or technique of removing those ties without the gravel back-fill collapsing out?

Additional question (but I think I know the answer): The ties are in an accessible spot being that the deck is open right to the house. Do you think this would entail removing the top decking covering the ties or could we remove them from the accessible side & replace them with stone blocks?
 
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Old 03-20-17, 02:50 PM
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There will be some collapse of the fill behind the ties when they are removed. How bad it is depends on the compaction. Hard to say without an onsite inspection whether or not it can be done without removing part of the deck BUT the better access you have, the easier the job will be.
 
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Old 03-20-17, 04:08 PM
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Possibly doing the work in winter might let you remove the ties without everything behind collapsing. If everything behind the wall was wet and frozen solid then there is a good chance it will remain in place when the wall is removed. Whether or not you can remove the ties when they are frozen in place is another question.
 
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Old 03-21-17, 08:54 AM
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Thanks all. We have a place near us that sells stone/gravel, I plan on going in and asking for their input. Good idea about using the freeze. It also seems like the type of job that's miles more pleasant in coll weather...
 
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Old 03-24-17, 05:14 PM
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Just wondering but what good is it retaining more really doing? What would happen if it wasn't there? Obvious easy gravel would flow out to some degree but it would you seek its own grade level where did want to spill any further. Is that gravel under the jack really serving any purpose? It certainly isn't obvious, I wonder if passably that was there prior to the deck being built?
 
 

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