Retaining Wall Construction Method Advice Needed

[Wallee1]

I need a retaining wall constructed that will be 85' in length and approximately 6' tall. The purpose of this wall is to allow me to level my yard, as the house pad was constructed on land that slopes towards the rear of the lot. This wall will not be seen (it's behind my house), so aesthetics are not important. Cost is certainly a consideration, but most importantly the wall must be functional and built correctly. Taking the lowest bidder is not worth sacrificing a quality job to me.

Thus far, I've received a quote for stone (Pavestone Anchor Diamond Pro) that is approximately $21k. This includes the proper geogrid every third course and drainage. I am gathering additional quotes, but this seems a little high to me - I was expecting it to be in the $15k range. Can someone tell me if this is in the right ballpark?

I also have a quote to install vinyl sheet piling (seawall bulkhead) that has come in around $13k. It will have drainage and deadmen piles and (I assume) installed correctly. Since aesthetics are not a consideration, this is a more attractive option right now due to the lower cost.

Between the two options of stone and sheet piling, can I get some advice on the pros and cons of each.

I would also appreciate any advice on how to ensure I am hiring a quality contractor to perform this job. After spending a little time researching, I am quite overwhelmed and have read enough horror stories about poor quality workmanship on a retaining wall of this height.

[Hardscaping]

The wall has to be engineered normally for anything over 4 ft at least in my area. The wall if i were to throw a guess out not seeing the property you would be looking at about 20k with using the cheaper solution of blocks, and all proper install technics. A wall of this height i would say leave it to the people that know what they are doing. Ask them how much experience and if they can show you other walls they have built. Ask for references from previous work.

I would probably be a bit higher then this depending on the amount of back fill and the access.

[Wallee1]

Thanks - I definitely want to leave it someone that knows what they're doing and I assumed that it would have to be eingineered due to the height. I'm getting more quotes for comparison and don't mind paying fair market value, but not having done this before I don't want to be taken advantage of either.

What about the vinyl sheet piling method - is this an acceptable method of earth retention for my application? I suppose it wouldn't matter if a seawall goes into an area where there's no water... (as long it's engineered and installed ccorrectly)

[Hardscaping]

I am not sure about this method as i have never installed it before.

But for the finding of fair market value in your area just get everybody that does that in your area to quote it, Remember if it is time sensitive there are alot of companies that take a while to get back with quotes. So just try to get as many uotes in a small period of time and choose from the prices don't just choose the lowest price. You should see the type of work they do and decide form there.

[DVS Hardscaper]

We build alot of walls, which in this case the proper term is 'Segmental Retaining Wall' (SRW).

The average cost for residential SRW's is in the neighborhood of $40 / square foot. Now, don't take that to heart. And I say that because most contractors do not charge by the SF, they charge by the job which is based on estimated materials and production hours. When it's all said and done, the average is somewhere around $40 / SF, maybe more, maybe less.

Also :) Homeowner's expectations of what something "SHOULD" cost, are always way less than what they DO cost :)

[DVS Hardscaper]

opps! I forgot!


Most SRW's that are 4-feet in height and taller need to be engineered by a retaining wall engineer. In most areas you call a geo-technical engineer.

An experienced, competent contractor WILL NOT build a 6-foot wall without a set of stamped plans from an engineer.

I have seen engineer costs for SRW's be as low as $400, and I have seen them be as high as $1200.00

Typically, we'll do some preliminary pricing for the client. If the preliminary pricing is acceptable for the prospective client, then the next step is engineering. We require the client to pay the engineering cost upfront. Once final engineering drawings are complete, we then do a final cost to build the wall based on the specifications specified by the engineer.

www.outdoorfinishes.com

[SimonCX]

Like others said 6ft your going to need to have an engineer, in my area if it's 36" or less I don't need permit's or engineer only have to show what I'm doing to the zoning guy so there aren't any problems. As soon as it goes 1" over 36" I need both. Pricing varies on all jobs because there are alot of factors that make every job different.

[Wallee1]

Thanks for all the help and advice, guys. My quotes for the job vary $8K from low to high, so I'm trying to figure out why there is such a large disconnect for the same job with the same material. I'll do some more asking about the engineering now that I have an idea of what should go into it. My first quote was in the $15k range, so I guess this is where the "expectation" came from.

[DVS Hardscaper]

First you need to find contractors that are competent and do SRW's everyday. Once you find experienced, competent contractors - then your prices will be within one another.

Do not call any companies that also mow grass. (I'd bet thats who your $8,000 estimate came from)

When you do have contractors come out, don't mention engineering. If the contractor does not mention engineering - then you don't want them, cross their name off the list.

If the contractor does tell you that first the wall needs engineered - them put them at the top of the list.

I'd love to give you some construction tips (things to see if any of your 'price quote providers' mention or spec in their proposals) (notice I DID NOT use the term "bidders"), but this is all I have time for today!

[PatriotLandscape]

Quick story....

I got a referral from my supplier of a guy who needs a srw wall. As it turned out he needed a wall finished. The contractor under bid the job by about 5k and came back to the customer telling him he needed it or he wouldn't dfinish the job. Now it had been 2 months and he's looking for someone else to finish it. be careful

[jamo1911]

Fair price for that wall is $22,100. Go with an NCMA certified contractor. Any less, money or qualified is risky.