Price Check, If you don't mind please.

Discussion in 'Hardscaping' started by White Gardens, May 8, 2010.

  1. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    I just ran an estimate for a retaining wall that is approx. 15,000 square feet (face).

    I was wanting to know what your guy's cost estimate would be approximately for a wall of this size, or at least your cost per square foot.

    I know my costs, the customer, etc. I just don't want to leave any money on the table, and to also make sure that I'm not over-charging.


    Nick W.
  2. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    typo. I meant to say 1500 square feet.
  3. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    no disrespect intended - but there is no way anyone can answer this question.

    1) We'd need to see the engineer's specs. Gotta know how much block is buried below grade. Gotta know if the grid is every course or every 3 courses. Gotta know the length of the grid. Gotta know all kinds of stuff.

    2) Walls are only used in less than ideal situations. Gotta know the site conditions - Steep, tight access, etc. Can the wall be backfilled with an excavator or must it be backfilled with hand shovels and wheel-barrs?

    3) Type of block. 66# block or 100# block?

  4. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    No disrespect taken. I understand.

    I'm honestly not sure about numbers for the blocks chosen (#66, #100). It's a decision between a Rockwood retaining block, and a paveloc creta stone.

    Two blocks below grade,(figured that in square footage). With consideration of different wall heights/location, and specifications for the block intended, one to two rows with geo-grid. Should be no problems to backfill with a mini skid, maybe some random hand work. No original fill will be hauled.

    My estimate came out around $26 a square with the paveloc creta stone and I feel comfortable with it. And it is a church.

    Here is a pic to put it into perspective.

    retaining wall.jpg

    retaining wall.jpg
  5. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    Those numbers I used as examples were the weight of the block.

    Another thing we use to cost a block job is: linear footage. See, a competent block installer knows how many linear feet of base course and aggregate base they can install in an hour. As well as how many linear feet of stepscan be installed in an hour.

    The pic tells me you do not have to bury 2 courses below grade (at least behind the dwelling). This is because the wall will be close to the dwelling and there will be very little pressure bearing down on the wall in that area, also the asphalt will fix the block firm in place.

    How much is the block you're thinkin of using gonna cost you? At $26 / sf your purchase price for the block should not be more than $5.55 / SF.

  6. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    So are you saying I'm not competent. :laugh: I haven't done a wall this large before, but have done walls with engineering specs similar to this on a smaller scale.

    The pressure issue is exactly what I was thinking. That's why I think only one course of geo-grid will be needed there. What you don't see in the design is a change that might need to be made adding another 40 feet of wall past the steps and above is an asphalt parking lot. I would think that there might be more pressure in that area, so I might end up burying two courses there to be on the safe side and going with at least 2 courses of geo-grid.

    The idea for the wall is to help create more parking for the church. The membership keeps growing and they are wanting to gain close to 20, so I might be able to give them 15 pull in spots along the drive next to the building and 4 parallel spots along the main parking lot. I'm leaning towards burying two courses as I don't want any cars kissing the wall and damaging it to badly when Grandma comes to church all groggy on a Sunday morning.:laugh:

    The block I would be using will probably be the creta stone and is 60lbs a piece. Otherwise it would be the Rockwood block that weighs closer to 80lbs, but might be over-kill and esthetically won't be what they are looking for.

    The Creta block is actually closer to $11.00 a square and the Rockwood block is closer to $5.50. My estimate for $25 a square is based off the cheaper Rockwood block, which I'm going to guess that is the direction they are going to go, but I don't know for sure yet.

    Asphalt will be laid in the area created by the wall after it is done. Another question I have is will there need to be an expansion joint needed between the block and the asphalt when it's laid. My only concern is the asphalt might interfere with the wall behaving correctly over-time. Another part of me though thinks that it won't matter as long as my base is built correctly.

    As a side note, a foundation guy came in last year and quoted a poured block wall for 16k. :hammerhead:. That number is going to be what kills me on pricing this correctly, as they "think" they already have an idea of what it should cost.

    Thanks for your help DVS. Thinking out-loud in this manner is going to ensure that it is built correctly. I also have talked to the church and the original grade was undisturbed, so my base should be OK. Fill was the only thing brought in and moved around.
  7. FLCthes4:11-12

    FLCthes4:11-12 LawnSite Senior Member
    Posts: 284

    I hope you didn't figure building the steps in a square footage price. I have bad expirence in that and learned a valuable lesson. Double the cost of a poured wall is going to be tough to beat. Might give them the option of going poured and stucco and sub it out. Litte bit of something is better than alot of nothing.
  8. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    I did figure that into my estimate.:hammerhead:.

    I did take a couple of things into consideration though as the wall will be easy to back-fill, location is good next to main road. A rental house is a block away for anything I need and a hardware store is two blocks away with all the drainage supplies. All materials will be delivered, etc..... and no dirt will be hauled away as it will all stay on site.

    Another thing that I'm taking into consideration is that it is a church, and a decendent of the original founder is a member of my BNI group and he is really pushing to get this job lined up for me. On top of it, it will be a great wall to do for my portfolio as I lost a retaining wall job this last spring because I didn't have one in my portfolio.

    Am I leaving money hanging out there?, maybe, but I think the long term affect of this job will make it worth it. It may be a little naive, but I did all my figures and even inflated the first estimate to get it where it's at.
  9. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    Well, in this case you absolutely do not have to bury additional block due to load surcharge.

    Buried block is for the most part for wall height. You bury 1-inch of block for ever 12-inches of wall height. So if the wall is 11 feet tall - you'd most likely bury 11-inches of block.

    The quantity, placement, and length of grid is what accounts for
    a) soil type
    b) degree of slope
    c) load surcharge

    We did a 10' wall on the steepest slope we've ever worked on. Naturally, we had an engineer involved. Ok, but.....we only had to bury 10" of block. How the slope and surcharge was contended with was dealt with via grid placement and length. Normally the rule of thumb is grid length is 80% of the wall height. Well the engineer had us do the grid at 100% of the wall height. Placed every 2 courses.

    We did a 7' wall in 2007. That engineer had us install grid on EVERY course.

    You do not need to bury 2 courses. If you want the job - take the 2nd course out. Thats more unnecessary digging and unnecessary block - which will lose the awarding of the contract to you.

  10. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    Good point. I guess I'm just the type that likes to over-build for the sake of redundancy in order to not have the wall fail ever.

    DVS, your right though. This situation isn't holding back a large hillside or anything of that nature. Two blocks would definitively be over-kill. On top of it, it amazes me how one course can change an estimate by 10% - 15%.

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