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View Full Version : Marcus I need your help


cleancutccl
01-31-2006, 05:42 PM
Okay I had a Gen. Contractor friend ask for a bid on this one. I have no idea how old these walls are but they have no geogrid and probably no base, just mortared limestone. The only part I'm concerned with is the part that is failing. I'm planning on ripping the upper wall down and putting it right back up. The customer is repairing it because he is going to be selling the house. My main questions are if it would be more cost effective to use new rock, or try to chip the mortar off the old stones and replace with new mortar? I will be digging down and putting in a base on the part that I am redoing, but should I need to do geogrid, and if so, how do I tie it into a mortar stone wall? I have quite a bit of experience with srw walls, but in this application it would not work, because home is surrounded with limestone walls, even right in front of where this wall is being repaired. Wall measures 120 linear feet and roughly 3' high. Marcus and Treedoc your replies would be greatly appreciated, along with others that might some experience.

MarcusLndscp
01-31-2006, 06:39 PM
Okay I had a Gen. Contractor friend ask for a bid on this one. I have no idea how old these walls are but they have no geogrid and probably no base, just mortared limestone. The only part I'm concerned with is the part that is failing. I'm planning on ripping the upper wall down and putting it right back up. The customer is repairing it because he is going to be selling the house. My main questions are if it would be more cost effective to use new rock, or try to chip the mortar off the old stones and replace with new mortar? I will be digging down and putting in a base on the part that I am redoing, but should I need to do geogrid, and if so, how do I tie it into a mortar stone wall? I have quite a bit of experience with srw walls, but in this application it would not work, because home is surrounded with limestone walls, even right in front of where this wall is being repaired. Wall measures 120 linear feet and roughly 3' high. Marcus and Treedoc your replies would be greatly appreciated, along with others that might some experience.
Unfortunately CleanCut the whole wall appears to be failing because of a lack of drainage behind the walls. Correct me if I am wrong but all the walls look as if they are leaning out quite drastically. I've done jobs in the past just like this one where we had to chip off all the mortar because we had no access to the particular stone the walls had to be built out of....it is VERY time consuming. How does the rock look up close? Is there mortar all over it or just a little bit? It looks to me as if they simply slushed the back sides of the stones in to hold them so the possibility of hammering mortar off a slushed in wall might be a bit easier. Grab a hammer and 3lb sledge and try it, see how easy it is. If you have access to the same stone easy enough I would say that would be your best bet but first look into the cost. We can get a ton of stone delivered up here for just over $50. My suggestion to you on this wall is to build it dry laid. There's simply no reason for the mortar if you know how to stack stone. Put down a good compacted crushed gravel base wrapped in fabric, build your wall, and back fill with drainage stone that is also wrapped in fabric. For extra insurance include a 4" pipe behind the wall to rid any water from the area. You do not need grid in a wall like this. Batter the wall 3" and use larger stones in the construction of the wall that tie all the way through...kind of like a deadman if you will. Break your joints as you build...it will give you a stronger wall. Same idea as brick really....1 over 2.
Any other questions I would be happy to help.
Marcus
PS---what's the site like? Is there alot of ground water?

cleancutccl
01-31-2006, 08:39 PM
wall has drainage pipe sticking out of it, but it is probably clogged with dirt. I know I can get cut limestone, but natural looking stone I'm not so sure, I will check into it. I did notice that just from the wall falling over some of the mortar had been chipped off, but I also picked up a rock and tried to hammer the mortar off on another rock, did not come off very easily. The site does not have much ground water, but the hill goes on up past this wall, and probably channels a lot of runoff water to it. The wall directly below this one doesn't look to bad, but there is another wall on the property that could be falling over at any time now. Just to clarify, when you say to use the larger stones are you saying to lay them into the hill like a deadman, or lay them with the wall to help tie it together?

treedoc1
01-31-2006, 09:05 PM
Excellent wall to learn on. Marcus said it correctly...drystack.

Price it as a complete new wall, new gravel footer, cut back the bank for your drain and backfill. Don't forget to include billable hours for the demo. Lay the rock out neatly in front so it's easy to get at.

Don't try to save those small undisturbed portions...it will just slow you down trying to patch them in...quicker to rebuild all.

footer example and similar retaining wall setup

MarcusLndscp
01-31-2006, 09:06 PM
Use larger stones that go from the face of the wall all the way through to the back...stones like this provide weight and support of the smaller ones. As you build up you want everything to lock together and that's what the larger stones aide in doing. Hydrostatic pressure obviously pushed the old walls down so do it right this time, no short cuts. Use fabric, a good base, and drainage drainage drainage. A dry laid wall has a benefit over wet laid walls in that hydrostatic pressure in theory is not as great a force on them because water still flows through the wall stone. If you don't have experience with a wall like this sub it out. They are not that hard it just takes a time or two doing it to understand the concept of how it's done. Aesthetics of a dry laid wall is the artistic part of it...you're either going to have it or you don't.

Squizzy246B
01-31-2006, 11:18 PM
All of the above is good advice. We get asked to re-use old stone all the time and mostly it is not cost effective. However here is what we do when pressed. We chuck all the old mortared stone into a heap with the excavator and then sought through it. Anything which chips off easily and has some nice shape or feature we keep. Anything thats going to need chipping away at for ages we toss. The ones we toss go behind the wall for extra mass and to help with drainage. The ones we keep generally get a blast with the pressure cleaner before re-installing and again after the wall has cured. This evens up the weathered look and any new stone you had to put into the wall. Generally we will build the wall with cut stone and fit the rough stone randomly along the face, protruding out a little to produce a nice effect.

Good base, good drainage and sound construction = good wall.

cleancutccl
02-01-2006, 01:50 PM
Okay an update to the story, I went back to the site to see how well the mortar would come off the stones. Good news, the stones have seen so much water that the mortar takes about one or two hits and comes off clean. Knowing this what would you expect for labor hours to just put the wall up, 95' x 3' tall? I know my labor hours for demo, excavation, base, and backfill, just not to sure about the rebuild part. I'm thinking somewhere in the neighborhood of 24-30 manhours. This would include knocking off mortar and dry stacking the stone. Thanks guys.

cleancutccl
02-01-2006, 03:12 PM
I think I severly understated my man hours on the rebuild. I just read a manual that said about 1 manhour per foot for a dry stack 3' high, including base. So for this one I should be in the range of about 85-95 manhours? I've got all this figured out but the rebuild part, thanks for any input.

cleancutccl
02-02-2006, 06:42 PM
All this help from you guys went to waste. I gave my bid to the GC, and he asked what all the drainage rock and tubing was for, I explained that is to keep the wall from failing again. He the replied that the homeowner just wants the wall stood back up straight again, with the least amount of money as possible. My reply was, then I can't do it, I have a growing reputation for quality and am not going to risk that on one job. Long story short, didn't get the job, and personally I won't even bid for this GC anymore. Thanks for all you guys help and it will help me in future jobs i'm sure.

MarcusLndscp
02-02-2006, 10:13 PM
I had a feeling when you said they were selling the house they just wanted it done cheaply. What did you come up with for price and facial SF per mHr? Just curious.

cleancutccl
02-02-2006, 10:51 PM
I measured the wall to 285 face feet and priced it at $23.00. Total job $6540.00. For man hours for the total wall i estimated 139 man hours. Might have been a little high but there was not an easy access to the site.

MarcusLndscp
02-03-2006, 06:18 AM
Were those mHrs for removing the old wall, putting a new base in, construction of wall, installing drainage pipe, and back fill w/ stone? All equipment and materials as well were in that price?

cleancutccl
02-03-2006, 10:01 AM
Yes, not much for materials because we were reusing the old wall, the only thing we have to rent would be a mini ex at 205 per day. $4500.00 in labor charges only. Do you think I was too low? Like I said i don't have much experience with dry stack, and none with tearing down an old mortar wall and rebuilding it so an estimate on labor hours would be great for future reference.

MarcusLndscp
02-03-2006, 10:50 AM
Yes, not much for materials because we were reusing the old wall, the only thing we have to rent would be a mini ex at 205 per day. $4500.00 in labor charges only. Do you think I was too low? Like I said i don't have much experience with dry stack, and none with tearing down an old mortar wall and rebuilding it so an estimate on labor hours would be great for future reference.
I think you were very close with your mHrs. I figurred it and was off 4 hours from you for the total job. Dollar wise you would be lower than what I would be but our operating costs are different I am sure of that. I came up with about $6100 dollars in labor alone. Depending on what type of structure you're building out of stone you can expect any where from .75 FSF/mHr up to 3-3.5 FSF/mHr. The drastic change is due to stone type/workability and how involved the job is. For example, the column posted below was quite involved because it had 8 corners and was really tight building conditions. For your wall I guessed at 3 FSF/mHr for a total of 95mHrs just to rebuild the wall...that doesn't include cleaning off mortar, demo,base prep, backfilling, and finish grading the backside of the wall when done.

In the first pic you can see the beginning construction of the split column, the purpose being to allow a motorized gate to slide through it from right to left. Each piece of this column measured 1'x3' wide leaving a 1' gap between the 2 sections for the gate.

The second pic is just a little further along in construction. You couldn't simply stack stone in this situation because of the size and detail involved with them. A majority of the corners were also custom made using a hydraulic splitter which involved more time. Also incorporated into them were key boxes for the fire department and security number pads for access which adds to the detail of the construction. I believe these were quoted at about 1 FSF/mHr