Sinking Gangway/Mudjacking

[Nazerac]

Has anyone tried mudjacking a sinking gangway?  I think that I'd rather just mudjack it then have a complete demo/repour.  The concrete is still good, it's not cracked, just tilts towards the house. 

[Robert Pauly]

What's mudjacking?  My brother-in-law just had something injected under his garage floor to raise some sections.

[Nazerac]

The cut up the concrete into sections, and drill a hole or more in each section, and just inject concrete/whatever through the holes beneath the slab to push it up.  This reduces the cost of a demo and its associated costs (labor+disposal).  I still have the old concrete, which is probably 4-6" deep compared to the new ones that are 3".  So my demo costs will be higher.

This old house covered it in one of their episodes.


http://www.servicemagic.com/article.show.Concrete-Mudjacking.8709.html

[BRoWN]

best material  to inject is  expanding foam in most cases.

[Nazerac]

which company uses foam?  Most of the ones that I have seen inject some type of slurry and various cement content.  Wouldn't the foam breakdown faster than concrete, and the slab will sink again?

I am getting estimates for raising the gangway and a total demo/repour ... we'll see the price difference.  If it is the same price, i may be more interested in a total demo/repour.  I am slightly concerned with how the material pumped underneath the slab will affect my foundation wall.

[n01_important]

How much does that cost?

[dukesdad]

Is it right next to your house? If not, walks like that are not that hard to raise manually. If you can get access to the sunken edge, you free it up by digging all along the edge, cut it into manageable sections along the expansion joints (may not need to cut it it may be already broken along those lines) then jack it up with a railroad jack. You may even be able to pry it up with a large 6" pry bar. Once you get it raised, pack gravel under the edge and backfill. I will be some work but you can take your time with it.

[Bonster]

Is it right next to your house?

If it is right next to your house I've heard from contractors there are methods where they cut holes, insert anchors, and can lift the slabs to backfill.

[BRoWN]

I'd use foam because it actually helps to lift the concrete during the application. Its also water resistant and should prevent further erosion. If your concrete has dropped you likely have a drainage erosion problem ....using the dirt gravel or limstone mixture would just be a temporary fix and the problem will come back . With the foam, it not only sets permanantly but expands to places the gravel mixture can't find. The foam sets within an hour. Foam is weatherproof and won't frost up and expand later 

[Nazerac]

I suspect a broken clay pipe that is connected to the gutters (soon to be disconnected.)  So once I disconnect my gutters my erosion probably will be over.  So do you know of any company that does foam lifting?

[BRoWN]

no. I'm sorry I don't know of a company using foam. I saw them using it on "This old House"  and I think they were here  in Chicago. Whoever you get be sure to get some sort of guarantee as mudjacking with ANY material....even foam... is not a sure fix.

[Nazerac]

My biggest concern is how any pressure filling will affect my foundation wall when the gang way is so close to it.

[BRoWN]

Contractor should know about how much PSI and how much material they are working with. 

[Nazerac]

First contractor came in this am.  This will be the "old fashioned" work.  Since the landing from my backporch steps are also sinking in, it seems that the stairs from the back porch, the stairs from the basement and all the gangway will have to be removed and then repoured/etc.  This seems to be plenty of $$.  I can't wait to see the options the concrete raising contractors give me.

[BRoWN]

maybe consider an overlay of cement where gangway sinks towards house?

[Nazerac]

I did think of that, I don't know how effective and long lasting the new layer of concrete will be on top of the old one.  Besides, will it sink again in 5 years?

[Bonster]

Since the landing from my backporch steps are also sinking in, it seems that the stairs from the back porch, the stairs from the basement and all the gangway will have to be removed and then repoured/etc.

That sounds like something other (or more than) a broken clay drainage pipe.  Previously leaky gutters?

I have one spot with three squares sinking toward the house which was due to the old, leaky outdoor spigot which likely leaked for 10+ years...

Basement stair sagging could be natural erosion not necessarly due to a property "defect" of sorts.

Curious to see what they tell you about raising them as well.

[Nazerac]

remember that the sinking is along the path to the catch basin.

[Nazerac]

I got three estimates.

X for mudjacking, 1 year warranty
2X for better concrete mix jacking, 4 years warranty
4X for demo/rebuild.

I am waiting fora couple more estimates.