support underneath old brick load bearing wall

[ashroyer]

I have a brick loadbearing wall that runs down the center of my house in the crawlspace. The bottom of the wall sits on the dirt crawlspace floor (no footer). I have dug out the dirt under a small portion (approximately 2 feet long) and several feet deep. I poured a large footer (with rebar re-enforcement) and plan to build up a cinderblock column underneath the brick wall to support it from beneath in that spot. I will stack up the concrete block and fill, my question is: is there anyway to get a little pre-load under the brick. Ideally i would jack up the house a 1/4" or so at that point and slide the block in so it fits tightly then let it back down on top of it. I don't think I can do this though because I don't think i can jack up the old brick wall from beneath (it might fail with that much pressure in one spot).

What would be ideal is if there were some type of artificial steel cinderblock contraption with adjustment screws that I could put in the column and put a few turns of the screw when i was finished building it to tighten it up (kind of like an adjustable lally column, only it could be placed in a cinderblock column.

thanks!

[charlie]

brick walls don't like to flex without cracking.

[aemeijers]

Build a temporary wall alongside the brick, to hold up the (still overlapping) joists, using about a 4-5 foot piece of steel, a couple of house-mover bottle jacks, and some steel plates on the dirt to set the jacks on. Maybe some cribbing if the jacks are not tall enough. A house moving company, or rental house that deals with the trade, will have this all in their yard. Just build the wall up underneath the brick as tight as you can, and use shims above the brick as needed to make the floor above level.

By the way, if you were adding footer under this section to catch a point load above (rather than just a sagging floor), you probably want to look at replacing that part of the brick with new concrete block, all the way up to the load, with a piece of PT or steel on top to catch and spread the weight. Old brick that has been undermined sometimes likes to crumble unexpectedly, or the mortar bond in that area lets go.

Just for giggles, may want to ask a house moving company, or their usual foundation company, for a price on the proper cure, if there is access from one end. To wit, support the whole run on jacks and cribbing, demo the brick, and replace with a steel beam on proper piers and footers every 8 feet or so. If they can get a straight shot at it, they can slide a beam in through a hole barely any bigger than it is.

Hard to give reliable suggestions, since we can't see the bottom of your house from here...

-- aem sends...

[Mike Paulsen]

If you just want to make sure it's a snug fit between the new supports and the bricks, expanding concrete might work.

Build up the wall with concrete blocks to within x inches of the brick. Top off with x inches of expanding concrete.

I have no idea what 'x' should be, how much aluminum to add to the mix, nor what the forms need to look like. I'd sure want to run the plan by an experienced mason before I tried it.

If you search for aluminum powder and concrete you should get on the right track.

[Joe]

I used a cheap 10 ton bottle jack to do raise the house and fit in lally columns. Used proper 1/2" steel plate chunks from local scrap yard under the joists, sills. House mover gear though, is good if you are doing a whole lot of supports at one time.

Joe

[ashroyer]

Thanks guys. That's some good information to think about. I will give it some consideration and let you know what I decide and how it works out.