What is the best product for repairing expanding gaps in a brick wall?

Question

I am trying to do a structural repair to a brick wall that has some large gaps - 1-3" between some of the bricks due to some foundation movement over the last 300 years. The gaps are essentially vertical cracks where the mortar has broken loose and the bricks are separating. I know that any foundation movement will cause more cracks but I want to at least stabilize the cracks so that the wall does not collapse. I am thinking that a mixture of something like sand or pea gravel and a strong adhesive will provide the support I need. I have tried Gorilla glue in matrix material but the foaming and expansion just doesn't work well. I think a tube adhesive with a high tensile strength will work, I just have little experience with the new ones out there.

Any ideas or suggestions are appreciated. I always do a "proof of concept" before going full scale so I can try several ideas.

Answer 1

Three inch gaps seem quite large - even for a 300 year old wall.

You just need to use a good mortar mix (sand and cement) on the narrower gaps.

Clean out all the old, lose material first to make sure that you get good adhesion and then push the mortar right into the gaps as far as it will go. Work on a small area (1 m²) at a time.

Adding pea gravel to give the mix more "body" might work on the wider ones.

However, I'd get a professional to have a look at the wall first to make sure you're not going to have to redo this work in a couple of years time. If the foundations have gone it might need something more substantial work doing.

Is the wall part of a house or just a garden wall? If it's the latter then dismantling and rebuilding might be the best long term option.

Answer 2

I don't think you can 'repair' the cracks. You'd have to repair the wall or foundation.

Please be aware that bricks don't 'stick' to the substrate as with a glue or bonding agent. A mechanical agent, like a brick tie, is used to keep bricks 'stuck' to a wall. The main force keeping bricks in place is gravity, and if you've got other forces working against it (like wind or soil load), you need mechanical help.

If you want to fill a large crack you may want to start with a backer rod or material of some sort. Very often products made to fill cracks are designed to work wide but not necessarily deep.

Backer rod is a dense foam product that simply occupies space so that your filler material doesn't have to.

Answer 3

The real answer to your problem is to dig out the dirt on the other side of the wall. Then drill 1/4" to 1/2" holes thru the wall. Use long threaded rods stainless preferred with nuts and large washers. Get some 1/4" steel plates, about 2-4 ft. length by 8" wide. Drill holes to match holes drilled in wall, put steel plates on both sides of wall tighten nuts cut of extra rod ends after nuts. Gaps should be filled with cement morter and then paint walls with flex seal both sides to keep moister out. Larger lengths of steel can be used but you will need to drill more holes. Multiply the amount of holes in plates to keep them from bowing or bending. You must reduced any water pressure that is pushing against wall drain tiles or drainage system to draw all water away from wall. Good luck lots of work and try and make it look good.