I highly recommend Ottawa Building and Foundation Repair Inc.
We were in the process of buying a house that needed work on the foundation - moldy wood paneling in the basement was a sure sign that the block concrete had cracks in it (house was built in 1940s or 50s).
Nathan came to look at the house and gave us an estimate. He was great - honest, not alarmist, friendly and knowledgeable. He gave us a very detailed quote which allowed to us to show the sellers of the house the work that needed to be done for easier negotiations.
We bought the house! And decided to go with Nathan's company based on the professionalism and detail that went into his quote and also just the general feel that he was a good guy (and the other Homestar ratings too).
The work was done to our complete satisfaction - excavated around the three original block concrete foundation walls, patched all the cracks (of which there were many), new weeping tile, water membrane, removing and reinstalled back steps/deck, repaving part of the driveway, replanting a tree (twice! because we wanted it "a little to the left" and they couldn't have been nicer about it), etc.
We had removed the moldy wood paneling before Nathan and his crew (great guys, super friendly) started and had revealed an old chimney hole for an old wood stove that was patched up oddly (someone way back in the day had stuck a rock in there and then just put insulation? like why?) and some other holes and Nathan had his guys fix that all up for us.
They also were going to install a new sump pump but the one that came with the house was in fine working order so they kept it and knocked off some of the price (honest company) but professionally re-did the sump pit (it was just like a makeshift hole in the corner but now is a real sump pit with a plastic drum and cover).
Anyway, quite the novel here but all this to say that Nathan was great to do business with and I highly recommend him and his company.