Damp basements are a common thing to see on home inspections here in NH. But there should never be standing water in a basement. But if there is, how can you fix it?
If there is already water in your basement, the first thing that should be looked for is damage within the interior walls. If you find any cracks or holes, this could be for a number of reasons.
Perhaps the main reason is from poor building of the home in the first place. If the wall is weak to start with, it will quickly succumb to the pressure that builds on the outside. Also, it should be noted that the house may have also settled which may cause cracks. In either case, fixing the problem is essential to prevent leaks and floods. If you suspect that cracks or holes are the cause of the problem, here are some steps you may want to take;
Firstly, try and identify all of the areas where water may be coming in. As well as cracks, look for any moisture on the walls as well as discolouration. If moisture is obvious but you have struggled to find the offending area, be sure to check every inch of the basement.
Secondly, small hairline cracks may be fixed with a combination of latex cement and epoxy. Since this formula is waterproof, it should prevent the problem from ever happening again. In truth, this will only really be effective for cracks smaller than 1/8th of an inch.
For any cracks larger than this, a mixture of one part cement and two parts fine sand should be made. Before using, add a splash of water so it turns into a stiff mortar. With large cracks, the mixture needs to be tightly-packed into the gaps so that no air bubbles can form. If there is no water coming through at the time of application, a simple trowel should allow you to apply the mixture perfectly.
If pressure from the outside is pushing water through, you will need a slightly different method. To start, you should be looking to chisel the mouth and along the length a little. If you can, cut a small dovetail groove along the crack and then apply the mortar ensuring it is tightly-packed once more. If done correctly, the pressure from the outside will struggle to make an impact because of the dovetail groove.