Our house (circa 1880) has a rubble foundation, mostly in solid condition though the summer plans were to repoint anything needing attention. Clearing our first corner (inside) we noticed dirt and some water seepage in a couple spots at the base of the foundation where the slab had been poured. We figure this may have been a dirt floor with a slab poured later at the level of the bottom of the foundation, but no matter, our question is what we should do with the gaps were the stones don’t dip below slab level to fill these voids where there is nothing but dirt?
In our preliminary research (we’re noobs here) we’ve discovered some discussions about hydraulic cement, mortar, and concrete. Does anyone have experience with this scenario and advice for us?
Replies
If you have noticed water seepage and gaps between the rubble foundation and the slab, it is important to address the issue to prevent further damage to your foundation and potential water damage inside your home. Here are some steps you can take to address the gaps and seepage:
Remove any loose debris and dirt from the gaps using a wire brush or similar tool.
Fill the gaps with hydraulic cement. Hydraulic cement is designed to expand as it dries and can fill in gaps and cracks effectively.
If the gaps are particularly large, consider using a backer rod or foam rod to fill the gaps partially before applying the hydraulic cement. This will help prevent the cement from sinking into the gap and leaving voids.
After the hydraulic cement has dried, you can use mortar to fill in any remaining gaps or to create a smooth surface between the foundation and the slab.
If you are concerned about water seepage, you may want to consider applying a waterproofing agent to the foundation after the gaps have been filled. This will help prevent water from seeping through the foundation and causing further damage.
It's important to note that if the water seepage and gaps are extensive, it may be necessary to consult with a professional to assess the situation and provide a more comprehensive solution.
ok
You write- "Stones don't dip below slab level". Not likely or the house would likely not still be standing. Water seepage in a rubble stone foundation is difficult to stop without sealing the outside below grade. Drylock paint can help but surface has to be clean with no loose material. Best resource would National Park Service Preservation Briefs.