Stone Basement Waterproofing / Foundation Footings?

troyce1 · 02-26-2012, 08:53 PM

I am looking to finish my basement in my house which is 13x30 ft wall to wall on the interior.

This may question may not exactly be DIY, but it prevents me from completing any DIY and other projects I have planned.

The foundation walls are stone / field stone, and the house was built in 1850. I had one waterproofing contractor come out and look at it, and quoted me $4,000 for the two 30ft walls and the 13ft wall to install a drain tile and barrier system. A husband of one of my wife's friends used to be a salesman for a basement waterproofing company. While he did not do the work, one of the things he said to be concerned about was other companies salesman or contractors quoting the waterproofing, but not understanding the job.

He said that because I have a stone wall there is a possibility there is no footer underneath the stones. I am not sure how far below grade, or below the concrete floor the foundation stone goes, so I am not sure how to confirm or look into this.

This also is of concern because we were planning on building a small addition abutting the rear of the foundation wall which would need footers and a foundation dug and installed and meet with the exisiting wall.

My questions are:
- What types of basement waterproofing applications would work IF there are no footers.
- How can I confirm what the status of any existing footers would be.
- What would need to be done to have the new footers of an addition meet up against the existing foundation wall if there are no footers.

I want to get info and input before other contractors or companies look at both of these jobs so that I can ask and address important questions and issues.

This is the biggest hurdle for us to get our basement renovation project moving.

Daniel Holzman · 02-26-2012, 11:11 PM

1. Basement waterproofing. Basement waterproofing typically refers to a coating placed on the exterior of the wall (usually block or concrete) designed to prevent water from infiltrating through the wall into the house. Typical coatings include tar (various bitumastic formulations), spray on polymer coatings, and elastomeric sealants (Grace makes a line of them). These types of coatings are generally applied before the wall is backfilled. I have not seen them used on a stone wall type of foundation. Installation of a perimeter drain, either exterior or interior, is not waterproofing per se, because the idea is to lower the water table so it is below the basement slab, thereby effectively eliminating the potential for water to infiltrate into the basement through the wall.

2. Footers. It is common for stone wall foundations to be placed without a footer. The only way to find out if there is one is to dig one or more test pits around the base of the wall to determine if there are any footers.

3. Addition. There is no reason the foundation for the addition needs to be tied to the existing foundation. As long as the new foundation is properly designed and constructed, the two buildings can be separate.