The wall is damp, and the mortar turns to sand when I touch it
Natural Resources Canada says older rubble and stone foundations "were rarely damp-proofed," and that their high mortar content "can absorb water from the soil." The U.S. National Park Service notes that masonry deteriorates "especially at the mortar joints." The stone usually outlasts the mortar around it.
Hamilton has a lot of older houses. The City's 2023 Housing Needs Assessment puts 32.8% of homes as built in 1960 or earlier.
What to do now: press a key against a few joints. Note where it's soft, and where the wall is wet. Take a photo of each spot.
It's worse in spring, and after every big rain
That points at water in the ground, not just the wall. Natural Resources Canada says persistent leaks and flooding "in the spring and when it rains" must be corrected.
Downspouts matter more than people think. A heritage masonry policy from Loyalist Township, Ontario, says faulty eavestroughs or downspouts focus water on masonry, "resulting in freeze-thaw damage." Wet masonry that freezes and thaws all winter takes damage.
What to try first: walk the outside of the house in the rain. Look for downspouts that empty against the wall, and ground that slopes toward it. Natural Resources Canada says minor leaks can sometimes be corrected by sloping the grade away from the foundation.
There's white powder on the stone, and the basement smells musty
Those are signs of dampness. Natural Resources Canada lists staining or mould, blistering and peeling paint, and efflorescence, "a whitish mineral deposit on the surface."
The powder is salt left behind as water dries out of the wall. It shows water moving through, not where it starts.
What to do now: brush the powder off, then check again in a week. If it's back, the water still is too. Photograph where it returns.
Someone told me to fill the joints with hard cement
Old stone walls were usually laid in soft lime mortar. The National Park Service says new mortar must be softer and more vapour permeable than the stone, and no harder than the historic mortar. Hard cement mortar can trap moisture in old masonry and damage it.
The same guide warns that new mortar alone won't fix a problem caused by something else, like leaking gutters. Find where the water comes from first. And ask whoever works on the joints what mortar they'll use.
Do I fix it from inside or outside?
Usually it starts outside. Natural Resources Canada says minor dampness may be corrected from the interior, and "more serious problems should be corrected from the outside." For major leaks, it says the solution often means excavating, waterproofing the basement and adding a drainage system.
Building scientist Joseph Lstiburek is blunt about rubble walls: "almost all rubble foundations leak and are damp," unless you are very lucky. His rule is to deal with the water first. Where digging outside isn't practical, he describes collecting the water inside and sending it back out.
What we do: Albany Contracting Group waterproofs foundations, basements and exterior surfaces. We look at the wall inside and out and find where the water gets in. You hear what it needs at a free consultation in your home. See basement waterproofing in Hamilton.
The stone above ground is a separate job. For porches, steps, walls and brick, see our stone and brick masonry.
Will I need a permit?
Possibly. The City of Hamilton lists waterproofing or damp proofing foundation walls, and repairs to structural members, among projects that require a building permit. Check with the City before work starts: Do I need a permit in Hamilton?
What affects the cost
Where the water gets in, and how much of the wall it reaches. Inside, outside or both. How easy the wall is to reach: driveways, porches and gardens count. Any permit. And what turns up once the wall is open.
That's why we don't quote from a phone call. We price waterproofing at a free consultation in your home, once we've seen the job. No obligation.
More old house problems: water in the basement after rain, or all the guides.
