This is where builders that are not familiar with PWF make their first and most problematic mistake! PWF ARE NOT a sealed system designed to keep water out! PWF IS designed to direct water away from the foundation! They also should never have drain tile installed… Drain Tile under a PWF will guarantee the foundation to fail! Backfill is mostly peagravel.
This is a system where there are no shortcuts. Also the builder may never think that he/she is making the foundation better by adding sealent somewhere the plans don’t indicate sealant to be! That will guarantee the foundation to fail also! The plans MUST be followed to the letter!
Vern;
Could it be that block foundations are failing because of the much deeper frost way up there north of the arctic circle:mrgreen: ? a friend of mine lived in Edmonton and said that the frost often reaches 4-5 feet into the ground. If true this would put additional stresses on the walls. certainly more so than found down here in the banana belt.
It depends on the spieces of wood used in mud sills, how close it is to grade or below grade, and weather, such as leeward side where snow builds up and melts in spring. I have seen lots of mud sills in century plus homes that have rotted out. Grading issues, and downspout water management, or lack of gutters all play a role in longevity.
Back in the 60’s the specs call for water proofing bituman to be painted on exterior of foundation. Later they called for 6 mill poly on the exterior.
Is this what you mean?
The code calls for foundations to be a minimum of 4’ 6" below grade.
Frost penetration depends on the amount of snow cover. Frost in the street can go 8 to 10 feet deep.
Peagravel plays a large part in a PWF. It is capable of redirecting more water then any drain tile.
Drain tile becomes clogged, cracks & creates large voids under foundations over time. These voids cause cracks in poured foundation walls and failures in all foundation walls! If the builder installs both drain tile with the peagravel… the drain tile will wash the peagravel away from under the foundation walls.
Poly is used on the exterior of PWF but is only sealed along the top edge! Not along the bottom, you want any moisture to be able to run down the poly to the peagravel so it can be directed away from the foundation! You always want the PWF to be able to breath!
This would be so much easier to explain in person. I have spent a lot of time learning about different aspects of PWF, But I feel there is more for me to learn yet.