I have rising damp. Do I need ag lines?
Rising damp is moisture drawn up from the ground into masonry walls, leaving tide marks, flaking paint, salty deposits and a musty smell. Ag lines, or subsoil drains, are slotted pipes in gravel trenches that collect groundwater and carry it away. They can make a big difference when water is pooling against the house. But ag lines alone won't fix every damp wall. Here's how to tell what's going on and what helps.
Where the moisture comes from
Water sitting against the house
Yards that slope towards the house, garden beds built up against walls, and downpipes discharging at the base of walls keep the ground wet.
Leaking pipes
A leaking water, sewer or stormwater pipe near the wall can soak the ground. See mould on walls.
Failed damp course
Older brick homes have a damp-proof course to stop moisture rising. When it fails or is bridged by soil or render, damp rises.
Poor sub-floor ventilation
Blocked vents under timber floors trap damp air.
When ag lines help
- When groundwater or surface water collects against the house after rain.
- Where the yard is higher than the floor level on one side.
- Along retaining walls and cut-in areas where water seeps out of the bank.
The ag line is laid below the problem area, wrapped in filter sock and gravel, and connected to the stormwater system so the water has somewhere to go. See backyard drainage.
When they won't be enough
If the damp course has failed or been bridged, the wall can keep drawing moisture even with dry ground. That needs a building or damp specialist. We focus on the plumbing and drainage side: fixing leaks, connecting downpipes properly, lowering surface water and installing ag lines, which is often a big part of the solution. You get a fixed price before any work starts.
In southern Eastern Suburbs homes
Older brick homes in Matraville, Maroubra and Kingsford commonly have damp lower walls, often made worse by downpipes discharging at the base of the wall, or gardens built up over the damp course. Sandy soil drains well, but where clay or rock sits underneath, water can collect.
Why locals call us
- Local to Matraville and the southern Eastern Suburbs
- Free on-site quotes, with a fixed price before any work starts
- Lifetime labour warranty on our workmanship
- 100+ five-star Google reviews
- Licensed plumbers and gasfitters (Lic. 398171C)
Common questions
Will ag lines fix rising damp?
They help when water is collecting against the house. If the damp course has failed, that also needs fixing.
What is an ag line?
A slotted pipe in a gravel-filled trench that collects groundwater and carries it to the stormwater system.
Can downpipes cause damp walls?
Yes. Downpipes discharging at the base of a wall keep the ground and wall wet.
Where does an ag line drain to?
Into the property's stormwater system, which drains to the street or another approved point.
Related help: backyard drainage, backyard flooding, stormwater, mould on walls and downpipes. Local pages: Matraville, Maroubra, Kingsford and Botany.