Perimeter Drain Around the House
Repair, Resize or Cover (2026)

Signs the drain round your house needs work

The open drain (longkang) that runs along the outside walls of a terrace, semi-D or bungalow carries roof water from the downpipes and rain off the apron to the monsoon drain. When it stops working, the symptoms show up around the house long before anyone looks into the channel itself.

Why old perimeter drains fail

• Silt and leaves. Sand from renovations, garden soil and leaves settle wherever the water slows down, and the drain gets shallower every year.
• Settlement. The ground beside a house often settles more than the house, so drain sections sink, crack at the joints and stop falling to the outlet.
• Tree roots. Roots push into cracks and joints looking for water; our tree roots guide covers what to do about the tree.
• More water than it was built for. A rear extension, a new porch roof or a paved-over garden all send more water into the same drain.
• Built over. Extensions and kitchens are sometimes built across the drain with no access left, so a blockage there cannot be reached.
• Downpipes discharging beside it. Water from a downpipe that misses the drain soaks the ground and undermines the drain wall.

Simple checks before you pay for anything

1. Walk round the house during or just after heavy rain and note where water stands, overflows or runs against the wall.
2. Pour a bucket of water at the high end of each run and watch where it stops moving.
3. Lift a few covers and look for silt, roots, broken pieces and connections from the kitchen or bathroom.
4. Check that every downpipe actually discharges into the drain and not onto the ground beside it.
5. Find the outlet: where the house drain meets the monsoon drain. A blocked or raised outlet makes the whole run pond.

For a new house still under its defect liability period, the developer should put falls and cracks right; our perimeter drain defects guide explains how to report them. This page is for the owner of an older house who has to fix it themselves.

Repair options, from small to large

Clearing is the first step for any drain problem, because it shows what is underneath. Our drain cleaning guide explains the methods. Where roots or packed silt run inside a buried pipe section rather than the open channel, hydro-jetting is the tool that clears the full bore.

When the drain is too small

A drain that overflows in heavy rain even when it is clean and falls correctly is undersized for the water it now carries. This is common after a house has been extended, a car porch roofed, or the garden paved, because every one of those adds roof or hard area that drains into the same channel.

• Check the outlet first. A bigger drain is useless if the pipe or opening into the monsoon drain is the bottleneck.
• Deepen or widen, not both blindly. The new channel still has to fall to the outlet, so its depth is set by the outlet level.
• Split the load. Sending part of the roof water to a second outlet or a separate run can be cheaper than rebuilding the whole drain.
• Check the boundary. The monsoon drain outside the lot belongs to the local council; work that touches it or changes the connection is a question for the council first.

Where the garden itself floods, the garden drainage guide covers channel drains, French drains and where the water can legally go.

Covering the drain: gratings, slabs or closed

Owners cover drains to stop trips, mosquitoes, smells and leaves, and to gain a wider path beside the house. The rule is simple: a drain you cannot open is a drain you cannot clear.

Under a driveway or car porch the cover must take a car's weight; our drain grating guide explains load classes and why light walkway gratings bend under wheels.

Drains under extensions and roofed yards

Before a back kitchen or yard is extended or roofed, decide what happens to the drain underneath. Building straight over a perimeter drain without access points is the most common reason a renovated terrace house floods its back kitchen years later.

• Reroute the drain round the new walls, or replace the buried part with a pipe that has access points at each end.
• Keep floor traps and wet-kitchen waste out of the rainwater drain where the layout allows.
• Bring the new roof's downpipes into the drain, not onto the yard floor.

Our rear kitchen extension guide covers the extension itself.

The apron and the joint at the wall

The concrete apron between the wall and the drain should fall away from the house so rain runs into the drain. When it has sunk or tilts towards the wall, water sits at the base of the wall and damp creeps up the paint. Re-lay or top the apron to a fall, and seal the joint at the wall with a flexible sealant rather than mortar, which cracks again. If the porch slab next to the drain is also cracking, our cracked porch slab guide helps decide between patching and recasting.

What it costs

These are ClickBina's published figures (indicative 2026, Klang Valley). Rebuilding or resizing a run is priced after the levels to the outlet have been checked, because depth, access and hacking drive the total.

Gutters that overflow along the wall add to the water the drain has to carry; the gutter and downpipe guide covers that side.

Keeping it working

• Desilt the drain before the monsoon months and after any renovation that washed sand or cement into it.
• Keep leaves out with gratings and by trimming plants that overhang the channel.
• Never let renovation workers wash cement, tile grout or paint into the drain.
• Look along the drain after heavy rain once in a while: standing water is the early warning.

How ClickBina can help

WhatsApp us your job details for a quote: your area, house type, the rough length of drain, and what is happening (overflowing, ponding, cracked, or you want it covered). ClickBina is an experienced KL & Selangor contractor that clears drains and coordinates the hacking, concrete, gratings and apron work as one job. We reply within the hour, and the price we agree is a flat price with no hidden charges.

Sources & methodology

• ClickBina drain cleaning guide — blocked-drain clearing prices and methods.
• ClickBina commercial drainage and grating guide — grating, cover, channel drain and desilting prices, load classes.
• ClickBina gutter and downpipe guide — gutter and downpipe repair price.
• ClickBina car porch flooring guide — hacking price.
• ClickBina perimeter drain defects, garden drainage, tree roots and rear extension guides — related repairs.

How we estimated prices: every RM figure on this page is quoted unchanged from the ClickBina guides named above; they are indicative Klang Valley ranges for 2026.