"Can hack lah" is the most expensive phrase in Singapore renovation. Contractors often say it with confidence, but you are the one who pays the fine if they are wrong. Here is what HDB's rules actually say.
The fundamental rule: structural walls cannot be touched
HDB flats are designed with specific load-bearing walls that support the floors above and the building's structural integrity. These cannot be hacked, reduced in thickness, or have openings cut into them under any circumstances.
Structural walls do not always look different from partition walls to the untrained eye. While thickness is an indicator (typically 100mm+), it is not definitive. Do not trust a "knock test" or a contractor's experience alone.
The safe way:
- Request your flat's original structural drawings from HDB via MyRequest@HDB before planning any hacking.
- These drawings show exactly which walls are structural.
- This service is free and typically takes a few days.
What requires HDB approval before hacking
Any hacking of walls — even non-structural partitions — requires an HDB renovation permit, which your contractor should submit before works begin.
Specific items requiring explicit approval:
- Enlarging openings: Changing the size of door or window openings, even in partition walls, requires separate HDB approval.
- Removing original walls: Removing original partition walls that form part of the approved layout may need HDB sign-off.
- Bomb shelter modifications: The walls around the bomb shelter are protected under civil defence regulations. The steel door cannot be permanently fixed open or replaced. While internal space can be adapted for storage, the structural shell is protected.
The wet wall trap
Bathroom and kitchen walls contain waterproofing membranes and plumbing pipes. Hacking a wet wall without proper restoration of waterproofing causes water to seep into the flat below, making you liable for their damages.
The correct process:
- Waterproof both the floor and walls up to 1.8m height before any new tiles are installed.
- Do not believe a contractor who says tiles alone provide enough waterproofing.
The floor overlay vs hack decision
There are two options for existing HDB tiles: hacking them out or overlaying new tiles on top.
Overlay:
- Permitted by HDB as long as the combined height does not exceed limits.
- It is cheaper, faster, and produces less dust.
- Ask your contractor: "Is overlay viable for this floor?"
Hack:
- Necessary when existing tiles are hollow or damaged.
- Required when the floor is uneven or when installing flooring like vinyl that needs a flat substrate.
Noise regulations that often get ignored
Hacking is noisy, and HDB permits such works only during specific hours. These are strict rules, and violations can result in warnings, fines, or work stoppages.
Permitted hours for noisy works:
- Monday to Friday: 9am to 5pm
- Saturday: 9am to 1pm
- Sunday and Public Holidays: Not permitted at all
The bottom line
Know your flat's structural layout and insist on a properly submitted renovation permit before day one. Never compromise on waterproofing in wet areas. If a contractor says "can hack," ask them to put it in writing and show you the structural plan that supports it.
