Every year I come across resale HDB transactions that get held up, sometimes at the eleventh hour, because of renovation work that was never approved by HDB in the first place. It could be a hacked wall, an enclosed balcony, or a bathroom that was moved without permission years ago by a previous owner. Buyers often assume that if a flat looks well renovated and move-in ready, everything behind the walls has been done properly. That is not always true, and finding out after you have signed the Option to Purchase is a far more stressful position to be in than finding out before. This guide walks through what unauthorised renovations actually are, how they can affect your purchase timeline and finances, and what to check before you commit.
What HDB Actually Considers an Unauthorised Renovation
HDB has fairly specific rules on what flat owners are allowed to change without approval, and what requires a permit before work begins. Anything involving structural elements, such as hacking a wall between the kitchen and living room, removing a portion of a bedroom wall, or altering the layout of the bathroom, typically needs HDB approval. Enclosing a balcony or service yard, changing the flat’s original floor finishes in certain wet areas, and installing certain types of flooring over existing tiles without proper waterproofing checks can also fall into this category depending on when the work was done and under what rules applied at the time.
The tricky part is that renovation rules have changed over the years, so a flat that was renovated in 2008 was subject to a different set of guidelines than one renovated in 2022. A previous owner may genuinely not have known certain work required a permit, or may have used a contractor who cut corners to save time and cost. Either way, if the work was never submitted to HDB and approved, it is considered unauthorised regardless of how long ago it happened or how good it looks today.
Why This Becomes Your Problem, Not the Seller’s
This is the part that catches buyers off guard. Once you take over the flat, you inherit responsibility for its condition, including any unauthorised works that were never rectified. If HDB conducts an inspection, whether routine, complaint-triggered, or as part of a separate approval process such as adding aircon ledges or applying for other renovation permits down the road, and finds unauthorised work from years before your purchase, you as the current owner are typically the one required to reinstate it at your own cost, not the previous owner who did the work.
This is why the resale process actually has a built-in checkpoint for this issue. When a resale application is submitted, HDB requires the flat to be free of unauthorised renovations before the transaction can proceed to completion. In practice, this means if unauthorised works are flagged during this stage, the seller is required to reinstate the flat to an acceptable condition before the sale can be completed, which can add weeks to your timeline. If it is missed at this stage and only surfaces after you have moved in, you carry the liability going forward.
How to Check Before You Sign the Option to Purchase
The most useful thing you can do as a buyer is look carefully during your viewings, ideally more than once, and ask direct questions. Look at wall thickness where rooms have been combined, check whether ceiling boards or feature walls seem to be hiding structural changes, and pay attention to bathrooms and kitchens that have clearly been relocated from their original position, since these are common areas for unapproved work. If something looks off, ask the seller or their agent directly whether the renovation was done with HDB approval, and ask to see the approval letter or permit if one exists.
You can also request that your own agent make enquiries with HDB on your behalf, or ask the seller’s agent to confirm in writing that there are no outstanding unauthorised works on record for the flat. Some buyers choose to include a condition in their offer or OTP negotiation that any unauthorised renovations must be reinstated and cleared by HDB before completion. This is a reasonable and fairly common request, and a seller with nothing to hide should not have an issue confirming this.
If you are working with a renovation contractor to plan your own works after purchase, it is also worth asking them to flag anything unusual they notice once they start work, since they will often spot signs of past unapproved changes that are not obvious to the untrained eye during a standard viewing.
What Happens If It Surfaces During the Transaction
If unauthorised renovation is identified during the resale application process, the standard outcome is that the seller is asked to reinstate the affected areas before HDB will approve the transfer. This usually falls on the seller since they owned the flat when the issue is being addressed pre-completion, but the timeline impact affects both parties. Depending on the extent of the work required, this can add anywhere from a few weeks to a couple of months to your completion date, so it is worth building some flexibility into your own moving plans if you know there is a possibility of this happening.
In some cases, buyers and sellers negotiate a price adjustment or a cash credit at completion to account for reinstatement costs, particularly if the buyer is willing to take on the reinstatement themselves after handover in exchange for a faster completion. This is a commercial decision between both parties and there is no single right answer, but it should be discussed openly and documented properly rather than left as a verbal understanding.
A Practical Note for Sellers Too
If you are selling a flat and you are not entirely sure whether past renovation work was properly approved, it is worth checking this before you list the flat rather than waiting for it to surface during the transaction. Delays caused by reinstatement work can affect your ability to complete your own purchase on the property you are moving to next, especially if you are relying on the sale proceeds or timing your CPF refund for your next move. Addressing it early gives you more control over cost and contractor selection, rather than scrambling under time pressure once a buyer has already committed.
Unauthorised renovation issues are usually manageable once identified early, but they can quietly complicate an otherwise straightforward transaction if they are only discovered late. If you are viewing resale flats and want a second pair of eyes on what you are looking at, or you are selling and want to check your flat’s renovation history before listing, feel free to reach out to me on WhatsApp or drop me a message. Happy to walk through it with you, no pressure either way.