The Complete Guide to Hacking: On Permits, Potential Hiccups and More

Your questions on hacking answered, plus tips for a smoother renovation.

If you’re intending to renovate soon, we’ll hazard a guess that hacking is part of the plan.

From knocking down walls in a tight BTO flat to removing decades-old tiling in a resale unit, there are plenty of reasons why hacking might be necessary in a renovation.

The details might be a little fuzzy though: do you need permits for hacking? How is it priced? Does hacking a half-wall cost half as much as a full wall?

We spoke to SG Interior Design to get down to the nitty-gritty about hacking so you know what you’re getting into – and what you should iron out with your ID before getting started.

What does hacking in a renovation entail?

According to SG Interior Design (SGID), hacking refers to two different things:

• Dismantling existing carpentry fixtures like cabinets
• Removing floor/wall tiles and demolishing walls, like those done up with solid masonry or concrete

During hacking, there’s haulage and debris clearing too. If you’re wondering, haulage usually involves transporting renovation materials like tiles to your unit.

On the other hand, debris removal is done later – after tiling and carpentry works are done – to get rid of renovation waste like leftover materials and debris.

Hacking regulations you should know

Permits

For HDB flats

You (or your ID/contractor, technically) must apply for HDB permits and get approval to remove walls and floor/wall finishes.

Getting these approvals usually takes about 1-2 weeks, but if HDB asks you to get a Professional Engineer (PE) endorsement, it could take a month or more. This requires a separate fee too.

Apart from that, the administrative fee for applying for the permits is usually included in an ID’s quote – either as a line item, or as part of the lump sum for hacking works.

For peace of mind, you can clarify this with your ID before the renovation starts.

For condos

As SGID shares, MCSTs usually require a PE endorsement for hacking walls. You’d have to bear the cost for applying for the PE endorsement.

Hacking restrictions

Demolishing walls and removing wall/floor finishes count as noisy renovation works, so they must be completed within 3 days for HDB flats.

For condos, depending on the MCST’s criteria, your ID/contractor may be required to finish hacking works anywhere between 1 day to 1 week.

Not all hacking requests get approved

If you’ve spent hours poring over floor plans, you’d know that the thick black lines in HDB floor plans indicate structural beams that cannot be hacked under any circumstance.

So, that means the blank/unfilled lines all indicate hackable walls, right…? Well, not all the time.

In cases where hacking a non-structural wall would affect the unit’s structural integrity (e.g. it has rebar supports or reinforced concrete inside), HDB may reject the request for a hacking permit.

One thing you should know is that for both HDB flats and condos, your application for a PE endorsement may be rejected. This is usually because of concerns about structural stability and the building’s outlook.

It’s best to keep this in mind since the application can be costly and you’ll be charged regardless of whether it’s approved or rejected.

To make a more informed decision, you can consult your ID/contractor about the likelihood of approval.

The hacking process

What percentage of the renovation contract does hacking account for?

Hacking sets the stage for all subsequent renovation works, so it’s naturally the first step.

As SGID shares, the scope of hacking for BTO flats is lesser than for resale flats, which are often in need of a refresh.

Most homeowners choose not to hack BTO floor and wall finishes (if their units come with them), since this would void the waterproofing warranty provided by HDB.

Based on SGID’s estimates, here’s how much of your renovation quote hacking could account for:

• For BTO flats – about 10-20%
• For resale flats – about 20%

Of course, this may vary depending on the extent of hacking your home needs, more so for condos given the differences with each unit (more on that next).

So, how is the hacking cost calculated?

SGID shares that there’s something akin to a ‘minimum order quantity’ for hacking. This is because “the amount of time and effort taken to hack a 30 cm wall is similar to that of a 1-metre wall”.

Here’s how hacking costs are typically calculated: it starts with a minimum quantity of about 3 feet (≈ 91 cm) at a fixed price, after which it’s priced per foot run.

This cost varies depending on:

• The interior design firm
• The housing type (condos are more expensive) and ceiling height

Apart from the above considerations, it depends on the complexity of the hacking. If you find a quote rather high, it might include the cost of the designer predicting and covering for unexpected finds (more on that below) so you don’t get a variation order (VO) later on.

SGID underscores that it’s best to have a quotation that is clearly itemised. If you’re in doubt, be sure to clarify with your designer so you don’t have any unpleasant disagreements in future.

Note: The cost of haulage and debris removal may be included as a lump sum cost together with hacking, or itemised separately depending on the firm.

Get an estimate of how much your hacking works could cost with our renovation calculator here!

If you hack half the wall, is the cost halved too?

We wish the answer was ‘yes’ – but it’s not. It might sound counterintuitive, but hacking off half the wall is more complex than taking down a whole wall.

As SGID shares: “A full wall just needs to be drilled and hacked off. On the other hand, for a half-wall, you need to use tools to cut the wall and then slowly hack it off to ensure the bottom half is not damaged.

Another thing most homeowners aren’t aware of is the ‘making good’ of it. After hacking, the surface won’t be smooth, so the tilers or masonry guys need to make good the edges of the walls or surfaces to ensure they’re smooth again.”

In essence, hacking half a wall would cost about the same as hacking the whole wall.

During hacking, expect the unexpected

“There are often surprises when it comes to hacking,” shares SGID. “Especially for resale flats, since we don’t know what’s behind the walls or existing built-ins.”

Such ‘surprises’ include:

• Floor/wall tiles that become loose, or get detached when hacking – these need to be replaced first before resuming renovation works
• Discovering water or mould damage to existing walls after removing built-ins – these may require plastering, waterproofing and anti-mould treatments
• Having to correct height differences between rooms in both BTOs and resale flats; for instance, when the bedroom floor is a few millimetres higher than living room floor

In such cases, you may be issued a variation order and works may be delayed. SGID highlights that for transparency, designers should inform their clients about such possibilities before the renovation starts.

Ideas to change up your home’s layout with and without hacking

Areas where walls are commonly hacked

We asked SGID for some common ways to change up your interior with hacking, depending on your needs:

• Hacking the kitchen walls for an open-concept kitchen and living space – you get more flexibility to design the space, like having a dry pantry or island
• Hacking the junior bedroom adjacent to the master bedroom for a walk-in wardrobe
• Hacking the junior bedroom adjacent to the living room for a dedicated dining space/relaxing nook or a space for kids to play

Of course, you might not want to hack any walls at all, like if you cook heavily and need to keep the kitchen closed off, or you need to keep the rooms intact for future-proofing.

Alternatives to hacking your walls

In such cases, there are ways to achieve a roomier space without hacking:

• Choose a brighter/lighter colour palette – these make a room feel more airy and spacious
• Avoid installing a lot of built-in carpentry as these take up space and make the room feel more cramped
• Avoid doing a false ceiling as this lowers the height
• Using the design or styling items, play with vertical and horizontal lines/shapes to create the illusion of a bigger and taller space with

There’s another solution if you want to keep spaces visually open but still close them off: by hacking walls, and then replacing them with glass panels/doors.

HDB’s white flats: a blank canvas for creativity

You might have heard of HDB’s upcoming white flats, units that don’t have internal partition walls separating the living area and bedrooms.

If you’re not sure whether to gun for them, SGID highlighted how it gives you (and your ID) the freedom and creativity to decide what you want to do with the space depending on your lifestyle needs. Plus, you can skip the hassle and cost of applying for hacking permits.

Of course, do remember that starting with a blank slate may not necessarily be cost-saving as it depends on how many walls you intend to build up, alongside other works like carpentry and masonry.

Given the skill and effort taken, building up a wall costs more than hacking one. These are either partition walls or solid walls.

Partition walls are the default for newer BTO flats, so many homeowners go for this option. You can easily identify them because they sound ‘hollow’ when you knock on them.

Conversely, a solid wall has better soundproofing and a solid feel that some may prefer. This also means it’s more expensive to build up than a partition wall.

Transparency and communication are the foundation of a successful renovation

When you’re getting ready for your home renovation, SGID underscores that the most important things are getting an itemised quotation and communication.

“An itemised quotation would help to clarify things. It’s also best to ask the designers if there are any surprises or other things you should be aware of if you plan to hack a wall. Since renovation is a long process, good communication and trust are vital.”

If you’re looking for reliable interior firms for your renovation, simply tell us your requirements below and we can get you personalised renovation quotes from five local interior design firms for free for a start.

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