Want a bigger wet kitchen at the back? Here is how far you can actually build, the by-laws that decide it, and what drives the cost.
You can usually extend a terrace-house kitchen to the back of your own lot, not onto the back lane or the drain behind it — and even within your lot the extension needs council building-plan approval before work starts. The back lane and the drain reserve are normally outside your title, the Uniform Building By-Laws require an open space to be kept at the rear, and any roof over that open space needs the council's written approval. Budget-wise, ClickBina's extension guide puts a full rear extension at RM40,000 – RM120,000 (indicative 2026, Klang Valley), depending on size, foundations and whether it holds a wet kitchen.
Almost every terrace owner who wants a bigger kitchen asks the same thing: can I build all the way back to the drain? The answer starts with a document, not a tape measure. Your land title and the lot plan show the rear boundary of your lot. On many older terraces the back fence, the concrete apron and sometimes an earlier extension already sit right up to the drain, which makes it look as if everything up to the drain is yours. Often it is not.
Behind a typical terrace row you will find some combination of three strips of land: the rear part of your own lot, a drain (sometimes with a reserve beside it), and a back lane shared by the whole row. Only the first is yours to build on, and only within the rules for open space. Check the title and the approved building plan before any design starts, and ask whoever draws the plans to mark the boundary on site.
| Strip of land | Whose is it? | Can a kitchen extension go there? | What to check |
|---|---|---|---|
| Rear yard inside your lot | Yours, within the title | Possibly, with council approval and enough open space left | Title, lot plan, approved building plan |
| Drain and drain reserve | Usually outside your lot | No; building over it is not something you can regularise | Where the drain sits relative to your boundary |
| Back lane | Usually outside your lot, shared by the row | No; it serves access, services and the row's open space | Width of the lane and what the council counts |
| Neighbour's side of a party wall | Your neighbour's | No; foundations must stay within your own lot | The party-wall line and the neighbour's structures |
Our guide to illegal extension enforcement explains why an extension built over a drainage easement is generally not one the council will regularise later. That is the key risk with building to the drain: it is not a paperwork problem that goes away with a late submission.
The Uniform Building By-Laws (UBBL) 1984 require every building to keep an open space attached to it. For a building on a street with a back lane, by-law 32 sets the open space for residential buildings at not less than one-third of the built-on area of the building lot, and says half the width of the back lane abutting the building counts as open space. Where a lot has no back lane, by-law 33 puts the open space at the rear, across the full width of the lot.
By-law 31 is the one that catches rear kitchens. It says nobody may alter an open space, or put a roof over part of it so that the open space shrinks, without the council's written approval. The council may allow it if the free movement of air is not impeded. In practice this means a covered rear yard is a planning question from the first sketch, not something to tidy up after the roof is on.
A rear kitchen extension is building work under the Street, Drainage and Building Act 1974 (Act 133), so it needs the council's approval before construction. The usual chain is: plans prepared by a qualified submitting person, structural drawings from a professional engineer where the work is structural, submission to the council, approval, then construction with inspections and a completion certificate at the end. The cost table below lists the plan-drawing and engineer fees, and our renovation permit guide walks through the council process step by step.
Skipping approval is not a small risk. Under Act 133 the council can stop the work, prosecute, and require an unauthorised structure to be demolished; the illegal extension guide notes a fine up to RM10,000 and/or imprisonment for building without approval. An unapproved extension also causes trouble when you sell or refinance, because the buyer's lawyer and bank compare the house with the approved plan.
For the most common small jobs on terrace houses, some councils publish a book of standard sketches, the pelan setara, which the owner fills in, signs and submits without a consultant. MBPJ's book includes a kitchen extension and a kitchen extension with a toilet, on the condition that the original wall is not demolished. MBSA limits its route to intermediate single- and double-storey terrace lots, so a corner lot goes the full route with a consultant's plan.
The sketch is a fixed design. A deeper extension, a concrete slab roof or taking down the original rear wall is outside it and needs a full additions-and-alterations plan. Our pelan setara guide explains how the application works and which councils publish their rules.
Even when the extension stays inside your lot, the drain behind it changes the foundations. UBBL by-law 78 says that within a distance not less than the depth of a drain, measured from the closer edge of the drain, no part of a building may have its foundation level higher than 450 mm below the drain invert level, unless the whole building is carried on piles other than timber piles.
In plain terms: the closer your kitchen gets to a deep drain, the deeper its foundations must go, or the engineer has to put it on piles. That is often where a rear extension's budget moves. Our piling and foundations guide explains how the engineer decides between footings and piles, and why the junction between an old house and a new extension is where cracks usually appear.
On a terrace, your rear extension almost always runs along one or both party walls. By-law 79 says that where an external wall is built against a party wall of an adjacent lot, the concrete foundations must not extend beyond your own lot boundary. That keeps footings on your side, which affects how wide the kitchen can be at its base.
Most rear extensions exist to hold a wet kitchen: a heavy-cooking zone that keeps smoke and oil away from the dry kitchen and living area. Plan it as a kitchen, not as a room that happens to have a sink. The essentials are a floor that falls to a trap, waterproofing under the tiles, a hood that vents outside, enough socket circuits for the appliances you actually use, and daylight and ventilation that the council will accept.
These figures come from ClickBina's published guides and are indicative Klang Valley ranges for 2026. They are reference points for budgeting, not a price for your house.
| Item | Indicative price | Source guide |
|---|---|---|
| Basic rear room (brick walls, simple roof and finishes) | RM18,000 – RM50,000 | House extension cost guide |
| Full rear extension (tiling, electrical, plumbing) | RM40,000 – RM120,000 | House extension cost guide |
| Adding a bathroom or wet kitchen to an extension | RM10,000 – RM30,000 extra | House extension cost guide |
| Mid-range enclosed wet kitchen | RM25,000 – RM40,000 | Wet kitchen build cost guide |
| Premium rear-yard wet-kitchen extension | RM45,000 – RM70,000+ | Wet kitchen build cost guide |
| Plans by an architect or draughtsman | RM3,000 – RM10,000 | House extension cost guide |
| Structural engineer drawings and supervision | RM3,000 – RM8,000 | House extension cost guide |
| Engineer's site visit and report on an existing extension | RM1,500 – RM3,000 | Piling and foundations guide |
WhatsApp us your job details for a quote — we reply within the hour.
💬 WhatsApp for a quoteMetal-deck roofing is listed at RM12 – RM20 per sq ft in the same extension guide. For the kitchen itself, see our wet kitchen build cost guide for the cabinet, worktop and ventilation side of the budget.
If the house already has an old rear extension, have it checked before you build onto it; our terrace house renovation guide covers what else usually gets done at the same time.
ClickBina is an experienced KL & Selangor contractor for whole-house refurbishment and trade coordination, and a rear kitchen extension is a multi-trade job: structure, roof, plumbing, electrical, waterproofing, tiling and cabinets. WhatsApp us your job details for a quote, with the address and what you want the extension to hold. We reply within the hour, the price we agree is a flat price with no hidden charges, and a site visit is RM150, waived if you go ahead.
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, not fixed rates. The by-law wording is summarised from the consolidated UBBL text; your council's application of it decides your case.
WhatsApp us your job details for a quote — we reply within the hour.
💬 WhatsApp for a quoteTell us what you need — we reply within the hour.