What to Pay Attention to in Interior Design and Renovation of Old Houses?

The interior design of old house renovation (renovation of pre-owned houses, old apartments) differs from that of new houses. The focus is often on pipeline (water and electricity) updates, structural and wall conditions, waterproofing and leakage, partition adjustments, and regulatory reporting. The following is a neutral planning consideration, not a comparison of contractors or engineering/legal advice.

Ministry of the Interior: Old House Life-Extension Policy Plan (Press Release) ↗

What is the general construction sequence for old house renovation? Which tasks can only be finalized after demolition?

The biggest difference between old house renovation and new houses is that many issues are only visible after demolition, so the arrangement of work steps affects subsequent change flexibility. The common construction sequence is:

Site survey and drawing planning: Measurement, assessment of house condition, confirmation of whether interior decoration review is needed.
Demolition and debris removal: Remove existing finishes and partitions, exposing original walls, floors, and pipelines.
Masonry and waterproofing: Leveling, slope for drainage, waterproofing for bathrooms and balconies.
Water and electrical pipelines: Water supply and drainage, electrical wires, low-voltage wiring, and distribution panel configuration (usually done after partition positioning).
Woodwork/system cabinets, ceilings: Carpentry work, storage, and ceiling construction.
Painting, flooring, equipment installation: Putty and painting, floor laying, kitchen and bathroom equipment, and lighting.
Cleaning and acceptance: Detailed cleaning followed by item-by-item acceptance.

Among these, water and electricity, waterproofing, and structural reinforcement often need to be finalized after demolition based on actual conditions. It is recommended to reserve a change confirmation and written addendum mechanism in the contract.

Actual sequence varies by house condition, construction method, and contractor planning. This page provides neutral information, not engineering advice.

How to prioritize inspections for old house renovation? A look at pipelines, waterproofing, structure, and fire safety at once.

With a limited budget, resources are generally prioritized for basic works that affect living safety and are difficult to change later. The following is a common priority list:

Priority	Item	Common Inspection Points
1	Structure	Beam and column cracks, exposed rebar, concrete spalling; main structure cannot be arbitrarily altered
2	Waterproofing/Leakage	Bathroom, kitchen, balcony, exterior wall water seepage and source of efflorescence
3	Water and electrical pipelines	Old water supply and drainage, electrical load, distribution panel, need for re-piping
4	Fire safety/Egress	Fire-resistant finishing materials, evacuation routes, necessary detection or extinguishing equipment
5	Surface and soft furnishings	Flooring, paint, doors and windows, cabinets, furniture (can be phased)

Priority may be adjusted based on house condition and usage needs. Whether updates are needed and their scope should be assessed on-site by professionals. This page provides neutral information.

What are common 'hidden issues' in old house renovation? Why set aside a contingency fund?

The uncertainty of old houses mainly comes from 'invisible places.' The following items are often discovered during demolition or construction and may lead to written addendums:

Pipeline aging: Rusted galvanized water pipes, insufficient electrical load, inadequate drainage slope.
Leakage and efflorescence: Must first find and repair the source, then treat waterproofing and surface; severe cases may require removal down to brick layer for rework.
Structure and beams/columns: Cracks, exposed rebar, or load concerns from existing illegal additions.
Uneven floors and walls: Requires additional masonry leveling.
Existing violations or HOA restrictions: Restrictions on exterior walls, pipe shafts, and common facilities.

Therefore, it is common to set aside about 10-20% of the total budget as a contingency fund to address issues found after demolition; the contract should specify the review conditions and cap for addendums.

Actual hidden issues and treatment methods vary by case. This page provides neutral information.

What to pay attention to regarding regulatory reporting and HOA when renovating an old house?

Renovation of old apartments and buildings may involve regulatory review and community management:

Interior decoration review: When involving partition walls, main structure, or a certain scale, or for public-use buildings or residential buildings above six floors, according to the 'Building Interior Decoration Management Regulations,' it may be necessary to entrust a licensed architect or interior decoration company to handle the review, obtain a permit, and undergo completion inspection.
Fire resistance and fire prevention: Ceiling, interior wall, partition, and other finishing materials must comply with fire resistance rating regulations.
HOA regulations: Construction hours, protective measures, elevator and common area use, deposits, and reporting are generally handled according to community regulations.
Neighboring property damage prevention: Before demolition and masonry, it is advisable to document the current condition of neighboring properties to reduce future disputes.

Whether review is required and community-related regulations depend on the case and local authorities/community regulations. This page provides neutral information, not legal advice.

FAQ

What items should usually be inspected first in old house renovation?

Commonly, the first assessments include aging of water and electrical pipelines, waterproofing and leakage, efflorescence, beam/column and structural condition, doors/windows and partitions, and whether existing finishes affect subsequent work. It is recommended to have a professional conduct a site survey before planning to determine the scope of work based on the house condition.

What is the difference between old house renovation and new house decoration?

Old houses often require updating or reinforcing existing pipelines and structures, removing existing finishes, and face the risk of addendums due to uncertain conditions; new houses are mostly configured from scratch. The two differ in work sequence, budget flexibility, and unforeseen items, so flexibility should be reserved.

Does old house renovation require applying for interior decoration review (reporting)?

For interior decoration involving partition walls, main structure, or a certain scale, according to the 'Building Interior Decoration Management Regulations,' it may be necessary to entrust a licensed architect or interior decoration company to handle the review, obtain a permit, and undergo completion inspection. Whether it is required depends on the case and local regulations; it is recommended to confirm with the competent authority or contractor.

How to find a legal contractor for old house renovation?

You can check whether a contractor is registered as an interior decoration company and its scope of registration through the Ministry of the Interior's 'National Building Management Information System.' This site also organizes data based on official registration records. This page provides neutral information and does not compare or recommend individual contractors.

During old house renovation, must all pipelines be replaced?

Not necessarily, but it is recommended to have a professional assess old pipelines (such as water supply/drainage and electrical wires) and decide. Whether a full replacement is needed depends on the house condition and safety considerations. It is recommended to have a contractor conduct a site survey before planning. This page provides neutral information.

How long is the typical warranty for waterproofing work in old house renovation?

The warranty period for waterproofing work varies by contractor and contract terms. The actual warranty scope and duration should be specified in the contract. It is recommended to choose a contractor with clear warranty terms and keep construction records. This page provides neutral information.

How to avoid unexpected additional costs during old house renovation?

Before signing the contract, conduct a detailed inspection of the house condition and clearly define the review conditions and cap for additional costs in the contract. It is recommended to set aside a flexible contingency fund to address hidden issues found after demolition. This page provides neutral information.

What are common treatment methods for efflorescence in old house renovation?

First, find and repair the source of leakage, then scrape off the efflorescence layer, apply waterproofing and primer, and finally repaint. Severe efflorescence may require removal down to the brick layer for re-waterproofing. The actual method depends on the house condition.

Can beam and column structures be adjusted during old house renovation?

Main beams and columns cannot be arbitrarily removed or modified to avoid affecting building safety. If adjustment is needed, a qualified engineer should be commissioned for evaluation, and a change application should be submitted to the competent authority according to regulations. This page provides neutral information.

References (official data sources)

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Updated: 2026-07-30 · This page is a neutral compilation of information for reference only. Please refer to the announcements of the competent authority for actual registration status and regulations.