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Full renovation: common mistakes before buying a property to refurbish

Buying a property to renovate can be an excellent decision. It can also spiral into a chain of costly surprises if you do not carry out proper due diligence before signing the deeds. These are the mistakes we see most often — and how to avoid them.

1. Not commissioning a structural survey

The most serious mistake, and also the most common. Most buyers visit the property with the estate agent, take photographs and form a visual impression. But what matters most — the condition of the structure, beams, floor slabs and columns — is not visible to the naked eye.

An architect or building surveyor can carry out a technical pre-purchase inspection for between €400 and €800, depending on the size of the property. That expenditure may save you from discovering, months after purchase, that the floor slab is degraded, that there is deep rising damp in the load-bearing walls, or that the roof requires complete replacement. In older properties in Málaga's historic centre — many built before the 1970s without current technical standards — these surprises are more frequent than people think.

2. Not checking the property's planning status

Before buying, you must obtain a certificate from the Land Registry and cross-reference it with the actual condition of the property. It is common to find extensions, enclosed terraces, pools or changes of use that were carried out without planning permission and therefore do not appear in the register and have no legal planning status.

These "out-of-regulation" constructions may not be legalisable if current planning regulations do not permit them. In that case, the new owner inherits an infringement that may be subject to a planning enforcement order. Although more than six years may have passed — the limitation period for restoration action on many works in Andalusia — the Junta de Andalucía amended the LISTA (Land Sustainability Promotion Act) and the time limits are no longer the same for all types of land. A municipal planning report clarifies the actual legal status of the building.

3. Overlooking hidden costs

A full renovation is not simply a matter of knocking down partition walls and laying new flooring. In older properties, you should systematically budget for:

• Complete electrical rewiring: buildings constructed before the 1990s typically have obsolete electrical installations that do not comply with the Low Voltage Electrical Regulations (REBT). Rewiring a 100 m² flat costs between €6,000 and €10,000.
• Plumbing: lead or asbestos cement pipes must be replaced. So must galvanised iron pipes. A new plumbing installation in an average property: between €4,000 and €7,000.
• Asbestos: present in false ceilings, ventilation pipes and construction materials dating from before 2000. Asbestos removal requires a licensed specialist contractor and can represent a significant unforeseen additional cost.
• Drainage: in ground-floor properties or buildings with basements, the condition of the horizontal drainage network can be an unpleasant surprise.

4. Not verifying the legal title

Beyond the planning situation, you must check whether there are any charges, mortgages, liens or usufruct rights encumbering the property. The Land Registry certificate is essential, but it must be requested as a current document — no more than three months old — and read carefully. A solicitor or legal manager can do this for less than €200.

5. Underestimating the construction timeline

A full renovation of an average property in central Málaga takes, under normal conditions, between four and eight months from the start of works to handover. To this you must add the design period (2–4 months), the permit process (between 1 and 6 months depending on the type of intervention) and material procurement. Anyone renting temporary accommodation or staying in a hotel during the works must size that cost realistically. Unrealistic timelines put pressure on contractors, which can lead to rushed work and falls in quality.

6. Hiring the contractor before the project is complete

It is tempting to approach contractors in parallel with the design process to start adjusting the budget. The problem is that without a complete project, quotes are rough estimates that cannot be compared with one another, and the contractor cannot commit to a real price. The correct approach is to complete the execution project — with all specifications and construction details — and then request several comparable tenders. This way you are comparing like with like and avoiding mid-build surprises.

7. Not reserving a 20% contingency

In any renovation project of significant scale, the professional recommendation is to reserve between 15% and 20% of the construction budget as a contingency allowance. Not because the project is poorly designed, but because existing buildings always contain surprises: a beam in worse condition than expected, damp that only reveals itself when the cladding is removed, a drainage system that does not match the existing drawings.

Clients who leave no contingency margin find themselves, mid-project, forced into hasty decisions: reducing material quality, temporarily halting works, or taking on unforeseen debt.

8. Ignoring the actual orientation and light of the property

A half-hour visit is not enough to understand how light behaves in a property throughout the day. A flat that seems bright at midday may be dark all morning if its main windows face west. In Málaga, a south-southeast orientation is the most valued: it receives morning light, has moderate heat in summer, and is the most comfortable in winter.

Buying a north-facing property on the Costa del Sol and renovating it without being able to change its orientation has limits: you can enlarge openings, add skylights or reorganise the layout, but you cannot create sun where there is none. Your architect can help you assess, before purchase, what real potential the property has in terms of natural light.

Consult before signing, not after

The ideal time to speak with an architect is not when you already own the property: it is when you are evaluating whether to buy it. A pre-purchase consultation — a couple of hours of technical and planning review — can reveal whether your renovation expectations are viable, what the true cost will be, and whether the purchase price makes sense given the works required.

At Santos Arquitectos we offer pre-purchase consultations for buyers who want to understand the real potential of a property before committing. Contact us before you sign.