Cockroaches in a New Build Apartment in Spain – Why It Happens and How to Stop It

You have just collected the keys to your obra nueva apartment. Brand new kitchen, freshly tiled bathrooms, that satisfying smell of new construction. The last thing you expect to find is a cockroach crawling across the worktop three weeks after moving in.

Yet this is one of the most common complaints from expats buying new builds across Spain – from the Costa del Sol to the Costa Blanca to the Balearics. The assumption that a new property equals a pest-free property is understandable. It is also wrong.

Why New Builds Get Cockroaches

A new apartment is not a sealed environment. It is connected to the same municipal sewer network as every other building in the area, through the same floor drains, sink traps, and waste pipes. From the moment the plumbing is connected, cockroaches have a highway into your home.

But there are specific reasons why new builds are often more vulnerable than established properties in their first year or two.

The Snagging Period and Builder Obligations

Your new build comes with a periodo de garantía – a warranty period governed by the Ley de Ordenación de la Edificación (LOE, Law 38/1999). This is structured in three tiers:

• 1 year for cosmetic and finishing defects (acabados)
• 3 years for defects affecting habitability (habitabilidad)
• 10 years for structural defects (estructurales)

Pest entry points caused by construction deficiencies – unsealed pipe penetrations, improperly installed drain traps, gaps in the building envelope – fall under the 3-year habitability guarantee. If you can demonstrate that cockroaches are entering through construction defects, the promotora (developer) is obliged to remedy them.

How to Make a Snagging Claim for Pest Issues

1. Document the defects. Photograph every unsealed pipe entry, every gap around waste pipes, and every missing or defective drain trap. Use a ruler or coin for scale.

2. Document the cockroaches. Photograph the insects, ideally near the entry points you have identified. A professional pest control inspection report identifying the species and entry routes strengthens your claim considerably.

3. Submit a formal written complaint to the promotora via burofax or through whatever defects reporting process they provide. Reference the LOE and specify that unsealed service penetrations constitute a habitability defect.

4. Set a deadline. Give the developer 30 days to remedy the defects. If they fail to act, you have recourse through the seguro decenal (compulsory building insurance) and ultimately the courts.

First-Year Prevention Protocol

Whether or not the developer fixes the construction defects promptly, you need to protect your apartment now. Here is the protocol for the critical first year in a new build.

Month 1: Seal and Block

Seal every pipe penetration. Get under the kitchen sink, behind the washing machine, behind the WC cistern, and under every bathroom vanity. Use silicone sealant or expanding foam to close gaps around pipes where they pass through walls and floors. This single action eliminates the majority of cockroach migration routes between apartments.

Install drain covers. Stainless steel mesh covers on every floor drain. Every bathroom, the utility room, and any kitchen floor drain. Non-negotiable. See our drain protection guide for product recommendations.

Run water through every drain weekly. If you have a guest bathroom or utility room that does not get daily use, run the taps for 30 seconds every week to maintain the water seal in the trap. A dry trap is an open pipe to the sewer.

Month 2: Bait and Monitor

Place gel bait preventively. Even if you have not seen a single cockroach, apply small dots of fipronil or indoxacarb gel bait behind the fridge, under the sink, behind the dishwasher, and in bathroom cabinets. This is cheap insurance. Replace every 3 months.

Set monitoring traps. Sticky traps (available at any ferretería or on Amazon.es) placed under sinks and behind appliances tell you whether cockroaches are entering before the problem becomes visible. Check weekly.

Months 3–12: Maintain and Escalate

Refresh gel bait quarterly. Gel bait dries out and loses effectiveness after 8–12 weeks in Spanish heat. Replace it in January, April, July, and October.

Monitor traps monthly. If sticky traps start catching cockroaches, identify the species. German cockroaches (small, light brown, found in kitchens) indicate an indoor colony and require immediate escalation with gel bait in every harbourage zone. American cockroaches (large, reddish-brown) indicate sewer entry – check your drain traps and seals.

Push the comunidad for building-wide treatment. A new development should establish an annual pest control contract for common areas within the first year. This covers drains, bin stores, garages, and service ducts. Raise this at the first formal junta meeting.

When Empty Neighbouring Units Are the Problem

This is the most frustrating scenario and the most common in new developments. Your apartment is sealed and baited. Your drains are covered. But cockroaches keep appearing because the empty unit next door has dry drains and unsealed pipes acting as a motorway for sewer roaches.

You cannot enter another owner’s property. But you can:

• Ask the administrador to contact the owner of the empty unit and request they maintain drain traps or authorise the comunidad to do so.
• Propose a comunidad motion to treat all drains in the building, including unoccupied units, as part of a building-wide pest control contract.
• Seal your shared wall penetrations – the pipe runs and service ducts that connect your apartment to adjacent units are your controllable boundary.

Bottom Line

A new build in Spain is not immune to cockroaches. The shared drainage system, construction gaps, disturbed land, and empty neighbouring units create conditions that established buildings have often already addressed through years of incremental sealing and treatment.

The good news is that the first year is the worst. Once you seal pipe entries, cover drains, maintain trap seals, and establish a bait-and-monitor routine, the problem becomes manageable. And if construction defects are the root cause, you have legal recourse through the LOE warranty to make the developer fix them.