Top 10 Mistakes to Avoid When Building a New House

Building a new home

Building a new home is one of the most significant investments you’ll ever make—both financially and emotionally. Whether you're planning your forever home or your first custom build, the process is filled with excitement, anticipation, and yes, complexity.

From choosing the right location and navigating planning permissions, to selecting materials and managing contractors, each phase brings its own set of challenges. Even small oversights early on can lead to costly setbacks, design regrets, or long-term inefficiencies.

Unfortunately, many new homeowners walk into the process unprepared. They rely too heavily on generic advice or underestimate the importance of early-stage planning and local expertise. This leads to avoidable mistakes—some minor, others compromising the home's functionality, safety, or resale value.

Mistake #1: Not Defining Clear Objectives
and Requirements

What kind of spaces do you use most frequently?
Do you need a home office, a playroom, or a guest suite?
Do you prefer open-plan living or clearly defined rooms?
Will this be a forever home, or are you planning to sell within 10–15 years?

Without clarity on these foundational elements, it becomes incredibly easy to get caught up in trends, overspend on unnecessary features, or end up with a layout that doesn’t suit your day-to-day life.

Designing with accessibility in mind (e.g., wider doorways, ground-floor bathrooms).
Incorporating flexible spaces that can evolve (e.g., a nursery that becomes an office).
Planning for energy efficiency and smart home technology that can be upgraded over time.
Leaving room for potential extensions or outdoor enhancements.

Thinking long-term not only improves your quality of life but can also protect your investment by ensuring the home remains functional and attractive to future buyers.

Pro Tip from O'MAR Construction

In our consultations, we encourage clients to create a “Lifestyle Brief.” This short document outlines everything from daily routines and storage needs to architectural styles and non-negotiable features. It becomes a guiding document for the entire build, helping keep everyone, from the architect to the builder, aligned with your vision.

Mistake #2: Inadequate Budget Planning

A well-thought-out budget is the backbone of a successful home build. In Dublin’s construction market, underestimating costs or failing to plan for the unexpected can turn your dream home into a financial nightmare.

Site-specific challenges (e.g. poor soil conditions, drainage problems)
Delays caused by weather, permits, or supply chain disruptions
Design changes or upgrades made during construction
Rising material and labour prices, especially in a competitive urban market like Dublin

Experts recommend setting aside **10–20% of your total budget** as a contingency fund. This buffer helps absorb surprises without compromising the build’s quality or forcing you to cut corners later in the process.

Mistake #3: Choosing the Wrong Location

A beautifully built house in the wrong area can lead to daily frustrations, lower quality of life,
and poor resale value.

Access to local amenities

Shops, GP surgeries, parks, and recreation facilities.
School catchment areas

Especially important for families, as this can affect both convenience and property value.
Public transport links

In Dublin, proximity to a DART station, Luas line, or key bus route can dramatically improve day-to-day commuting and accessibility.
Commute times

Assess how traffic patterns or limited infrastructure might impact your routine.

O'MAR Construction Tip: Never Buy Before Surveying

We strongly advise clients to never purchase land without a full site survey and planning consultation. We work with planning consultants and engineers to identify red flags early, ensuring you're not blindsided by hidden costs or permit issues down the line.

Mistake #4: Poor Communication with Builders

Even the best-designed plans can fall apart without clear, consistent communication between the homeowner and the builder. Misunderstandings, missed details, and costly delays often stem from one simple issue: poor communication.

Materials or finishes being selected without your input
Minor errors are becoming major problems because they weren’t caught early
A breakdown in trust if timelines slip or decisions are made without you
At O'MAR Construction, we recommend **weekly site meetings** or progress calls, especially during key phases like groundworks, roofing, and fit-out. These check-ins help ensure everyone is on the same page and allow you to address small issues before they become major ones.

Even if you’re not available in person, request digital updates including:
- Progress photos
- Schedule trackers
- Budget summaries
This level of transparency keeps your builder accountable—and gives you peace of mind.

Mistake #5: Underestimating the Importance of Design Details

Design isn’t just about how your home looks—it’s about how it works. A common mistake among new homebuilders is rushing through the design phase or focusing too heavily on surface-level aesthetics while ignoring critical functional details.

Neglecting Aspects Like Natural Light, Room Flow, and Storage Solutions

Key design considerations that are often overlooked:

Natural light orientation, room flow, storage integration.

Positioning living spaces to maximise daylight, especially in grey Irish winters, can dramatically improve mood and energy use.
Ensuring a logical progression from entrance to kitchen to lounge makes daily life smoother and more intuitive.
Built-in wardrobes, under-stair storage, and utility rooms reduce clutter and increase functionality, especially in family homes.

Choosing Aesthetics Over Functionality

A freestanding bath looks elegant, but may be impractical for families with young children.
Open shelving might suit a minimalist look, but creates more cleaning and less hidden storage.
Glass walls or open-plan layouts may reduce privacy or cause acoustic issues in busy households.

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Neglecting Aspects Like Natural Light, Room Flow, and Storage Solutions

Mistake #6: Selecting Inappropriate Materials

Choosing inappropriate or low-quality materials is one of the most expensive mistakes you can make in a self-build. Unfortunately, it’s often driven by budget pressures, misinformation, or aesthetic preferences without considering local context.

Opting for Low-Quality or Unsuitable Materials for the Local Climate

Irish climate—particularly in Dublin—is defined by high humidity, frequent rain, and seasonal temperature swings.

This means your materials must be:

Moisture-resistant (especially for roofing, external cladding, and foundations)
Thermally efficient to minimise heating needs in colder months
Resilient against wind and salt exposur* in coastal or elevated areas

Using imported materials that aren’t tested for Irish weather can result in:

* Cracking and warping
* Mold or condensation issues
* Rapid wear and fading of finishes
* Structural failures over time

For example:

Timber cladding might look stunning, but untreated wood deteriorates quickly in damp conditions.
Certain stone types may absorb water and crack in freezing temperatures.
Metal finishes can corrode without proper protection or ventilation design.

Mistake #7: Ignoring Acoustics and Soundproofing

When building a home, people often obsess over visuals—flooring finishes, paint colours, lighting—but forget about one crucial element of daily comfort: sound. Poor acoustic planning can lead to a home that looks beautiful but feels noisy, chaotic, or unsettling to live in.

Not Considering Noise Transfer Between Rooms or From External Sources

Have you ever stayed in a home where you could hear every footstep upstairs? Or where the TV in the living room echoes into your bedroom at night?

Without proper sound planning, you could face:

Internal sound issues like echoing stairwells, noisy pipes, or footsteps on upper floors
Room-to-room transfer, particularly in semi-open-plan homes, where sound from kitchens or media rooms travels easily
External noise intrusion, especially if you're near a busy Dublin road, train line, school, or commercial area

To mitigate noise effectively, you need to incorporate:

Acoustic insulation in internal partitions and floor voids
Double-stud wall systems or acoustic plasterboard in sensitive areas (e.g., bedrooms, offices)
Carpet or underlay in upstairs rooms to reduce footfall noise
Acoustic sealing around doors, windows, and ducts

Also consider using resilient channel systems and decoupling techniques to separate noise-producing surfaces.

Mistake #8: Neglecting Outdoor Spaces

While the focus during a home build naturally leans toward interiors—kitchens, bathrooms, layouts—it’s surprisingly common for homeowners to treat outdoor spaces as an afterthought. This mistake often leads to missed opportunities, expensive retrofits, and an overall home experience that feels disconnected from its surroundings.

Overlooking Garden Design, Drainage, and Outdoor Living Areas

A well-planned outdoor area adds enormous value and can become a daily-use extension of your living space.

Key areas often overlooked:

Drainage planning – Poor drainage can lead to water pooling, slippery surfaces, or even foundation problems. Permeable paving, soakaways, and correct site grading are essential.
Garden layout – The garden can feel disconnected or unusable without thoughtful design. Consider zones for relaxing, dining, kids’ play, and storage.
Access and flow – Think about how you’ll move between indoors and outdoors. Is the patio off the kitchen? Can bins be discreetly accessed? Are there covered spaces for Irish rain?

Outdoor living areas should be treated with the same intention as interior rooms. Consider:

Weatherproof dining and lounge zones
Durable, slip-resistant paving
Strategic planting for privacy or sound buffering
Space for future features like a shed, home office pod, or EV charger

Mistake #9: Underestimating Timeframes

Ask almost anyone who’s built a home, and they’ll tell you: it always takes longer than expected. One of the most frustrating—and entirely avoidable—mistakes is assuming an overly optimistic construction timeline.

When homeowners underestimate how long it really takes to build a house, it leads to:

Budget strain due to extended rental or mortgage overlaps
Project fatigue and frustration
Rushed decisions that compromise build quality

Setting a realistic timeframe from the outset is not just smart—it's essential for keeping your sanity and your finances intact.

Not Accounting for Potential Delays Due to Weather or Supply Issues

Ireland’s climate can be wildly unpredictable, particularly in winter and early spring. Rain, frost, and wind all affect:

Groundworks (e.g., digging foundations)
Concrete curing times
Roof installations and external finishes

On top of that, global supply chains have become increasingly volatile. Delays in sourcing timber, insulation, windows, or specialist materials are now common, especially with post-Brexit import changes or supplier shortages.

Other typical delay triggers:

Late client decisions on finishes
Snagging and rework in the final phase
Unexpected discoveries on-site (e.g., rock beds, poor soil)

Mistake #10: Making Last-Minute Changes

Whether it's swapping out kitchen finishes, moving a wall, or choosing a different window style mid-project, these seemingly small decisions can snowball into delays, budget blowouts, and builder-client frustration.

Altering Designs or Materials During Construction Causes Delays and Cost Overruns

Once your build has started, every element is interconnected. Altering one detail—such as flooring, electrical outlets, or cabinetry—can affect multiple trades, delivery schedules, and installed components.

Common last-minute changes that cause major disruption:

Moving plumbing fixtures after the slab is poured
Upgrading to a heavier roof tile that requires additional structural support
Changing window sizes after frames are ordered
Replacing appliances that require different connections or cabinetry dimensions

These types of changes almost always result in:

Delays while trades wait for revised drawings or rework previous installations
Wasted materials or labor, which still need to be paid for
Lost momentum, particularly if sub-contractors have to be rescheduled

In tight Dublin construction schedules, delays can set you back weeks, especially during busy periods when rebooking trades is challenging.

Conclusion

Building a new home is an exciting and deeply rewarding journey—but it’s also one filled with potential pitfalls that can derail your budget, delay your timeline, or leave you with lasting regrets.

Let’s quickly recap the key lessons we’ve covered:

Define your vision clearly from the start—think beyond square footage and style, and consider how you want to live in the home.

Budget realistically, with contingency funds for the unexpected and allowances for long-term running costs.

Choose your location wisely by researching schools, transport, and site-specific challenges.

Prioritise function alongside form, especially in layout, lighting, acoustics, and materials.

Plan outdoor spaces as intentionally as your interior.

Stick to your decisions once construction begins to avoid costly change orders and delays.

O'MAR Construction

At O'MAR Construction, we’ve helped hundreds of clients across Dublin and beyond bring their dream homes to life—without the stress, surprises, or setbacks that plague so many self-builds.