One of the most frequent questions I get asked is ‘’What is the cost per square foot to build a new house’’. There is no definitive answer to this.
I will outline below what the average cost is and what effects the costs involved in construction.
So, first off what is the 'average' cost per sqft to build a house in Ireland. Building costs normally range between €110 to €160 euro per sqft for builders’ finish. They can be more, and they can be less depending on what part of the country you live.
A large straightforward design with a standard spec is in the lower range (>3000sqft) and a smaller complex design with high spec is in the higher range (<1800sqft).
Georgian designs are the cheapest to build and contemporary designs are the most expensive.
I normally build to builders’ finish. This is the main elements of the house constructed with the final finishes left for the client to complete.
Builders' finish does not include Kitchen, Utility, Wardrobes, Tiling, Flooring, Painting etc. Externally, builders' finish does not include driveway finishes such as tarmac, driveway drainage, kerbs, site shaping, spreading of topsoil, lawns, planting, entrance walls, gates, patios, retaining walls, external painting etc.
A rule of thumb is that it costs a further 40% extra on top of builders' finish cost to finish the house internally and externally. 20% for internal finishes and 20% for external finishes.
If for example builders' finish costs €250,000 allow €50,000 for inside completion and €50,000 for outside completion.
Allow around €20,000 for such items as planning permission fees, engineer for site inspections, signing off stage payments, solicitor fees, council development charges, utility connection charges, connection charge to main sewage if one available etc.
What dictates house build costs
There are three main elements.
Design - The simpler you can make the design the cheaper it is to build.
Site topography/ ground conditions – Is the site level or sloping. Is the ground good for foundations and sewage percolation?
Specification – Do you want a basic roof over your head, or do you want all the bells and whistles?
Item 1 - Design - The simpler you can make the design the cheaper it is to build.
This is relatively straight forward. The more complex you make something the more expensive it is to build.
Examples are complex shapes, flat roofs, balconies, corner windows, apex windows, bay windows, acres of glass, dormer windows, loads of lead valleys and trays, natural stone facing, vaulted ceilings, sliding doors, structural steelwork, zinc or cedar cladding etc
All these things require additional materials and labour so therefore increase the cost.
Item 2 - Site topography / ground conditions - Is the site level or sloping. Is the ground good for foundations and sewage percolation?
Sloping sites are more expensive to build on due to increased excavation costs to level up the site, stepped foundations, retaining walls to hold up high banks, possibly pumping effluent from your septic tank up to percolation area etc. The flatter your site the cheaper it will be.
Ground Conditions - Is the ground soft or hard, is there rock, is there clay etc. If the ground isn’t suitable for the cheapest form of foundations to support your house (i.e., strip footings), you might require a raft foundation. This is basically a big slab of concrete and steel that goes under the full floor area of your new home. It spreads the weight over a greater surface area therefore making it ‘float’ on top of poor ground.
You might possibly require a raft if you have varying ground conditions. If the ground is all rock or there is part rock and part soil.
You might also require concrete piles and a ring beam if the ground is very poor.
If your site is full of rock it will cost more to remove as it will need an excavator and rock breaker. This is expensive as it is slow. You could spend days or weeks breaking out a rocky site.
Clay can cause problems on a site also. Clay is great for foundations as it has an excellent bearing capacity but has very bad soakage which can cause flooding, ponding or high-water table if the site is fairly flat. It also causes problems for the percolation area as your effluent from the septic tank will not filter through the ground fast enough causing ponding on the surface. In these cases, you may need a soil or sand polishing filter. These are more expensive to construct than a standard percolation area.
Does your site need a standard septic tank or a biocycle unit to process the sewage from your new home? A septic tank is basically a tank that separates the solids from the liquids. The liquid then passes to your percolation area where it percolates through the ground. There is a bit of science goes on here but I’m a builder not a scientist so I won’t get into that. A biocycle unit requires a power supply and has a pump that blows air into the sewage. Septic tank being the cheapest and biocycle being nearly 4 times the price. Biocycles also require more maintenance.
Item 3 - Specification - Do you want a basic roof over your head, or do you want all the bells and whistles?
Things like triple glazing rather than double, aluminium clad windows over PVC, precast concrete first floor slabs, concrete stairs, natural slate roof over a standard fibre cement slate, MHRV (mechanical heat recovery ventilation) over natural ventilation, high airtightness, thicker insulation, loads of plugs and spotlights, Smart Home wiring, Oak rather than painted timber, high end kitchen etc. You get the picture.
We all like looking at Instagram, Facebook, Pinterest etc for ideas but be aware alot of these houses and finishes are on the higher end of the scale.
Economies of Scale
There is also a thing called ‘Economies of scale’. Put simply a large house is cheaper per square foot to build than a smaller house.
I will give an example. Say we have two identical sites. One person builds a 2000sqft 4-bedroom bungalow and the other builds a 4000sqft 4-bedroom two storey. The following costs are similar between both.
Management Costs – If both houses have similar spec, straight forward design, and require the same number of subcontractors there won't be a massive difference in managing its construction. It certainly will not be double the cost.
Site excavation – The bungalow has the same footprint as the two storey, so it's as easy on both houses to get the site level.
Sewage disposal. – The septic tank and percolation area will be the same as they both have 4 bedrooms. The amount of drainage pipes, gullies, manholes around the house again will be similar.
Driveway – Excavating and stoning the driveway around the house is the same for both.
Roof - The cost of roofing both should be similar as both have a roof plan area of 2000sqft.
Concrete Footpaths to perimeter – The perimeter measurement will be similar.
Electrical – The 4000sqft house will be slightly more expensive to wire but it certainly will not be double the cost of the 2000sqft bungalow if there are a similar amount of rooms.
Foundations – Both will be similar. The 4000 sqft house will even be a fraction cheaper as it will have less internal walls downstairs as its rooms are spread over two floors.
Utilities – Utility Connection charges will be similar for both.
Say for example all these costs came to €100,000. That's €50 euro per sqft for the 2000sqft bungalow but only €25 per sqft for the 4000sqft 2 storey. Some costs stay the same or similar even if you double the size of the house.
Another item that can hike the price up are changes and extras during construction. I can't stress enough how important is it to finalise your construction drawings and specification before the builder breaks ground.
If you're someone who can't visualise the build, consider a 3D model or 3D visualisation. You might think this is unnecessary, but it will cost a lot less than changes down the line during construction.
There are always going to be small changes during construction but try not to move walls or put in windows or doors after the wall has been constructed for example. Mistakes like these can be costly. If you have to make changes give the builder as much notice as possible. There might be little or no cost implications for minor changes if they are highlighted early enough.
Set a realistic budget and expectations.
The key is setting a realistic budget but also have your expectations in line with that budget. If your budget is tight that is not a problem, we’ll work within anyone’s budget. The problems arise when people’s ideas and dreams overtake their budget.
The house design and specification can be adjusted if you're at pre-planning stage to come within budget. If full planning has been granted only the specification can be adjusted to come within budget.
It's imperative you know your budget at pre-planning stage as you can only cut the specification so far. You'll never bring an expensive design down to a tight budget no matter how much you cut the specification.
Hopefully my explanation will give you an idea of what your house will cost and what you can expect for your money.