How much does a loft conversion or second storey addition cost in the United States

These days many people are deciding to stay in their homes and maximize the space they've got. Here is how you can make the most of your attic while keeping renovation costs down. 

Skylights in a renovated house with a loft conversion.
ARTICLE Stephanie Matheson

These days many people are deciding to stay in their homes and maximize the space they've got. Here is how you can make the most of your attic while keeping renovation costs down. 

Where do I start?

Attic conversions typically require structural and foundation work, as the original house was not built to hold the weight of a second storey. In many cases, extra steel and or timber beams have to be installed to support the new first floor. Keeping the number of steel beams down – and using timber for strengthening where possible – will help you keep your building costs down. In addition to the new steel or timber sub-structure, often the existing flooring needs to be underpinned and strengthened. This kind of foundation work is usually the biggest unknown factor in terms of renovation costs – until it’s been properly designed and engineered by your architect.
hand drawn architectural illustration of wooden attic, perspective view
Weather-proofing during the build is one of the main concerns when the roof has to be removed. Full scaffolding that can be wrapped in plastic shrink wrap is a good option that provides water-tightness and allows the builders to work in any weather thus helping to avoid weather-related delays that can be costly both in terms of time and money.
With all this extra building work required, it’s not surprising that loft conversions are typically more expensive than same-level extensions. They do however allow you to maximize space while maintaining the home’s footprint, which is often key in denser, urban areas. For a smaller home, the average cost to add a second story is around $105,000* whereas for a larger home, costs rise to about $175,000*.
Cost of an attic conversion
From $90,000*

Is my roof suitable for a conversion?

Generally speaking, the steeper the pitch of your roof the more likely it is that your roof will be suitable for a conversion. Not having to alter the roof itself will keep your costs down, as you will only need to install skylights or dormer windows into the pitch of the roof to provide natural light. 
Skylights of a house that has been renovated with a loft conversion

What type of window styles can I choose from?

Skylight windows are the most cost-effective window style to install. They let in plenty of light; however, as they are flush with the roofline they will not help create any more headroom. Dormer windows create this precious extra headroom that protrudes from the sloping roof, so they are a great option when you want to maximize the available attic space. If your budget allows, you can even consider installing French doors or sliding doors with a glass balustrade or small balcony. These solutions create the feeling of a more open space and let natural light flood in.
bathroom in loft conversion with sky lights

How do I maximize my attic space?

Making provisions for well-designed, built-in storage will help you maximize the space you’ve got and keep your attic conversion looking neat and tidy. Custom-made cabinetry and storage solutions are the most efficient options if your budget allows this. You’ll be able to use every nook and cranny and create a seamless look that helps to streamline your loft layout. In addition, choosing the same color or  tone throughout your whole extension will help create the illusion of more space.

What are my stairway options?

Carpet wrapped steps are your most cost-effective option when it comes to stairways. A set of straight stairs are easiest to build and install, and hence very affordable. Depending on your space and requirements, however, a set of turning stairs might be required. If you choose different materials such as hardwood timber or glass for the steps or the balustrade, this will increase the cost. Floating steps or curved staircases – in the upper regions when it comes to price – add a bit of drama and visual impact. Floor level lighting and art embedded into the steps add further to the wow factor. 
loft conversion with custom staircase
Stairs are generally easy to build and install, however, careful planning and positioning at the outset of your project is important to ensure you don’t lose precious space on your ground floor. As a rule of thumb, it’s likely that stairs will take up about half a small room. Where space is extremely tight you could consider a small spiral staircase, keeping in mind though that access can be an issue and items of furniture may have to be lifted in and out through the upstairs windows.

What is involved in a roof conversion?

Not changing your roofline means that you are likely able to leave most of your roofing untouched. You will simply need to tidy up and repair roofing where your windows will be inserted. However, any work done on a roof requires a scaffold or edge protection, which will add to the cost of your project (and is factored into the rough estimate). Also, it’s not uncommon for problems such as old leaks and rot of roof beams to be uncovered during the build. Ensure you have a contingency budget of at least 15% planned in.
If your roof conversion is a more substantial project you may have to replace some or all of the roofing. Costs for replacing or repairing a roof depend on the roofing material of your house and other factors. 
Asphalt shingles are becoming more popular, as they are generally low maintenance and very tough, with some heavyweight shingles offering 50-year warranties. Concrete tiles are also hardwearing and have the advantage of reducing heat loss and noise levels from the outside.

Looking for inspiration? Make sure you check out our completed loft conversion projects.

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*Costs are rough estimates and are subject to change  For a fixed-quote accurate to your specific project, please consult your local Refresh Remodeling Consultants. All Refresh Renovations franchises are independently owned and operated.

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