We ask building experts to walk us through the key steps to adding an upstairs level.
1. Get your plans drafted
Professional plans will help ensure the design is structurally sound.
Lindsay Jack, Co-Owner of LJ Home Builders in Brisbane has worked on three vertical housing extensions in the past two years and says it’s paramount owners get their ideas on paper so they can see exactly what’s achievable.
“Homeowners really need to engage an architect or draftsperson to produce design drawings at the start to understand what is realistic, because you will have to sacrifice room downstairs to create enough space for the stairwell and, if you have an existing hallway sometimes you can use that to lead people to the new stairwell. But as a rule of thumb I say allow almost a room to create enough space,” says Jack.
“That can come as a surprise to some people who are working with limited floor plans and have very ambitious plans.”
Questions you should raise with your architect include:
- Can you extend outwards to gain some more space?
- How high can my second storey ceiling go?
- How deep do my stairs need to be?
- How can I maximise natural light flow?
- Can I plan according to the views?
- What can I do to make my new upstairs level feel bigger?
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2. Is the design structurally sound?
Before the build starts, assess your current home’s suitability for the vertical extension, says Daniel Mazzei, Director of Mazzei Homes.
Questions to ask at this stage include:
- Is it structurally sound, particularly the foundations and roofing?
- Can a stairway be practically added?
“An architect or registered builder will be able to assist you with these questions,” Mazzei says.
“Extending upwards does mean adding extra weight to the existing house and you need to be sure that it is able to handle the pressure as some older style slab homes and package homes are not structurally built to handle the extra weight and an engineer’s assessment may be required to establish feasibility,” Jack advises.
3. Find your preferred registered builder
Speak to several builders, meet with them, get written quotes and ask about their future schedules.
How busy are they? How long does a project such as yours typically take to complete? Ask for examples of past work and check references.
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4. Does it comply with regulations?
Speak to your council to ensure the build complies with the relevant regulations.
The build may require planning approval and will usually require building approval, which means it must comply with local zoning regulations and the local neighbourhood plan.
Sometimes a Development Approval (DA), plumbing approval and or a “siting variation” to build within the boundary setbacks of your property may be needed.
“Depending on where you live in Australia, your second storey may also need to satisfy additional building standards if inside a fire, flood or cyclone zone. So once you have your design finalised, you must seek approval of your design plan from council planning. Your (council) certifier will know your town planning regulations,” says Jack.
Mazzei agrees: “Speaking to council or your architect will give you clarity over these questions.”
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5. What happens when you take your top off?
“Once the certifier is satisfied, and you have permission to proceed with your plan, you can take off the roof or roof sheeting,” Jack says.
Sometimes your downstairs storey’s ceiling can remain intact, which will make your build less intrusive.
Many homeowners will move out once the builders move in, although Jack says some people do chose to stay: “They do need to understand we’ll need to turn off services at key stages.”
A typical upstairs extension will take 12 to 20 weeks to complete, he says.
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If your home does not have a pitched roof your builder may attach roof “joists” following the roof line of your existing house, which helps get your second storey’s floor down quickly to reduce exposure to the elements.
“It’s all about pre-planning and getting the downstairs protected as soon as possible,” Jack says.
“Extending upwards will require the roof to be removed while the work is completed so your builder will need to provide protection by applying a tarp to the exposed areas in case of bad weather and the like.”
6. Building a house on a house
Just like building a house on ground level, your builders will first link electrical wiring, plumbing and sewerage lines to the upstairs level.
Next they will frame-up and build the new roof’s trusses “and then it’s just like building a new home”, Jack says.
“You move through the construction process and then complete the internal fit-out, cabinetry, painting, tiling and so on.”
7. The final inspection
A council certifier and engineer will inspect your project at key stages to make sure it’s on track.
On completion there will be a final comprehensive inspection. If the construction is deemed satisfactory, your second storey will get certification.
This is the all-clear to occupy the new extension, thank your builder, settle your bill and move in.
Tip on successfully adding another storey
Try and find the same roof tiles to match the existing ones.
- Jack says to make sure you have adequate insurance protection. “Most home and contents insurance (policies) do not include damage to the existing property when it is under construction and while our contracts works policy covers all new work, it does not cover the existing property either. So we recommend extending that policy to include your existing structure.”
- Expect unexpected costs: “There can be unexpected, expensive costs that should be budgeted for,” Mazzei says. “For example you may have to rewire, re-plumb or update services. Your roof plumbing may also have to be redone.”
- Try to avoid unexpected costs by doing your due diligence. In older leafy suburbs this should include termite inspections. “By spending a relatively small amount of money upfront to find out what you are up against, it can save you thousands later on,” Mazzei says. “The main professionals to engage are structural engineers, architects and building inspectors.”
- To keep the same style as your existing home, you’ll need to find suitable building materials. “Salvage centres can be a great starting point to keep materials the same. Spend a few weekends to find your perfect pieces,” Mazzei suggests.
- Factor in the cost of facade refurbishment. “For your renovation to look complete, your existing doors, windows and exterior paint will need to match existing home.”
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