What everyone ought to know
Need extra space but can’t afford to financially commit to an expensive addition? Your roof space (or attic) can be the perfect place for a new bedroom or kid’s area. 
If done properly you could greatly increase the value of your home, but there are a few essential things you need to know.
- Ease and safety of access and egress – ensure you design stairs that you will actually use. Locate the stair so it does not ruin the use of other spaces below and ensure that it is safe.
- Ventilation - Attic space needs ventilation as is stated in the NCC.
7 easy steps to ensure your roof space is a viable option
1. Assess the structure
This is the dirty part. Roof & sub-floor spaces are rarely dust free and often house the odd vermin. Take a torch and ensure you are wearing practical shoes with good traction. While in the roof area, only stand on the ‘timber’ roof members. Other materials will not be load bearing and you can easily damage your ceiling if you stand on something other than timber.
You must engage a qualified structural engineer to view your home’s structure, but firstly undertake the following:
Assess the structure - Assess the structure yourself noting down the type of roof structure. Does your house have “trusses” or a “traditional” roof structure? Traditional roof structures do not have cross members making it more cost effective to renovate.
Lighting - Organise temporary lighting for your assessment so you can easily see the roof structure as a whole element.- Assess roof structure - Assess the roof members by using a torch to highlight specific spots, viewing each truss systematically. Tap lightly with a hammer and or screwdriver to ensure there is no termite, water or mould damage. While taping with your tools it will become obvious if there is damage as the sound will alter as you are tapping. Take pictures and note any areas that sound odd, for further discussion with your engineer.
- Take measurements - Take dimensions and note the thicknesses of your external and internal walls.
- Assess wall types - Note what type of walls you have, timber studs can be seen in floor of the roof space, you may need to remove insulation to see this.
- Assess roof cladding - Note what type of roof cladding is loading onto your roof structure - tiles, slate, “Colorbond” etc.
- Assess the sub-floor area - Look in your sub-floor space (if your floors are suspended above ground). Note if there is a timber floor structure or concrete or another type.
- Assess the footing structure - If you’re not sure what footing type you have, take a look at this article on footings that can help you identify what type of footing structure you have.
It is important to know the above information as your engineer will mostly likely ask about the structure when booking the initial consultation. It is also important for you to understand how your building hangs together, so during your build you will have a good understanding of what is going on and what looks right.
2. Take some measurements
While in the roof space take some measurements of the space you are thinking would suit the new attic space. Ensure this space only includes walls that will have a minimum wall height of 1400mm. This will ensure that your attic space will not have any head height and ceiling height issues.
Check for possible views while in the roof space. Assess potential views by pushing up very slightly on a few roof tiles. If you have roof sheeting this will not be possible, unless the roof has gable end roof vents.
3. Draw a rough plan
Drawing a rough plan is easy. Take a look at this article about drawings plans or you can download this cool little app.
4. Consult a structural engineer
This is the most important step of your attic conversion. Once you have a rough plan (preferably to scale) it’s time to call a structural engineer. Search for an engineer on our directory. The engineer will be able to assess if your building can take the extra live load (people & furniture) the way it is currently constructed, or whether the building will need to be structurally enhanced to ensure the buildings ongoing integrity.
5. Have your plans drawn up to scale
Once the engineer has assessed your structure and they have suggested the financial viability of the attic plan you will need to draw up the plans with details and possibly elevations and a reflected ceiling plan (to detail lighting placement and skylights etc.). BTW sky windows are often design to fit neatly between roof trusses which are spaced at 600mm centres.
6. Send your drawings to the engineer
Send the drawings to the engineer with images inside the existing roof space. The engineer will specify everything that will need to be done to ensure your existing home can take the extra load of the new attic plan.
7. Starting your build
Now you’re ready to start fitting out your attic. You will need to engage a carpenter to install the structure based on the engineer’s details. Once the structure is installed the engineer will need to view the work and certify that the structure complies with the original engineering details.
Once the space has been certified the services can be roughed in and the space can be fitted out with wall, ceiling and floor linings. All that is left is painting and the fitting off of electrical items.
Hot Tips
- Minimum ceiling heights - Habitable ceiling heights should be 2400mm but you can have portions of the ceiling lower than this (read the National Construction Code (NCC)).
- Ventilation - A minimum of 10% of your wall space should be ventilated to the outside.
- Get it certified - Any extra structural, electrical and plumbing works will require certification from that professional and may require private certifier assessment. Check with a local private building certifier or your local council.
- Plan your stairs - Ensure the stair is in a useful and out of the way space. (Consider a ladder stair – see the NCC). See our article on stair design for more information.
- Ongoing roof access - Try to provide ongoing access to roof space not to be used so that pest inspectors can continue to assess your roof structure on routine pest inspections.