Aluminium subframes
Aluminium Deck Subframes & Outdoor Framing
Not every deck needs timber joists underneath. Adjustable aluminium subframes are a genuinely useful alternative in the situations where timber framing struggles — very low clearances, decks over existing concrete, and tiled outdoor rooms that have to finish flush with the floor inside.
We use them regularly, and there are real examples in the project gallery: a tiled patio, a narrow courtyard deck and a kwila deck laid over an existing slab.
Where an aluminium subframe makes sense
The common thread is tight tolerances and damp conditions. Where you have millimetres to play with, or the framing is going to sit on concrete that stays wet, aluminium takes the guesswork out.
- —Low-clearance decks where there is not enough depth for timber joists
- —Decking or tiles over an existing concrete patio or slab
- —Tiled outdoor areas that have to match an indoor floor level
- —Pool surrounds and other wet areas
- —Narrow courtyards where the finished level has to be dialled in
- —Adjustable systems where the ground below is uneven
Why it works in those situations
Aluminium does not rot and it does not move with moisture the way timber does, which matters most when the framing is sitting flat on concrete with nowhere for water to go. Adjustable pedestals and bearers let each support point be set individually, so the finished surface can be brought dead flat with a slight fall built away from the house.
- —Does not rot in permanently damp positions
- —Dimensionally stable — no shrinking, twisting or cupping in the frame
- —Height adjustable at each support point
- —Suits both decking boards and outdoor tiles
- —Works where there is not enough depth for a timber substructure
Outdoor tiled areas
Tiles on an adjustable subframe or pedestal system are how you get a patio that flows straight out from an indoor floor without a step or a lip. Everything sits flat, joints stay tight, and the fall is built in rather than relying on the ground below.
Decking over an existing slab
Where there is an old concrete patio you do not want to break out, an aluminium subframe lets the deck be built over the top and brought up to the right height — including around obstacles like existing posts, thresholds and drains.
Timber or aluminium?
Timber framing is still the right answer for most standard decks and it is generally the more economical option. Aluminium earns its place in the specific conditions above. We are happy to price both where the job could go either way.
Related projects
- Tiled outdoor patio on an aluminium subframe
- Hardwood courtyard deck with planters and screening
- Kwila deck built under an existing louvre roof
Common questions
- Can aluminium framing be used under a deck?
- Yes. Adjustable aluminium subframes carry both decking boards and outdoor tiles, and are particularly useful in low-clearance and wet positions.
- Is aluminium framing better than timber?
- Not universally. It is better in specific conditions — low clearance, over concrete, permanently damp areas and tiled outdoor rooms. For a standard deck off the back of the house, treated timber framing is usually the sensible option.
- Can it be used over an existing concrete patio?
- That is one of its best uses. The subframe sits over the slab and each support is adjusted to bring the finished surface level.
- Does it work with outdoor tiles?
- Yes — tiles on adjustable pedestals or subframes are how a tiled patio is brought flush with an indoor floor with the fall built away from the house.
Tight clearance or an existing slab?
Send through a photo of the area and we will tell you whether an aluminium subframe is worth pricing.