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SFS, timber, and masonry are the three main options for building a wall. Each has advantages and disadvantages. This guide compares them honestly, on the factors that actually matter for most projects: cost, longevity, fire, acoustics, environmental impact, and where each wins. If you've ever asked "should I use SFS or timber?" — this is the honest answer.

Quick overview

Cost comparison

Material cost (per m² of wall)

• SFS — typically £30–£60/m² for the frame and boards (varies by stud size, gauge, coating)
• Timber frame — typically £25–£50/m² for the frame and boards
• Masonry — typically £80–£150/m² for the blockwork and finish

SFS and timber are similar in material cost. Masonry is significantly more expensive.

Labour cost

• SFS — fast to install, but requires specific skills
• Timber frame — fast to install, widely available skills
• Masonry — slow to install, requires specific skills (bricklayers)

SFS and timber are similar in labour cost for the frame. Masonry is significantly more expensive because of the time and skills required.

Total cost (installed)

• SFS — £60–£120/m² installed, including boards and finish
• Timber frame — £50–£100/m² installed, including boards and finish
• Masonry — £150–£250/m² installed, including plaster and finish

Timber is typically the cheapest option for the wall itself. SFS is comparable to timber. Masonry is significantly more expensive.

Longevity

SFS

• Internal environments — 50+ years (limited mainly by the building's life, not the SFS)
• External environments — 50+ years with C5 coating, 15–25 years with standard galvanised in harsh environments
• Corrosion risk — minimal if coating is appropriate for the environment

Timber frame

• Internal environments — 50+ years if protected from moisture
• External environments — 15–25 years typically, less in damp conditions
• Rot risk — significant if exposed to water, poor ventilation, or ground contact
• Pest risk — vulnerable to woodworm, termites (in some areas), and rodents

Masonry

• Internal environments — 100+ years
• External environments — 100+ years with normal maintenance
• Movement — settles and cracks over time, requires maintenance (repointing, etc)

Masonry lasts the longest, but the building's life is usually the limiting factor — not the wall material. SFS lasts as long as the building; timber may need maintenance or replacement in external applications.

Fire performance

SFS

• Non-combustible — doesn't contribute to fire spread
• Up to 120 minutes fire resistance achievable with tested systems
• Fire ratings are consistent and predictable

Timber frame

• Combustible — contributes to fire spread
• Fire resistance achievable (typically up to 60 minutes with heavy timbers and cladding), but harder to achieve and less predictable
• Building regulations increasingly restrict timber in tall buildings (post-Grenfell)

Masonry

• Non-combustible — doesn't contribute to fire spread
• Inherent fire resistance — a 100mm blockwork wall has substantial fire resistance
• Fire ratings are straightforward to achieve

SFS and masonry both perform well in fire. Timber is the weakest of the three, especially for higher fire ratings.

Acoustic performance

SFS

• Highly flexible — can achieve Rw 35 (basic) to Rw 65+ (twin frame with heavy boards)
• Stud size, stud centres, board layers, and insulation all tunable
• Resilient bars can add isolation
• Consistent and predictable

Timber frame

• Similar acoustic potential to SFS
• Acoustic performance depends on stud size, board layers, and insulation
• Timber frame requires additional mass or isolation for higher acoustic performance (timber is less dense than steel)

Masonry

• Mass helps with low-frequency sound (traffic noise)
• Standard masonry walls typically achieve Rw 45–55
• Can achieve higher with cavity construction or additional mass
• Less tunable than SFS or timber frame

SFS is the most flexible for acoustic design. Masonry has natural advantages for certain frequencies. Timber is comparable to SFS but slightly less performant at high acoustic targets.

Weight and foundation

SFS

• Very light — typically 15–25 kg/m² for the frame plus boards
• Low foundation loads — suitable for ground screws or lightweight slabs
• Can be installed on upper floors of existing buildings

Timber frame

• Light — typically 15–25 kg/m² for the frame plus boards
• Low foundation loads
• Similar to SFS in weight

Masonry

• Very heavy — typically 200–400 kg/m² for blockwork alone
• High foundation loads — requires substantial foundations
• Not suitable for upper floors without structural upgrades

SFS and timber are both lightweight, suitable for any foundation type. Masonry is heavy and requires substantial foundations.

Environmental impact

SFS

• Steel is infinitely recyclable
• High recycled content (typically 30–50%)
• Production has significant CO₂ footprint (steel making)
• Long lifespan offsets initial CO₂ impact

Timber frame

• Renewable material (if sustainably sourced — FSC or PEFC certified)
• Sequestered carbon (stores CO₂ absorbed during growth)
• Low embodied carbon if sourced responsibly
• Can be incinerated at end of life (releases CO₂ but can be recovered)

Masonry

• Concrete and blockwork have very high embodied carbon (cement production)
• Not recyclable in the same way as steel or timber
• High transport costs (heavy material)
• Long lifespan partially offsets initial impact

Timber has the lowest embodied carbon if sourced from sustainable forests. Steel (SFS) has higher embodied carbon but is infinitely recyclable. Masonry has the highest embodied carbon.

Construction speed

SFS and timber are both very fast to install. Masonry is significantly slower, weather-dependent, and requires more trades (bricklayers, plasterers, etc).

Where each wins

SFS wins when:

• Fire rating is important (60+ minutes)
• The environment is damp, humid, or corrosive (C5)
• Weight is a constraint (upper floors, lightweight foundations)
• Speed is important (fit-outs, refurbishments)
• Precision matters (dimensional stability)
• Pest risk is a concern (vermin, woodworm)
• The wall might need to be modified in future

Timber frame wins when:

• Budget is the top priority
• Sustainability is the key driver (and FSC timber is used)
• The wall will be protected from moisture (internal walls)
• Standard acoustic and fire performance is sufficient
• Traditional construction is preferred for the project type

Masonry wins when:

• Longevity is the top priority (100+ years)
• Mass is beneficial (acoustic, thermal, structural)
• The building type requires masonry (e.g. traditional house)
• Fire rating is required and other options don't achieve it
• The client prefers the "solid feel" of masonry

Summary

SFS, timber, and masonry are all valid wall materials. Each has advantages and disadvantages. SFS is the best choice for fire performance, corrosion resistance, weight, precision, and speed. Timber is the best choice for budget and embodied carbon. Masonry is the best choice for longevity and mass.

The honest answer is that there's no single "best" material — it depends on the project. For garden buildings, SFS is usually better than timber (no rot, no vermin, no maintenance). For large commercial buildings, SFS infill with masonry cladding is common. For traditional houses, masonry is standard.

Get advice for your specific project. The right answer is rarely the cheapest option — it's the option that delivers the performance the project needs at a reasonable cost.