ICF versus timber frame: what to compare

ICF and timber frame are different ways to form a building’s structure and envelope. For a homeowner, the useful comparison is the complete design, its compliance evidence and the agreed scope. Material alone does not establish airtightness, acoustics, running costs or long-term maintenance.

What each system does

Nua Living’s ICF construction uses a reinforced concrete core poured on site between permanent insulation layers. Timber frame uses a structural timber frame with a specified wall build-up. Both need foundations, weather protection and properly designed junctions. The Department’s auxiliary dwelling guidance, Part D recognises several construction methods; a timber or steel structure is not inherently temporary.

Energy performance needs design evidence

Thermal bridging, airtightness detailing and testing need attention in either construction system; the finished dwelling must meet Part L. Technical Guidance Document L 2022.

Continuous insulation does not remove the need to detail floor edges, roofs, openings and service penetrations. Ask for the proposed junction details and the commissioning and testing plan. We do not promise a percentage saving over timber frame or infer a heating bill from a wall material.

Nua Living’s A0 energy rating is a design target, not a BER certificate. SEAI BER Advertising Guidelines, July 2026.

The Department’s guidance says a BER is not legally required for a standalone building under 50 m². Department auxiliary dwelling guidance.

A design target, a calculated performance assessment and an issued certificate are different things. Discuss which evidence is included in your quote. Read more about Nua Living’s ICF construction.

Programme and price

Primestructures carries out the on-site ICF structural build in 5–10 days once foundations are ready. This is a structural stage, not a move-in promise: design, site preparation, statutory processes, fit-out and service connections need their own programme.

Compare complete written scopes instead of a frame kit price against a finished home. Ask who covers foundations, drainage, connections, professional fees, finishes and certification. Current Nua home prices, including VAT totals and exclusions, are on the models and prices page. We do not claim that future savings will offset a price difference.

Planning depends on the dwelling and site

Condition 7 of Class 3A sets a 32–45 m² external-footprint band, counted together with earlier Class 3 garden structures. S.I. No. 340/2026, Class 3A.

The construction material does not itself determine planning status. Read the full planning conditions before choosing a design.

A Class 3A auxiliary dwelling follows the normal Building Control process, including a Commencement Notice, design and assigned certifiers, a competent builder and a Certificate of Compliance on Completion. Department Circular BC07-2026.

The planning notification and Building Control submission are separate. Lodge the BCMS Commencement Notice 14–28 days before starting work; allow at least 14 days after the council notification too. Start with the BCMS submission, then the council notification, so the periods can run together. Check the pre-start paperwork guide for current council forms and professional responsibilities.

Discuss your garden

Tell us about access, the intended use and the finished specification you want to compare. Request a callback and a free, no-obligation site visit. We can discuss site eligibility and prepare a written scope and quote.