Building Process

Typical Building Process with Altherm ICF

From foundations to super structure in 1 – 12 days, the following content outlines a the typical building process based upon a pair of 100 sq m semi detached houses. Manpower crew refers to certified Altherm ICF installers. 

Day 1

Foundation Rising Walls

  • 1 crew
  • 1 day

For thermal bridging reasons normally the Altherm ICF process starts from above the foundation. The main contractors site engineer will set out the details on the foundations and the Altherm certified Installer will work to these parameters.

The Altherm ICF foundation wall will rise to the agreed level. Access points are cored through the foundation walls for service at locations agreed by the Main Contractor. DPCs and floor insulations are placed as per standard practice.

Key Points for ICF use

  • Manpower: 1 day for 1 crew
  • Concrete pour: 9 m3 per semi
  • Minimal thermal heat loss

Continue with standard building practice

  • Set out
  • Backfill
  • Insulation

Typical foundation section

Set Out

ICF rising walls minimise thermal heat loss.

Back Filling

As per standard practice.


4 & 6″ holes for services before concrete pour.

Radon DPC

As per standard practice.

Sub Floor

Insulation and concrete installed as per typical building practice.

Day 2-3

Ground Floor

  • 1 crew
  • 2 days

The Altherm ICF block is taken off the rising wall in the same method as a tradition block would be constructed. Altherm ICF certified installers prop the walls along with strapping any areas of concern. Pockets are left to attach joisting.

Scaffolding rises with the wall structure. Steel is placed with the Altherm ICF Structure. The full pair of semis are poured in one continuous pour per floor.

Key Points for ICF use

  • Manpower: 1 crew 2 days
  • Concrete floor poured – Approx. 8m3 for the pair of semis
  • Steel placed horizontally and vertically
  • Pockets are left to attach joisting
  • Cavity Closers applied to window & door reveals

Continue with standard building practice

  • Main contractor signs off on window and door openings

Ground floor walls

ICF blocks are constructed on top of DPC.

Steel Detail

Steel bars placed horizontally and vertically.

Construction process

Propping supports the structure whilst steel is placed into the void.


Electrical and data services are installed at this stage.

Joist Voids

Voids are cut out of the ICF to bolt 9 x 2 joisting board.

Cavity Closers

Windows and door openings are formed using the Altherm ICF proprietary cavity closer, preventing any heat loss around these areas.

Typical window & door

cavity closer

These form a thermal break around windows and doors along with a shutter for concrete.

Vertical closer

400mm high vertical closers for windows and doors.

Propping of closer

Opening heads only need propping with the Altherm closer.

No reveal

The Altherm ICF closer allows the window to be place anywhere in the opening.

Day 5

Joisting / Precast Flooring

  • 1 crew
  • 1 day
Following recommended curing time of the concrete pour of the ground floor the carpenter can commence the installation of the timber or concrete joisting. Pockets are left out of the ICF to allow the carpenter to bolt fix a ledger beam. This process ensures the health and safety of the erection crews. Altherm ICF can be used in conjunction with timber or precast floors for one off housing or developments. The Altherm wall on the next floor can then be propped off this floor.

Key Points for ICF use

  • Manpower: 1 day for 1 crew
  • Altherm ICF is compatible with timber or precast floors

Continue with standard building practice

  • Joisting applied using construction carpenters

Remove Shuttering

The shuttering is removed to expose the concrete.

Expose Concrete

Ledger Board

9 x 2 ledger board is bolt fixed to the exposed concrete.


Finished ply can now be fixed to the joisting.


Precast floors placed.


Steel on precast.


Steel beam connection.


Precast stairs.


Precast stairs.


Lift shaft.

Day 6-8

First Floor

  • 1 crew
  • 2 day


  • 1 crew
  • 1 day

The Altherm ICF installation for the first floor is done in the same manner as the ground floor. There is a steel detail connecting the ground floor to the 1st floor.

The concrete Is poured for the complete 1st floor structure following sign off from the client. The process then moves to the apexes.

There is now a safe working area on the first floor. Windows and stair Installation can be commenced​. Once the concrete is cured there is structural integrity in the walls and external finishes as well as the roof can be installed​.

Key Points for ICF use

  • First floor: 2 days for 1 of crew
  • Apex Structures: 1 day for 1 crew
  • Concrete poured: approx. 8m3 including the adjoining apex





Propping apex.


Day 8-12


Roofing the Altherm ICF system is the same construction method as for traditional build methods whether a preformed truss or a cut roofing structure is used.

Continue with standard building practice

  • Trussing and roofing typically performed by others

Typical roof section

Placement of Trusses

Placement of Trusses

Showing safety netting and wall plate.

Fire Stopping

Fire quilt applied to the party wall.

Finished Truss Roof

Finished roof as typical.