ICF-Therm polystyrene blocks are assembled on-site to create a formwork wall into which horizontal and vertical steel reinforcement are fixed for extra strength. Once braced, the formwork is then filled with readymix concrete. The ICF-Therm blocks remain in place permanently to create a super-insulated monolithic concrete structure.
The Raft Therm system combines the strength of reinforced concrete with the insulating benefits of expanded polystyrene to deliver long-term thermal benefits to the building user.
ICF Therm offers two core thicknesses 150mm and 200mm core.
Conventional timber roofs cut on-site or pre-fabricated roof trusses are both compatible with ICF-Therm walls
External Render:
NSAI approved EPS external render and cladding systems, with a minimum B-s1, d0 fire classification, can be applied directly to the Castleforms ICF Therm EPS forms. The external faces of the Castleform ICF Therm panels are lightly grooved vertically and horizontally to receive the applied finishes, a light rasping of the entire surface of the ICF wall is essential to ensure good adhesion of the polymer base coat. Corner and reveal beads are first fixed in position using the same polymer base coat. For thin coat render systems a 4-5mm base coat is applied directly onto the ICF-Therm forms using a notched trowel, prior to the base coat curing reinforcing mesh is then floated in. A second lighter base coat (1mm) is then generally applied to remove any surface blemishes or trowel marks thereby providing a smooth flat surface for the final finish coat. After the final layer of base coat has cured it may be necessary to apply a primer coat, thereafter the wall is finished with a pre-mixed Silicone textured colored top coat.
Brick / Stone cladding:
ICF Therm may be externally finished with natural brick or stone cladding. There are a number of options for fixing masonry cladding to the ICF-Therm wall.
- Suitable wall ties are cast into the ICF concrete core or screw-fixed into the core after concrete placement at pre-determined locations to align with brick/stone courses.
- Wall ties are screw fixed to plastic web embedded at 200mm centres in each ICF-Therm panel (plastic webs have limited loading capacity, consult with project engineer as to their racking suitability) .
- Stainless steel C-channels are securely fixed to ICF concrete wall, adjustable height ties are attached to the C-channel to align with courses.
It is advisable to always render the ICF wall prior to the laying of brick/stone cladding. Refer to cladding manufacturer or project engineer for correct fixing instructions.
Flanges on each side of the web are indicated behind the ICF Therm logo on the external surfaces of the blocks at 200mm vertical centers. These embedded flanges are used as fixing points for bracing of the wall during construction, later the flanges also provide a fixing point for plasterboards when providing an interior finish to the ICF wall.
Light to medium weight items such as shelves or curtain rails, these can be hung using the same method for hanging plasterboard mentioned above.
For heavier items such kitchen cabinets it is recommended to use fixings that can be connected to into the concrete core.
To prevent the buildup of heat and avoid plasticizer migration all electrical cables must be ducted through a PVC conduit which is recessed into the ICF formwork. The cables and PVC conduit must be sized to minimise heat build-up with resulting fire risk, in accordance with I.S. 10101. A hot wire knife or circular saw is used to cut and remove an appropriately sized slot into the insulation.
To accommodate service pipework, a sleeve or ducting is inserted through the ICF-Therm block prior to concrete placement, care should be taken to ensure correct concrete consolidation around the sleeve or duct. Alternatively, where the location of services permits, penetrations may be core drilled after concrete placement for the insertion of ducts or sleeves. Care should be taken to ensure all gaps around service penetrations are effectively sealed to prevent the ingress of moisture or vermin.
Castleforms ICF Therm wall system enables the use of different flooring systems including timber open web joist, timber solid joist, concrete pre-cast beams and hollow-core slabs.
The concrete structural elements of Castleforms ICF-Therm wall have a class O rating and are non-combustible as per TGD of Part B of the building regulations 1997 to 2021 Ireland.
Castleforms ICF-Therm blocks are manufactured from flame-retardant EPS in accordance with IS EN 13163:2012+A2. The EPS has a Class E reaction to fire when measured in accordance with IS EN 15715 and classified in accordance with IS EN 13501-1.
The internal and external finishes of Castleforms ICF Therm walls have a Class 0 ‘spread of flame’ rating and Castleforms ICF Therm wall with a 150mm concrete core has over 60 minutes fire performance.
What type of walls are used for internal and party walls?
Internal load-bearing walls are constructed using either the 150mm or 200mm ICF-Therm concrete core options. Alternatively, these walls may be constructed using traditional methods such as blockwork or timber stud, it is important to ensure these walls are securely tied to the external ICF concrete core.
Where underfloor heating is specified as part of the building design this is generally fitted below the steel reinforcement by a specialist contractor. To preserve the structural integrity of the Raft Therm system and prevent any potential damage to the underfloor heating pipes it is important to always ensure there is adequate clearance between the reinforcing steel and the underfloor heating pipes. Large banks of underfloor heating pipes should be a maximum 200mm wide with a minimum space of 100mm between the banks, banks should also run perpendicular to thickened areas of the slab and not parallel. If in doubt consult with project engineer.
The design and specification of the Raft Therm system for each building is the responsibility of the project main consulting engineer.
The Raft-Therm system must be designed to suit the site and ground conditions of each building. A ground investigation survey should be carried out by a qualified geotechnical specialist to determine the depth of the good natural ground, the allowable bearing capacity and the ground water conditions. The Raft-Therm system should never be constructed on made ground.
The main project consulting engineer must review the ground investigation report and determine the most suitable hardcore build-up. They must also inspect the ground before any stone fill is placed to ensure the ground conditions are consistent over the full area of the building. Any soft spots or inconsistencies must be remediated as per the main consulting engineer’s recommendations.
Insulated foundation systems compatible with ICF, Timber frame, Concrete Block and Light Guage Steel structures.
To obtain a quote for our ICF Therm ( Insulated Concrete Formwork) Wall System or Raft Therm - Insulated Foundation System - Send your plans and a brief email to info@castleforms.com
