Overview

The i-House system using H+H Celcon Elements (vertical panels) was used on the re-development of a residential site in Stanpit, Dorset.

i-House introduced developer and contractor Karm Homes to the concept of Modern Methods of Construction (MMC) while also providing the familiarity of a traditional building material.

Project detail

Karm Homes re-developed the site of a previously detached property with large garden to build 5 homes, comprising a pair of 3-bedroom semis and a terrace of 3-bedroom townhouses.

The full i-House system package was used for each unit, comprising the structural inner skin, insulation, floor cassettes, roof cassettes, soffits and facias. The i-House system is manufactured offsite by Roofspace Solutions who also supply a 3-person team and crane operator to create each structure.

The walls of each unit are constructed using storey-high Celcon Elements that are craned into place and secured using a fast-setting mortar specifically created by H+H for use with vertical panels.

On this build, the panels, floor cassettes and roofs went up in 10 days per house, leaving a watertight shell for interior work to begin. As soon as the shell had been completed, work began on the ground-floor insulation, underfloor heating and liquid screed, closely followed by the timber studwork for upstairs walls and staircases. While the internal work was happening, the roof was being tiled and the bricklayers put on notice to commence the outside skin.

The already incredibly quick process of creating the watertight structures would have been expedited had there not been some logistical issues, in part due to the tightness of the site. This was also Karm Homes’ first time working with i-House and they received on-site technical support from Roofspace with an H+H Building Solution Manager supporting throughout the build.

The external walls are finished with brickwork and the U-Value of the entire wall structure is 0.23W/m2K, similar to that of a traditional build.

Products used / aircrete specification

H+H Celcon Elements form the basis of the structure for the homes, being used for the inner leaves of all the load-bearing external walls. These vertical wall panels are manufactured to the design storey height of a standard house with a width of 600mm and a thickness of 100mm.

Where the required width of the modules is less than 600mm, or in cases where the panels are used under windows, they can be cut to size on site. The knock-on effect is less product waste on site and cleaner work environments.

Celcon Elements are lightly reinforced to facilitate the handling and transportation without damaging the product.

Foundations

Built using traditional strip foundations.

External walls

Finished with external brickwork and render.

Roof

2 roofs are a standard truss roof construction and 3 are ‘Roofspace i-Roof’, a panellised room-in-the roof system designed for the UK new-build residential housing market.

i-Roof by Roofspace is manufactured offsite in a controlled environment making it a faster, cost-effective construction. Safety benefits include reduced working at height and the removal of the risk of gable block work collapse.

Floor

Prefabricated timber i-Floor Joist cassette floors are used in conjunction with the system to maintain the speed of build. Each cassette is lowered into place by crane, sitting on top of the first lift of Celcon Elements.