Part 5 - Superstructure

20 July 2016 Brent Ackerman, Delta Project Management
Brent Ackerman is a regular presenter of the Self Build Academy courses and events and was the Project Manager for the build of our Elsworth show home. Brent explains the stages of building the superstructure of our Elsworth show home.

1. Levelling the Sole Plates

Levelling sole plates on self build site
The first pieces of timber to get fitted on every project are never the most glamourous but arguably the most important.

The sole plate is a single strip of solid timber that runs around the top of the foundations, fitted to the top of the ‘kicker brick’ course; the last element of the foundations. It’s essential that the sole plates are level and set out accurately in accordance with the setting out drawings.

Mistakes incorporated at this stage of the build invariably cause much bigger problems further down the line and so the job has to be done correctly.

If there are any errors with the foundation construction then these should be addressed before work proceeds.

2. Installing the ground floor panels

Groundfloor Structural Insulated Panels being installed
Once the sole plates are set then the ground floor internal and external Kingspan TEK® Building System wall panels can be delivered and erected.

The panels are fabricated in elevation or part elevation form, depending upon access conditions on site, so that the number of joints requiring attention are minimised. The ground floor panels are nailed first to the sole plate and then fixed to each other.

The erectors brace the panels to ensure that they are vertical. Panel junctions are sealed with an insulating foam and sealant to help ensure that they are airtight.

Corner junctions on the ground floor need particular attention as they must be set square. Internal wall panels, which can be load-bearing, non load-bearing or contribute to the overall building stability normally, get added into the structure as the build progresses.

3. Fitting the post and beam membranes

post and beam membranes
This Passivhaus is not simple: it has large open plan spaces on the ground floor, a central courtyard area and a spectacular feature window measuring approximately 8x3m.

The courtyard is framed with four posts and the large openings are constructed using portal frames to provide stability to the structure. These large post and beam members are fitted as the ground floor build progresses and care must be taken again to ensure that they are accurately located and aligned.

Large members are typically fixed using resin anchors and shimmed (wedged using shims) into position with steel strips. It’s essential that once the resin fixings have set, and before the ground floor is screeded, the shims are grouted using a structural non-shrinking grout.

Building a Passivhaus Show Home

A complete step by step guide, we take you through the story of building our Passivhaus show home. From the design process, constructing the superstructure, achieving airtightness right through to the finishing touches.

Download the guide here.

Building a Passivhaus Download

4. Constructing the first floor

MiTek Posi-Joist Floor installation
We elected to construct our first floor using open metal web joists with Norbord Cabershield floor decking.

We use open metal web joists (MiTek Posi-Joists) on all our projects — they’re great because they really do simplify the installation of the services, particularly the large ducts required by MVHR (mechanical ventilation with heat recovery) systems.

They can also be manufactured to a variety of depths and widths so that a range of span and load conditions can be accommodated.

The Cabershield chipboard is a new product for us — a departure from traditional plywood. It has a permanent protective coating that protects the product from moisture during construction; we now know that it works very well.

In this build the Posi-Joists are hung off of the external Kingspan TEK® Building System walls using metal hangers to help reduce thermal bridging. The Cabershield floor deck is then glued and screwed, using a special gap-filling adhesive to the top of the Posi-Joists.

The adhesive helps prevent squeaks and creaks in service and contributes to the moisture protection performance of the system during construction.

5. Raising the roof

Potton show home SIPs in construction
The Kingspan TEK® Building System 172mm panels used for the roof are capable of spanning over 3m without requiring any additional support.

Where spans are longer than 3m then the panels are either sat on a load-bearing wall, supported by a purlin running underneath, or have rafters incorporated into them. While our overall build is somewhat complex, the roof itself is relatively straightforward so we were able to design and deliver some large-format panels to simplify the build and reduce the time spent working at height.

Once the large panels are laid on to the supporting structure, they can be nailed together and fixed through on to their supports.

6. Sealing the structure

Potton's Passivhaus show home SIPs shell
Being a Passivhaus, the building has to be very airtight. All of the panels are prefitted in the factory with a Wraptite System membrane, so once the superstructure is complete the final job is to seal up all of the panel junctions with a narrow sealing strip to provide continuity of performance.

The next step is fitting the Vieo standing seam roof from Euroclad, and installing the rooflight and the Kloeber windows.
Potton Elsworth Passivhaus Show House

The Elsworth is open to the public

Come and expereience the Elsworth show house for yourself. Built using the Kingspan TEK Building System, this is the UK's first show home built to Passivhaus standard.

Take me to the Elsworth Show House


Potton Head Office

Eltisley Road

Great Gransden


SG19 3AR

441767 676400

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