Installing insulation between timber studwork – retrofit

Installing insulation between timber studwork - case study

Offices in industrial mills, modern flats in village churches and even Victorian water towers converted into homes, the last decade has seen an increasing number of period properties brought back to life in one form or another.

The external aesthetic of these buildings is a key part of their charm; however, most require a significant upgrade in energy performance to make them suitable for the modern world. The solution, both for these properties, and many of the solid walled homes within the UK is to fit insulation internally.

In internal insulation applications, every millimetre counts, and that’s part of the reason we recently launched our Kooltherm K100 range. With a thermal conductivity of just 0.018 W/m.K – the products are designed to allow specifiers and contractors to achieve the desired level of thermal performance quickly, and with a slim construction thickness.

Over the past few years, we’ve seen several unusual renovations take advantage of our Kooltherm range. In 2013, Pete Fagg converted the derelict, empty shell of a 19th Century windmill into a large detached home complete with a new barn extension. The following year, Phil Evans and Joanne McGirr restored a grade II listed church in the village of Gamblesby, turning it into a spacious holiday home. And just last year, Carol and Majid Nadry completed work transforming a 1930’s water tower into a large, multi-storey family home.

In all three cases, timber battens were fixed internally to the brickwork with a layer of Kingspan Kooltherm K12 Framing Board fitted between. Last month we launched the product’s successor – Kingspan Kooltherm K112 Framing Board – further enhancing the space saving advantages for homeowners. To take full advantage of these benefits, it’s essential to ensure insulation is installed in accordance to best practice.

Retrofitting insulation onto a solid brickwork wall

Before installing timber studwork, guidelines should be marked out at maximum 600 mm centres around the perimeter of the external walls. Timber studwork, backed with a strip of damp-proof course, should then be mechanically fixed in place. The timbers must be deep enough to allow the desired thickness of Kingspan Kooltherm K112 Framing Board to be fitted between them along with a 25 mm (min.) air gap between the insulation layer and the brick wall.

Once the timbers are installed, the gaps between them should be carefully remeasured to ensure the insulated framing board fits snugly. Treated softwood ‘stops’ should be fixed to the side of the wall battens to maintain the air gap and to keep the K112 Framing Board flush with the face of the timber battens. The insulation boards can then be cut to size with a fine-toothed saw and any gaps filled with flexible sealant or expanding urethane sealant and flexible sealant.

Once the boards are installed, Kingspan Kooltherm K118 Insulated Plasterboard can be fixed to the battens. The boards should be cut approximately 5 mm short of the floor to ceiling height. They should be located centrally over the timber battens, lightly butted together, and fixed using either drywall screws at 300 mm centres (or 200 mm at external corners), or large headed galvanised clout nails at 150 mm centres.

Fixings should be driven straight through the board so the head is slightly embedded below the plasterboard surface and positioned no less than 10 mm. Fixings should penetrate at least 25 mm into the timber battens without exiting the other side and care should be taken to ensure they’re not overdriven. Where sheet joints occur over battens they should lap by at least 19 mm. Once all the boards are fitted, the 5 mm gap at the base of the wall should be filled with flexible sealant.

Renewed hope

Old buildings add diversity to our built environment and rich heritage to properties. By taking advantage of the top-performing insulation materials such as Kingspan Kooltherm K112 Framing Board, homeowners and building developers can achieve modern levels of thermal and energy performance, whilst retaining internal space.

You can find out more about the Kingspan Kooltherm K100 range in our knowledge base, or to see more examples of our products in action, take a look at our case study section.

This concludes our series on timber frame construction. View the previous posts here:

  1. Tackling the housing shortage – going offsite
  2. Back to the future – the revival of timber frame construction
  3. Insulating timber frame – new build

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Kingspan Insulation is a market leading manufacturer of optimum, premium and high performance rigid insulation products and insulated systems for building fabric and building services applications.

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