How to run pipes through insulation

Solid walls can often lead to draughty homes and high energy bills for owners, so it’s no wonder more and more people are looking to get them insulated. The typical way of achieving this is by fitting an external wall product behind a render or brick slip facing. Alternatively, if the owner wants to keep the existing building façade, you can fit dry-lining products such as insulated plasterboard.

Whichever route you pick; it’s important to maintain a continuous layer of insulation around the building envelope, which begs the question: Should pipework be run through the insulation?

The simple answer is, wherever possible, no. Every time you cut or penetrate through insulation you run the risk of damaging the performance of the insulation layer and vapour barrier. In an ideal world, any services should be moved to an area where no insulation will be fitted, however, the realities of retrofit applications mean that this simply isn’t always possible.

If you have no choice other than to penetrate through the layer, best practice details are available to guide you. By following these details, you should be able to ensure that the system limits the risk of condensation or additional heat losses as a result of air leakage and thermal bridging.

Obviously there are a number of different pipes which you may need to accommodate, from water pipes to flues, and the requirements may be slightly different for each.

If, for example, you have to run a gas or oil pipe through a solid wall fitted with insulated plasterboard, you should use a pad saw or core drill (a circular disc drill bit) to cut through the insulation to provide a snug fit and reduce the oversize to a bare minimum. Any damage to the insulation board should be made good by filling any large gaps larger than 10 mm with expanding foam insulation. The perimeter of the pipe should also be sealed with a flexible sealant.

For flue pipes, there may be a requirement to create a separation layer between the insulation and the flue pipe. This will vary depending on the operating temperature of the flue and the flue specification itself so be sure to check carefully beforehand.

In all cases, the installation of gas, oil pipes, flues, electrics and telecoms should only be done by a competent person such as a qualified electrician, Gas Safe, OFTEC, HETAS or BT certified engineer. It is also vital that ventilation requirements for certain combustion appliances are not removed, blocked or reduced in size. All works involving appliances, fittings or flues should be carried out in accordance with Approved Document J for England & Wales, or Section 3.17 – 3.24 of the Scottish Technical Standards and / or manufacturer’s guidance.

Getting to know… Kingspan Kooltherm K17 & K18 Insulated Plasterboard

Both Kingspan Kooltherm K17 & K18 Insulated Plasterboard have been designed on a simple principal: why do three jobs when you can do it just as well in one? The products combine insulation, dry-lining and vapour control in a single board, saving you a lot of time and hassle during installations.

As well as making your life a bit easier, the products also deliver when it comes to space-saving. As you know, for every millimetre of insulation installed in an internal wall application is a millimetre of living space lost, so it’s essential to keep constructions as thin as possible whilst also reducing heat loss. Thanks to their premium performance Kooltherm insulation cores, both products can achieve thermal conductivities as low as 0.020 W/m×K, helping to keep build-ups slim and the owner happy.

The products feature a 12.5 mm plasterboard facing which is pre-bonded to the insulation core. Kingspan Kooltherm K17 Insulated Plasterboard has a glass tissue based reverse surface making it suitable for plaster dab or adhesive bonded applications, whilst the composite foil based facing on Kingspan Kooltherm K18 Insulated Plasterboard make it an ideal choice for mechanically fixed applications.

For assistance calculating what type and thickness of insulation you need for an application, simply visit Kingspan Insulation’s free online U-value Calculator. The calculator is also available as a free app for Windows, Apple and Android devices.