A Guide to Installing Polystyrene Insulation Sheets

With a cold winter on the way and energy bills continuing to skyrocket, there has never been a better time to make sure that your property is properly insulated. There are several methods available and, here at Greengates builders merchant Accrington, we have a comprehensive selection of materials always in stock and made available to our customers at an extremely competitive price.
In this edition of the Greengates blog, we'll share with you a step-by-step guide on how to securely fix polystyrene sheet insulation to masonry walls. Polystyrene is a highly-efficient insulator and is also exceptionally cost-effective. 

  • First you will need to prepare the special adhesive. Follow the manufacturer's instructions exactly. 
  • Make sure that the surface you will be applying the insulation to is clean, dry and free of any defects.
  • Apply adhesive to the edges of your first polystyrene sheet. This should be done evenly and to a depth of not more than one inch. Then apply more adhesive to the reverse side of the board. If the wall is completely level, apply adhesive to the whole board and spread evenly using a comb trowel. For very irregular walls, apply six symmetrically-placed mounds of adhesive in equal volume.
  • Starting from the bottom corner, gently press the board into place horizontally. Check that it is completely level. 
  • Continue repeating the above steps with further polystyrene sheets until you reach the end of the row. Ensure that the edges are properly aligned: any gaps will reduce the performance of the insulation. If you need to cut a smaller piece of board to complete the row, do this using a handsaw. 
  • The next row should be installed in the same way except this time install the boards vertically. This will make the installation much stronger. Continue until the entire wall is covered. 
  • Leave the adhesive to fully cure. This can take up to 36 hours depending on environmental conditions. 
  • When the adhesive is fully dry, use a hammer drill with #10 bit to make holes at the intersections of board corners and in the centre of each board. The holes should be two to three inches longer than the thickness of the polystyrene boards. 
  • You can now begin inserting dowels into the prepared holes. This can usually be done by hand. If you need to use a hammer, apply minimal force to prevent damage to the dowels. 
  • Plastic screws can then be inserted to cover the heads of the dowels. Position the screw and lock into place using a hammer. Make sure that the screws are aligned with the surfaces of the boards. 

Polystyrene insulation sheets are available from Greengates builders merchants at a standard size of 2400mm x 1200mm with thicknesses of either 25mm or 50mm. Other sizes and thicknesses can be provided on request. Find out more details on the product page and look forward to a cosy winter!

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