Pilkington Spacia from Pembroke & Nash Traditional Sash Windows
Their is now an alternative to the Slim line or Slimite double glazed unit. Pilkington have developed a fantastic new unit “Spacia” which offers the thermal performance of conventional double glazing in only the same thickness as single glass. Although their may be no financial benefits in this new technology, the performance is literally amazing. If your budget allows this new technology is available and suitable for nearly all properties regardless of planning status.
Traditional timber sash windows windows have always had aesthetic issues with thick double glazed units. We are now very competent in manufacturing sash windows to a slim profile whist incorporating 14mm and thicker double glazed units. These units are absolutely fine in all period properties, including properties with an “article 4” planning restriction. Their is an exception this rule, Listed building. Listed buildings council and planning committees are very vocal and instrumental in enforcing very strict criteria, when upgrading the performance of traditional wooden sash windows in listed buildings.
Not only is the thickness of the double glazed unit an issue for planning so is the depth of the spacer around the edge of the unit. As you can see by the diagram on the left, the slim line unit has a very narrow putty line within the rebate width. These timber sashes were designed for single pane crown glass which has no edge to conceal. So when upgrading listed buildings to double glazed we are required to fit units that do not have the edge of the spacer on show past the rebate of the sash – (Putty line & glazing bar edge). So what is the issue with narrow edge units? Although the slim units have a very good thermal performance the answer to that question is the failure rate of the unit. Failure of a double glazed unit is when the unit leaks, mists up and therefore becomes redundant as a thermal insulator. We have fitted thousands of these types of units over the years and the failure rate is nearly in double figures, roughly 2% of these unit fail within the first 18months. If you compare this to the failure rate (0.02%) of a standard double glazed unit with a 15mm rebate, which we use as standard in conservaton areas, the failure rate is huge. This costs us considerable expense in warranty replacements and inconvenience for our clients whilst the sashes are removed and the failed unit replaced. The manufacturers give us a 10 year warranty, but this a merely a token gesture when you calculate the labour expense and inconvenience of replacing the unit and the touching up of any damaged paint, which is not rembursed. These unit are not cheap either, with a square metre having a standard supply cost of around £100 + VAT, with a minimum unit cost of 0.3m. So for example a Georgian sash that is a meter square split into 9 panes will have a unit manufacturer cost of £100 / 0.3 x 9 (£300 + VAT). The cost of Pilkinton Spacia works out on a standard order of around £400 + Vat per sash for the glass supply cost Plus glazing. As with Slimlite units their is a minimum glass order size/cost.
Pembroke & Nash through Pilkington Glass UK are now thrilled to be offering this latest technology. We have been given the latest literature for your information. Please see the specification brochure below. You will require a suitable internet browser with a PDF viewer. Please give the document a couple of minutes to download.