Especially in the case of informative offers, they can be misleading, because you are comparing apples and oranges and you not even notice it. So how can you objectively compare the offers obtained and what should we look out for?

  1. To start with, make sure that you are really comparing windows made of the same materials. PVC windows with PVC windows, aluminium windows with aluminium windows, wood windows with wood windows, wood-aluminium windows with wood-aluminium windows. Price differences between one and the other can be as much as 50 % or more.
  2. Check that the thickness of the window profiles is the same. The price difference between 68 mm or 78 mm and 92 mm profiles can be 10% or more.
  3. Check that the window profiles are made of the same wood species (spruce, larch, oak, etc.). The species of wood also affects the insulation of the windows. 👉 Read more here.
  4. Check that the insulation of the insulated glass unit is the same between offers at the same position (0.5 W/m2K, 0.6 W/m2K…) 👉 Read more here. Additionally, check that the IGU spacer does not constitute a thermal bridge. 👉 Read more here.
  5. If your elements are of larger dimensions, make sure that the structure of the glass in the offer is of the same thickness. For normal sized elements (e.g. 1000 x 2300 mm), 4 mm thick glass (e.g. 4:/18Ar/18Ar/:4) is sufficient, but for larger elements (e.g. 2000 x 2300 mm), static requirements require 6 mm thick glass (e.g. 6:/16Ar/6/16Ar/:4) or more is needed (e.g. 8:/16Ar/8/16Ar/:8. Price differences can be significant. 👉 Read more here.
  6. In special circumstances, so-called safety glasses are recommended or even required. Where there is a possibility of falling to depth, laminated glass is recommended. For ground-level glazing, where there is a possibility of impact, toughened or laminated glazing is recommended. In windy areas (e.g. hurricane areas), glass of greater thickness is required due to the sheer static nature of the glass. Please check that the offer takes this into account.
  7. For panoramic (sliding) doors, check that they are comparable types. The most common choice, the lift and slide door, differs significantly in terms of price, aesthetics and functionality from the tilt and slide door.
  8. If you have tall and large elements, check two things: (I) Whether the manufacturer has offered reinforcements in timber elements with heights above 2.5 m (8.2 ft), so that you don’t have problems with bending of your windows later on. (II) If the element assemblies are on top of each other, the window manufacturer must check and calculate the static and wind loads, and consequently adjust the glazing panes and the window profiles accordingly, and, if necessary, provide additional reinforcements.
  9. Check whether the installation is calculated as standard or “RAL installation” or installation in three-level tape sealing, which is definitely recommended. If the installation of your windows is outside the plane of the external walls of the building (in the insulation layer), check that the offer includes additional elements or another system for fixing the windows outside the plane of the walls. If the windows will need to be installed on several floors or in a difficult to reach location of the building, check that the manufacturer has made provision for the windows to be handled and installed using lifts and that it is coordinated who prepares the scaffolding.
  10. Check that the accessories (roller blinds, blinds, screens, external shelves, etc.) are of comparable quality and features. Check with the window supplier who the manufacturer of these accessories is. In any case, the key is a coordinated and systematic solution of all the accessories connected to the window. This is best ensured by the window manufacturer, who knows the solutions from the accessory manufacturers, and these are supported by technical details.

Once you have checked all of the above, you may find that the offers are not objectively comparable and you will need to request a new offer. The differences between quotes can be as much as 50 % or more at the beginning, but later on the cost of your windows can increase dramatically once you are in the implementation phase. We want you to make an objective decision and to keep the cost of your investment as you intended it, so that your window investment is worth your investment.