"Is there a grading standard used for aluminium products supplied by the various suppliers?
The reason why I ask the question is because of the huge price differences for what appears to be the same/similar products.
Your assistance will be appreciated."
There is no "standard" grading for aluminium doors or windows. The pricing will depend entirely on the quality of the product that you want to install. If it is not fully specified then anything goes and you take what you get.
The whole process starts with the quality of the aluminium that the particular manufacturer uses. There is cheap inferior aluminium from certain suppliers and then there is obviously good quality aluminium from known reputable suppliers.
The second and most common mistake that the end user makes is that they don't specify the aluminium casement thickness that the windows are to be made of. Some manufacturers may use the thinnest casement and a low quality aluminium while another will set a minimum casement standard for his business and only use quality aluminium. The casement thickness selected for any door or window will also depend on the application. Windows and doors that are subject to high wind or rain could have a different casement to ones in less exposed areas.
At the lower end of the scale is the 26mm and 28mm casement thicknesses. The 30.5mm casement is the most common one used in a domestic application if nothing is specified.
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The next step up in the range is the 34 and 38 casement sizes and for those who require a better quality product for aesthetic reasons. For really bad weather or special applications there is a 42mm casement thickness that can be considered. There is also an application where an outer frame using a 72mm section is combined with a 26mm or 28mm casement insert which will be suitable in some instances.
The last area that will make a price difference is the profile finish which can be anything from plain annodised to epoxy coated and the quality of the hinges and locks that are used.
Each combination of aluminium quality, profile thickness, finish and hardware will make a difference in the final quote and my advice to you would be to consult with a reputable manufacturer and sort a detailed specification for your particular application out so that when you are getting prices from various suppliers, all of them are quoting on the same thing.