Firrings (tapered wedges)Price CalculatorWe cut our firrings (tapered wedges) from timbers to your bespoke sizes. They are mainly used to form a slope or taper on flat roofs to make sure the rain water runs off. They can be used to level floors or ceilings. They are fastened, using nails, to the top of existing joists and then sheeted over. See the diagram below which illustrates the general shape of a firring. We stock an off the shelf firring that may work out cheaper.
As a guide for deciding on firring height a minimum gradient of 1:80 is usually required. Anything steeper that 1:80 could be a waste. Using the drop down menus below please choose from our standard heights and gradients or enter your own. This site is easier to use on a desktop computer than on tablets or phones. You can collect your firrings or have them delivered. For help using this calculator please ring 01623553797 during working hours. If you require firrings greater than 9.6m or firrings beyond the scope of this calculator please contact us for a price.
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Calculator Help and Information
Length of firring
The maximum stock length we have is 5.4m from which we can achieve a firring length of 10.8m by folding one half over the other. See diagram below. If you need longer please give us a ring or email in.
There are two timber thicknesses to choose from, 44mm and 69mm. 44mm is the most common. We have a far greater range of timbers in 44mm. There is no structural reason why 69mm should ever be used for a flat roof but we have included it anyway in case matching up to 69mm joists is desired. Delivery will cost more for the 69mm due to increased weight.
Treatment of firrings is not needed for flat roofs but we have included it just in case it has been insisted upon. Treatment is only available in the 44mm thickness. WARNING: treatment will be cut away from the tapered edge and maybe from the bottom edge as well.
Different cutting techniques
Photo of treated firring