North Wales Flat Roofing Contractors
Flat roofs must be built right and water tight let us survey your roof
As quality North Wales builders and experienced roofing contractors we construct many flat roofs across the area. Although a flat roof must be flat it also ideally needs to be constructed slightly off the level in order to drain and there are clear processes to follow and materials to specify as outlined here.
The flat roof needs to be load bearing so constructed from materials calculated and known to be strong enough to take a load across the roof span.
With new roofs the joist specification usually part of the design calculation and where we are dealing with a replacement or small extension we can call on proven experience or ask our building design people to specify timber joist sizes and if there is any need for wall plates or steel joists.
The joists are also retained using wall bars anchored to block work so that high winds will not lift the roof which is also constructed to minimise the risk of high wind getting under the structure. All these elements can be discussed with the local authority for confirmation if necessary along with insulation and roof covering.
The photos here are examples showing a timber construction with tapered top rails ready for the boarding and a lead lined valley for rain water drainage. The boarding is load bearing and laid flat and anchored onto the joists. Using quality modern roof felting with water repellent adhesive pre-applied the bond is torched to melt the pre-applied thermal bond onto boarding. The single torch and roll operation seals the boards preventing water getting under the felt or through the boards and the process bonds the felt preventing this from lifting under high winds.
Where the flat roof meets a wall we channel into pointing to introduce a lead weatherproof seal to encapsulate the joint into a waterproof line where rainwater running down the wall drains off across the waterproof flat roof. Overlaps on the felt rolls ensure water does not penetrate through the joints and typically such a roof is 15 years before any maintenance is needed.