Annexe Knowledgebase & FAQ's

Cladding your annexe with uPVC

Cladding an annexe, in construction terms, is the external waterproof layer placed on the skeleton of the structure. The most common form of cladding these days is Poly Vinyl Chloride (PVC). Also known as PVCu or uPVC.

It is a form of plastic which, in its plasticised state, is very flexible and used for operations such as the insulation coating on electric wires and cables. In its unplasticised state it is hard (although generally still fairly flexible) and in this state it is called unplasticised or simply uPVC.

uPVC is rolled and pressed into many different profiles and as a waterproof covering it is extremely versatile, easy to cut and not too difficult to fix to a building.

Its uses include facia boards, soffit boards, internal and external cladding, gutters and guttering parts, windows doors and a host of other components of a modern building.

By making uPVC sheets thin and doubling them up with a void in between the uPVC remains flexible and strong yet very light for ease of installation.

First, as with tile or steel cladding, a frame must be fixed to the building onto which the cladding sheets, or boards, are fixed.

PVC Cladding is a popular, versatile and maintenance free option for covering external elevations. It comes in a variety of colours and cladding panels can be fixed horizontally, vertically, or even diagonally should the design require. External Cladding can be installed over walling made up of any number of different materials including traditional brickwork, block and timber frames.

PVC Weatherboard Cladding is very traditional in appearance, echoing the barn style constructions of North America. Pastel coloured embossed cladding in general , and of course the perennial white option, has seen a huge rise in popularity in recent years.

PVC Cladding technology has progressed greatly in recent years, enabling manufacturers to now offer a totally colour-stable system by embracing plastic co-extrusion processes.

Styles of uPVC cladding
Shiplap and V Joint Cladding are differentiated by size and profile, Shiplap Cladding is a wider 150mm (6″) board as opposed to the V Joint Cladding which is 100mm wide (4″).

When comparing Shiplap and V Joint Claddings, Shiplap tends to look a little more traditional in appearance due to the wider overlap between each board.

Features and benefits of cladding an annexe in uPVC
PVC Cladding is effectively maintenance free as its skin is weather resistant and thus moisture cannot penetrate into the core of the board. Unlike timber therefore PVC Cladding does not deteriorate through rot, and also does not require the application of protective coatings to maintain its appearance and climate resistance.

Cladding provides an additional external barrier, it will benefit the building’s insulation properties and reduce thermal loss. This has been recognised by the A+ rating under the Code for Sustainable Homes. As well as its insulating properties, our PVC Panels also have acoustic properties leading to a reduction in background noise.

Much like timber, PVC Cladding is easily cut and nailed using traditional tools, and despite its durability these products are relatively lightweight so can be easily manoeuvred into position.

Is PVC Cladding Safe?
Shiplap and v-joint cladding boards all carry a reaction to fire classification of D-s3, d2/(AHM). This means that the system is not classified as non-combustible and may be used on buildings with no storey 18m or more above the ground and 1m or more from a boundary. With minor exceptions, the system should be included in calculations of unprotected area.

Although the spread-of-flame across the surface of PVC is limited, the material does tend to char and may fall away when exposed to fire. Due consideration should always be given to any combustible materials behind the cladding, which may become exposed in the event of fire.