Also referred to as concertina doors, multifold doors and trifold doors their continued use in home improvement projects featured in magazines and television programs such as 'Property Ladder' mean that Bi-folding doors are becoming a very popular alternative to French or patio doors. This is due to the much wider unobstructed opening possible and the low threshold options which make them ideal for use onto your patio or into your garden.Folding sliding doors are now specified in many new home extensions as standard as homeowners realise the added value this type of door will bring not just to their lifestyle but also to make their property stand out from the crowd when it's time to sell.