Loft extensions can turn out to be costly projects, whilst true that they can accentuate the value of your home it’s recommended that you check that what you want will fall within your budget before you start to avoid any unfinished works.
The cheapest option is a basic ‘room in room’ extension and these usually start around £15,000. They include, the reinforcement of the floor, a couple of skylights to allow in natural light, added insulation, a staircase to access the loft, electrics lighting and heating, and finally, fire safety measures to comply with Building Regulations.
The second option which does not require dramatic changes to the roof is to do the above and add dormer windows instead of skylights. This will increase the usable floor space and can be used to add head height in the loft which gives you more options when it comes to placement of the stairs. This will cost upwards of £20,000. However the average dormer loft conversion with a double bedroom and ensuite costs about £35,000–£45,000.
The most expensive option would be a loft conversion that includes ‘raising’ the roof or even changing the roof structure entirely. This option is the most expensive as it require the removal and rebuild of the existing roof. It also requires planning permission approval so you local planning permission application cost must be added on.
Another expense will be the additional design work that may be needed as it can be significantly more complicated than one of the other two types of loft conversion. This type of work is likely to cost upwards of £40,000.
Some companies will create a package type ready-made room which is fabricated off-site and craned into position. The benefit of this is that it is quicker than replacing the rafters and rebuilding the roof thus reducing scaffold hire and labour costs. However, this option can cost around £55,000 for the average home.