Good Question. Below we have tried to indicate possible costs - this isn't a sales piece, more information. - If you'd like to see our kits go here. Otherwise this is an information post.
There are quite a lot of variables, such as post code - The market dynamics mean a roof in London and the SE will cost more to instal than a roof in say Leeds. This is due to labour and overheads costs being higher.
The big question however is are you going to do this yourself or pay for a builder/roofer to do it?
The cost impact for DIY is highly beneficial on your bank balance. Modern fibreglass roofing kits, such as those supplied by RKD and others, are easy to instal if your are a reasonably competent diyer (especially if you can get a mate to help). There is lots of advice and installation guides around, (RKD supply this) - it's not rocket science.
Obviously cost is dependent upon roof size , overboarding, new woodwork and so forth - so to give you something to work from we will use a 20sqm roof (typical garage or extension size) as an example.
A reputable and professional installer will charge about £90 per square metre for install - this would include OSB3 overboarding of the current deck once stripped back, all the materials and edge trims to complete the job in total. So the professional builder will charge anything between £1500 - 1800 for the 20sqm roof - probably more in the SE/London.
You also need to consider access, height, is scaffolding required etc which will increase the bill (not considered below).
So what do the materials cost?
Well a 20sqm kit from RKD will cost between £155 for a standard kit, £199 for a premium 450 gsm kit and £225 for a premium 600gsm kit (foot traffic) - Trims would cost about £80 - £100.
Assuming you have basic diy tools, screws. nails etc lets add a fibreglass tool kit just to be safe - this would cost about £40. Oh yes you'd need to include delivery charge and allow for VAT.
So the total materials cost for a premium, 25+ year guaranteed top of the range 600gsm kit with everything to complete the job wouldn't exceed £444. inc VAT
What about the woodwork - well RKD recommend use of OSB3 T&G boards which cost about £20 each (we don't stock these) - you would need 14 or 15 for a 20sqm roof - so with delivery let's say £300 - and add £25 for sundries such as screws, nails, silicon etc
Therefore the total cost of a top of the range fibreglass roof kit materials - including boards would be around £750 - All you then need to decide is if you are going to do this yourself or get a roofer to do it.
If you choose to do it yourself allow 2 days or a week-end - this time is how the extra grand for a roofer to complete arises.
REMEMBER WE'VE GIVEN YOU A TOP OF THE RANGE PRICE FOR A 20SQM ROOF which is 25 guaranteed and one YOU CAN WALK ON, SAY A BALCONY OR ELEVATED DECK.
What would a standard or premium 450 fibreglass roof materials cost then?
Approximately - £600 for a standard 450 gsm roof including boards, trims, tools - £300 without the boards
Approximately - £650 for a premium 450 gsm roof, including boards, trims tool etc. - £350 without the boards
So if you have the time, do it yourself - If you don't, and many don't. make sure you get at least 3 quotes, and if you can, get a personally recommended roofer who specialises in fibreglass.