Just to illustrate the minefield of conservatory and window warranties this is an actual insurance claim we (my employer) are currently dealing with.
We (my employer) bought a 5 bed detached house for a member of staff which was 2 years old.
It came with a very large and spectacular Victorian conservatory attached to the back of the house and a 10 year guarantee (not insurance backed - but issued by the small family business that erected the conservatory)
The conservatory was so large and good looking, PR photographs were taken and the house we bought was featured in all the marketing material for the small family business as an example of their Victorian conservatory range.
Our employee moves in and during the first winter, reports several small roof leaks. The conservatory is now 3 years old.
The conservatory company send out an engineer and they adjust the roof panels and install new gaskets. Most of the leaks are cured - not all.
The employee complains every time it rains of persistent roof leaks. The conservatory company make two further remedial visits - then say sorry, the conservatory roof is twisting due to subsidence.
We notify our insurers, who send out a specialist engineer and he confirms that because the house and conservatory are built on highly shrinkable clay - it is indeed subsidence.
The NHBC foundations to the house are 8 feet deep - the conservatory foundation is 1 foot deep - just below the top soil and resting nicely on a thick band of highly shrinkable London clay.
We go back to the conservatory company and their 10 year warranty to make a claim - only to find the person we bought the house from, in order to save money, put in his own base, floor and foundations - the conservatory company erected their structure on his base but very wisely excluded any claim to do with the base and foundation from the warranty.
So we have a non-insurance backed guarantee, from a small family business which basically covers the frame of the conservatory but not what it rests on. The original owner skimped on the cost of the base to save money.
The base and foundation have now twisted so badly that the whole structure has to be demolished and rebuilt with new foundations.
The cost of demolishing and rebuilding the conservatory on a "like-for-like" basis is just under £35k and now 2 years after we bought the house the conservatory is still leaking every time it rains and the subsidence has become a lot worse. One corner of the conservatory has now dropped 3 inches and the roof is very badly twisted.
We ran the conservatory "warranty" past our company solicitors at the time of purchase and they thought it was OK as far as private company warranties go but as the warranty only covered the work which the conservatory company carried out - the foundations and base were not covered.
Buyer beware indeed.