The bones of your Trex composite deck is the sub structure or stud. Spacing of joists TrexProtect Joist tape and Composite posts all add up to a long life decking project along with graded timber.
Have you asked your contractor about the build?
So you have had your quotes and one company is £900 cheaper Bargain! or is it ? What Timber are they using? how will they protect the joists ? how will they prevent post rot?
Always ask for a run down of the sub structure and components.
What do I ask ?:
What grade is the timber
Do you treat cut ends
Do you use joist tape
Do you use composite posts
What gauge fixings will be used