Answer
.
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double glazing will add
little value to your house, but it will make it more saleable as the prospective buyers will consider this to be one less thing they will have to do if the buy your house.
a conservatory however, if done tastefully will add thousands to the value of your house,
if it has heating, nice blinds, and opens out on to a lovely garden.
by the way i used to be an estate agent
