It really depends on the type of doors you have - e.g. do they swing outwards or inwards? Do they have a 3-point locking system (top, middle and bottom)? Are the doors going to be exposed to heavy rainfall or excessive weather? If the doors are in-swinging, how old/what condition is the weather strip in? Do you know the make and quality of the doors/
If the doors are in-swinging e.g. they open into the room this may increase the chances of them leaking due to the fact that the internal seal will be open to the elements. If they open outwards then the seal should be fairly well protected.
A 3-point locking system will also help as in this instance the door will be locked to the frame in the top middle and bottom positions, ensuring that the seal is firmly sealed against the frame. If the door only locks in the centre, then at the top and bottom the seal may not necessarily be firmly against the frame and provide an adequate seal.
If the doors themselves are on the side of the house that is essentially weather facing and you are in a part of the country that experiences a lot of rain and/or strong wind then this may increase the chances of them leaking.
If the doors swing inwards then at the base of the door you should have a weather strip. This is a section that is fixed just above the base of the frame, to the door that prevents any rain water from just running down the door and sitting/seeping through the seal at the base. If you do have one, have a look at it and see what condition the seal is in.
As you can see there are quite a few different factors that could influence whether the doors could leak or not but if they are in good condition and of good quality and swing outwards with decent condition seals they should be ok.
If in doubt then it may be a good idea to get a upvc window/door company to check them out. Make sure you do your research on the company beforehand to ensure that they are reputable. We have a find a tradesman service that may help you here: http://www.diydoctor.org.uk/find-tradesmen/
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