UPVC Door frame fixings

[bantamsilver]

Doing a refurb on bungalow and have discovered water at both bottom corners of a external door frame. Must have been happening for a long time as the floor boards are rotten at these corners. Can I assume that there should be no fixings at the bottom of the frame. In this case there are fixings about 1" from the corners so I assume that water is either going past the rusted fixings or the frame is cracked. Budget was tight on this job and to date it is well over budget so replacing the door and frame is not really an option. Has anyone seen these sort of leaks before and is the solution a can of squirty foam.
Ta

 

[Gazman16]

Timber, Ali, PVC, Composite?
What sort of threshold?
Is there a cill?

Pictures speak a thousand words!

 

[bantamsilver]

Gazman16,
Apologies for the late pics. As you can see not a pretty sight, and in my trade shoddy work can mean fatalities. Install was done by "Reputable" company(now defunct) a few years ago with fully trained and experienced installers.....
No pics of the reveal, but from memory it is about 1" gap. Looks like they had shares in the silicone factory - if 1 tube don't fill the gap then use 2, and if 2 don't..... There were no packers under the frame and the gap you see was covered by a saddle inside and plastic cover strip on outside. Basically a Sh1t job but seems par for the course with some trades. I am going to try the dye trick and pour down the front section. Water does exit the drain holes but the frame might be cracked thus leaking at mitred corners.
Anyway, for all looking, this is how not to install a UPVC door and frame.

 

[Gazman16]

Lovely thats better.

Technically top and bottom fixings are recommended by manufacturers, Personally I don't (except on very large doors or doors with sidelights) as like this it does increase chances of leaks.

All fixing should be at least 150mm away from the corner welds to prevent cracking from thermal expansion, Especially on a dark colored frame.

I cant see if the bottom fixings are on the internal or external half of the threshold? Basically the external half is the drainage system so if they have drilled through that its only going to increase the chances of leaks. Also any fixings down through should be siliconed so the screws can seal the holes as they go through.

As you have a good bit of access under the frame I would seal up the fixing holes (top & bottom) and do away with those fixings. Also check that the frame wasn't made incorrectly, They may have routed out concealed drainage holes underneath the frame for being fitted on a cill.
If you google "pvc door concealed drainage" and click on images you will see what I mean.
If it has these holes seal them up too.

Once those holes are sealed pour a few cups of water into the threshold to make sure it only comes out of the 2 drainage caps on the front of the frame.

2 other things to consider are:
Thermal bridging as the concrete threshold goes right through to the inside it will always be cold and attract condensation/damp/mold. Generally this is something you just have to live with as its the way the house was made but as you have half of it dug out anyway you could try to find a way to add an insulation barrier and some DPC.

The other thing is penetrating damp again due to the concrete, A few good coats of blackjack should sort that though if your not going to go through the hassle of adding insulation and DPC.