Bifold door leaking at corner

[Super_Paulie]

Hello everyone. 

One set of my bi-folds leak in the corner(s). The obvious suspect is behind the end cap not sealed correctly, to get to it I had to remove a brick from my (almost) new wall.

I poured a pan of water in the drain, barely anything came out of the drain so I stabbed at the silicone and it all came pi££ing out.

 

Sure enough the silicone was a bit flakey, it took no persuasion to breach.

 

Now, when you open the door the track is basically bone dry, so the seals are all ok. Where is the water coming from...? It is open to the elements so I suspect the driving rain is going in-between the cill and the door, into the lower drainage and that's either blocked or the end cap silicone is happy to let it out right above my damp course instead. The drain and thus water is above the thermal break in the below image.

 

Would I be on the right lines to fill that miniscule gap between the door and the cill? I tested the drainage and must of the water came out at that point rather than through the "official" concealed drain. 

 

If so, what sealant is recommended, OB1, CT1, bog standard silicone?

[BotusBuild]

We had a similar situation. Our problem turned out to be a combination of a manufacturing fault that meant water was staying inside the frame rather than draining out and an installation fault.

Our fitters came back, removed the whole unit, dismantled the outer frame, fixed the manufacturing fault,  then bunged a tube of sealant in each end of the bottom rail to stop any water getting out the ends.

They refitted the frame with proper DPC. All good now

[BotusBuild]

On other windows I have put SWS air tightness sealant on the out join between the window and the cill

[Super_Paulie]

This has been ok for 8 years but since it was moved to the new outer wall of the extension I'm getting this situation.

 

Really there shouldn't be any water getting into it, the seals are sound.

[Super_Paulie]

It looks to me like water is getting in between the cill and the door. When I spray water there you can see it via the drain hole from inside the track.

However, there is no where for it go once it's in there, there is seemingly no way for it to exit the internal structure unless anyone can shed some light on it? Looking down the length on it I can't see any way for it to enter the cill lip and thus drain away. 

 

Should I silicone all along the front edge to stop this penetrating rain?

[BotusBuild]

That is where I put sealant.

 

What goes on the end of the cill? Is that where water is coming out (leaking)? Maybe you need to put sealant at the end of the cill to stop the water coming out of the ends.

[Super_Paulie]

It's an end cap but with sealant, I'll replace. But the fact remains that water getting under the cill is entering somewhere where I can't see a drain and it's sitting there for god knows how long with no where to go. Interestingly there are drains in the door track that lead to it, again with no where to go. When you look into them you can see standing water. Difficult to see, but the angled section of the internal cill can be seen here and it doesn't have any drains along it from that inside section.

 

I'll clean it off and seal all along the front I guess?

[Super_Paulie]

I drilled my own drain hole and tested the theory, sure enough any water getting between the cill and door then drained from this hole into the main cill that has drainage on the lip. I can only assume these holes were meant to be drilled by the installer, who for some reason didn't. I then siliconed all along the front edge. Filled the ends and put the caps back on. 

 

Fingers crossed this time.