French door with low threshold aluminium on top of cill

[Shlumaan]

hi, for my self-built garden room I've ordered a french door (1400x1990) with low profile aluminium threshold and a 150mm cill to sit below the aluminium frame. The reason for the low profile is this is going to be used as a woodwork space and the room being already elevated by 30cm off the ground seated on top of a concrete base, I thought it would be sensible to have minimal obstacles entering the room especially when carrying stuff in and out of the room. As for the cill, it is to make sure that water is drained outward. There is a overhang of 400mm at the front of the room so not so worried about water ingress. However the company said due to the Aluminium profile there are no drainage holes in the cill which surprised me.

Is it common to install low threshold ali on top of upvc cill? Can this set up lead to issues with water drainage and insulation?

Is the installation as straight forward as normal framed French doors? I can't find any videos demonstrating this particular installation, not even on the website where I purchased the door from.

Any thoughts would be helpful. Thanks, Shlomi

 

[crank39]

Really need to know what profile the frenchdoors and threshold are. Then depends if the doors open in or out but theres nothing wrong with sitting a low ali threshold on a cill infact its much better because A/ you get a overhang and B/ its easier to seal under a 150 cill and seal the ali threshold to the cill

 

[Shlumaan]

Not sure what profile it is, or what you mean but it's an option when you purchase French doors from AWM online. I can measure if you guide me what to measure. Sorry I didn't say the doors open outward.

I'm not sure how to sit the aluminium on top of the cill, does it go all the way back to the lip or is there another way of 'slotting' in? Do I screw it down through the aluminium or just let it rest with silicone in between?.

 

[crank39]

Ok from my brief research it looks like they use Synseal profile, Legend 70 to be precise and looking at my Synseal product catalogue it shows this low threshold for outward opening doors, it appears that it's not a drained threshold, the weather bar profile part screws to underneath each door so as not to allow water by, there's also the upstand which won't allow water into to building.

The low threshold just sits on top of the 150 vill right back against the little upstand, just run a bead of silicone along the 150 cill just away from the upstand and sit the ali threshold on top, also don't forget to close the ends off with the same silicone by running forwards at each end to stop water tracking sideways between the two cills and potentially wetting the inside walls

 

[Shlumaan]

Oh wow that's incredible! The company itself didn't give me any of this level of information and in fact quite the opposite they didn't want to give much advice knowing I'm not a qualified window installer. But your research must be right because they did say there are no drainage holes. It sounds like the design is good, is it not? In keeping water away.

Would you start with the cill, laying it level on packers and screwing it down? And then offer the door on top in the same way you described above? When you say to close off the ends you mean of the cill or aluminium or both? Thanks so much

 

[mrrusty]

Would you start with the cill, laying it level on packers and screwing it down?

My method of fitting french doors is to secure one side of the frame all tight and the other side only at the top with the cill just sitting on whatever packers it needs to be firm and level. Hang the doors and then any twist in the frame can be tapped in and out to get a perfect alignment on the door openers. I then secure the second side properly and cill. Works for me. No idea what others do....

 

[Shlumaan]

That's good advice thank you. Just wondering how would the aluminum threshold hold its position over time with heavy traffic if it is not screwed into the cill? Is it not a good idea to drive a couple of screws into the cill? Or even longer one that will be driven into the floor? Sorry for the amateur questions.

 

[crank39]

Ideally you wouldn't want to screw down through the threshold but if you absolutely must then I'd use some stainless steel self drilling screws, put them in then remove and pump the hole with clear silicone then refit the screw. A more failsafe method would be to screw through the 150 from underneath into the first chamber of the ali threshold near the back

 

[Shlumaan]

Okay thank you for the swift reply. I think I prefer the first method (just spoke to awm and they also said the same), as I would feel more comfortable with having the cill secured down first and then resting door on top of it. Good idea with silicone into the hole. I might be able to have the screw countersunk into the metal to avoid it sticking out, depending on the thickness of the aluminium. I think I'm ready then!