Bifold doors and cavity wall Help........

[shauny007]

Hello,

I have googled the hell out of this after I fell out with my architect for lying to me and can’t find the answer, so I thought I would join the fun and ask. I am not a builder but so far this has been an amazing learning curve.

I am building an extension and we have planned to put 3.1m bifold doors in to open up the back. Can anyone give me some advice on where they would position them in the cavity and how to support them if they bridge or go in the gap? I have taken the cavity closers out as they fall out when windy.

Pics below, thank you in advance

 

[Notch7]

Its hard to know the answer as it depends on the type of bifolds and frame section.

You need to consider head sides and bottom differently.

If the bifolds are top hung you need rigid fixings into the lintel. If you have a single steel you need to position the track so the fixings miss the web.

If you have double steels you need a packer or something bolted in place for your fixings.

For the sides, if the fixings end up in the cavity, you might need to fix with straps or special aly frame attachments.

At the bottom, hopefully you might get a few fixings in the cill. However carrying the cavity across an opening is not necessarily the best method -if the door sits on the outer skin, the inner blockwork should stop at concrete slab level so the insulation and screed can continue so floor tiles stop at the door threshold.


The in / out position of a bifold frame is up to you, but generally it can go about 25mm or so back from the outside face -and should be positioned so the cill protudes enough for drainage holes and or the drip to clear the outside.

Aly frames are thin enough to be fixed to the outside skin -I would think

 

[shauny007]

Notch7 thanks for the advice, hugely appreciate it

The bifolds are aluminium and the panels are nearly 100mm wide so there will be a bit of overhang, hopefully I can get away with it.

I love the idea of the outside skin and taking the floor up to the door, would you recommend I follow the dpc over some insulation for the cavity, before I screed up to the door (worried I will cold bridge the gap).

The steels an IG, I would like to think they will secure with side, top and bottom fixings but will have to wait and see. When you say web do you mean the strip in the middle (the weak point that bridges the gap)?

Thanks again, this group is awesome

 

[Notch7]

View attachment 165642 Notch7 thanks for the advice, hugely appreciate it

The bifolds are aluminium and the panels are nearly 100mm wide so there will be a bit of overhang, hopefully I can get away with it.

I love the idea of the outside skin and taking the floor up to the door, would you recommend I follow the dpc over some insulation for the cavity, before I screed up to the door (worried I will cold bridge the gap).

The steels an IG, I would like to think they will secure with side, top and bottom fixings but will have to wait and see. When you say web do you mean the strip in the middle (the weak point that bridges the gap)?

Thanks again, this group is awesome

On the floor, usually the inner skin of blockwork finishes flush with the concrete oversite. Then the insulation runs across and the screed finally over that. Ideally the insulation should be supported, but its possibke to get away with a 100mm cavity -sometimes builders put in some slate or a bit of steel plate or even a few backets screwed in place

In terms of the web, I was referring to an I beam -ie a structural steel that may be needed with a wide opening. An IG heavy duty lintel may have enough meat to use tek fixings straight in. Bear in mind bifolds often specify every 300mm and every 100mm where the doors park when open. Obviously if top hung.

You need to make sure the threshold is dead flat when fixed, a hump in the middle will stop smooth running.

100mm frame depth is ok, just sit back from external brickwork a bit, say 20mm.

 

[shauny007]

Thanks bud. Makes perfect sense