Door threshold detailing over cavity

[SBMS]

I think this might have been done to death, very often with no good conclusions, but we've got a significant amount of door thresholds on our ground floor (quite a bit of glazing).  I'm trying to solution the different options and have summarised three possible details (traditional brick and block with a 200mm cavity - blown EPS beads, not that that matters).

 

Can anyone comment on whether any of these options are not recommended, or whether the additional effort/cost, say, of running marmox or compacfoam (Detail 3) outweighs the potential heat losses from thermal bridging?  Does option 2 work (with the doors effectively bearing onto PIR and screed)?

 

This is to allow bottom fixing and support for a 160mm triple track slider system, and also sitting into the cavity as much as possible.

 

[nod]

Detail 2 

you need to break the block away and take the membrane and insulation right up to the outer skin To avoid cold spots 

Have a look at previous posts I put quite a few pics up showing this 

[SBMS]

3 minutes ago, nod said:

Detail 2 

you need to break the block away and take the membrane and insulation right up to the outer skin To avoid cold spots 

Have a look at previous posts I put quite a few pics up showing this 

Is this sufficient support for 9m of aluminium triple glazed sliding doors to sit on? The PIR/Screed won't cause undue deflection?

 

Also, if building from scratch, can you not just finish the inner block at that height, rather than breaking it away?

Edited September 2 by SBMS

[Andehh]

We were forced to do detail 3 by sliding door company, for flush internal to external floor detailing. It has left a noticable cold bridge of a few inches as the tile butt's up against the door on cold mornings, but with 8m of 2.4m glazing they wouldn't honour warranty unless sat on concrete.

 

Wife tells me to stod standing with my toes up against the glass complaining it's cold under foot. 😁

 

 

[SBMS]

3 minutes ago, Andehh said:

We were forced to do detail 3 by sliding door company, for flush internal to external floor detailing. It has left a noticable cold bridge of a few inches as the tile butt's up against the door on cold mornings, but with 8m of 2.4m glazing they wouldn't honour warranty unless sat on concrete.

 

Wife tells me to stod standing with my toes up against the glass complaining it's cold under foot. 😁

 

 

Detail 3? With the marmox blocks on top?

[Andehh]

Edit.... Double checked drawings and it might actually be detailing 1, it's been 18 months now and I can't fully remember! Apols

 

Ours doors are sunk flush with the screed though, so we have a flush threshold inside and out to the tiles, and no cill.

 

Means the metal frame sucks up the cold from the thermal bridge and then sends it into the tile/screed, hence my cold feet when I stand next to the frame... But 20cm out it's all lost in the warmth of the slab (hence wife 'well don't stand so close to the door then' comment)

 

Doing it again I should have done a thin layer of aerogel on the inner door frame, between them and the screed and had the tile bridge the 10mm gap... As a crude solution I have retrospectiveky considered.

 

It's the only thermal detail we really messed up tbh (albeit for the top 10% anal self builder, not the buildhub top 0.5% OK insulation detailing).

Edited September 3 by Andehh

[Andehh]

With the above in mind, I'd prob do detailing 3 but then aerogel as a thermal break against the block to the screed? Fix it in place prior to screeding so it is sandwiched.

[SBMS]

29 minutes ago, Andehh said:

With the above in mind, I'd prob do detailing 3 but then aerogel as a thermal break against the block to the screed? Fix it in place prior to screeding so it is sandwiched.

We also have a flush threshold - so our track is sitting so its flush with FFL/screed level (adjusted diagram below).

 

You've got me thinking.. Is the majority of the thermal bridging from the 'back' of the door track, and would the following detail - which is a variation of detail 1, help reduce that bridging - effectively reduce the cavity to the known bearing width of the door track and then do detail 1 with a PIR upstand adjacent to the screed:

 

I don't know where the majority of the bridging would occur.. obviously the track would still suck up heat from the concrete, but would transmission be limited with the PIR behind??

 

 

 

[Dave Jones]

if you want a level threshold, which you probably do. to thermal break it marmox directly under the cil same level as screed. Dont fill behind it with foam or any other non load bearing material as this is your finished floor surface. You are extending your internal floor to the outside skin and at same time breaking the thermal bridge with the PIR under the screed and the marmox block at screed level.

 

[SBMS]

1 minute ago, Dave Jones said:

if you want a level threshold, which you probably do. to thermal break it marmox directly under the cil same level as screed. Dont fill behind it with foam or any other non load bearing material as this is your finished floor surface. You are extending your internal floor to the outside skin and at same time breaking the thermal bridge with the PIR under the screed and the marmox block at screed level.

 

Hi @Dave Jones

 

Is the below right? Detail 5 or Detail 6?

 

[Dave Jones]

neither. need to look like this

 

 

 

[SBMS]

54 minutes ago, Dave Jones said:

neither. need to look like this

 

 

 

@Dave Jones  - would only one row (deep) of marmox across the cavity be required for a 186mm deep sliding door track? With your detail above most of the doors and track are bearing down on the PIR?

[Dave Jones]

no, the cill sits on and is fixed through the marmox block. insulation butts upto it.

 

the photo i posted shows it clearly.

Edited September 3 by Dave Jones

[SBMS]

19 minutes ago, Dave Jones said:

no, the cill sits on and is fixed through the marmox block. insulation butts upto it.

 

the photo i posted shows it clearly.

Marmox block = 65mm width. Track depth = 186mm. So where under the track is the marmox block positioned?

[Mr Punter]

1 hour ago, SBMS said:

Marmox block = 65mm width. Track depth = 186mm. So where under the track is the marmox block positioned?

 The Marmox are 100mm wide or optionally 215mm.  Depth (height) is 65mm or optionally 100mm.

[JohnMo]

Mine looks pretty close to this, but just used thermolite blocks, but installed a 70mm wide PIR upstand inside the blocks before the screed (in our case 100mm concrete), our doorway straddles the block and PIR, weight taken by brickwork.

 

[Dave Jones]

you need the 25mm pir the full perimeter, can include against the marmox but not needed.

[SBMS]

3 hours ago, Mr Punter said:

 The Marmox are 100mm wide or optionally 215mm.  Depth (height) is 65mm or optionally 100mm.

Is the thermal break just required across the cavity to outside brick junction (irrespective of the depth of the track), or should it extend past the inside edge of the track?

 

My example scenario shown below with a 186mm deep track:

 

 

Detail A looks much easier to construct? 

[Mr Punter]

Your door track is creating a thermal bridge between the brick and the screed.  A small strip of PIR before the screed would solve this.

[SBMS]

48 minutes ago, Mr Punter said:

Your door track is creating a thermal bridge between the brick and the screed.  A small strip of PIR before the screed would solve this.

@Mr Punter in both details or just in detail 2? Is the second matrix block required in detail 1?