Door threshold

[Callismichael]

Hi all

I would really appreciate some help. I replaced a window with a door and was left with an open cavity beefier the new door that sits on the outside wall. I have some under the sill of the door.

The void/cavity was fairly deep so I filled the void and left a depth of one brick thickness and had some spare rigid insulation. I lined the existing small void with a dpm and have cut insulation to size to bring it almost to floor level. My next job is to screed over the insulation.

What I'm worried about is as I've now filled the void am I creating a cold bridge which could lead to damp or is this fine?

Thank you in advance.
Michael

 

[John D v2.0]

Really the door should be in line with the insulation, but adding insulation to close the cavity will help.
Bear in mind the cavity space is pretty much outside temperature, so you don't want to connect it to inside.

 

[Callismichael]

Thank you. So now I've bridged this cavity (I think that's the term) should I have left it open as I've effectively joined the inner and outer brickwork. I'm struggling getting my head round how deep the dpm needs to go and whether I should have left the cavity empty and just users a closer so my flooring can rest on that?

 

[Callismichael]

Also am I right in thinking there could be a dpc deep below where the ground? I couldnt see one in the void but it was filled with rubble.

 

[Callismichael]

Really stuck and floor needs to be laid. Please help. I don't want damp problems.

 

[John D v2.0]

No I meant it's a good thing, a bridge would be something like steel or mortar. Insulation is much more insulating than air so you've made it even harder to get heat across.
My point was there's still a chance of a thermal bridge I.e. condensation due to the fact that the door is not inline with the insulation. However you can't do much about that.

 

[John D v2.0]

And regarding rising damp, your insulation should go down below in the cavity but the fill at the base of the cavity should slope outwards to keep the water out. You should avoid penetrating damp by ensuring ground levels outside are 2 bricks below the damp proof course at all places.

 

[Callismichael]

Thanks for the advice. There are 2 courses of bricks outside. Cavity was really deep so would be hard to make a slope of that makes sense. My concern was that I had joined the inner and outer with mortar but I guess all front doors are like that. Would i be best laying the dpm on top of the insulation or lap under insulation and up the door frame? How would I join it to the Dpm sticking out of the inside of the door sill?

 

[Callismichael]

Also where do i find the existing dpm? all I can see is a strip of DPM which I presume the cavity wall bricks sat on. I'm not sure if also I can get enough screed fill to stop cracking beacuse the insulation is there I will probably only get 20mm screed on top. Before filling and leaving a depth of one brick course im not sure whether I should have lined the cavity with DPM first. May have to get a builder to finish off as i'm feeling a little baffled. Read other posts but they seem slightly different from the way i'm doing it.

 

[Callismichael]

No cavity fill on this one? confused.

 

[Callismichael]

is this overkill? ie insulation etc? Shoulf i have lined the cement with DPM or does this not matter as its below door DPM? just dont want to create a load of damp and it be trapped under the DPM but is that normal anyway to have tonnes of damp below dpm so long as it's not entering the house?