Advise needed please

[sdpurr]

Hello,

First post so hope this is in the right place. I have fitted (removed patio doors) and installed French doors. The new doors are thinner than the old ones.

So I have plastered the gap on 3 sides of the doors, however the gap on the floor span’s the cavity wall. I really want to concrete the gap level to the floor. But the cavity is about 1 meter deep. I was thinking of just filling most of it with expanding foam and then concerting over the top. But would this hold? Any idea welcome.

Thanks in advance
Steve

 

[Richard C]

What do you mean by thinner, what type of French doors have you fitted? Assuming this is an external wall, fitting replacement doors/windows is controlled building work which requires a certificate of compliance. The doors & their installation must comply with current Building Regulations & is notifyable unless you use a FENSA registered installer.

What gap have you plastered? If you’ve bridged the cavity you will have continual damp problems. Similarly you must not fill or bridge the cavity in the floor; the way to do it is to extend the damp membrane in the floor over the cavity & up inside the new door frame & then level the floor over that; several ways you can do it depending on how much depth you have.

 

[sdpurr]

Thank you for the reply, as the patio doors were sliding doors they had a wide track, the new UPVC french doors are thinner. So the plaster on the inside of the house did not meet the new frame, so I have only plastered about 50mm of the old brick work so it is level with the the new frame.

The new damp membrane comes from under the door and meets a little lower than the level of the floor. If I just used a self leveling compound to level them up, under the membrance there is the cavity and this would not whole the weight of a person. I will try and take some picuters tonight.

Thanks again..... but still need advise

 

[sdpurr]

The first picture is the floor with damp proof, the second one is the damp proof lifted up and you can see the cavity. I need to get the floor level to the door but there is about a 1m cavity under the damp proof.

Please help.

 

[^woody^]

Expanding foam will do and then screed (50mm) on the top - too thin and it will crack

Ensure the DPM is fitted appropriately to stop moisture bridging and rising.

If you are unsure then you can place expanded metal across the cavity to reinforce the screed across the threshold

If using foam, wet the walls first to allow the foam to stick and not fall all the way down the cavity