Fitting pvc french doors.

[carlos21]

Hi iam hoping to fit french doors into a new build extension, the wall is concrete block with cavity and pir insulstion.

Is the positioning of the door within the wall the same as with windows? Ie mostly inline with the insulation. Are the doors then fixed in place with tie straps? 

 I have found a second hand door which is the right colour etc but is about 200mm narrower in width, and iam wondering the best way to make good on the exterior.

 

If the door is positioned inline with the insulation should i place compqfoam in the cavity for a base.

Hope this makes sense, a few photos of the doorway at present.

Thanks carl

[Nickfromwales]

On 23/04/2026 at 20:46, carlos21 said:

Hi iam hoping to fit french doors into a new build extension, the wall is concrete block with cavity and pir insulstion.

Is the positioning of the door within the wall the same as with windows? Ie mostly inline with the insulation. Are the doors then fixed in place with tie straps? 

 I have found a second hand door which is the right colour etc but is about 200mm narrower in width, and iam wondering the best way to make good on the exterior.

 

If the door is positioned inline with the insulation should i place compqfoam in the cavity for a base.

Hope this makes sense, a few photos of the doorway at present.

Thanks carl

You could use 2 layers of CF200x50mm thick, either side, bridging both internal and external blocks, which would also close the cavity whilst giving you something solid to fix into. Way overkill but if you want a good standard then that's easy and robust (but not cheap).

 

Other option is to close with masonry, but that would need to be tied / toothed in to the existing blockwork to survive.