Measuring for new french door

[omph]

We currently have a patio door which we want to replace with a french door. The patio door has a timber frame around it. I plan on removing the timber frame and installing the door up to the walls. Questions:

1. Do I measure it from the inside or outside ? I have measured from the inside and found the top width to be about 1cm smaller than the bottom width. I am guessing I should use the smaller reading as a base and subtract 10mm from it. With that said, the plaster does look a little wonky and I suspect that may be what's giving me a different reading for the top.

2. What trims will I need to conceal any gaps.

3. I would prefer it to be a tight squeeze, 2-5mm on each side, so that I can plaster around it and not have to use any trims (they tend to look tacky imo), is this advisable ? I know plastic expands.

 

[^woody^]

You measure the structural opening on the outside, not the plaster on the inside. I would give the supplier the opening dimension and let them make the allowances. Make sure you allow for any protruding bricks

You should not need trims if you are making the plaster good.

 

[Notch7]

We currently have a patio door which we want to replace with a french door. The patio door has a timber frame around it. I plan on removing the timber frame and installing the door up to the walls. Questions:

1. Do I measure it from the inside or outside ? I have measured from the inside and found the top width to be about 1cm smaller than the bottom width. I am guessing I should use the smaller reading as a base and subtract 10mm from it. With that said, the plaster does look a little wonky and I suspect that may be what's giving me a different reading for the top.

2. What trims will I need to conceal any gaps.

3. I would prefer it to be a tight squeeze, 2-5mm on each side, so that I can plaster around it and not have to use any trims (they tend to look tacky imo), is this advisable ? I know plastic expands.

whether it can butt up to the existing plaster line depends on whether the profile depth of the new frame works in the same place

also French doors are installed with the doors swinging in the frame -you then move the frame around until the doors sit nice and in line with the frame. So you cant guarantee the new frame will sit tight against the plaster line.

is there a vertical dpc needed?

 

[omph]

is there a vertical dpc needed?

Vertical DPC ? why would I need that ? some low mod silicone should be more than enough ? The walls are rendered, although I may need to patch it up.