What size opening and lintil for standard size fire door

[mrbg07546]

hi we are fitting a standard size door from hallway to garage.

What is the size opening required.

Some one said door size plus 80mm. That makes 918 which means a 1200 lentil would be just short to for a 150mm bearing. So I'm thinking 1300? Thoughts?

Also white should the height be

 

[kazuya]

my thoughts are measure the door frame you fitting and use those sizes

 

[^woody^]

No one makes a 1300 lintel.

A 1200 lintel is standard for many of the standard single doorsets though.

The height should be to match your other door head heights, unless you want odd heights

Don't listen to that someone again for any building advice.

 

[noseall]

There are small variations in frame sizes in terms of external, fire etc. I'd go and buy the frame and build the opening to suit. If you are doing a knock through then I'd allow at least 25mm up each side extra then line the opening out with dabbed plasterboard then fix your frame to the nice straight surfaces.
Don't forget to mark off your fixing points before dabbing.