arch way in wall

[suffolklad]

hi all i am about to knock through the old outside living room wall to my new extension, but got some probs.to start with is there a minimum width of opening for building regs? about seven inches to the left of the opening is the chimney breast and the right hand side of the opening above is a 3" x8" joist for wooden stud wall above and more2"x8" joists for floors spaced at 13" apart , this wall is gable end but supports floors.will cutting a slot and putting a box lintel for each side be ok i will support the floor joists under slot . and ? at reveals walls should be tied every 9" so how would i go about doing it after i have cut hole? all advice gratefully received cheers

 

[Static]

800mm clear opening for internal doorways is about minimum, but 900mm makes a nicer doorway size. Assuming a cavity tray was fitted at higher level when extension was added, a couple of box lintels should be fine. If not put in a standard external wall cavity lintel (which would be prob be cheaper either way).

A little worried about the " i will support the floor joists under slot " comment.

 

[noseall]

some builders make their openings (where applicable) 100mm wider than they need to be. this gives you the opportunity to fix 100x50mm studs down each side of the exposed masonry. this in turn gives you multiple fixing points for the door casing. only downside is you need to carry the wood -masonry join with plasterboard (to prevent cracking).

 

[suffolklad]

hi so is 800mm minimum wide a building reg requirement? and do i need to tie the cut walls together every 225mm at reveals as u would when building a new opening ? if so whats best way ? i had thought about 4" x 2" each side in cavity with frame ties to tie them together if needed anyway thanks for advice so far

 

[Nige F]

Resin Anchors.(not rhyming slang) like the replacement walltie firms use