Squaring off an arch

[EdTurtle]

We have an archway in the house that we want to square off and put doors in. Cant find presence of metal with magnets or metal detector, so i took a little bit of the plaster off. Is this a conrete lintel, and if so, am i ok in squaring the arch off - to the pencil line shown in the picture? Also, can i remove the bonding plaster from the bottom of the 'lintel' so i can put the door casing in? And finally, i will square off the arch to the pencil line, leaving a space between between the side of the arch and the new door casing, can i just fill this in with a breezeblock wall built alongside the old arch, or will i have to tie it into the blockwork thats there now?

Thanks.

IMG_20180123_210655

• EdTurtle
• 23 Jan 2018

IMG_20180123_210724

• EdTurtle
• 23 Jan 2018

 

[oldbutnotdead]

First one- the bonding plaster is doing nothing structural so hack off as much as you like. You might find some love and care was put into forming the arch-or you might not! Use your bolster with care near your pencil line- knocking plaster off is fine, you don't want to be chopping mortar or bricks.

Second one(your lintel)- hard to tell with only a brick-sized bit of plaster chopped off but it doesn't really matter since you aren't planning to remove any of the supporting brickwork columns.

For such a skinny little infill that won't be structural I wouldn't mess about with blockwork and tieing in- just get some 4 x 2s , frame out the sides, board and skim.
Fixing the head of your doorframe will be the biggest problem- if that is a prestressed lintel then drilling a load of holes in the underside isn't a good idea. Maybe use restraint straps (5mm heavy ones) fixed to the timbers and fixed to the masonry above the lintel.

 

[EdTurtle]

Would it be worth me taking a little bit more of the plaster off either side? Would the odd hole be ok in the lintel, in the front - for attaching the new architrave? I assume a restraint strap is L shaped, full of holes? If so, yes, that makes sense, and is very helpful - I wouldnt have thought of that!

Thanks

 

[EdTurtle]

Like these? https://www.screwfix.com/p/corner-braces-zinc-plated-103-x-103-x-22mm-10-pack/14177

or could this work?

https://www.screwfix.com/p/sabrefix-builders-band-stainless-steel-20mm-x-9-6m/59863

Thanks

 

[oldbutnotdead]

Well worth knocking a bit more plaster off to see what you've got (for peace of mind/sleepless night purposes, though if that arch has been up for more than a couple of years then however it has been supported is probably adequate).

The builders band is a bit more flexible than I'd like to use- the top of the verticals are going to be under a fair bit of lateral (to the wall) load when the doors are open. When the doors are closed the load will transfer to the headplate of the frame.

Those angle brackets are going to be a bit short

I'd be looking at some of these https://www.toolstation.com/shop/p50096?table=no- Screwfix probably do the same but the search on their site is hateful. Cuts OK with a hacksaw, if you've got a vice and a big hammer you can make your own angles. If you are accurate with your vice you can make U shaped pieces but it won't be essential as long as the verticals are flat to the brickwork. You could get 3 brackets (250 vertical, 83 horizontal) out of one of the above, gives plenty of space for fixing above the lintel

With the architrave you'd be best off using lost head nails to pin it to the new doorframe- no-one will see any gap between architrave and wall unless it is massive, everyone will notice a gap between architrave and timber. If the gap between plaster and architrave looks as if it will be massive when you offer it up then either plane the high edge of the doorframe down or caulk the gap or try (if you have relatively thin and flexible architrave) fixing architrave to plaster with no more nails or similar, let it go off then spike it to the woodwork.

 

[EdTurtle]

Thanks for the link, i did try and search screwfix as they are the only place we have here (except for builders merchants who i will ring around when i have time anyway) and yes, couldn't find what i wanted!

The arch has been that way for (we think judging by the dates written on the walls underneath wallpaper) about 30 years. It has definitely been that way for 4 and a half years since we have seen it anyway. No cracks, etc... i also dont think its a supporting wall, but cant be certain ( have made a small hole in ceiling and think there's a joist on top of it, but haven't made the hole bigger yet to be sure).

Only one more thing i'm unsure about. I can attach 4x2 to the floor, and the existing straight bit of the arch, but how will I attach it to the top of the archway, where it curves at the moment, if I am unable to drill the joist? Should i use the straps again, though i cant see this providing much strength, what would stop movement laterally, use two straps - one either side?

Thanks