Converting a doorway into an arch

[Simpo Two]

I'd like to convert an internal doorway into an arch - but not the rubbish sort of semicircle you get from Wickes and stick into the corners. I want to widen the doorway by about 6" and raise the top so I can have a nice Brunel-style flat arch. Only trouble is - there's a steel lintel in the way holding the bricks above up.

I'm pretty good at DIY but have never got involved with anything structural - is this something I could tackle myself or do I have to get a hairy-arsed builder and steel pit-props?

[Engineer1]

I'm no builder but from what you say the fact a lintel is in the way will mean that you will need to move it up and probably get a longer lintel as well as the current one will be 6" too short.

[Simpo Two]

Well, I presume there's a lintel. There are steel lintels over the windows (a great source of amusement when trying to fix curtian rails!) so it was a presumption. Property is bog-standard 1988 vintage, if that helps?

[robinhood21]

Something like This.

ETA: Oops, forgot to add the link. A tad late though!

Edited by robinhood21 on Wednesday 9th September 12:42

[Dark Helmet]

This depends on if it's a supporting wall, but generally if it's brick-built and there's more than a couple of feet of brick above the lintel and below the ceiling/floor above it should be possible. You will more than likely have to support the wall above the doorway whilst carrying out the work though.

If, when the frame is widened and the brickwork above removed, the remaining brickwork forms a natural bridge over the gap it will be OK. You'll only be able to judge this once the plaster is removed.

If in doubt don't take chances though.


BG

Edited by Dark Helmet on Tuesday 8th September 23:44

[Sam_68]

Simpo Two said:

I want to widen the doorway by about 6" and raise the top so I can have a nice Brunel-style flat arch. Only trouble is - there's a steel lintel in the way holding the bricks above up.

What you want is a segmental arch lintel.

The one shown is for an external cavity wall, but they'll make you one for a single skin internal wall too, and you can specify the rise and span you require to make the arch as 'flat' as you want.

The link given is to a company called Keystone Lintels, but Catnic and othe major lintel manufacturers will be able to produce equivalent products.

[Simpo Two]

Thanks Sam - although the arch in the link is the wrong shape - by 'flat arch' I mean one where there's a constant but decreasing radius curve so the ends finish vertically. Easier to draw than describe!

So, it seems that the secret is to let the lintel define the curve, then, er, bosh it in. It's the last part I'm not sure about!

[King Herald]

Simpo Two said:

Property is bog-standard 1988 vintage, if that helps?

Take an old hacksaw blade, pierce a hole in the wall with an old screwdriver, use the hacksaw blade to cut the cardboard wall to the shape you want, repair with papier mache, lick of paint. Job done. Good as new.

[herbialfa]

Half of an ellipse?

[Sam_68]

Simpo Two said:

by 'flat arch' I mean one where there's a constant but decreasing radius curve so the ends finish vertically. Easier to draw than describe!

Ah, sorry. I'd only just dragged myself out of bed before. On to my third cup of coffee now...

What you want is a parabolic arch lintel then.

If you're not sure about the boshing-it-in bit, it's time to start looking for a builder; also, technically if you're altering the opening in a loadbearing wall, it comes under the control of Building Regulations and you should really be submitting a Building Notice to your local authority Building Control department, but many people would just chance it...

[Simpo Two]

herbialfa said:

Half of an ellipse?

That's probably right, yes. Well defined that man! And I can draw one with two drawing pins and some string

Sam_68 said:

What you want is a parabolic arch lintel then.

That's the one (but it's not actually a parabola, even if it says it is - a parabola is the path described by an object thrown or fired from a gun, and since the start of the arch is vertical, the bullet would come back on your head)

Edited by Simpo Two on Wednesday 9th September 10:24

[Sam_68]

Simpo Two said:

That's the one (but it's not actually a parabola, even if it says it is)

Quite correct - what the lintel manufacturers call a parabolic arch is strictly speaking a 'three centred arch'; the alternative, as Herbialfa says, is a true semi-elliptical arch, but in practice you'd be hard pressed to tell the difference, visually, over a narrow opening width.

[Simpo Two]

Excellent - well that's the lintel sorted. Now I just need how to fit it without my house falling down... I think it may be time to find a 'no-job-too-small' geezer. (But certinly not the lying git who's currently building a nearby extension!)

[eps]

Are you able / willing to post a photo of the current arch?

[Simpo Two]

eps said:

Are you able / willing to post a photo of the current arch?

Have to pop out now but will do so later.

[eps]

Tip top, it might help to make a more informed decision..

How thick is the wall in question? (mm please)

What span are you looking to create? (mm please)

[herbialfa]

Hey Simpo!

Rather than buying a elliptaical arch (cost) you could buy a standard lintel and, as I emailed you get something like this!

Hope the link works............

http://www.stevensons-of-norwich.co.uk/products/ty...

They manufacture to the length/ width/ height you need!

[Simpo Two]

eps said:

Tip top, it might help to make a more informed decision.. How thick is the wall in question? (mm please) What span are you looking to create? (mm please)

Wall is 130mm thick
Span would be 950-1000mm

Current position:

herbialfa said:

http://www.stevensons-of-norwich.co.uk/products/ty...

They manufacture to the length/ width/ height you need!

Ooh, I like that! Where's my toga?

[herbialfa]

If you like that idea, I might be able to get someone to do it cheaper!

All it is, is a plywood mould, some savy and some expertise!

You've got my number so if you want any further info let me know!

[Sam_68]

I have to say, 900-1000mm will look a little 'weak', as you won't be able to get enough rise in the arch over that distance for it to look right.

Peresonally, I wouldn't consider that type of arch unless you had an opening width of at least 1500mm, preferably 1800mm.

And if that's the door in question (into a hallway), bear in mind that removing the door and just leaving an arched opening could compromise fire safety; depending on the configuration of the upstairs windows, you could actually be in breach of the Building Regulatuions (which could have insurance implications and/or cause an issue when you come to sell).