Creating a doorway

[ECP90]

Hello, 

 

I am going to make a doorway between my bathroom and bedroom, making it ensuite. 

 

I've been watching a few videos and reading about how to do it. It seems doable even for a DIYER.

 

This post is looking for any information people can share about making a doorway. 

 

Points I've noted down, standard UK doorways are 826mm wide. Anyone go bigger? Lintel above the doorway is extra 100mm either side of the door. Would anyone go bigger? What thickness would be acceptable?

 

Above the wall where the doors going, there is only one beam across it. A builder had a look at it and said there no structural issues/its not supporting anything about it. 

 

Any thoughts/information would be much appreciated. Thanks. 

 

[Russell griffiths]

Minimum bearing for a concrete lintel is 150 each end I believe. 

[Oz07]

1 hour ago, Russell griffiths said:

Minimum bearing for a concrete lintel is 150 each end I believe. 

I think thats rule of thumb but can go smaller like maybe 100mm in some circumstances. I'm sure I've seen it written down before. @Gus Potter

[Nickfromwales]

100mm in concrete is fine.

[ECP90]

1 hour ago, Nickfromwales said:

100mm in concrete is fine.

 

How thick would you say it needs to be minimum?

[Nickfromwales]

1 hour ago, ECP90 said:

 

How thick would you say it needs to be minimum?

How thick for what? Wall or lintel?

 

The reference to 100mm is for each end of the concrete (pre-stressed) lintel to be sat over 100mm masonry the same thickness as the lintel. 
 

For this, you’d be using a 3” x 4” lintel

 

https://www.diy.com/departments/expamet-concrete-lintel-l-1050mm-w-100mm/150790_BQ.prd

 

[Russell griffiths]

The problem I’ve seen in these situations isn’t having sufficient bearing of the concrete lintel onto brickwork below, it’s the condition and location of the lintel onto small pieces of badly secured brickwork. 
 

cutting a hole up through a wall could end up with the lintel sitting on a small cut piece of brick instead of a full brick. 
removal of the plaster is needed as is proper placement of the opening or removing any small slithers of brick and replacing with full or half bricks minimum. 
 

[ECP90]

On 31/01/2026 at 00:46, Nickfromwales said:

How thick for what? Wall or lintel?

 

The reference to 100mm is for each end of the concrete (pre-stressed) lintel to be sat over 100mm masonry the same thickness as the lintel. 
 

For this, you’d be using a 3” x 4” lintel

 

https://www.diy.com/departments/expamet-concrete-lintel-l-1050mm-w-100mm/150790_BQ.prd

 

Apologises, I didn't mean thickness either side. I mean thickness of the lintel itself. 

 

I've seen one from jewsons with the measurements of 1200 x 140 x 100mm. Would that be standard spec?

 

https://www.jewson.co.uk/p/supreme-concrete-prestressed-lintel-r15120-1200-x-140-x-100mm-LNBRN155

 

The DIY one you shared is £18. The Jewson one is £68. Any reason for such a big difference?

 

Thanks. 

 

Edited 3 hours ago by ECP90

[Gone West]

I knocked through a block cavity wall, on my bungalow, a couple of years ago and fitted 1500 x 100 x 65mm lintels and they were about £15 each from the local builders merchants.

Edited 1 hour ago by Gone West

[Nickfromwales]

2 hours ago, ECP90 said:

Apologises, I didn't mean thickness either side. I mean thickness of the lintel itself. 

 

I've seen one from jewsons with the measurements of 1200 x 140 x 100mm. Would that be standard spec?

 

https://www.jewson.co.uk/p/supreme-concrete-prestressed-lintel-r15120-1200-x-140-x-100mm-LNBRN155

 

The DIY one you shared is £18. The Jewson one is £68. Any reason for such a big difference?

 

Thanks. 

 

Yes. The same reason I’ve been in Jewsons twice in as many decades. Also you’re looking at too big a lintel   

 

You don’t need a 6x4” as a 4x3” (100x65) is plenty for a doorway in single skin in most situations.

 

You mount this in portrait orientation, not landscape, btw.