French Doors in Place of Window - Lintel Advice (RSJ?)

Hi All,

Long time browser, first time poster. Hopefully I can contribute at some point rather than just ask. Now in our second Victorian house which we are renovating while we live there one room at a time!

I am going to replace the dining room window (which is in a bad way) with patio doors, which I have already bought. They are solid pine and double glazed. I have done a lot of reading on this so know about all of the building reg implications etc. The opening for the door is only about 200mm wider than the current window but I will obviously need to replace the lintel. Catnic recommended the CN71C as this is an external wall on a two storey house and I think the joists above run perpendicular to the wall.

My friend has a spare 152x89 section RSJ which I thought would probably be a suitable replacement. It is long enough to allow at least 150mm bearing at each end. What do you guys think? I would probably use some engineering bricks as a padstone but where would I install the lintel? The wall measures around 270mm in width so it should just be solid brick. Do I place the lintel right in the middle or towards the inside wall or is this RSJ simply not wide enough? Maybe I would need two of these or could use steel bearing plates to spread the load. The external wall is rendered so no problems with cosmetics on that front.

Any help would be greatly appreciated because I want to do a good job on this.

I forgot to mention the opening is only 1260mm wide.

TomaszP said:

I forgot to mention the opening is only 1260mm wide.

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The 152x89 won't be wide enough to support a 9" wall, unless you use 2 of them or weld a plate on the bottom.

RonnyRaygun said:

TomaszP said:

I forgot to mention the opening is only 1260mm wide.

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The 152x89 won't be wide enough to support a 9" wall, unless you use 2 of them or weld a plate on the bottom.

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Thanks for the advice Ronny.

Would the plate not be better welded onto the top of the rsj to support the bricks above it? It has the padstones at the bottom to spread the weight although i suppose i could weld plates at either end of the bottom.

The beam is actually 2100 long so could i just have extra long bearings and not have padstones?

I will probably just get another 152x89 beam as it will still be cheaper than a £100 catnic lintel.

I would definitely use two 140x100mm concrete lintels.
So much easier for plastering & rendering over, and no chance of the extermal one corroding...

themiddleagedun said:

I would definitely use two 140x100mm concrete lintels.
So much easier for plastering & rendering over, and no chance of the extermal one corroding...

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Getting two 140x100mm concrete lintels would actually be cheaper than buying an extra piece of rsj, which would be about £55. And true that they would be easier to finish. I guess I was just unsure about what would be strong enough and would much rather over spec as I don't intend on consulting a structural engineer but surely two prestressed concrete lintels would do the job.

If your BCO is anything like ours then he'll want calculations from a structural engineer if you use RSJs. For a prefabricated lintel he'll just check the bearing, look at the makers label and sign it off.