Recent experience putting RSJ for a new window

[Venture321]

Hello
Just want to get some feedback - if anyone has cost experience of making a new window opening on outside wall at ground floor on a detached property with ground and first floor. The opening will be 3m x 1.5m in the centre of the wall and the RSJ I shaped (150mm x 250mm )will be around 3.5m.

Solid or cavity wall? For a cavity, you need a catnic.

Sorry - it's 2 bricks outside wall and another side of house there is a I Shape RSJ above a window so he assumed it would require RSJ

I would have thought a span that long would be ok with a catnic……they are not cheap at that length but easier than installing an rsj.. if the floor joists are sitting on it then I’d go rsj. But i suppose a window opening is lower down so one of those would be fine. 150mm bearing on each side would be fine.

www.wadebuildingsupplies.co.uk/products/catnic-thermally-broken-lintel-tx90-100?variant=45108519796982

You can get different sizes ( widths ) of them depending on the size of your cavity, or if you have no cavity.

Hi - from the building work I have done in the past would I be right in assuming that this can be achieved in a day - using a catnic. I have mostly seen RSJ being installed.

I doubt a day is enough time. A 3m wide hole will probably require needles to be put in with acrows to support. Then use a disc cutter to cut the hole, and remove enough for the lintel, then knock it all out and make necessary repairs. Possibly, though unlikely, you need padstones fitting. You may need the external brickwork repaired. If it’s old brickwork that’s essentially only held together by compression then some may come lose and need relaying.
You have a builder involved by the sounds of it?

The joist in the ceiling are not resting on the wall in question. Not sure if that makes it easier to create the opening

Makes it worse in fact. The joists can be supported and then hold up brickwork above.
Do you have an external photo of the wall in question?
The problem with old houses is the brickwork might be decent and stay up relatively well, or be rotten and start sagging.

@HellsBalls External is rendered this is the inside of loft on the first floor.

It makes no difference. The brickwork above can be supported using strongboys on the acro props while the lintel is installed.

I would say its more than a days work, maybe 2 people could get the opening cut out and the lintel in,in a day ? Depends on if they are cutting through with a disc cutter or toothing out. Toothing out is a lot more work.

No loft insulation?!?!?!
As it’s rendered, as @Diyextension says, a bit quicker as they can use a disc cutter, at least outside.
What quotes have you got so far?

Also to add, while cutting the hole may be quicker as it’s rendered, they also need to make good the rendering. A box lintel/catnic would be better than an RSJ. Hopefully it’s decent and doesn’t just all come off. If it’s painted then you’ll want the whole wall repainted at some point.
You might also want to consider internal or external insulation. In for a penny, in for a pound.

@Diyextension I always wondered when the acro props support only part of the brickwork is there a risk that the unsupported brick give way😀 like the red line in the picture

The acrow is not just supporting what is directly above it, it’s supporting an upside down triangle. So the 2 acros load bearing triangles intersect about 3 courses up. This only leaves about 9 bricks either side unsupported. Sorry for the mansplaining!

So I guess if you are opening up 3m then probably need 3 strongboys and props?

Maybe 4. Any quotes?

You are right in theory, the bricks that are not supported could be/come loose with the banging thats going on , if you like you can put something across to support all the bricks .

like this.

@HellsBalls 1 guy that came said big job anything from 3-4k. My guy ain't paying that - I am going to try and get a couple more quotes. Nice to learn from other peoples experience.