Advice on opening up current external wall to new extension

[Anonnewbie]

We are in the early stages of planning an extension & remodel and trying to understand what we can do in terms of opening it up Vs avoiding cost where possible.

The back of the house is about 7m and we are adding a 3x7m extension onto that. it currently has 2m patio doors and a normal door in that wall.

Clearly if we leave the openings as they are it will save a lot of money compared to opening it up across the whole width which would give us so much more scope for great plans, but may be really expensive. What we really don't know is whether it would cost less to open it up but leave space for a structural column, or two columns, or a bit of wall, or only open the current 2m opening by another metre.

Does anyone have an idea how much difference the size of the opening makes once you start knocking out structural walls? I guess I'm thinking if you pay £5k to open the 2m to 3m but it's only £7k to have the whole lot removed then I'd maybe rather pay the £7k, or at least keep it as an option if it would really improve plans.

And as it stands with the various plans we have it'd be really easy to work in a column somewhere in the middle so does that save much money?

A benefit of keeping existing opening is you keep echoing noise to a minimum. The drawback of any open concept is you risk the space being cacophonous.

Don't know about the cost difference I'm afraid but one thing to consider is the light - the more you open it up, the more chance you have to get light into the existing house as there is the potential for this to get very dark when the extension goes on. Equally you don't want it too open as then you don't have any walls to put anything against! I think the main thing re cost is whether you need a supporting beam, I suspect if you need one there won't be that much difference in cost between say 3m and 4m.

It's hard to visualise exactly what you mean but when I extended I took down the wall otherwise it would have looked weird with an external window and door in the middle of the house. In my case I had to add steel works which was around £3k at the time (10 years ago). I considered it money well spent.

If you're worried about the room being too big you can always add sliding doors but to be honest you'd probably find the room rather gloomy. I added a sloping roof in my extension so I could put velux glass windows in which keeps it all light and airy.

You're only doing this extension once so I wouldn't scrimp on costs to make it how you want it to be. You'll never regret the money you spent to get it right. You'd definitely regret not spending a few extra thousand to get it perfect.

More than cost it will have an impact on the size of the beam you are likely to need. When I looked at putting in a 7m opening the beam had to be so thick that it impacted headspace, with an extra support in the middle it was much more acceptable.

Thanks that's really helpful. It's a small house and only going out 3m so most of it should remain light with skylights and I don't think it will feel cavernous. It's more a case of ideally we still want walls but about a metre back from where they are now. I think realistically we've done as much planning as we can and need a professional now!
The low beam is interesting but actually probably not a problem. If we have a kitchen in the extension, being able to tuck a fridge and pantry under the beam will give us the ability to make the kitchen really nice and not overcrowded.
Totally agree about the cost being worth it - a builder gave me the impression that if we want to keep costs down the best thing to limit is use of steel, but a bit of research suggests it's only a few thousand, which I don't think is huge for the benefit. I definitely want to spend on the structure - we can always scrimp on furniture and decor which can be updated later!