We would like a side door on our extension and our engineer has specified that the wall width between the support column and door opening needs to be 665 min as per the image below, which is causing us some problems and seems excessive to me. 

 

I would like a second opinion on this please and if there may be a way to reduce this or a justification for why this dimension is required.

Thanks, in advance

Think it's needed to buttress the wall. As you would have openings both sides. See also Approved Document Part A.

You may be able to use windposts or another structural steel solution.

Windpost at the corner. Ask your SE for a detail.

 

5 hours ago, Temp said:

Think it's needed to buttress the wall. As you would have openings both sides. See also Approved Document Part A.

Good suggestion as a starting point. The justification for the 665mm comes from general guidance for small buildings. Once you move away from the the general guidance these simple (but also conservative) rules no longer apply.

 

3 hours ago, Mr Punter said:

You may be able to use windposts or another structural steel solution.

Yes agree on looking at wind posts.

 

Your SE may well have gone for the simple option to save you money.

 

What is also important is you maintain overall building stabilty so it does not blow sideways in the wind, or lean over if things are a bit off the vertical plumb.

 

Suggest you go back to your SE and ask them what needs to be done to meet your requirements and the cost implications. A good SE will be able to walk you through the design issues and explain in laymans terms what it is all about. Then you will be in a position to make an informed judgement. Communication is the key!