Altering roof bracing?

[Monkey Mark]

Our loft isn't suitable to be used as a room (such a shame) , but it's fine for storage. I've boarded one half and intend to do the rest at some point.
I'd like to put in a larger loft hatch as it's size and position in relation to the current bracing makes access awkward. Due to the layout of the hallway, it can only really go in one orientation. Problem is there will be a roof bracing right in the way.

What's the best way to alter the bracing whilst maintaining structural rigidity?

I've googled for answers including looking through loft conversions but can't seem to find the answer to this as they all seem to focus on the flooring.

 

[Myfordman]

I assume you have these horrid factory trusses made from minimal timber and metal plate joiners?

With some doubled up joists and rafters, and horizontal ties part way up the affected rafters and maybe short purlins bracing across to unaffected adjacent rafters you should be fine.
All down to maintaining timber stiffness and triangles to brace them.

 

[geoffshep]

This is what I did to put in a trapdoor, oriented across the joists - the recommendation is not to cut more than one joist.

 

[JonnyW]

Did the same as Geoff (as per his diagram). I lengthened and widened an existing access hatch so I could install an insulated hatch with the built-in ladder.

Just added a tie a cross the face of the cut truss, attached to the trusses either side.

My rooff is still up and has survived all that Scotland's tropical weather can throw at it.

Jonny

 

[gregmcateer]

+1 for the above comments.
Some also recommend doubling up the joists marked 1 in geoff's picture, to give some more rigidity. Though probably not necessary if they are decent sized joists, (which they may not be if only designed as ceiling joists).

 

[Phil Pascoe]

If there is even the most remote chance you will sell the property, I would get a structural engineer and building regs on any roof alteration. Having moved twice in three years I can tell you they are picking up on everything.

 

[MMUK]

All very well for a traditional build roof but I think the OP may have a pre-built truss roof

 

[geoffshep]

Yes, the picture seems to be of a traditional roof - but it works equally well in modern roof trusses. I've done it in two new-style roof spaces using that method. Incidentally, I scanned the picture from the Collins DIY book which is a great reference book but is very traditional in its methods and in its diagrams.

 

[JonnyW]

I've altered two designed truss roof to install a loft hatch. If it's done as per the diagram then she'll be fine.

Phil touched on a good point, the works may require a building warrant as it's classed as a structural alteration. So best check. I really don't think selling solicitors would notice, but you never know.

Jonny

 

[skipdiver]

Done loads of them for myself, family members and customers. Cut out the timber, put in 2 trimmers as per picture, job done. You are then left with a hole at a set width and may need to put timbers in to reduce the size of the hole if you buy a pre built loft hatch. If you are making your own, then that is not an issue. Never had any comebacks.

The only concern here is that boarding out a loft and storing stuff up there can lead to problems with ceilings sagging/cracking and plasterboard fixings popping. It needs to be done so it is somehow supported independent of the ceiling joists and there are a few ways of achieving this, depending on the structure you have.

 

[YorkshireMartin]

No option to relocate the opening entirely to avoid the truss work?