Enlarging loft hatch question

Joined
16 Nov 2013
Messages
76
Reaction score
3
Location
Kent
Country
United Kingdom
Hi All

I've got a loft hatch in a hallway that needs to be made bigger. This is a bungalow whose main pitched roof is of Purlin type, with 4 x 2 joists running at ° to rafters.
The plan is to change the position of one of the trimmers - hatch door hinge side - then make a bigger door and reinstate the existing design only 1/4 larger in one direction (more rectangular).

I know it may be a "how long is a piece of string" question without knowing where all the load bearing walls are etc, but just wondering if you think a small mod like this would only have a negligible effect... or not.

I understand that joists are under tension if they run in the same direction as the rafters and prevent the external walls spreading (in a simple roof example) but I have joists that are at 90° to rafters, so I've been scratching my head envisaging what's currently under tension or compression, if at all, at the point of the existing hatch frame. However, there are purlin struts and ties at each end of the main pitched roof which I guess counters wall spread.

I've attached a few drawings and pics, so I look forward to your comments.

Thanks a lot

- All timbers in hatch drawing are 4 x 2
- I've included lengths of some the surrounding joists/timbers as it may help clarity

Drawings etc:
"Loft Hatch - RSJ" shows the location, in red, of the hatch in the building and an RSJ (therefore well supported from a loft load perspective)
"Loft Hatch Frame" shows existing loft hatch Joists/timbers (without hatch liners etc). The shaded trimmer is the one I intend to reposition so it will be moved to 102cm from the trimmer opposite.
Pics 1 to 3 are various photos of hatch itself. FYI, The ladder is temporarily mounted on the wrong side just for access.
 

Attachments

  • Pic - 3.jpg
    Pic - 3.jpg
    336.5 KB · Views: 44
  • Pic- 1.jpg
    Pic- 1.jpg
    247.9 KB · Views: 43
  • Pic- 2.jpg
    Pic- 2.jpg
    223.7 KB · Views: 47
  • Loft Hatch - RSJ.jpg
    Loft Hatch - RSJ.jpg
    193.9 KB · Views: 49
  • Loft Hatch Frame.jpg
    Loft Hatch Frame.jpg
    163.2 KB · Views: 46
Sponsored Links
Joined
3 Sep 2006
Messages
36,512
Reaction score
5,155
Location
West Mids
Country
United Kingdom
Doing what you propose should be no problem with that existing arrangement. Don't dwell too much on compression and tension or whatever, none of that is relevant.

You're better off screwing brackets and hangers etc, not nailing.
 
Joined
16 Nov 2013
Messages
76
Reaction score
3
Location
Kent
Country
United Kingdom
Thanks a lot Woody, just what I wanted to hear and definately, yes, I'm not a big fan of nails although they have their place.
 
Joined
16 Jan 2022
Messages
166
Reaction score
18
Country
United Kingdom
As woody said use hangers and screw it … you won’t have any issue making it bigger but I would double brace the headers
 
Sponsored Links
Joined
16 Nov 2013
Messages
76
Reaction score
3
Location
Kent
Country
United Kingdom
Hi Jake, thanks.

When you say double up the headers, I take it that's what I've called the trimmers (one of which is Horizontal in my sketch and shaded). Maybe terminology depends on the application. Apologies, this isn't my field.

If so, are you saying double brace, i.e. double up each "trimmer" 4 x 2, so have an additional 4 x 2 beside and fixed to the existing top "trimmer", then do the same for the bottom one? So, total 4 timbers, two at the top and two at the bottom?

Alternatively, is it the vertical timbers I've measured at 77cm centres in my sketch and double those up (although I think you mean the former)?
 
Joined
16 Jan 2022
Messages
166
Reaction score
18
Country
United Kingdom
Hope.this.helps., Yes trimmers., Not sure why I call them.headers ...always have lol .
 

Attachments

  • OIP.jpeg
    OIP.jpeg
    20.6 KB · Views: 36
Joined
16 Nov 2013
Messages
76
Reaction score
3
Location
Kent
Country
United Kingdom
Ah, gotcha. Brilliant, thanks for digging up that graphic, I'm crystal now. Good one Jake.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Top