Remove a purlin in a loft?

[Beckside]

Hi, hoping this is an easy yes/no answer before I go looking for a SE...

4 years ago we had an extension out to the hip side of our 1960’s semi.

I want to now remove the purlin running from front to back that used to support the roof hip rafters before the extension.

It doesn’t support anything above it now but I want to be sure it doesn’t have another structural function such as a cross-tie (not sure of the name here) bracing the sides of the roof to prevent spreading.

There is one hoist hanger coming from it to stiffen the ceiling joist below but can probably find a way around that.

Photo here of the purlin looking from the new hip side. I can dig out the original and new roof drawings from the extension work if that would help.

Thanks a lot for any help, Dave

 

[Fred61]

Hi Dave it looks from your pic as if there is a post from under the hip board on the right down to a ? Wall. If that’s the same on both sides then the purlin dose nothing. Very often we leave them on cos it’s easier than trying to get them out. They are often not needed after this type of extension. Fred

 

[Doggit]

But is that a purlin, or acting as a brace.

 

[Ian H]

It's keeping the front and rear purlins apart isn't it? Without it the small rafters and roof tiles front and rear will be able to push inwards.

I'm no expert by the way, I just pulled off my own roof which looked very similar. The purlins lifted off the posts slightly when the tiles were pulled off so there are definitely some forces involved.

 

[bobsuerita]

yes i wouldnt remove as said above it will be bracing the 2 purlings either side
aslo the hips will be a weak part of the roof without the jacks so gotta stay

the only way to get over it is if you have a spline wall through the center you could brace it down to them but you wouldnt be gaining anything

 

[Beckside]

Thanks for all your comments guys.

Sounds like it it staying in then unless I get someone to take a closer look. There isn’t any spline or other internal wall to take load down or brace from.

 

[tony1851]

IMO it's now not doing anything. Its original purpose would only have been to support the relatively small rafters over the long span from ridge down to wall plate. The main structural items are the hips; as long as they are adequately propped, the roof will be fine. The original ceiling joists (presumably running front-to-back) will tie opposite sides of the roof together.

 

[John D v2.0]

Think of it this way, there's effectively a break/hinge in every rafter that crosses the old hip. If the hip is held in place nothing moves. If the hip is bending, you have a problem.
Since hip boards are not really fundamental structural elements of the roof, they just tie all the rafters together in the right relative positions, you need to make sure the hip board is adequate supported.
Now the remaining purlins and posts may provide that, but you need to confirm that they won't tilt inwards when you remove it.
Probably it will be fine, but when it's your roof it pays to be sure!
Good luck.

 

[tony1851]

Think of it this way, there's effectively a break/hinge in every rafter that crosses the old hip. If the hip is held in place nothing moves. If the hip is bending, you have a problem.
Since hip boards are not really fundamental structural elements of the roof, they just tie all the rafters together in the right relative positions, you need to make sure the hip board is adequate supported.
Now the remaining purlins and posts may provide that, but you need to confirm that they won't tilt inwards when you remove it.
Probably it will be fine, but when it's your roof it pays to be sure!
Good luck.

In conventional cut, hipped roofs, it's the hip that supports the purlin, not the other way round.
Granted, you will often see the purlin propped very near its connection with the hip, giving the impression that it is supporting the hip. This is just a convenience for the carpenter, because it is easier to prop the flat underside of a purlin, than it is to cut a skew-prop to the underside of the hip. But ultimately it is the hip doing the supporting, that's why it is often a very deep section, such as a 12 x 2.

 

[Ian H]

How do you like these ones Tony: 12x2's and a level wall plate for the Dutch end

 

[Mb constr Essex]

What was the outcome? Was it just for storage purposes? Me personally I'd build a dwarf wall either side and put collars across, above head height to stop potential spreading.