Internal Roof Timber question

**illcrabmagik** · 8th October 2009, 12:54 PM

I've been exploring our roof cavity with a view to converting it into a storage space. It's a pretty standard (if large) roof space for a house with a pitched roof, but attached to every roof timber supporting the battons that support the tiles is a pair of timber beams forming a triangle with the roof beam itself.

That may not have made sense and I don't have a photo so I'll try again.

There is a vertical timber joined to the angled roof timber near the apex of the roof. That extends down to roughly half the height of the roof , from that point another horizontal timber is connected back to the roof timber. Making a triangle.

Every main timber has one of these hanging off it. I have no idea what they are for because they don't appear to be supporting anything. Can anyone give me an insight?

Thanks very much.

**thumpergman** · 8th October 2009, 05:20 PM

its to strengthen the roof against outside loads (wind)
best thing to do is get the original roof plans and get a drafts person to draw up plans for your loft space otherwise it could or come tumbling down
cheers

**1canetoad** · 8th October 2009, 10:32 PM

I think you are referring to collar ties and yes they are necessary

Ben

**illcrabmagik** · 9th October 2009, 03:00 PM

Collar ties go from from rafter to opposing rafter. These things hang off the same rafter - so attached at the top near the apex, vertically down about 2m, then they make a right angle back to the same rafter. Making a triangle with the rafter.

I can appreciate that they do something but if all they do is form a triangle with the rafter without being attached to anything else it's hard to envisgae what sort of additional support they are giving.

**rat52** · 9th October 2009, 03:21 PM

Don't remove any part of a roof without an engineers approval

**rat52** · 9th October 2009, 03:25 PM

Sounds like you are talking about a truss roof

Are there metal plates each side connecting the timbers ( pics would help)

**illcrabmagik** · 9th October 2009, 03:35 PM

I dont have a pic but I drew one. Here it is. As you can see these things are attached to the rafter but because they don't brace against anything else it's hard to see what they do. If anything they would be adding downward weight to the rafter wouldn't they?

On a side note. I'm not proposing removing anything from the roof. I just want to know what these are.

Thanks.

**rat52** · 9th October 2009, 03:53 PM

I have, over the years, seen some strange things in roofs but from that drawing I have no idea what purpose they serve.

**glenn k** · 9th October 2009, 04:38 PM

Do you mean they don't conect the left rafter with the right rafter? Bit strange.

**1canetoad** · 9th October 2009, 07:46 PM

They may be left over dodgy scaffolding from when the roof was built. My boss when I was an apprentice was always coming up with demented scaffolding ideas.

**joe greiner** · 9th October 2009, 09:34 PM

Real photos would help in assessment, especially of their connections to everything else. At minimum, they probably enhance the stiffness of the roof framing against lateral and distributed vertical loads, by reducing the free length of the rafters; otherwise the rafters could buckle.

As said, don't remove anything without consulting an engineer - a local engineer, please; not one you meet on the Internet.

Cheers,
Joe - an engineer you met on the Internet

**mrp** · 11th October 2009, 06:53 PM

a picture would help alot :P

how large are the rafters themselves? it sounds like some weird truss

when was the house made?

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