Re Purlin-re roof

[scruffybiker]

Hello again,

We are getting our roof re felted/battened etc in the near future along with 3 rafters. But I found some rot in the purlin which I told the roofer about but didn't say anything at the time , just said he'd would be in touch once they have got through some of there work load. They are reputable firm who have done many of the roofs in the terrace. Now I don't know if repair is possible due to it being unsupported through its 5m span. The purlin is just under 7x3 inches in size. Would it be easy enough to completely swap it for a new timber once the tiles are off etc? I personally cant see it being massively difficult? The rafters bird mouth over purlin. Also there is no obvious sag in the purlin at the moment. Thanks

 

[^woody^]

It's not as easy as you think, but is possible with a a lot of messing about. Its not normally a job for a roofer though.

It's much easier and cheaper to treat the rot and then reinforce the purlin. There is very rarely any advantage in replacing a purlin that can be repaired

 

[scruffybiker]

Thanks Woody, what would a repair be to this? The rot is about an inch deep and extends about 5/6 inches along the length of purlin and is situated about a metre away from the brick corbel. I was tempted to get a 2 metre length of say 7x2" timber and coach bolt & spur connector them together? One end of the new timber would be resting on the brick corbel. Saves them having to charge me to do something similar? What do you reckon? Cheers

 

[catlad]

You could buy a length of angle iron 5x3" and when they strip the roof off you can get it in, you could also get it pre drilled with 10 mm holes.

 

[scruffybiker]

You could buy a length of angle iron 5x3" and when they strip the roof off you can get it in, you could also get it pre drilled with 10 mm holes.

Thanks. Sounds like a good plan. Just a few questions.

What kind of thickness should the angle iron be roughly? Also what sort of length. Should I go a metre or so past the rot? Thanks

 

[catlad]

I would say 10mm should be sufficient and I would get the biggest piece you can manage.

 

[^woody^]

Presumably the rot was caused by a leak which is now dealt with? Treat it with a copper based or other preservative 1m or so either way, then nail or coach bolt your timber or just some 6x1 to the side. Or a 1200 length of 15mm ply nailed and glued. both sides