Rotted / Cracked purlin

houser · 2 Jun 2006

Hi,

One of the purlins in my roof is rooted and has caused the roof to sag, both at the level of the purlin and around the ridge in the area of the crack.

What is the best approch to replacing this? I have heard of an epoxy solution, or perhaps some form of steel plate to fix another length of timber onto the purlin to replace the weakened part? Would all this need to be done with the rafters etc stripped?

Also, what are my options for taking the sag out of the ridge, is this possible without a rebuild of the roof?

Thanks

Mike

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noseall · 2 Jun 2006

any of the major timber elements, in the photograph can be re- inforced using steel beams.

a large section steel could be fed through a smallish hole in the gable end, central to the ridge and above the ceiling line.

this can be supported on the external gable end wall and (structurally permitting) at the other end ( where the purlins in the picture will be built in).

from this steel beam supporting sprags could be fitted either diagonally to the purlins or vertically to the ridge.

unfortunately, i think time and gravity has shaped the timbers into a stubborn permanent state.
if you were to try and jack the roof , off the steel beam, back into shape, then you may do more harm than good.

splinter · 3 Jun 2006

houser,
Looking at the photos I cannot see anything drasticially wrong with you're roof ,no cracks rot in the purlin .I think all that is wrong with it is it's old therefore slightly tired and will still be standing in another hundred years

Mick Leek · 4 Jun 2006

I would be more worried with the size of the butterflys in your area

I would hate to see the size of pidgeons.

Nige F · 5 Jun 2006

I`m no chippy but isn`t that Oak beams with the nail rust marks

Make that 100 nearer 500

Static · 5 Jun 2006

To remove the sag in the roof you would be pretty much looking at re-roofing it. Check how plumb the walls are to the vertical, it may be the roof has kicked the walls out. As Nige F says the roof is old, so you need to determine if the sagging is recent or happened 100 years ago.
Also looks like you have sarking felt, which is a more modern idea. Has the roof been retiled?

houser · 5 Jun 2006

Thanks for all the responses. I have checked the walls for plumbness and the external walls look OK, there is no sign of the walls beings forced outwards as a result of the roof sagging. There is some movement on internals walls as a result of a supporting wall being removed and an inadequate beam being installed. Most of the movement, including any in the roof appears to be longstanding, but I intend to install extra support in both cases (just so any future purchasers surveyors wont raise any concerns)

I had a chap look at it today and suggested either steel plates to strenghthen the existing purlins, or installing new ones above the existing ones. I will put nosealls suggestions to him also.

Thanks

Mike

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Rotted / Cracked purlin

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