Slipped purlin - Help please

[nopy99]

So,

Just bought a house - That was the easy bit.

The surveyer pointed out that one of the purlins had slipped slightly and that it was probably historic. He recommeded some suplemental additional supporting of the purlin corners using brackts.

Went up in the loft on the weekend to have a good look and it appears that the purlin has escaped its socket in the wall. The remaing 3 corners are also not brilliant and it looks like the original roofer cut the purlins too short.

Slipped socket

This has led to weight bearing on the cross braces and joists and it is bowing significantly.

Also it looks like the whole roof has spread by about an inch as the supporting timber on the opposite side has twisted by about 45 degrees. This shows the effect, the timber on the right is flat and sqare at 90 degrees on the rafters whereas the one on the right is at about 45 degres probably to the slipped purlin.

So - comments/suggestions/recommendations please.

Currently I have placed a couple of 2X3 timbers to provide additonal bracing to the slipped corner but this is temporary only.

Ideally I would like to jack the purlin back into its original place as the ridge tiles are not sitting flat. I realise this may not be possible though.

Also the purlin is split lengthways for about 1/3 of its length due to the weight bearing on to it.

Solutions i can think off are

1) Place additional cross bracing towards the apex on the roof - ala - loft room conversion. This will future proof the option of making a loft room in tthe future.

2) place 4 X hanger brackts at each purlin corner to prevent further slippage

3) Place vertical timbers supporting the purlins.

4) put head in the sand and leave as is.

 

[greenlane]

Would it be possible to put a new purlin to the side of the original one, jack up the original and bolt together. I realise there would be a problem getting the new purlin into the roof space, possibly the only way would be to knock a hole through and slide the new purlin in from the outside.
Other than that a metal plate either side of the purlin, bolted together and sat into the brickwork.

 

[stevebamford]

Get the surveyor to pay !

 

[schiz]

Some purlins rest on corbelling, so if you can manage to get it supported, you can always take a brick out below, put in a larger pad stone of the right size, then rest it on that. It may be easier than extending it.

Be careful how you jack/support it though. It's possible that you want to go right down
to the ground and not rely on even the first floor for support, meaning a long acro or two.

 

[noseall]

I am seeing a wall plate fitted ABOVE the joists. This is uncommon but not incorrect. There is little chance the wall plate has slipped. What i do see though is two separate (age wise) pieces of timber as though a section of wall plate has been replaced or added.

The purlin prop is inadequate and has warped. These should be fitted in opposing pairs with a collar brace across at purlin height, linking the two. Again this does not indicate purlin activity.

As for the purlin bearing point, i can not comment only that the purlin has natural shrinkage shakes and that there does not seem to be recent activity.

Does there appear to be any outward movement? Has the purlin dropped out of level? Has the uppermost masonry cracked?

 

[nopy99]

Would it be possible to put a new purlin to the side of the original one, jack up the original and bolt together. I realise there would be a problem getting the new purlin into the roof space, possibly the only way would be to knock a hole through and slide the new purlin in from the outside.
Other than that a metal plate either side of the purlin, bolted together and sat into the brickwork.

Its a terrace not a semi so cant slide a new one in form the side.

 

[nopy99]

Get the surveyor to pay !

Surveyor pointed out the slippage but said it was minor. He mentioned that it needed bracing but that the movement was historic.

I think he has covered his posterior in the report.... if you know what i mean

 

[nopy99]

I am seeing a wall plate fitted ABOVE the joists. This is uncommon but not incorrect. There is little chance the wall plate has slipped. What i do see though is two separate (age wise) pieces of timber as though a section of wall plate has been replaced or added.

The purlin prop is inadequate and has warped. These should be fitted in opposing pairs with a collar brace across at purlin height, linking the two. Again this does not indicate purlin activity.

As for the purlin bearing point, i can not comment only that the purlin has natural shrinkage shakes and that there does not seem to be recent activity.

Does there appear to be any outward movement? Has the purlin dropped out of level? Has the uppermost masonry cracked?

Thanks - I think it may have been due to timber shrinkage. Hadnt thought of that.

I dont think the roof has been touched since it was built in the 30's so dont see which timbers would have been replaced.

At this point im thinking worst case scenario is to take off portion of roof and put in a RSJ for support.

I think I need to leave this one for a reputable roofer to fix.

 

[noseall]

I think I need to leave this one for a reputable roofer to fix.

I don't see any distortion to the purlin itself. What needs fixing?