Painting/treating roof trusses?

[Flyfisher]

Regarding what looks like ‘charring’, I found something similar on some rafters in an outbuilding when repairing the roof. It was fairly localised and I didn’t understand how that could have happened if there had been a fire. I mentioned it on here and someone suggested that it was common practice to use a blowtorch on timbers that had been affected by dry rot. This made sense as the charring was definitely localised in a number of places across the roof and there was certainly signs of rot. In fact, it was a much bigger job to restore the outbuilding roof than the house roof and I guess that was a reflection of the difference in build quality, which is not really surprising. This may not be relevant in this case but I thought I’d mention it.

 

[chippy1]

Regarding what looks like ‘charring’, I found something similar on some rafters in an outbuilding when repairing the roof. It was fairly localised and I didn’t understand how that could have happened if there had been a fire. I mentioned it on here and someone suggested that it was common practice to use a blowtorch on timbers that had been affected by dry rot. This made sense as the charring was definitely localised in a number of places across the roof and there was certainly signs of rot. In fact, it was a much bigger job to restore the outbuilding roof than the house roof and I guess that was a reflection of the difference in build quality, which is not really surprising. This may not be relevant in this case but I thought I’d mention it.

Thanks Flyfisher...that would seem to make sense as its definitely localised to just one or two timbers...Can I ask, as the rest of the timbers/trusses are in good condition, it is possible to "sister" (slide in) a couple of new timbers next to it, so I can strengthen individual trusses? There is only a couple of trusses that are giving me concern so a full restoration isnt needed in this case...

The truss we are talking about seems to have been like this for a long time and is best described as "historical damage" but didnt want to just leave it, if there is an option to bolt/screw a couple of timbers full length either side of it to add extra support.

Is that possible and worth while doing?

Thank you again for all the replies

 

[Flyfisher]

As the roof has been in that state for a long time, 3 or 4 previous owners didn’t feel the need to do anything and no apparent deterioration is apparent then I’d guess that there is no great urgency to do anything. It would certainly be worth trying the ‘bradawl/screwdriver test’ mentioned by The Forge to better determine the condition and strength of the timber.

However, you’re clearly concerned about the state of these timbers so perhaps peace of mind is more important than structural necessity. It’s certainly possible to strengthen the roof, whether or not it’s worthwhile will depend on its condition and/or your peace of mind. A structural survey would give a definitive opinion on the condition but only you can decide what would give you peace of mind.

 

[Flyfisher]

Regarding the possible ‘charring’, here’s my topic about something similar that I mentioned above:

https://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=13303&p=181068

 

[MatthewC]

Can I ask, as the rest of the timbers/trusses are in good condition, it is possible to "sister" (slide in) a couple of new timbers next to it, so I can strengthen individual trusses? There is only a couple of trusses that are giving me concern so a full restoration isnt needed in this case...

The truss we are talking about seems to have been like this for a long time and is best described as "historical damage" but didnt want to just leave it, if there is an option to bolt/screw a couple of timbers full length either side of it to add extra support.

Is that possible and worth while doing?

On my 150 year old roof we sistered two rafters, and a bit later I did the same with quite a few joists which were undersize (2 x 2!!). I didn't think anything of it and didn't tell the CO. I suggest you do it if you are worried - the point is that you don't want to remove old timbers or hide the heritage design in any way. Hence if it's a new bit of C16 bolted alongside something old and worth keeping, I reckon that's OK.

However I'm sure Gareth will be along soon to tell me not to give such bad advice in future! 8)

 

[chippy1]

As the roof has been in that state for a long time, 3 or 4 previous owners didn’t feel the need to do anything and no apparent deterioration is apparent then I’d guess that there is no great urgency to do anything. It would certainly be worth trying the ‘bradawl/screwdriver test’ mentioned by The Forge to better determine the condition and strength of the timber.

However, you’re clearly concerned about the state of these timbers so perhaps peace of mind is more important than structural necessity. It’s certainly possible to strengthen the roof, whether or not it’s worthwhile will depend on its condition and/or your peace of mind. A structural survey would give a definitive opinion on the condition but only you can decide what would give you peace of mind.

Hi Flyfisher,

I have just been up in loft and did the screwdriver test as you and The Forge mentioned....the wood on the truss in question is hard and very dry but the outer skin(if thats the right wording) is cracking and "flaky"...Looking at all the timber, I dont see any wet/damp timber and there is good airflow. I've looked into adding (sistering) a few timbers to a couple of the trusses that need some TLC and the cost of a good Carpenter/joiner seems to be fair (£500?)....A structural survey is likely to cost around £700 and could come back as no major issues with the trusses. Atleast if I used that money to strengthen whats already there, the only downside is that its stronger than needed? If that makes sense....

The options....pay £700(roughly) to confirm the condition of those timbers and then pay to have the timbers strengthened, if needed.....OR....pay to add support to the timbers and I could end up with more than I needed but covered either way!

 

[chippy1]

Can I ask, as the rest of the timbers/trusses are in good condition, it is possible to "sister" (slide in) a couple of new timbers next to it, so I can strengthen individual trusses? There is only a couple of trusses that are giving me concern so a full restoration isnt needed in this case...

The truss we are talking about seems to have been like this for a long time and is best described as "historical damage" but didnt want to just leave it, if there is an option to bolt/screw a couple of timbers full length either side of it to add extra support.

Is that possible and worth while doing?

On my 150 year old roof we sistered two rafters, and a bit later I did the same with quite a few joists which were undersize (2 x 2!!). I didn't think anything of it and didn't tell the CO. I suggest you do it if you are worried - the point is that you don't want to remove old timbers or hide the heritage design in any way. Hence if it's a new bit of C16 bolted alongside something old and worth keeping, I reckon that's OK.

However I'm sure Gareth will be along soon to tell me not to give such bad advice in future! 8)

Hi MatthewC...thanks for your comments! I agree, I didnt want to remove any of the old, original trusses as they are full of history but felt if I added support by bolting some timber alongside the 2 or 3 that need alittle TLC...it might extend the life of those old beams.... I just didnt know if bolting C16 to the old trusses was the right way to go about it but it sounds like its worked well for you.

 

[a twig]

Can I ask, as the rest of the timbers/trusses are in good condition, it is possible to "sister" (slide in) a couple of new timbers next to it, so I can strengthen individual trusses? There is only a couple of trusses that are giving me concern so a full restoration isnt needed in this case...

The truss we are talking about seems to have been like this for a long time and is best described as "historical damage" but didnt want to just leave it, if there is an option to bolt/screw a couple of timbers full length either side of it to add extra support.

Is that possible and worth while doing?

Did exactly that here, had had DW beetle, all gone now, but some slightly friable timbers remained, ll. When I re-done the whole roof we sistered all of them with 2" X 6" alongside, mainly fixing to ridge and plate incase truss/rafter was worse than we thought. It was more as insurance, bit belt and braces, but was worth doing while we had the tiles and felt off

 

[chippy1]

Can I ask, as the rest of the timbers/trusses are in good condition, it is possible to "sister" (slide in) a couple of new timbers next to it, so I can strengthen individual trusses? There is only a couple of trusses that are giving me concern so a full restoration isnt needed in this case...

The truss we are talking about seems to have been like this for a long time and is best described as "historical damage" but didnt want to just leave it, if there is an option to bolt/screw a couple of timbers full length either side of it to add extra support.

Is that possible and worth while doing?

Did exactly that here, had had DW beetle, all gone now, but some slightly friable timbers remained, ll. When I re-done the whole roof we sistered all of them with 2" X 6" alongside, mainly fixing to ridge and plate incase truss/rafter was worse than we thought. It was more as insurance, bit belt and braces, but was worth doing while we had the tiles and felt off

Thanks Twig.....All my tiles and felt are in place but I have very high/steep roof/loft space , so just enough space to slide in some 2 x 6's.........I need a little piece of mind over it as every time I go up in loft the trusses seem to be staring me in the face! ha! (dont worry I not going mad!) It good to read a few people have added extra support and its worked well, even if it was just as extra insurance......thanks again

 

[88v8]

Sagging? No?
Not soft?
Then OK.
It has been damp in the past, hence the cuboid cracking as Theforge points out.

As a lesser intrusion than sistering, screw some metal strip under the offending beams. Then a future owner can take it off with no harm done. The metal strip, although it looks feeble, is amply strong in tension. Which is why it needs to go under the beam, so it is in tension.
https://www.wickes.co.uk/Wickes-Multi-Purpose-Builders-Fixing-Band---20mm-x-10m/p/246015

Easy DIY job. Screws 1.25" x 10 stainless, at 6" intervals. Stretch it tight by hand, as you go along.
No need to extend it the whole of the length. Just three feet either side of the split or either side of the centre.

Did this in our previous house where the softwood joists were 2x4" and a bit saggy. The builder was poor and used what he could afford, as he told us when he was in his 90th year.

Ivor