Loft trussed roof ideas
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Yea, let us know how that works out! 
No, you would not. And it's pointless you repeating yourself.
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You may want to apologise to @chickenlips ,he's onto something possibly good here. Details later.
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Dude, the only trolling here so far is from you it seems. I didn't expect much at all from manufacturer, not only because roof is ~27 year old but they also changed business in that time and are more of a specialised building merchant now. Still, sent them an email last night and got a very helpful reply first thing this morning, effectively saying: "Sure, call this guy in the afternoon on this number, he's one of the guys that designed your roof and he will be able to advise, hope this helps!".
Bonkers, but I will definitely call him and ask so yeah, it appears that @chickenlips was right and you were wrong. Whether he will help or not, is to be seen.
Bonkers, but I will definitely call him and ask so yeah, it appears that @chickenlips was right and you were wrong. Whether he will help or not, is to be seen.
Wasnt trying to troll, genuinely trying to help. I've been a Truss & Engineered joist designer for over 25 years, worked for a number of manufacturers, used Mitek, Wolf and Alpine software. Dealt with remedial details like this and far worse, not once have I sent it out to a SE. Ive always used the software or the Software providers (Mitek, Wolf etc). I would always advise going to the manufacturer 1st when it involves altering a roof truss.
Hope you get things sorted either way.
Hope you get things sorted either way.
I'm going with lower triangles sheathed out in half-inch ply, 5x2 timber sistered to the ridge, going as far down as practical, and some sort of timber ridge beam.
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So a quick update to say, I'm still "chatting" to SEs. It seems almost impossible to get someone to chat to, emailed quite few and only two responded, one was clearly an apprentice, didn't really know what I was talking about and tried to sell me telebeams. The other one after couple calls and three emails understood the whole idea so I'm hoping to continue to chat to him when he's back, he has all the details now.
The engineer that designed my trusses seems to be extremely busy or unavailable, called him twice this week and he wasn't at his desk and emailed him and the company and also not heard back.
The part good news is that I found TWO loft conversion companies that have done almost exactly what I suggested and chopped the webs in their conversions and replaced them with a steel beam sitting on the internal wall holding the rafters at the top, the only difference is they just used standard H beam and some rafter ties on both side of the beam(because they had approx half a meter taller trusses) and I want an L shaped beam for maximum space and therefore still need an SE to tell me if a 10mm thick beam with 100mm arms would suffice but looks like these webs can definitely be replaced with a ridge beam. The bad news is that both companies are effectively on the other side of the country.
The engineer that designed my trusses seems to be extremely busy or unavailable, called him twice this week and he wasn't at his desk and emailed him and the company and also not heard back.
The part good news is that I found TWO loft conversion companies that have done almost exactly what I suggested and chopped the webs in their conversions and replaced them with a steel beam sitting on the internal wall holding the rafters at the top, the only difference is they just used standard H beam and some rafter ties on both side of the beam(because they had approx half a meter taller trusses) and I want an L shaped beam for maximum space and therefore still need an SE to tell me if a 10mm thick beam with 100mm arms would suffice but looks like these webs can definitely be replaced with a ridge beam. The bad news is that both companies are effectively on the other side of the country.
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So, a final update to wrap up this truss discussion I originally started last year.
Over the past couple of months I’ve discussed my roof structure with several smart people, and one thing became clear: there’s surprisingly little clear information online about fink trusses. You mostly find either horror stories suggesting the entire house will collapse the moment you touch a truss, or people saying you shouldn’t even enter a loft with trusses at all. At the same time, there are people who go in with a hacksaw, don’t understand how trusses work, and then end up needing very expensive repairs, so both extremes exist.
My original idea was to remove the longer inner webs and replace them with a ridge beam or a triangular steel beam. While that can work structurally, I initially misunderstood why it works.
In a typical fink truss, the longer inner webs are generally not compression members(that's why they feel flimsy), they are usually in tension and are often referred to as hangers. Their primary role isn’t to stop the roof from collapsing, but to hang the bottom chord from the apex and to complete the triangulation that gives the truss its stiffness and strength.
If those inner webs were cut, the roof wouldn’t instantly collapse. Instead, the immediate effect would be a significant weakening of the loft floor / first-floor ceiling, because the bottom chord would lose its hanger support. The roof itself would only be at risk if the bottom chords began to buckle or spread. In my specific case, that risk is reduced because there are supporting walls directly beneath the web junctions, but the floor would still be substantially weaker, and the bottom chord would be under much higher tension, with increased outward thrust on the external walls.
This is where tie beams (telebeams) come into play in proper loft conversions. Their main role is to tie the external walls together and take over the tension role of the bottom chord, while also creating a much stronger floor structure. A ridge RSJ is primarily there to replace the shorter outer webs, which are under compression, not the inner tension webs.
So technically, it is possible to remove the longer inner webs and rely on stronger rafters and ridge support, but only after the bottom chord’s role has been replaced by proper wall-to-wall ties. Strengthening and tying the walls together is the first critical step, not the ridge beam.
Interestingly, the first structural engineer I spoke to (straight out of university) immediately insisted on telebeams. At the time, that didn’t make much sense to me because I wasn’t planning a full habitable loft conversion, just storage. He didn’t really explain the reasoning well, and I’m not even sure he fully articulated it himself, but in hindsight, he was absolutely right.
As for my loft today, I've finished plastering it and about to paint it today, trusses will stay as they are, don't have the budget for telebeams and if I had, may as well, replace the whole roof while there. As capable as I think I am when it comes to DIY, getting the telebeams or tying the walls together would be significantly more difficult than installing a ridge beam. I also got better at not hitting my head on the trusses so there is that!
Fully insulated and plastered loft made the whole house significantly warmer this season, even when we had -8.5C outside during recent cold spell, the lowest it dropped to was 12.4C. No issues with condensation, apart from two bottom Velux corners everything is bone dry. Normal loft temp is around 15C. Dew point is normally around 8-9C.
The whole space is much nicer and much more usable now, painting today, then lvt flooring and some trim and a walk in floor glass panel and that should be all done before spring.
For anyone wondering, this will be used for light storage only, basically clothes, shoes and some travel cases. Very happy with results so far, think overall costs approx £3k in materials. Many many hours spent on research, probably too many so really hope this might help someone in the future with similar questions!
Over the past couple of months I’ve discussed my roof structure with several smart people, and one thing became clear: there’s surprisingly little clear information online about fink trusses. You mostly find either horror stories suggesting the entire house will collapse the moment you touch a truss, or people saying you shouldn’t even enter a loft with trusses at all. At the same time, there are people who go in with a hacksaw, don’t understand how trusses work, and then end up needing very expensive repairs, so both extremes exist.
My original idea was to remove the longer inner webs and replace them with a ridge beam or a triangular steel beam. While that can work structurally, I initially misunderstood why it works.
In a typical fink truss, the longer inner webs are generally not compression members(that's why they feel flimsy), they are usually in tension and are often referred to as hangers. Their primary role isn’t to stop the roof from collapsing, but to hang the bottom chord from the apex and to complete the triangulation that gives the truss its stiffness and strength.
If those inner webs were cut, the roof wouldn’t instantly collapse. Instead, the immediate effect would be a significant weakening of the loft floor / first-floor ceiling, because the bottom chord would lose its hanger support. The roof itself would only be at risk if the bottom chords began to buckle or spread. In my specific case, that risk is reduced because there are supporting walls directly beneath the web junctions, but the floor would still be substantially weaker, and the bottom chord would be under much higher tension, with increased outward thrust on the external walls.
This is where tie beams (telebeams) come into play in proper loft conversions. Their main role is to tie the external walls together and take over the tension role of the bottom chord, while also creating a much stronger floor structure. A ridge RSJ is primarily there to replace the shorter outer webs, which are under compression, not the inner tension webs.
So technically, it is possible to remove the longer inner webs and rely on stronger rafters and ridge support, but only after the bottom chord’s role has been replaced by proper wall-to-wall ties. Strengthening and tying the walls together is the first critical step, not the ridge beam.
Interestingly, the first structural engineer I spoke to (straight out of university) immediately insisted on telebeams. At the time, that didn’t make much sense to me because I wasn’t planning a full habitable loft conversion, just storage. He didn’t really explain the reasoning well, and I’m not even sure he fully articulated it himself, but in hindsight, he was absolutely right.
As for my loft today, I've finished plastering it and about to paint it today, trusses will stay as they are, don't have the budget for telebeams and if I had, may as well, replace the whole roof while there. As capable as I think I am when it comes to DIY, getting the telebeams or tying the walls together would be significantly more difficult than installing a ridge beam. I also got better at not hitting my head on the trusses so there is that!
Fully insulated and plastered loft made the whole house significantly warmer this season, even when we had -8.5C outside during recent cold spell, the lowest it dropped to was 12.4C. No issues with condensation, apart from two bottom Velux corners everything is bone dry. Normal loft temp is around 15C. Dew point is normally around 8-9C.
The whole space is much nicer and much more usable now, painting today, then lvt flooring and some trim and a walk in floor glass panel and that should be all done before spring.
For anyone wondering, this will be used for light storage only, basically clothes, shoes and some travel cases. Very happy with results so far, think overall costs approx £3k in materials. Many many hours spent on research, probably too many so really hope this might help someone in the future with similar questions!
So the truss manufacturer couldn't pop it into his software and let you chop chunks out of their trusses then? OMG that's a surprise.
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I have no idea what you're referring to, that post was regarding @chickenlips saying to contact truss manufacturer and that they are often very helpful. He was right and they were
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Well, I never planned to "do it" technically, was more after a detailed explanation and just to see what's possible.
I did also discuss this purely theoretically with another SE as a potential "bodge/cheap" DIY approach. The idea was that, because in this house there are supporting stud walls directly underneath the truss web junctions, if I were to remove the longer inner webs, any additional chord support(basically sistered chords plate to plate) could be run inner wall to inner wall and properly tied into those walls as a new load path.
The external walls would still remain tied together as normal; the intention was simply that any extra tension introduced by removing the longer inner webs would be transferred into this new inner support and down through the internal walls, rather than being left in the original bottom chord.
Obviously this only applied to this specific house as I do have these walls but if I were to go that way I would need to thoroughly inspect these walls which would involve removing a lot of plasterboard just to make sure that they can take additional load and possibly even rebuilding them from scratch just to make sure they can. This would also technically strengthen the loft floor significantly and I could store anything in there, provided the inner walls could handle the weight so theoretically - although it would all have to be calculated/checked(to not be a bodge) and what not it would be possible to cut these inner longer webs out and just replace them with stronger chords
PS
This is a bit of simplification of this idea because we of course discussed strengthening the outer shorter webs, and doubling rafters at the same time(which I already did for Velux of course), but this wouldn't change how the roof would look, all plastered, etc, it would look exactly like it does now, minus inner longer webs so there is that!
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