Modified Truss Advice

[relicmata]

Hello,

Looking at a house that appears to have modified/height extended trusses, by glueing another piece of full length timber on top. Survey suggests no other concerns about the roof, just that this has been done and it's not standard.

How concerned should I be about this? Or what steps do I need to take to make sure it's safe? Should there be a paper trail of engineering sign off / what can I do if there's not? Or is it probably fine?

Thanks!

 

[freddiemercurystwin]

They've presumably fitted those on top of the existing trusses during a re-roof with (presumably) heavier tiles than were on there before?

 

[relicmata]

Yeah combination of re-roof / new extension I think.

 

[evdamadiynot]

It doesn't look to be badly done.

The "non standard " language could strike up a potential if a mortgage lender kicks off about it.
If its not your lender then it could be a future buyers lender.
Finding someone other than the person who did it to sign it off as ok could possibly be difficult.

 

[noseall]

They've presumably fitted those on top of the existing trusses during a re-roof with (presumably) heavier tiles than were on there before?

Are you sure they are not (measure cock-up) add on strips? Are they the same size all the way down?

Roof truss manu's ALWAYS make their roofs under pitched, when having to guess or assume (pitch) when marrying into an existing roof. It means they can supply knock-on strips for any discrepancies. They never over-pitch for that reason.

 

[freddiemercurystwin]

Dunno, how would we know with the little info we have.

 

[relicmata]

Are you sure they are not (measure cock-up) add on strips? Are they the same size all the way down?

Roof truss manu's ALWAYS make their roofs under pitched, when having to guess or assume (pitch) when marrying into an existing roof. It means they can supply knock-on strips for any discrepancies. They never over-pitch for that reason.

Thanks that would be a good explanation here and makes sense. Do those strips have a formal name I could ask the manufacture about to see if they support/supply them?

 

[noseall]

Thanks that would be a good explanation here and makes sense. Do those strips have a formal name I could ask the manufacture about to see if they support/supply them?

Knock-on strips or furrings.

 

[^woody^]

The strips are clearly no altering the pitch.

Have the roof tiles been raised and counter-battened, or the roof boarded to accommodate a tile unsuitable for the pitch?

The only reason that comes to mind for those battens is to widen the 38mm truss section to support a wider timber to be fitted on top of it.

Either way it's been glued and screwed, and the fitting of those other noggins implies that the work has been done to a good standard and for a good reason by someone who's given it some thought

 

[stevie888]

I suspect the acid question is would the truss manufacturers condone it and I suspect the answer would be no.

What level of survey did you get? Your "surveyor" isn't being over helpful.

 

[^woody^]

I suspect the acid question is would the truss manufacturers condone it and I suspect the answer would be no.

Why would that not condone it? It's not doing anything structural to the truss to be of any concern.

 

[relicmata]

The strips are clearly no altering the pitch.

Have the roof tiles been raised and counter-battened, or the roof boarded to accommodate a tile unsuitable for the pitch?

The only reason that comes to mind for those battens is to widen the 38mm truss section to support a wider timber to be fitted on top of it.

Either way it's been glued and screwed, and the fitting of those other noggins implies that the work has been done to a good standard and for a good reason by someone who's given it some thought

Thanks, agree it all looks like decent work and survey said the same. This was just an extension, joining parallel to an existing gable end roof, can't really see signs of anything being raised or out of place.

It's 10+ years old so I think as long as it doesn't suggest a cowboy roofer did it then I'm not that worried, it's more just I'd like to know how difficult it might make selling in the future because it's likely not what the manufacture spec'd and could alter structural properties if it was done wrong. There is building control sign off on the extension as a whole, which is good but I guess i'd need some kind of structural engineer report to know for certain it's safe. The level 3 survey just said no concerns about this or the quality, but it's not standard.

 

[^woody^]

I don't know why you're worrying about it. I'd not even bother to note this in a report as it's not significant enough to even mention.