Repair cracking roof strut

revengep8nt14

Section62 said:

revengep8nt14 said:

So the extra rafters are not sistering or supporting the main rafters at all? I don't know who the builders were. Property is over 10 years old.

Did you get a survey done when you purchased?  Did they go in the loft?

My guess is someone messed up when specifying the trusses, and when they got to installation they found the roof didn't match up with the existing building next door, so had to do a bodge.  Or, much less likely, they had some trusses from another job and thought it was Ok to use them with some modification.

Hopefully they consulted a SE before going ahead, but I have some doubts as putting the additional rafters to the side of the trusses will generate eccentric loading, and the possiblity of introducing forces (including bending) the truss wasn't necessarily designed to take.  If these were firrings on top of the rafter that would be less of a concern.

My own view remains the same, before doing anything I'd want to have a SE take a look and comment on the arrangement and possible defects with the trusses.  This isn't to say the roof is necessarily in imminent danger of collapse, but a surveyor looking in your loft when you come to sell might flag these issues up and cause you problems.

I'd also comment that there appears to be a tapering gap between the end of the two rafters of the truss in your latest pictures.  This could be as it was made, but normally members in compression would be cut so the ends are bearing over their full surface area - i.e. cut 'square', or at the correct angle.  Tapering gaps between members which are supposed to be in contact over their full surface area could be a sign of movement, if not poor workmanship or damage in transit/installation.

Yes a survey was carried out and he did enter the loft. He didn't raise any concerns other than odd bits of mould which has been addressed.

Seems odd for a gap to form if the truss was manufactured specially. Makes me think it was assembled onsite. I will try and find a sticker, pretty sure I have found the firms name on some timber..

stuart45

They shouldn't be assembled on site. You need special machinery to press the connector plates in. They are engineered in the factory to take the specific loads that the structure will take. When cut roofs are used they use a lot more timber and this is done on site.

Section62

revengep8nt14 said:

Section62 said:

Yes a survey was carried out and he did enter the loft. He didn't raise any concerns other than odd bits of mould which has been addressed.

Seems odd for a gap to form if the truss was manufactured specially. Makes me think it was assembled onsite. I will try and find a sticker, pretty sure I have found the firms name on some timber..

As stuart45 says, this type of tooth plate connector is almost always done in a factory.  It is possible to hammer them in on site, but it usually shows and won't necessarily give the connection adequate strength.  I've designed and made trusses using nail plates, but I seriously doubt anyone would attempt to do that on site (on a commercial basis) using tooth plates.

The 'additional' rafters probably account for about a third of the timber you'd need for a cut roof, so it makes no sense to buy manufactured trusses to intentionally add these rafters.... you'd either buy the right trusses, or do the whole roof as a cut one.

Really surprised a surveyor would see that roof and not comment....