C16 Timber

[FRAN1870]

For my Loft conversion I need to strengthen the 3x2 rafters ( which are actually 2 1/4 thick ) ..... with 2inch C16 glued and screwed... the BC has agreed this is ok BUT the timber yard are telling that once they trim the 3 x 2 C16 down to 2 1/4 x 2 then its no longer c16 certified ?

I can't get hold of my BC officer because she's in a meeting all day and I need to order the wood so I can crack on over the weekend.

I can't use standard 2x2 ( normalised ) because its only actually 45mm square and will leave a 1/4 in gap either side of the celotex !!

thoughts ideas welcome please ..

TIA

 

[paulandfrodo]

My gut feeling, will prob. be the same as yours. Basically do what you had agreed with BC and ignore what the timber yard are saying. I would also say that any time your alter/change/trim a graded timber C16 or C24 you will alter it's strength, but if BC are happy, go for it.

 

[^woody^]

If you are strengthening existing rafters, then the C16 rating is irrelevent as the combined new rating will be for both rafters, and you can't prove its rating without calculating it.

 

[FRAN1870]

If you are strengthening existing rafters, then the C16 rating is irrelevent as the combined new rating will be for both rafters, and you can't prove its rating without calculating it.

I agree ... My SE says it's ok.

Will I experience any problems using sawn over normalised ? The rafters are sawn and all shapes anyway. Can't see the advantage of using CLS in an older house ?

 

[paulandfrodo]

You won't experience any issues. Depending on how you SE has suggested you fix the two together, screws/bolts ect you'll prob. notice the new timber splitting as it dries out. Don't worry about that.

 

[FRAN1870]

Glued and screwed

 

[paulandfrodo]

Prob. won't split if your gluing as well.